PASSIVATION LAYER, PREPARATION METHOD THEREFOR AND APPLICATION THEREOF

Abstract

Disclosed are a passivation layer (200), a preparation method therefor and an application thereof. The passivation layer (200) comprises a first passivation layer (210), the first passivation layer (210) being disposed adjacent to a secondary battery negative electrode plate (100) and having ionic conductivity and a thickness of 0.1-10 nm. The passivation layer (200) also comprises a second passivation layer (220), the second passivation layer (210) being disposed at a side surface of the first passivation layer (210) distant from the negative electrode plate (100) of the secondary battery, comprising a corrosion-resistant material and having a thickness of 0.1-5 nm. The passivation layer (200) has the effect of increasing safety performance and cycle performance of a secondary battery. The preparation method is simple and has high applicability. Furthermore, the obtained passivation layer (200) can be applied in multiple types of batteries and multiple fields.

Claims

1. A passivation layer, wherein the passivation layer comprises: a first passivation layer, wherein the first passivation layer is set on the surface of a negative electrode plate of secondary battery, having ionic conductivity and a thickness of 0.1-10 nm; and a second passivation layer, wherein the second passivation layer is set on the surface of the first passivation layer on one side away from the negative electrode plate of the secondary battery, wherein comprising a corrosion-resistant material, with a thickness of 0.1-5 nm.

2. The passivation layer according to claim 1, wherein the first passivation layer comprises at least one of a binary oxide and a ternary oxide.

3. The passivation layer according to claim 2, wherein the binary oxide has a general formula of AO.sub.m; in the AO.sub.m, A is selected from at least one of the group consisting of V, Mo, Nb, Sb, Ge, Sn, Cd, In, Co, 3ammy, Fe, Mn, Ni, W, Cu, Mg, Si and Cr; and 1?m?3.

4. The passivation layer according to claim 1, wherein the corrosion-resistant material is selected from at least one of the group consisting of Al.sub.2O.sub.3, HfO.sub.2, SiO.sub.2, ZrO.sub.2, MgO, Si.sub.3N.sub.4, AlN, CaF.sub.2, LiF, MgF.sub.2, LiCO.sub.3, Li.sub.3PO.sub.3 and LiPON.

5. A preparation method for the passivation layer according to claim 1, wherein the preparation method is: atomic layer deposition method, chemical vapor deposition method, physical vapor deposition method, or a combination thereof.

6. The preparation method according to claim 5, wherein the atomic layer deposition method comprises at least one of static atomic layer deposition method and dynamic atomic layer deposition method.

7. The preparation method according to claim 5, wherein the physical vapor deposition method is one of evaporation method, magnetron sputtering method and pulse laser deposition method.

8. A negative electrode, comprising the passivation layer according to claim 1, an active material, a binder, a conductive agent, and a current collector; preferably, the active material comprises at least one of graphite, graphene, carbon nanotubes, vapor grown carbon fibers, silicon carbon, silicon, lithium metal, sodium metal and transition metal oxides.

9. A secondary battery, comprising the negative electrode according to claim 8.

10. (canceled)

11. The passivation layer according to claim 2, the ternary oxide satisfies at least one of the general formulas shown as B.sub.2SnO.sub.4, C.sub.nSnO.sub.3, DSb.sub.2O.sub.6, XY.sub.2O.sub.4, Li.sub.4Ti.sub.5O.sub.12, MgTi.sub.2O.sub.5 and TiNb.sub.2O.sub.7; wherein: in the B.sub.2SnO.sub.4, B is selected from at least one of the group consisting of Mg, Mn, Co and Zn; in the C.sub.nSnO.sub.3, C is selected from at least one of the group consisting of Ca, Sr, Li, Mg and Co; and 1?n?2; in the DSb.sub.2O.sub.6, D is selected from at least one of the group consisting of Co, Ni, and Cu; in the XY.sub.2O.sub.4, X is selected from at least one of the group consisting of Mn, Fe, Co, Ni and Cu; Y is selected from at least one of the group consisting of Mn, Fe, Co, Ni and Cu; and the condition is that the X and the Y are different.

12. The preparation method according to claim 6, wherein the static atomic layer deposition comprises the following steps: A1. placing the negative electrode plate of the secondary battery in a chamber of an atomic layer deposition instrument, and first sequentially depositing an adsorption layer of a first precursor and an adsorption layer of a reactant on the surface of the negative electrode plate of the secondary battery, performing cyclic deposition based on the sequence to obtain a first passivation layer; the first precursor contains non-oxygen atoms in the first passivation layer; A2. sequentially depositing an adsorption layer of a second precursor and an adsorption layer of a reactant on the surface of the first passivation layer of the component obtained in step A1 on one side away from the negative electrode plate of the secondary battery, performing cyclic deposition based on the sequence to obtain a second passivation layer; the second precursor contains non-oxygen atoms in the corrosion-resistant material.

13. The preparation method according to claim 6, wherein the dynamic atomic layer deposition comprises the following steps: B1. placing the negative electrode plate of the secondary battery into the chamber of atomic layer deposition instrument under the protection of isolation gas, and then purging the chamber with flushing gas; B2. introducing the first precursor and the reactant into the deposition area of the chamber in step B1, starting the mechanical moving mechanism at the same time, enabling the negative electrode plate of the secondary battery to move through the deposition area, and depositing the first passivation layer on the surface of the negative electrode plate of the secondary battery; B3. in the operating state of the mechanical moving mechanism, introducing the second precursor and the reactant into the deposition region in step B2, and depositing the second passivation layer on the surface of the first passivation layer on one side away from the negative electrode plate of the secondary battery.

14. The preparation method according to claim 7, wherein the magnetron sputtering method comprises the following steps: C1. placing the negative electrode plate of the secondary battery into high vacuum magnetron sputtering system; C2. sputtering an intermediate layer target material by using a direct-current power supply, depositing on the surface of the negative electrode plate of the secondary battery to obtain an intermediate layer; C3. sputtering target material of the first passivation layer by using a radio frequency power supply, depositing the first passivation layer on the surface of the intermediate layer on one side away from the negative electrode plate of the secondary battery; C4. sputtering target material of the second passivation layer by using the radio frequency power supply, depositing the second passivation layer on the surface of the first passivation layer on one side away from the negative electrode plate of the secondary battery;

15. The preparation method according to claim 5, wherein the chemical vapor deposition method is one of atmospheric pressure chemical vapor deposition method, low pressure chemical vapor deposition method and plasma enhanced chemical vapor deposition method.

