CURRENT COLLECTOR WITH SOLID ELECTROLYTE INTERPHASE AND METHOD THEREOF

Abstract

The present disclosure discloses a current collector, and a surface of the current collector comprises a solid electrolyte interphase.

Claims

1. A current collector, wherein a surface of the current collector comprises a solid electrolyte interphase.

2. The current collector according to claim 1, wherein the solid electrolyte interphase defines a multilayer structure.

3. The current collector according to claim 1, wherein the solid electrolyte interphase defines an alternating inorganic-organic multilayer structure.

4. The current collector according to claim 1, wherein a material of the current collector is at least one of copper, an alloy of copper, nickel, an alloy of nickel, carbon, or silicon.

5. The current collector according to claim 1, wherein a configuration of the current collector comprises at least one of a flat foil, a three-dimensional mesh, a three-dimensional foam, a three-dimensional cylinder, or a nanostructure.

6. A method for preparing the current collector according to claim 1, comprising: introducing a sacrificial lithium layer on the current collector, stripping the sacrificial lithium layer on the current collector functioning as a working electrode in steps to obtain the solid electrolyte interphase.

7. A method comprise the following steps: applying the current collector with the solid electrolyte interphase according to claim 1 to function as a lithium-free anode in a lithium-ion battery, or applying the current collector with the solid electrolyte interphase prepared by an electrodeposition method or a molten lithium covering method in a lithium thin film anode of a secondary battery.

8. The method according to claim 7, wherein: the secondary battery comprises one of a lithium-ion battery, a lithium-sulfur battery, or a lithium-oxygen battery.

9. A method for preparing a current collector with a solid electrolyte interphase, comprising: 1) adding a current collector and a lithium metal foil respectively functioning as a working electrode and a counter electrode into an electrolytic cell, injecting an electrolyte into the electrolytic cell, applying a cathodic potential or a cathodic current to the working electrode to enable lithium to be electrodeposited on the working electrode to obtain a sacrificial lithium layer, or heating to enable metal lithium to be melted to obtain molten lithium metal, dipping the current collector into the molten lithium metal for a preset time, then taking the current collector out, and cooling to room temperature to obtain the sacrificial lithium layer, and 2) after step 1) is completed, applying an anodic potential or an anodic current to the working electrode to enable the sacrificial lithium layer disposed on the working electrode to be stripped in steps, and reducing the electrolyte in steps to obtain the solid electrolyte interphase.

10. The method for preparing the current collector with the solid electrolyte interphase according to claim 9, further comprising: 3) after step 2) is completed, applying an anodic potential or an anodic current to the working electrode to enable a residual sacrificial lithium layer disposed on the working electrode to be completely stripped to obtain the current collector with the solid electrolyte interphase.

11. The method for preparing the current collector with the solid electrolyte interphase according to claim 9, wherein the sacrificial lithium layer is lithium metal with a thickness of 5 μm-30 μm prepared by an electrodeposition method or a non-electrodeposition method.

12. The method for preparing the current collector with the solid electrolyte interphase according to claim 9, wherein in step 1), the cathodic potential is −0.2 V to −0.05 V, and the cathodic current is −2 mA/cm.sup.2 to −0.05 mA/cm.sup.2.

13. The method for preparing the current collector with the solid electrolyte interphase according to claim 9, wherein in step 2), the anodic potential is 0.2 V to 2.0 V, and the anodic current is 100 mA/cm.sup.2 to 300 mA/cm.sup.2.

14. The method for preparing the current collector with the solid electrolyte interphase according to claim 10, wherein in step 3), the anodic potential is 0.05 V to 1.2 V, and the anodic current is 0.01 mA/cm.sup.2 to 5 mA/cm.sup.2.