16. The preparation method according to claim 15, wherein the low pressure chemical vapor deposition method comprises the following steps: D1. placing the negative electrode plate of the secondary battery in the chamber of low pressure chemical vapor deposition system cleaned by flushing gas; D2. simultaneously introducing the first precursor and the reactant into the chamber in step D1 to deposit the first passivation layer on the surface of the negative electrode plate of the secondary battery; D3. simultaneously introducing the second precursor and the reactant into the chamber of step D2 to deposit the second passivation layer on the surface of the first passivation layer on one side away from the negative electrode plate of the secondary battery.

17. A negative electrode, comprising the passivation layer according to claim 4, an active material, a binder, a conductive agent, and a current collector; preferably, the active material comprises at least one of graphite, graphene, carbon nanotubes, vapor grown carbon fibers, silicon carbon, silicon, lithium metal, sodium metal and transition metal oxides.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0134] The following is a further explanation of the present disclosure in conjunction with the accompanying drawings and embodiments, wherein:

[0135] FIG. 1 is a schematic diagram of the secondary battery negative electrode plate loaded with the passivation layer obtained in Example 1 of present disclosure;

[0136] FIG. 2 is a cycle curve for the lithium batteries consisting of untreated commercial negative electrode plates, and negative electrode plates prepared in Example 1 and Comparative Examples 1-2 of present disclosure;

[0137] FIG. 3 is a cycle curve for the lithium batteries consisting of untreated commercial negative electrode plates, and negative electrode plates prepared in Examples 3-6 of present disclosure;

[0138] FIG. 4 is a specific capacity-voltage curve of the lithium batteries consisting of untreated commercial negative electrode plates, and negative electrode plates prepared in Example 1 and Comparative Example 1 of present disclosure at first cycle and the 100.sup.th cycle;

[0139] FIG. 5 is the cycle performance result for the lithium batteries consisting of untreated commercial negative electrode plates, and negative electrode plates prepared in Example 1 and Comparative Examples 1 of present disclosure;

[0140] FIG. 6 is a rate performance curve for the lithium batteries consisting of untreated commercial negative electrode plates and negative electrode plates prepared in Example 1 of present disclosure.

REFERENCE NUMERALS

[0141] 100: negative electrode plate, 110: current collector, 120: negative electrode coating layer; 200: passivation layer, 210: first passivation layer, 220: second passivation layer.

DETAILED DESCRIPTION

[0142] The concept of the present disclosure and the resulting technical effects will be clearly and completely described below in conjunction with examples, so that the aims, features, and effects of the present disclosure can be fully understood. It is clear that the described examples are merely some rather than all of examples of the present disclosure. All other examples obtained by those skilled in the art based on examples of the present disclosure without creative labor shall fall within the protection scope of the present disclosure.

[0143] In the description of the present disclosure, the description with reference to the terms one embodiment, some embodiments, exemplary embodiment, example, specific example, some examples etc. refers to the particular features, structures, materials or characteristics described in combination with the embodiment or example are included in at least one embodiment or example of the present disclosure. In this specification, the exemplary expression of above terms does not necessarily refer to the same embodiments or examples. Furthermore, the specific features, structures, materials, or characteristics described can be combined in any suitable manner in any one or more embodiments or examples.

[0144] Unless otherwise specified, the commercial graphite negative electrode plate 100 used in the embodiments of the present disclosure comprises a current collector 110 and a negative electrode coating 120 coated thereon, which is purchased from Canrd, the plate number is SM0201, the active material ratio is 95.7%, the material gram capacity: 330 mAh/g (0.005-2.0 V), the current collector has a thickness of 8 ?m, and the coating surface density is about 5.8 mg/cm.sup.2 (at different positions, the surface density after compaction may fluctuate within a certain range). The commercial graphite negative electrode plate does not be rolled. Specific examples of the present disclosure are described in detail below.

Example 1

[0145] This example prepares a Co.sub.xOAl.sub.2O.sub.3 double passivation layer (x=0.75-1), this passivation layer is deposited on a commercial graphite negative electrode plate, and the preparation method is atomic layer deposition method, which specifically comprises the following steps: [0146] A1. a commercial graphite negative electrode was placed into a chamber of an atomic layer deposition system, vacuumizing by using a mechanical pump to reduce the air pressure of the chamber to 0.01 Torr, then a small amount of nitrogen (100 sccm) was introduced to keep the fluidity of inert gas inside the chamber; [0147] A2. a first passivation layer 210 (the material was Co.sub.xO film) was deposited on the surface of the electrode plate by using the atomic layer deposition method; [0148] A2a. pulsing a precursor bis(2,2,6,6,-tetramethyl-3,5-heptanedioate) cobalt was pulsed into a reaction chamber at 150? C. The valve opening and closing time was 1 s, the reaction chamber pressure reached 15 Torr, the pressure maintaining time of the precursor was 5 s, the number was 1 time. A cobalt atomic layer was formed; [0149] A2b. 2000 sccm nitrogen was introduced to purge, time was 30 s; [0150] A2c. the reactant ozone (O.sub.3) was introduced into the reaction chamber. The pressure of the reaction chamber reached 5 Torr, time of maintaining was 15 s, the number was 5 times, and a second reactant adsorption layer was obtained; [0151] A2d. 2000 seem of nitrogen was introduced to purge, time was 60 s; [0152] A2e. steps A2a to A2d were cycled, the cycle number was 40 times, and a first passivation layer with a thickness of 1.6 nm was obtained; [0153] A3. the second passivation layer 220 (the material was Al.sub.2O.sub.3 film) was deposited on the surface of the first passivation layer Co.sub.xO using the atomic layer deposition method; [0154] A3a. a precursor trimethylaluminum was pulsed into the reaction chamber at 150? C. The valve opening and closing time was 0.5 s, the reaction chamber pressure reached 2 Torr, the pressure maintaining time of the precursor was 1.5 s, the number was 2 times, and an aluminum atomic layer was obtained; [0155] A3b. 2000 sccm N.sub.2 was introduced to purge, time was 30 s; [0156] A3c. O.sub.3 was introduced into the reaction chamber. The pressure of the reaction chamber reached 2 Torr, time of maintaining: 15 s, the number was 2 times, and a second reactant adsorption layer was obtained; [0157] A3d. 2000 sccm N.sub.2 was introduced to purge, time was 60 s; [0158] A3e. steps A3a-A3d were cycled, the cycle number was 5 times, and the negative electrode plate 100 loaded with the passivation layer 200 was obtained. The Al.sub.2O.sub.3 film had a thickness of 1.6 nm.

[0159] By controlling the number of the cycles in step A2e and step A3e, this example also obtained Co.sub.xOAl.sub.2O.sub.3 double passivation layers (x=0.75-1) with a thickness of 1 nm/0.1 nm, 10 nm/0.1 nm, 10 nm/5 nm and 5 nm/0.5 nm.

Example 2

[0160] This example prepares a Co.sub.xOZrO.sub.2 double passivation layer (the value range of x is the same as in Example 1), this passivation layer is deposited on a commercial graphite negative electrode plate, and the preparation method is atomic layer deposition, which specifically comprises the following steps: [0161] A1. a commercial graphite negative electrode plate was placed into a chamber of an atomic layer deposition system, vacuumizing by using a mechanical pump to reduce the air pressure of the chamber to 0.01 Torr, then a small amount of N.sub.2 (100 sccm) was introduced to keep the fluidity of inert gas inside the chamber; [0162] A2. a Co.sub.xO base layer film was plated on the surface of the electrode plate by atomic layer deposition method; [0163] A2a. a precursor bis(2,2,6,6,-tetramethyl-3,5-heptanedioate) cobalt was pulsed into the chamber of ALD at 150? C. The valve opening and closing time: 1 s, the ALD reaction chamber pressure reached 15 Torr, the pressure maintaining time of the precursor was 5 s, the number was 1 time, and a cobalt atomic layer was obtained; [0164] A2b. 2000 sccm N.sub.2 was introduced into the above chamber and time of purging was 30 s; [0165] A2c. the ozone (O.sub.3) was introduced into the reaction chamber. The pressure of the ALD reaction chamber reached 5 Torr, time of maintaining: 15 s, the number was 5 times, and a second reactant adsorption layer was obtained; [0166] A2d. 2000 sccm N.sub.2 was introduced into the reaction chamber and time of purging was 60 s; [0167] A2e. steps A2a to A2d were cycled, the cycle number was 40 times, and a first passivation layer was obtained; [0168] A3. a ZrO.sub.2 top layer film was deposited on the surface of the electrode plate by atomic layer deposition method; [0169] A3a. a precursor tetrakis(dimethylamino)zirconium was pulsed into the reaction chamber at 150? C. The valve opening and closing time: 0.5 s, the ALD reaction chamber pressure reached 2 Torr, the pressure maintaining time of the precursor was 1.5 s, the number was 2 times, and a zirconium atomic layer was obtained; [0170] A3b. 2000 sccm N.sub.2 was introduced into the above chamber and time of purging was 30 s; [0171] A3c. deionized water was introduced into the reaction chamber. The pressure of the ALD reaction chamber reached 15 Torr, time of maintaining: 20 s, the number was 5 times; [0172] A3d. 2000 sccm N.sub.2 was introduced and time of purging was 120 s; [0173] A3e. steps A3a to A3d were cycled, the cycle number was 5 times, and the negative electrode plate loaded with the passivation layer was obtained.

Example 3

[0174] This example prepares a Fe.sub.xOAl.sub.2O.sub.3 double passivation layer (x=0.67-1), this passivation layer is deposited on a commercial graphite negative electrode plate, and the preparation method is an atomic layer deposition method, which specifically comprises the following steps: [0175] A1. a commercial graphite negative electrode plate was placed into a chamber of an atomic layer deposition system, vacuumizing by using a mechanical pump to reduce the air pressure of the chamber to 0.01 Torr, then a small amount of N.sub.2 (100 sccm) was introduced to keep the fluidity of inert gas inside the chamber; [0176] A2. a Fe.sub.xO layer (first passivation layer) was deposited on the surface of the electrode plate by atomic layer deposition method; [0177] A2a. a precursor ferrocene was pulsed into the reaction chamber at 200? C. The valve opening and closing time: 1 s, the ALD reaction chamber pressure reached 15 Torr, the pressure maintaining time of the precursor was 10 s, the number was 1 time, and an iron atomic layer was obtained; [0178] A2b. 2000 sccm N.sub.2 was introduced into the above chamber to purge for 60 s; [0179] A2c. the reactant ozone (O.sub.3) was introduced into the reaction chamber. The pressure of the ALD reaction chamber reached 5 Torr, time of maintaining: 15 s, the number was 5 times, and a second reactant adsorption layer was obtained; [0180] A2d. 2000 sccm N.sub.2 was introduced into the above chamber to purge for 120 s; [0181] A2e. steps A2a-A2d were cycled, the cycle number was 30 times, and a first passivation layer was obtained; [0182] A3. an Al.sub.2O.sub.3 layer was deposited on the surface of the negative electrode plate by using atomic layer deposition method; [0183] A3a. a precursor trimethylaluminum was pulsed into the reaction chamber at 150? C. The valve opening and closing time: 0.5 s, the ALD reaction chamber pressure reached 2 Torr, the pressure maintaining time of the precursor was 1.5 s, the number was 2 times, and an aluminum atomic layer was obtained; [0184] A3b. 2000 sccm N.sub.2 was introduced into the above chamber to purge for 30 s; [0185] A3c. the reactant O.sub.3 was introduced into the reaction chamber. The pressure of the ALD reaction chamber reached 2 Torr, time of maintaining: 15 s, the number was 2 times, and a second reactant adsorption layer was obtained; [0186] A3d. 2000 sccm N.sub.2 was introduced into the above chamber to purge for 60 s; [0187] A3e. steps A3a to A3d were cycled, the cycle number was 5 times, and the negative electrode plate loaded with the passivation layer was obtained.

Example 4

[0188] This example prepares a CuOSiO.sub.2 double passivation layer, this passivation layer is deposited on a commercial graphite negative electrode plate, and the preparation method is low-pressure hot-wall chemical vapor deposition, which specifically comprises the following steps: [0189] D1. a commercial graphite negative electrode plate was placed into a chamber of a low-pressure hot-wall chemical vapor deposition system, vacuumizing by using a mechanical pump to reduce the air pressure of the chamber to 0.01 Torr, then N.sub.2 (2500 sccm) was introduced to clean the chamber for 15 min; [0190] D2. 500 sccm oxygen/ozone (O.sub.2/O.sub.3) mixed gas was introduced into the chamber of the hot-wall chemical vapor deposition system to reach the pressure of 1 Torr and maintain the pressure for 360 s. The ozone (O.sub.3) oxidized the surface of the negative electrode plate and sufficient oxygen-containing functional groups were generated on the surfaces of the active substance and the binder; [0191] D3. 50 sccm copper acetylacetonate and 100 sccm oxygen were introduced into the reaction chamber at 200? C. The carrier gas was 2500 sccm N.sub.2, the pressure in the reaction chamber was maintained at 0.04 Torr, the reaction time was 30 min, and a CuO film was deposited on the surface of the negative electrode plate; [0192] D4. 60 sccm monosilane and 1200 sccm nitrous oxide were introduced into the reaction chamber at 200? C. The plasma gas was generated by using 125W radio frequency power, the pressure in the reaction chamber was maintained at 0.3 Torr, reaction time was 5 s, and_a silicon dioxide layer was obtained. The negative electrode plate loaded with the passivation layer was obtained.