15. The method for preparing the current collector with the solid electrolyte interphase according to claim 10, wherein: a lithium salt used in the electrolyte in steps 1) to 3) is at least one of lithium imide, lithium perchlorate, lithium borate, or fluorine-containing lithium compound, a concentration of the lithium salt in a non-aqueous electrolyte is 0.3 M-4 M, and a non-aqueous solvent used in the electrolyte is at least one of carbonates or ethers.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] FIGS. 1a and 1b illustrate scanning electron micrographs (SEMs) of lithium deposition morphologies on a normal copper foam current collector and a copper foam current collector with a solid electrolyte interphase prepared by a sacrificial lithium thin layer according to Embodiment 7. FIG. 1a illustrates a lithium deposition morphology on the normal copper foam current collector, and FIG. 1b illustrates a lithium deposition morphology on the copper foam current collector with the solid electrolyte interphase prepared by the sacrificial lithium thin layer according to Embodiment 7.

[0030] FIGS. 2a and 2b illustrate performance diagrams of the normal copper foam current collector and a copper foam current collector with a solid electrolyte interphase prepared by a sacrificial lithium thin layer according to Embodiment 12 directly used as lithium-free electrodes. FIG. 2a illustrates a cycle Coulombic efficiency diagram at 4 mA/cm.sup.2 (1 mAh/cm.sup.2) of a copper-lithium battery comprising the normal copper foam current collector and a metal lithium electrode, and FIG. 2b illustrates a cycle Coulombic efficiency diagram at 4 mA/cm.sup.2 (1 mAh/cm.sup.2) of a copper-lithium battery comprising the copper foam current collector with the solid electrolyte interphase prepared by the sacrificial lithium thin layer according to Embodiment 11 and a metal lithium electrode.

[0031] FIGS. 3a and 3b illustrate performance diagrams of various lithium-ion batteries. FIG. 3a illustrates a performance diagram of a lithium-ion battery comprising a normal copper foil current collector and lithium iron phosphate, and FIG. 3b illustrates a performance diagram of a lithium-ion battery prepared according to Embodiment 25.

[0032] FIGS. 4a and 4b illustrate performance diagrams of various lithium-ion batteries. FIG. 4a illustrates a performance diagram of a lithium-ion battery comprising a lithium electrode and lithium iron phosphate, in which 5 mAh.Math.cm.sup.−2 of lithium was introduced on a normal copper foil current collector by electrodeposition to form the lithium electrode, and FIG. 4b illustrates is a performance diagram of a lithium-ion battery prepared according to Embodiment 26.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0033] The present disclosure will be further disclosed below in combination with the accompanying embodiments and drawings. The specific embodiments are as follows, but the scope of the present disclosure is not limited to the specific embodiments described below and covers any combinations of the specific embodiments.

Embodiment 1

[0034] A method for constructing a solid electrolyte interphase on a current collector using a sacrificial lithium thin layer (i.e., sacrificial lithium layer) is as follows:

[0035] 1) Introducing a sacrificial lithium thin layer: a current collector and a lithium metal foil (e.g., a lithium metal sheet) were added into an electrolytic cell and were functioning as a working electrode and a counter electrode, respectively. Electrolyte was injected into the electrolytic cell, and −0.2 V to −0.05 V of a cathodic potential or −2 mA/cm.sup.2 to −0.05 mA/cm.sup.2 of a cathodic current was applied to the working electrode to enable lithium to be electrodeposited on the working electrode to obtain the sacrificial lithium thin layer with a thickness of 5 μm-30 μm; or metal lithium was heated to be melted to obtain molten lithium metal, the current collector was dipped in the molten lithium metal for a certain period of time (i.e., a preset time), and then taken out to cool to room temperature (i.e., 20° C.-28° C.) to obtain the sacrificial lithium thin layer with the thickness of 5 μm-30 μm;

[0036] 2) Constructing the solid electrolyte interphase: after step 1) was completed, 0.2 V-2.0 V of an anodic potential or 100 mA/cm.sup.2-300 mA/cm.sup.2 of an anodic current was applied to the working electrode to enable the sacrificial lithium thin layer disposed on the working electrode to be stripped in steps. At the same time, the electrolyte was reduced in steps to obtain a lithium-rich, dense, compositionally adjustable solid electrolyte interphase having an alternating inorganic-organic multilayer structure; and

[0037] 3) Dissolving the sacrificial lithium thin film layer: after step 2) was completed, 0.05 V-1.2 V of an anodic potential or 0.01 mA/cm.sup.2-5 mA/cm.sup.2 of an anodic current was applied to the working electrode to enable the residual sacrificial lithium thin layer disposed on the working electrode to be completely stripped, and thus a current collector with a stable solid electrolyte interphase was obtained.