Example 5

[0193] This example prepares a Co.sub.2SnO.sub.4Al.sub.2O.sub.3 double passivation layer, this passivation layer is deposited on a commercial graphite negative electrode plate, and the preparation method is magnetron sputtering method, which specifically comprises the following steps: [0194] C 1. a commercial graphite negative electrode plate was placed into an O.sub.2 plasma processing system. 150 sccm O.sub.2 was introduced and O.sub.2 plasma was generated by using 150W of radio frequency power, to oxidize the surface of the negative electrode plate. Sufficient oxygen-containing functional groups were generated on the surfaces of the active substance and the binder; [0195] C2. the commercial graphite negative electrode plate was transferred into a magnetron sputtering system, and the air pressure of the chamber in system was reduced to 0.002 Torr by using a mechanical pump and a molecular pump; [0196] C3. 80 sccm Ar was introduced, and the pressure in the system chamber was raised to 0.01 Torr.

[0197] A pure titanium target material was sputtered by using a 150W direct current power supply. The substrate was applied at bias voltage of ?50V and, rotated at 30 rad/min, time of maintaining was 3 min, and a titanium layer was deposited on the surface of the negative electrode plate; [0198] C4. a pure Co.sub.2SnO.sub.4 target material was sputtered by using a 300W radio frequency power supply. The substrate was applied at bias voltage of ?50V and, rotated at 30 rad/min, maintaining time of sputtering was 30 min, and a first passivation layer with the material of Co.sub.2SnO.sub.4 was obtained; [0199] C5. a pure Al.sub.2O.sub.3 target material was sputtered by using a 300W radio frequency power supply, The substrate was applied at bias voltage of ?50V and, rotated at 30 rad/min, maintaining time of sputtering was 5 min, and a second passivation layer with the material of Al.sub.2O.sub.3 was obtained. The negative electrode plate loaded with the passivation layer was obtained.

Example 6

[0200] This example prepares a NiOAl.sub.2O.sub.3 double passivation layer, this passivation layer is deposited on a commercial graphite negative electrode plate, and the preparation method is an atomic layer deposition method, which specifically comprises the following steps: [0201] A1. a commercial graphite negative electrode plate was placed into a chamber of an atomic layer deposition system, vacuumizing by using a mechanical pump to reduce the air pressure of the chamber to 0.01 Torr, then a small amount of nitrogen (100 sccm) was introduced to keep the fluidity of inert gas inside the chamber; [0202] A2. a first passivation layer NiO film was deposited on the surface of the electrode plate by using the atomic layer deposition method; [0203] A2a. a precursor bis(cyclopentadiene) nickel was pulsed into the reaction chamber at 200? C. The valve opening and closing time was 1 s, the reaction chamber pressure reached 1 Torr, the pressure maintaining time of the precursor was 5 s, the number was 1 time, and a nickel atomic layer was obtained; [0204] A2b. 2000 sccm nitrogen was introduced for purging, time was 30 s; [0205] A2c. the reactant ozone (O.sub.3) was introduced into the reaction chamber. The pressure of the reaction chamber reached 5 Torr, time of maintaining was 15 s, the number was 3 times, and a second reactant adsorption layer was obtained; [0206] A2d. 2000 sccm nitrogen was introduced for purging, time was 120 s; [0207] A2e. steps A2a to A2d were cycled, the cycle number was 30 times, and a first passivation layer was obtained; [0208] A3. a second passivation layer Al.sub.2O.sub.3 film was deposited on the surface of the first passivation layer NiO by the atomic layer deposition method; [0209] A3a. a precursor trimethylaluminum was pulsed into the reaction chamber at 150? C. The valve opening and closing time was 0.5 s, the pressure in reaction chamber reached 1 Torr, the pressure maintaining time of the precursor was 1.5 s, the number was 2 times, and an aluminum atomic layer was obtained; [0210] A3b. 2000 sccm N.sub.2 was introduced for purging, time was 30 s; [0211] A3c. the reactant O.sub.3 was introduced into the reaction chamber. The pressure of the reaction chamber reached 5 Torr, time of maintaining: 15 s, the number was 2 times, and a second reactant adsorption layer was obtained; [0212] A3d. 2000 sccm N.sub.2 was introduced for purging for 60 s; [0213] A3e. steps A3a to A3d were cycled, the cycle number was 5 times, and the negative electrode plate loaded with the passivation layer was obtained.

Example 7

[0214] This example prepares a NiOLi.sub.3PO.sub.4 double passivation layer, this passivation layer is deposited on a commercial graphite negative electrode plate, and the preparation method is an atomic layer deposition method, which specifically comprises the following steps: [0215] A1. a commercial graphite negative electrode plate was placed into a chamber of an atomic layer deposition system, vacuumizing by using a mechanical pump to reduce the air pressure of the chamber to 0.01 Torr, then a small amount of nitrogen (100 sccm) was introduced to keep the fluidity of inert gas inside the chamber; [0216] A2. a first passivation layer NiO film was deposited on the surface of the electrode plate by using the atomic layer deposition method; [0217] A2a. a precursor bis(cyclopentadiene) nickel was pulsed into the reaction chamber at 200? C. The valve opening and closing time was 1 s, the reaction chamber pressure reached 1 Torr, the pressure maintaining time of the precursor was 5 s, the number was 1 time. A nickel atomic layer was obtained; [0218] A2b. 2000 sccm nitrogen was introduced to purge, time was 30 s; [0219] A2c. the reactant ozone (O.sub.3) was introduced into the reaction chamber. The pressure of the reaction chamber reached 5 Torr, time of maintaining was 15 s, the number was 3 times, and a second reactant adsorption layer was obtained; [0220] A2e. 2000 sccm nitrogen was introduced to purge, time was 120 s; [0221] A2f steps A2a to A2e were cycled, the cycle number was 30 times, and a first passivation layer was obtained; [0222] A3. a second passivation layer Li.sub.3PO.sub.4 film was deposited on the surface of the first passivation layer NiO by the atomic layer deposition method; [0223] A3a. a precursor tert-butyl lithium was pulsed into the reaction chamber at 200? C. The valve opening and closing time: 0.5 s, the reaction chamber pressure reached 0.7 Torr, the pressure maintaining time of the precursor was 20 s, the number was 1 time. A lithium atomic layer was obtained; [0224] A3b. 2000 sccm N.sub.2 was introduced to purge, time was 60 s; [0225] A3c. the reactant H.sub.2O was pulsed into the reaction chamber. The valve opening and closing time: 0.2 s, the ALD reaction chamber pressure reached 1 Torr, the pressure maintaining time of the H.sub.2O was 5 s, the number was 1 time, and a second reactant adsorption layer was obtained; [0226] A3d. 2000 sccm N.sub.2 was introduced to purge, time was 60 s; [0227] A3e. a reactant trimethylphosphate was pulsed into the reaction chamber. The valve opening and closing time: 0.5 s, the reaction chamber pressure reached 1 Torr, the pressure maintaining time of the trimethylphosphate was 5 s, the number was 1 time. A lithium atomic layer was obtained; [0228] A3f. 2000 sccm N.sub.2 was introduced to purge, time was 60 s; [0229] A3g. steps A3a to A3f were cycled, the cycle number was 8 times, and the negative electrode plate loaded with the passivation layer was obtained.

Example 8

[0230] This example prepares a Co.sub.xO/NiO nano-laminated-Al.sub.2O.sub.3 double passivation layer (the value range of x is the same as in Example 1), this passivation layer is deposited on a commercial graphite negative electrode plate, and the preparation method is atomic layer deposition, which specifically comprises the following steps: [0231] A1. a commercial graphite negative electrode plate was placed into a chamber of an atomic layer deposition system, vacuumizing by using a mechanical pump to reduce the air pressure of the chamber to 0.01 Torr, then a small amount of nitrogen (100 sccm) was introduced to keep the fluidity of inert gas inside the chamber; [0232] A2. a first oxide film (Co.sub.xO) was plated on the surface of the electrode plate by atomic layer deposition method; [0233] A2a. a precursor bis(2,2,6,6,-tetramethyl-3,5-heptanedioate) cobalt was pulsed into the reaction chamber at 200? C. The valve opening and closing time was 1 s, the reaction chamber pressure reached 1 Torr, the pressure maintaining time of the precursor was 5 s, the number was 1 time, and a cobalt atomic layer was obtained; [0234] A2b. 2000 sccm nitrogen was introduced to purge, time was 30 s; [0235] A2c. the reactant ozone (O.sub.3) was introduced into the reaction chamber. The pressure of the reaction chamber reached 5 Torr, time of maintaining was 15 s, the number was 5 times, and a second reactant adsorption layer was obtained; [0236] A2d. 2000 sccm nitrogen was introduced to purge, time was 60 s; [0237] A2e. steps A2a to A2d were cycled, the cycle number was 5 times, the Co.sub.xO layer was obtained; [0238] A3. a second oxide film (NiO) was plated on the surface of the electrode plate by the atomic layer deposition method; [0239] A3a. a precursor bis(cyclopentadiene) nickel was pulsed into the reaction chamber at 200? C. The valve opening and closing time was 1 s, the pressure of ALD reaction chamber reached 1 Torr, the pressure maintaining time of the precursor was 10 s, the number was 1 time, and a nickel atomic layer was obtained; [0240] A3b. 2000 sccm nitrogen was introduced to purge, time was 60 s; [0241] A3c. the reactant ozone (O.sub.3) was introduced into the reaction chamber. The pressure of the reaction chamber reached 5 Torr, time of maintaining was 15 s, the number was 5 times, and a second reactant adsorption layer was obtained; [0242] A3d. 2000 sccm nitrogen was introduced to purge, time was 120 s; [0243] A3e. steps A3a to A3d were cycled, the cycle number was 3 times, the NiO layer was obtained; [0244] A4. steps A3 to A4 were cycled, the number was 5 times, and a first passivation layer was obtained; [0245] A5. a second passivation layer Al.sub.2O.sub.3 film was deposited on the surface of the nano-laminated layer by the atomic layer deposition method; [0246] A5a. a precursor trimethylaluminum was pulsed into the reaction chamber at 150? C. The valve opening and closing time was 0.5 s, the pressure of reaction chamber reached 1 Torr, the pressure maintaining time of the precursor was 1 s, the number was 1 time, an aluminum atomic layer was obtained; [0247] A5b. 2000 sccm nitrogen was introduced to purge, time was 15 s; [0248] A5c. the reactant ozone (O.sub.3) was introduced into the reaction chamber. The pressure of the reaction chamber reached 5 Torr, time of maintaining was 15 s, the number was 2 times, a second reactant adsorption layer was obtained; [0249] A5d. 2000 sccm nitrogen was introduced to purge, time was 30 s; [0250] A5e. steps A5a to A5d were cycled, the cycle number was 10 times, the negative electrode plate loaded with the passivation layer was obtained.

Example 9

[0251] This example prepares a Co.sub.xOAl.sub.2O.sub.3 double passivation layer (x=0.75-1) (the value range of x is the same as in Example 1), this passivation layer is deposited on a commercial graphite negative electrode plate, and the preparation method is roll-to-roll atomic layer deposition method for preparing a large area, which specifically comprises the following steps: [0252] B 1. a negative electrode plate coil stock with a width of 1000 mm and a length of 1000 m was placed into a chamber of an atomic layer deposition system, vacuumizing the system to 0.05 Torr, and inert isolation gas with a flow rate of 400 SLM, cobalt source precursor gas used by Co.sub.xO passivation layer material with a flow rate of 200 SLM and 500 mg/L ozone gas used by the passivation layer material with a flow rate of 200 SLM were simultaneously introduced into the chamber for atomic layer deposition; [0253] B2. the moving mechanism was started to enable the electrode plate to be deposited to pass through the inner cavity deposition area of five cycles in two directions for four times at the speed of 50 m/min to obtain a Co.sub.xO layer (the first passivation layer); [0254] B3. when all the graphite negative electrode plates had moved forward, the cobalt source precursor carrier gas and ozone gas were turned off; [0255] B4. The inert isolation gas with a flow rate of 400 SLM, the trimethylaluminum precursor gas with a flow rate of 200 SLM, and the 500 mg/L ozone gas used in the passivation layer material with a flow rate of 200 SLM were simultaneously introduced into the atomic layer deposition chamber; [0256] B5. the moving mechanism was started to enable the electrode plate to be deposited to pass through the inner cavity deposition area of five cycles for one time at the speed of 40 m/min to obtain an Al.sub.2O.sub.3 layer (the second passivation layer); [0257] B6. when all the negative electrode plates had moved forward, the flushing gas, the trimethylaluminum carrier gas and the ozone gas were turned off. the heating was turned off, and the air was filled back; [0258] B7. the winding-up device was opened to move the negative electrode plate loaded with the passivation layer away.