[0038] In some embodiments, a lithium salt used in the electrolyte in steps 1) to 3) was at least one of lithium imide, lithium perchlorate, lithium borate, or fluorine-containing lithium compound, a concentration of the lithium salt in a non-aqueous electrolyte was 0.3 M-4 M, and a non-aqueous solvent used in the electrolyte was at least one of carbonates or ethers.

Embodiment 2

[0039] This embodiment differs from Embodiment 1 in that in step 1), a copper mesh was used as the working electrode and the cathodic potential applied to the working electrode was −0.2 V to enable lithium to be electrodeposited on the working electrode to obtain the sacrificial lithium thin layer with a thickness of 5 μm. The rest of the process was the same as the process of Embodiment 1.

Embodiment 3

[0040] This embodiment differs from Embodiment 1 in that in step 1), a copper mesh was used as the working electrode and the cathodic potential applied to the working electrode was −0.05 V to enable lithium to be electrodeposited on the working electrode to obtain the sacrificial lithium thin layer with a thickness of 30 μm. The rest of the process was the same as the process of Embodiment 1.

Embodiment 4

[0041] This embodiment differs from Embodiment 1 in that in step 1), a copper foam was used as the working electrode and the cathodic potential applied to the working electrode was −0.1 V to enable lithium to be electrodeposited on the working electrode to obtain the sacrificial lithium thin layer with a thickness of 15 μm. The rest of the process was the same as the process of Embodiment 1.

Embodiment 5

[0042] This embodiment differs from Embodiment 1 in that in step 1), a copper mesh was used as the working electrode and the cathodic current applied to the working electrode was −2 mA/cm.sup.2 to enable lithium to be electrodeposited on the working electrode to obtain the sacrificial lithium thin layer with a thickness of 5 μm. The rest of the process was the same as the process of Embodiment 1.

Embodiment 6

[0043] This embodiment differs from Embodiment 1 in that in step 1), a copper foam was used as the working electrode, and the cathodic current applied to the working electrode was −0.05 mA/cm.sup.2 to enable lithium to be electrodeposited on the working electrode to obtain the sacrificial lithium thin layer with a thickness of 15 μm. The rest of the process was the same as the process of Embodiment 1.

Embodiment 7

[0044] This embodiment differs from Embodiment 1 in that in step 1), a copper foam was used as the working electrode and the cathodic current applied to the working electrode was −1 mA/cm.sup.2 to enable lithium to be electrodeposited on the working electrode to obtain the sacrificial lithium thin layer with a thickness of 30 μm. The rest of the process was the same as the process of Embodiment 1.

Embodiment 8

[0045] This embodiment differs from Embodiment 1 in that in step 1), a copper foil was used as the working electrode, the metal lithium was heated to be melted, and the copper foil was dipped for the certain period of time, and then taken out to cool to the room temperature to obtain the sacrificial lithium thin layer with a thickness of 25 μm. The rest of the process was the same as the process of Embodiment 1.

Embodiment 9

[0046] This embodiment differs from Embodiment 1 in that in step 2), a copper mesh was used as the working electrode and the anodic potential applied to the working electrode was 0.2 V to enable the sacrificial lithium thin layer disposed on the working electrode to be stripped. At the same time, the electrolyte was reduced. The rest of the process was the same as the process of one of Embodiments 1-8.

Embodiment 10

[0047] This embodiment differs from Embodiment 1 in that in step 2), a copper mesh was used as the working electrode and the anodic potential applied to the working electrode was 2.0 V to enable the sacrificial lithium thin layer disposed on the working electrode to be stripped in steps. At the same time, the electrolyte was reduced. The rest of the process was the same as the process of one of Embodiments 1-8.

Embodiment 11

[0048] This embodiment differs from Embodiment 1 in that in step 2), a copper mesh was used as the working electrode and the anodic potential applied to the working electrode was 1.0 V to enable the sacrificial lithium thin layer disposed on the working electrode to be stripped. At the same time, the electrolyte was reduced. The rest of the process was the same as the process of one of Embodiments 1-8.