Example 10

[0259] This example prepares a Co.sub.xSnO.sub.2+x/Al.sub.2O.sub.3 double passivation layer (0<x<2), this passivation layer is deposited on a commercial graphite negative electrode plate, and the preparation method is atomic layer deposition method, which specifically comprises the following steps: [0260] A1. a commercial graphite negative electrode plate was placed into a chamber of an atomic layer deposition system, vacuumizing by using a mechanical pump to reduce the air pressure of the chamber to 0.01 Torr, then a small amount of nitrogen (100 sccm) was introduced to keep the fluidity of inert gas inside the chamber; [0261] A2. a first passivation layer 210 (the material is Co.sub.xSnO.sub.2+x film) was deposited on the surface of the electrode plate by using the atomic layer deposition method; [0262] A2a. a precursor tetrakis(diethylamine) tin was pulsed into the reaction chamber at 150? C. The valve opening and closing time was 1 s, the pressure of the reaction chamber reached 15 Torr, the pressure maintaining time of the precursor was 5 s, the number was 1 time. A tin atomic layer was formed; [0263] A2b. 2000 sccm nitrogen was introduced to purge, time was 30 s; [0264] A2c. the reactant ozone (O.sub.3) was introduced into the reaction chamber, the pressure of the reaction chamber reached 5 Torr, and time of maintaining was 15 s; [0265] A2d. 2000 sccm nitrogen was introduced to purge, and time was 60 s; [0266] A2e. a precursor bis(2,2,6,6,-tetramethyl-3,5-heptanedioate) cobalt was pulsed into the reaction chamber at 150? C. The valve opening and closing time was 1 s, the pressure of the reaction chamber reached 15 Torr, the pressure maintaining time of the precursor was 5 s, the number was 1 time. A cobalt atomic layer was formed; [0267] A2f 2000 sccm nitrogen was introduced to purge, time was 30 s; [0268] A2g. the reactant ozone (O.sub.3) was introduced into the reaction chamber, the pressure of the reaction chamber reached 5 Torr, time of maintaining was 15 s, the number was 5 times. A second reactant adsorption layer was obtained; [0269] A2h. 2000 sccm nitrogen was introduced to purge, time was 60 s; [0270] A2e. steps A2a to A2h were cycled, the cycle number was 40 times. The first passivation layer with a thickness of 1.6 nm was obtained; [0271] A3. a second passivation layer 220 (the material is Al.sub.2O.sub.3 film) was deposited on the surface of the first passivation layer Co.sub.xSnO.sub.2+x by using the atomic layer deposition method; [0272] A3a. a precursor trimethylaluminum was pulsed into the reaction chamber at 150? C. The valve opening and closing time was 0.5 s, the pressure of reaction chamber reached 2 Torr, the pressure maintaining time of the precursor was 1.5 s, the number was 2 times, and an aluminum atomic layer was obtained; [0273] A3b. 2000 sccm N.sub.2 was introduced to purge, time was 30 s; [0274] A3c. the reactant O.sub.3 was introduced into the reaction chamber, the pressure of the reaction chamber reached 2 Torr, time of maintaining was 15 s, the number was 2 times, and a second reactant adsorption layer was obtained; [0275] A3d. 2000 sccm N.sub.2 was introduced to purge, time was 60 s; [0276] A3e. steps A3a to A3d were cycled, the cycle number was 5 times, the negative electrode plate 100 loaded with the passivation layer 200 was obtained. The obtained Al.sub.2O.sub.3 film had a thickness of 1.6 nm.

[0277] By controlling the cycle number of steps A2e and A3d, this example also obtained Co.sub.xSnO.sub.2+x/Al.sub.2O.sub.3 double passivation layers with thickness of 1 nm/0.1 nm, 10 nm/0.1 nm, 10 nm/5 nm and 5 nm/0.5 nm.

Example 11

[0278] This example prepares a Co.sub.x0/MgF.sub.2 double passivation layer (0.75<x<l), this passivation layer is deposited on a commercial graphite negative electrode plate, and the preparation method is atomic layer deposition, which specifically comprises the following steps: [0279] A1. a commercial graphite negative electrode plate was placed into a chamber of an atomic layer deposition system, vacuumizing by using a mechanical pump to reduce the air pressure of the chamber to 0.01 Torr, then a small amount of N.sub.2 (100 sccm) was introduced to keep the fluidity of inert gas inside the chamber; [0280] A2. a Co.sub.xO base layer film was plated on the surface of the electrode plate by atomic layer deposition method; [0281] A2a. a precursor bis(2,2,6,6,-tetramethyl-3,5-heptanedioate) cobalt was pulsed into the chamber of ALD at 150? C. The valve opening and closing time: 1 s, the pressure of ALD reaction chamber reached 15 Torr, the pressure maintaining time of the precursor was 5 s, the number was 1 time, a cobalt atomic layer was obtained; [0282] A2b. 2000 sccm N.sub.2 was introduced into the above chamber to purge, time was 30 s; [0283] A2c. the ozone (O.sub.3) was introduced into the reaction chamber, the pressure of the ALD reaction chamber reached 5 Torr, time of maintaining: 15 s, the number was 5 times, a second reactant adsorption layer was obtained; [0284] A2d. 2000 sccm N.sub.2 was introduced into the reaction chamber to purge, time was 60 s; [0285] A2e. steps A2a to A2d were cycled, the cycle number was 40 times, the first passivation layer was obtained; [0286] A3. an MgF.sub.2 film was deposited on the top of the surface of the electrode plate by the atomic layer deposition method; [0287] A3a. a precursor magnesium bis(2,2,6,6-tetramethyl-3,5-heptanedioate) was pulsed into the reaction chamber at 150? C. The valve opening and closing time: 0.5 s, the pressure of ALD reaction chamber reached 2 Torr, the pressure maintaining time of the precursor was 1.5 s, the number was 2 times, and a zirconium atomic layer was obtained; [0288] A3b. 2000 sccm N.sub.2 was introduced into the above chamber to purge, time was 30 s; [0289] A3c. titanium tetrafluoride was introduced into the reaction chamber, the pressure of the ALD reaction chamber reached 15 Torr, time of maintaining: 20 s, the number was 5 times; [0290] A3d. 2000 sccm N.sub.2 was introduced into the above chamber to purge, time was 120 s; [0291] A3e. steps A3a to A3d were cycled, the cycle number was 5 times, and the negative electrode plate loaded with the passivation layer was obtained.