Embodiment 12

[0049] This embodiment differs from Embodiment 1 in that in step 2), a copper foam was used as the working electrode. The anodic potential applied to the working electrode was first 1.6 V, then 0.6 V, then 1.0 V, and finally 0.6 V to enable the sacrificial lithium thin layer disposed on the working electrode to be stripped in steps. At the same time, the electrolyte was reduced in steps. The rest of the process was the same as the process of one of Embodiments 1-8.

Embodiment 13

[0050] This embodiment differs from Embodiment 1 in that in step 2), a copper mesh was used as the working electrode and the anodic current applied to the working electrode was 100 mA/cm.sup.2 to enable the sacrificial lithium thin layer disposed on the working electrode to be stripped. At the same time, the electrolyte was reduced. The rest of the process was the same as the process of one of Embodiments 1-8.

Embodiment 14

[0051] This embodiment differs from Embodiment 1 in that in step 2), a nanostructured copper was used as the working electrode and the anodic current applied to the working electrode was 300 mA/cm.sup.2 to enable the sacrificial lithium thin layer disposed on the working electrode to be stripped. At the same time, the electrolyte was reduced. The rest of the process was the same as the process of one of Embodiments 1-8.

Embodiment 15

[0052] This embodiment differs from Embodiment 1 in that in step 2), a copper foam was used as the working electrode. The anodic current applied to the working electrode was first 300 mA/cm.sup.2, then 100 mA/cm.sup.2, and finally 200 mA/cm.sup.2 to enable the sacrificial lithium thin layer disposed on the working electrode to be stripped in steps. At the same time, the electrolyte was reduced in steps. The rest of the process was the same as the process of one of Embodiments 1-8.

Embodiment 16

[0053] This embodiment differs from Embodiment 1 in that in step 3), a copper foam was used as the working electrode and the anodic potential applied to the working electrode was 0.05 V to enable the residual sacrificial lithium thin layer disposed on the working electrode to be completely stripped. The rest of the process was the same as the process of one of Embodiments 1-15.

Embodiment 17

[0054] This embodiment differs from Embodiment 1 in that in step 3), a copper foam was used as the working electrode and the anodic potential applied to the working electrode was 1.2 V to enable the residual sacrificial lithium thin layer disposed on the working electrode to be completely stripped. The rest of the process was the same as the process of one of Embodiments 1-15.

Embodiment 18

[0055] This embodiment differs from Embodiment 1 in that in step 3), a copper foam was used as the working electrode and the anodic potential applied to the working electrode was 0.5 V to enable the residual sacrificial lithium thin layer disposed on the working electrode to be completely stripped. The rest of the process was the same as the process of one of Embodiments 1-15.

Embodiment 19

[0056] This embodiment differs from Embodiment 1 in that in step 3), a copper mesh was used as the working electrode and the anodic current applied to the working electrode was 0.01 mA/cm.sup.2 to enable the residual sacrificial lithium thin layer disposed on the working electrode to be completely stripped. The rest of the process was the same as the process of one of Embodiments 1-15.

Embodiment 20

[0057] This embodiment differs from Embodiment 1 in that in step 3), a copper foam was used as the working electrode and the anodic current applied to the working electrode was 5 mA/cm.sup.2 to enable the residual the sacrificial lithium thin layer disposed on the working electrode to be completely stripped. The rest of the process was the same as the process of one of Embodiments 1-15.

Embodiment 21

[0058] This embodiment differs from Embodiment 1 in that in step 3), a copper foam was used as the working electrode and the anodic current applied to the working electrode was 1 mA/cm.sup.2 to enable the residual the sacrificial lithium thin layer disposed on the working electrode to be completely stripped. The rest of the process was the same as the process of one of Embodiments 1-15.