Example 12

[0292] This example prepares an electrode protection layer made of Fe.sub.xO/Al.sub.2O.sub.3(x=0.67-1), and this electrode protection layer is attached to a commercial graphite negative electrode plate, and the preparation method is roll-to-roll atomic layer deposition method, which comprises the specific steps of: [0293] P1. a negative electrode plate coil stock with a width of 1000 mm and a length of 1000 m was placed into a chamber of an atomic layer deposition system, vacuumizing the system to 0.05 Torr, inert isolation gas with a flow rate of 400 SLM, mixed gas of ferrocene source precursor and nitrogen carrier gas used by a Fe.sub.xO (x=0.67-1) electrode protection layer with a flow rate of 200 SLM and 500 mg/L ozone gas used by an electrode protection layer material with a flow rate of 200 SLM were sequentially or simultaneously introduced into the atomic layer deposition chamber to obtain a Fe.sub.xO layer (the first passivation layer); [0294] P2. the moving mechanism was started to move the deposited electrode plate to a second chamber at a speed of 10 m/min. Inert isolation gas with a flow rate of 400 SLM, mixed gas of trimethyl aluminum source precursor and nitrogen carrier gas used by the Al.sub.2O.sub.3 electrode protection layer with a flow rate of 200 SLM and 500 mg/L ozone gas used by the electrode protection layer material with a flow rate of 200 SLM were sequentially or simultaneously introduced into the atomic layer deposition chamber to obtain an Al.sub.2O.sub.3 layer (the second passivation layer); [0295] P3. the moving mechanism was started to enable the electrode plate to be deposited to pass through the inner cavity deposition area of five cycles in two directions for four times at the speed of 10 m/min; [0296] P4. when all the negative electrode plates had moved forward, the flushing gas, cobalt source, aluminum source precursor carrier gas and ozone gas were turned off. The heating was turned off and the air was filled back. The winding-up device was opened to remove the graphite negative electrode plate after completing the deposition processing.

Comparative Example 1

[0297] This comparative example prepares a Co.sub.xO single passivation layer, the passivation layer is deposited on a commercial graphite negative electrode plate, and the difference between the preparation method and that of Example 1 is:

[0298] (1) step A4 was not included, that is, the Al.sub.2O.sub.3 layer did not be deposited.

Comparative Example 2

[0299] This comparative example prepares an Al.sub.2O.sub.3 single passivation layer, the passivation layer is deposited on a commercial graphite negative electrode plate, and the difference between the preparation method and that of Example 1 is:

[0300] (1) step A3 was not included, that is, the CoO layer did not be deposited.

Test Example

[0301] The schematic structural diagram of the negative electrode plate loaded with the passivation layer obtained in example is shown in FIG. 1. It can be seen from FIG. 1 that a double ALD passivation protective layer is formed on the surface of the negative electrode plate including current collector and active material layer, wherein the active material layer comprises graphite, a binder and a conductive agent. The negative electrode plate with the double passivation protective layer can further enhance the electrochemical performance of the lithium-ion battery.

[0302] This test example also tests the performance of the negative electrode plates loaded with the passivation layer obtained in examples and comparative examples, and the specific test method comprises the following steps:

[0303] (1) Assembling of a graphite electrode plate-lithium plate half-cell. A wave elastic sheet of the button-cell shell made of 316 stainless steel (Canrd, 15.4 mmx 1.0 mm), a gasket of the button-cell shell made of 316 stainless steel (Canrd, 15.5 mm?0.5 mm), a metal lithium plate, a separator (Celgard, a thickness of 25 m, made of polypropylene) and a graphite negative electrode (Canrd SM0201) that was or was not processed by the passivation layer were sequentially placed in the button-cell shell made of 316 stainless steel (Canrd). Wherein several drops of electrolyte (graphite button battery electrolyte, Canrd KLD-1230C) were dripped into the surface of the lithium plate and the separator before and after the separator was installed. Finally, the installed battery above was compacted by using a hydraulic tablet press to complete the assembly of the half-cell buckling.

[0304] (2) Cycle test of the half-cell cycle test. The half-cell was installed on a LANHE cell test system and placed in a test environment of 25(?1) ? C. for testing. In the first 2 cycles, the battery was activated by charge and discharge at a constant current of 0.1C. In subsequent cycles, charge and discharge was performed at a constant current of 0.2C. and if it was a rate test, the charge and discharge was performed in corresponding cycle intervals at a constant current of 0.1C, 0.2C, 0.5C, 1C, 2C and 5C, each rate was subjected to 6 charge and discharge cycles, and the specific discharge capacity at the corresponding rate was the average value of the obtained results of the 6 cycles. The voltage of electrochemical performance test was 0-2.0 V.

[0305] The discharge gram capacity results in the cycle process of the lithium-ion test batteries comprising the negative electrode plates obtained in Example 1 (the thickness of passivation layer is 1 nm/0.1 nm) and Comparative Examples 1 to 2 (the thickness of passivation layer is as that of the corresponding material layer of Example 1), and the negative electrode plate raw material used in Example 1 (without any treatment) are shown in FIG. 2. The cycle curves of the lithium batteries comprising untreated commercial negative electrode plate and the negative electrode plates (the thickness of passivation layer is 5 nm/0.5 nm) prepared in Examples 3-6 of the present disclosure are shown in FIG. 3. The specific capacity-voltage curves of the lithium batteries comprising the untreated commercial negative electrode plate, the negative electrode plate prepared in Example 1 (the thickness of passivation layer is 1.6 nm/1.6 nm) of the present disclosure, and the negative electrode plate prepared in Comparative Example 1 (the thickness of the passivation layer in the comparative example is the same as the that of the corresponding material of Example 1) at the first cycle and the 100.sup.th cycle of are shown in FIG. 4. the cycle performance results for lithium batteries comprising untreated commercial negative electrode plate and the negative electrode plates prepared in Example 1 of the present disclosure (the thickness passivation layer is 1.6 nm/1.6 nm) and Comparative Example 1 (the thickness of the passivation layer in the comparative example is the same as the that of the corresponding material of Example 1) are shown in FIG. 5. The rate performance curves of the lithium batteries comprising untreated commercial negative electrode plate and negative electrode plate prepared in Example 1 of the present disclosure (the thickness of passivation layer is 1.6 nm/1.6 nm) are shown in FIG. 6.