Embodiment 22

[0059] This embodiment differs from Embodiment 1 in that in step 1), a nickel foam was used as the working electrode and the cathodic potential applied to the working electrode was −0.1 V to enable lithium to be electrodeposited on the working electrode to obtain the sacrificial lithium thin layer with a thickness of 15 μm. In step 2), the anodic potential applied to the working electrode was 1.0 V to enable the sacrificial lithium thin layer disposed on the working electrode to be stripped. At the same time, the electrolyte was reduced. In step 3), the anodic current applied to the working electrode was 0.1 mA/cm.sup.2 to enable the residual sacrificial lithium thin layer disposed on the working electrode to be completely stripped. The rest of the process was the same as the process of Embodiment 1.

Embodiment 23

[0060] This embodiment differs from Embodiment 1 in that in step 1), a carbon paper was used as the working electrode and the cathode current applied to the working electrode was −0.05 mA/cm.sup.2 to enable lithium to be electrodeposited on the working electrode to obtain the sacrificial lithium thin film layer with a thickness of 25 μm. In step 2), the anodic potential applied to the working electrode was 1.0 V to enable the sacrificial lithium thin layer disposed on the working electrode to be stripped. At the same time, the electrolyte was reduced. In step 3), the anodic potential applied to the working electrode was 0.5 V to enable the residual sacrificial lithium thin layer disposed on the working electrode to be completely stripped. The rest of the process was the same as the process of Embodiment 1.

Embodiment 24

[0061] After the stable solid electrolyte interphase on the current collector was obtained using the sacrificial lithium thin layer according to one or any combinations of Embodiments 1-23 or other embodiments, the current collector and lithium metal define a copper-lithium battery. 1.0 M (mol/L) of LiTFSI/DME-DOL (1/1, volume to volume (V/V)) was used as the electrolyte, and Celgard 2400 was used as a separator.

Embodiment 25

[0062] After the stable solid electrolyte interphase on the current collector was obtained using the sacrificial lithium thin layer according to one or any combinations of Embodiments 1-23 or other embodiments, the current collector and lithium iron phosphate define a lithium-ion battery. 1.0 M of LiPF.sub.6/EC-DMC-EMC (1/1/1, V/V/V) was used as the electrolyte, and Celgard 2400 was used as a separator.

Embodiment 26

[0063] After the stable solid electrolyte interphase on the current collector was obtained using the sacrificial lithium thin layer according to one or any combinations of Embodiments 1-23 or other embodiments, 5 mAh.Math.cm.sup.−2 lithium was deposited on the current collector to obtain a lithium thin film electrode using electrodeposition. The current collector (i.e., the lithium thin film electrode) and lithium iron phosphate define a lithium-ion battery. 1.0 M of LiPF.sub.6/EC-DMC-EMC (1/1/1, V/V/V) was used as the electrolyte, and Celgard 2400 was used as a separator.

Embodiment 27

[0064] After the stable solid electrolyte interphase on the current collector was obtained using the sacrificial lithium thin layer according to one or any combinations of Embodiments 1-23 or other embodiments, 5 mAh.Math.cm.sup.−2 lithium was deposited on the current collector to obtain a lithium thin film electrode using electrodeposition. The current collector (i.e., the lithium thin film electrode) and a sulfur cathode define a lithium-sulfur battery. 1.0 M of LiTFSI+0.5 M LiNO.sub.3/DME-DOL (1/1, V/V) was used as the electrolyte, and Celgard 2400 was used as a separator.

Embodiment 28

[0065] After the stable solid electrolyte interphase of the current collector was obtained using the sacrificial lithium thin layer according to one or any combinations of Embodiments 1-23 or other embodiments, 5 mAh.Math.cm.sup.−2 lithium was introduced on the current collector to obtain a lithium thin film electrode (i.e., lithium thin film anode) by a molten lithium covering method, and the lithium thin film anode and a Super P positive electrode were then assembled to obtain a lithium-oxygen batter. 1.0 M of LiTFSI+0.5 M LiNO.sub.3/DME-DOL (1/1, V/V) containing saturated oxygen was used as the electrolyte, and Celgard 2400 was used as a separator.

[0066] Test result analysis of the abovementioned embodiment is as follows.

[0067] FIGS. 1a and 1b illustrate scanning electron micrographs (SEMs) of lithium deposition morphologies on a normal copper foam current collector and a copper foam current collector with a solid electrolyte interphase prepared by a sacrificial lithium thin layer according to Embodiment 7. FIG. 1a illustrates a lithium deposition morphology on the normal copper foam current collector, and FIG. 1b illustrates a lithium deposition morphology on the copper foam current collector with the solid electrolyte interphase prepared by the sacrificial lithium thin layer according to Embodiment 7. Referring to FIG. 1a, a lithium deposition on the normal copper foam current collector is very uneven, and deposited lithium metal blocks the pores of the normal copper foam current collector. Referring to FIG. 1b, the lithium deposition on the copper foam current collector with the solid electrolyte interphase prepared by the sacrificial lithium thin layer, the deposited lithium metal grows closely confined to the skeleton of the copper foam current collector, and pores of the copper foam current collector are not blocked. These results indicate that the stable solid electrolyte interphase ensures uniform deposition and growth of lithium and a high utilization of surface and electroactive spaces of the three-dimensional structure.

[0068] FIGS. 2a and 2b illustrate performance diagrams of the normal copper foam current collector and a copper foam current collector with a solid electrolyte interphase prepared by a sacrificial lithium thin layer according to Embodiment 12. The normal copper foam current collector and metal lithium or the copper foam current collector with the solid electrolyte interphase prepared by the sacrificial lithium thin layer and metal lithium define a copper-lithium battery, respectively, cycling at 4 mA/cm.sup.2 (1 mAh/cm.sup.2). FIG. 2a illustrates the normal copper foam current collector, and FIG. 2b illustrates the copper foam current collector with the solid electrolyte interphase prepared by the sacrificial lithium thin layer according to Embodiment 12. Referring to FIGS. 2a and 2b, the lithium metal on the normal copper foam collector can be only circulated for about 50 cycles, and a Coulombic efficiency is only 95%. The lithium metal on the copper foam current collector with the solid electrolyte interphase prepared by the sacrificial lithium thin layer according to Embodiment 12 can be stably circulated for at least 400 cycles, and a Coulombic efficiency is as high as 97.5%. Therefore, the three-dimensional current collector with the solid electrolyte interphase prepared by the sacrificial lithium thin layer shows a significantly improved Coulombic efficiency and significantly prolonged cycle stability.

[0069] FIGS. 3a and 3b illustrate performance diagrams of various lithium-ion batteries. FIG. 3a illustrates a performance diagram of a lithium-ion battery comprising a normal copper foil current collector and lithium iron phosphate, and FIG. 3b illustrates a performance diagram of a lithium-ion battery prepared according to Embodiment 25. Referring to FIGS. 3a and 3b, after the normal copper foil current collector and lithium iron phosphate define a lithium-ion battery, the lithium-ion battery can be only circulated for about 40 cycles, and a Coulombic efficiency is only 93.6%. However, the lithium-ion battery prepared according to Embodiment 25 can be stably circulated for at least 100 cycles, and a Coulombic efficiency is as high as about 100%. Therefore, the current collector with the stable solid electrolyte interphase can be directly used as an anode to improve a performance of lithium-ion batteries.

[0070] FIGS. 4a and 4b illustrate performance diagrams of various lithium-ion batteries. FIG. 4a illustrates a performance diagram of a lithium-ion battery comprising a lithium electrode and lithium iron phosphate, in which 5 mAh.Math.cm.sup.−2 of lithium is introduced on the normal copper foil current collector by electrodeposition to form the lithium electrode, and FIG. 4b illustrates a performance diagram of a lithium-ion battery prepared according to Embodiment 26. Referring to FIGS. 4a and 4b, after the lithium electrode prepared using the normal copper foil current collector and lithium iron phosphate define the lithium-ion battery, the lithium-ion battery can be only circulated for about 10 cycles, and a Coulombic efficiency is only about 90%. However, the lithium-ion battery prepared according to Embodiment 26 can be stably circulated for at least 100 cycles, and a Coulombic efficiency is as high as about 97%. Therefore, the metal lithium thin film anode prepared by the current collector with the stable solid electrolyte interphase can improve a performance of the lithium-ion battery.