[0306] It can be seen from FIG. 2 that the specific capacity of the double-layered Co.sub.xOAl.sub.2O.sub.3-coated electrode plate in Example 1 shows the slowest decreasing trend after 100 charge-discharge cycles, followed by single-layered Co.sub.xO-coated electrode plate and single-layered Al.sub.2O.sub.3-coated electrode plate. In contrast, the specific capacity of the untreated commercial electrode plate begins to significantly decrease after 60 cycles, and decreases to less than 150 mAh/g after 100 charge-discharge cycles. It can draw preliminarily conclusion that coating of the single-layer atomic layer deposition film helps maintain the specific capacity of the negative electrode plate, and the use of double-layer structure can further optimize the cycle performance of lithium batteries, which can more stably maintain battery capacity after longer cycles.

[0307] The above results can be further reflected in the voltage-specific capacity diagram, that is, as shown in FIG. 4. The double-layer Co.sub.xOAl.sub.2O.sub.3-coated electrode plate has the closest specific capacity-voltage curve at the first and 100.sup.th cycles, indicating that it has the best stability in charge and discharge cycles, and followed by the single-layer Co.sub.xO-coated electrode plate. The capacity of the untreated electrode plate decreases most significantly.

[0308] FIG. 3 is the discharge gram capacity curve of the negative electrode plates obtained by multiple double passivation layer materials and multiple deposition methods in the cycle process. It can be seen that combining the double passivation layer materials provided by the present disclosure with the deposition method provided by the present disclosure can obtain a comparable effect: the specific capacity of the lithium-ion battery comprising the corresponding negative electrode has almost no decreasing trend after 100 charge-discharge cycles.

[0309] FIG. 5 is cycle performance result for Co.sub.xOAl.sub.2O.sub.3 double-layer coated electrode plate, single-layer Co.sub.xO-coated electrode plate, and untreated electrode plate. It can be seen that the electrode plate coated by the atomic layer deposition does not influence Coulombic efficiency, and the obtained result is close to that of the untreated electrode plate.

[0310] FIG. 6 is the rate test graph of Co.sub.xOAl.sub.2O.sub.3 double-layer coated electrode plate and untreated electrode plate. It can be seen that the electrode plate coated by atomic layer deposition can also improve the rate performance of the battery to a certain extent. The specific results are shown in Table 1:

TABLE-US-00001 TABLE 1 Rate test results of Co.sub.xOAl.sub.2O.sub.3 double-layer coated electrode plate and untreated electrode plate Capacity retention rate Current density Untreated electrode plate Co.sub.xOAl.sub.2O.sub.3-coated 0.1 C .sup.93% 99.9% 0.2 C 82.9% 94.7% 0.5 C .sup.57% .sup.77% 1 C 18.3% 25.2% 2 C 3.2% 4.8% 0.1 C 97.9% 99.9%

[0311] In Table 1, the capacity retention rate is a ratio to the first-cycle discharge rate of the battery.

[0312] The cycle performance of the lithium-ion battery is also improved to varying degrees by the battery assembling the passivation layer of the negative electrode plate formed by using other substances according to the present disclosure.

[0313] The electrochemical performance of the negative electrode plate obtained in Examples and Comparative Examples is also counted in this test example, and the results are shown in Table 2.

TABLE-US-00002 TABLE 2 (Cycle) Performance results of Examples and Comparative Examples First-cycle discharging specific Capacity retention rate % Thickness capacity 50 100 150 Material (nm) (mAh/g) cycles cycles cycles 373 97 63.5 44.7 Example 1 Co.sub.xO/Al.sub.2O.sub.3 1/0.1 369 98.7 98.6 97.8 Co.sub.xO/Al.sub.2O.sub.3 10/0.1 370 99 98.8 97.5 Co.sub.xO/Al.sub.2O.sub.3 10/5 366 98.8 98.7 97.4 Co.sub.xO/Al.sub.2O.sub.3 5/0.5 368 98.6 98.5 97.6 Example 10 Co.sub.xSnO.sub.2+x/Al.sub.2O.sub.3 1/0.1 369 99 98.6 98 Co.sub.xSnO.sub.2+x/Al.sub.2O.sub.3 10/0.1 372 99.2 98.7 97.3 Co.sub.xSnO.sub.2+x/Al.sub.2O.sub.3 10/5 368 98.8 98.6 97.6 Co.sub.xSnO.sub.2+x/Al.sub.2O.sub.3 5/0.5 364 98.6 98.5 97.7 Example 2 Co.sub.xO/ZrO.sub.2 5/0.5 369 99.1 98.6 98.2 Example 11 Co.sub.xO/MgF.sub.2 5/0.5 371 98.6 98.2 97.6 Example 3 Fe.sub.xO/Al.sub.2O.sub.3 5/0.5 372 99.1 98.3 97.5 Example 6 NiO/Al.sub.2O.sub.3 5/0.5 371 98.3 98.3 98 Example 7 NiO/Li.sub.3PO.sub.4 5/0.5 367 98.8 98.6 97.3 Example 8 Co.sub.xONiO/Al.sub.2O.sub.3 5/0.5 368 98.5 98.2 97.1 Example 9 Co.sub.xO/Al.sub.2O.sub.3 5/0.5 369 98.7 98.5 98 Example 12 Fe.sub.xO/Al.sub.2O.sub.3 5/0.5 365 99.1 98.6 96.9 Example 5 Co.sub.xSnO.sub.4/Al.sub.2O.sub.3 5/0.5 367 98.6 95.4 95.2 Example 4 CuO/SiO.sub.2 5/0.5 371 98.8 94.3 93.7

[0314] In Table 2, material refers to the material of the passivation layer, thickness refers to the thickness of the passivation layer, and - indicates unset or untested.

[0315] The results in Table 2 show that the passivation layer provided by the present disclosure can significantly improve the electrochemical performance of the negative electrode comprising the corresponding passivation layer. Specifically, after having the passivation layer, the capacity retention rate at 50 cycles?98.3%, the capacity retention rate at 100 cycles?94.3%, and the capacity retention rate in 100 cycles?93.7%. And considering that the test example uses button battery for testing, the cycle performance can not be fully exerted. Therefore, the cycle performance of the full cell is greatly superior to the test result in Table 1 when the passivation layer provided by the present disclosure is used for the negative electrode of the full cell.

[0316] The results in Table 2 further show that, in the thickness range provided by the present disclosure, the adjustment of the thickness of each sub-layer in the passivation layer has no significant effect on the performance of the obtained negative electrode. However, the cycle performance of the obtained battery may have a certain difference based on the material composition of the passivation layer.

[0317] The above provides a detailed explanation of the examples of the present disclosure in conjunction with specific embodiments. However, the present disclosure is not limited to the aforementioned embodiments. Within the scope of knowledge possessed by ordinary skilled in the art, various changes can be made without departing from the aim of the present disclosure. In addition, the embodiments of the present disclosure and features in those embodiments can be combined with each other without conflict.