NEGATIVE ELECTRODE PLATE, LITHIUM METAL BATTERY CONTAINING SAME, AND ELECTRONIC DEVICE

Abstract

A negative electrode plate includes a negative current collector and a piezoelectric layer. A polarization electric field exists on the piezoelectric layer. A direction of the polarization electric field is directed from the negative current collector to a surface of a negative electrode. A material of the piezoelectric layer includes at least one of a piezoelectric polymer, piezoelectric ceramic, piezoelectric monocrystal, or an inorganic piezoelectric material. The negative electrode plate can control lithium deposition sites, effectively suppress the growth of lithium dendrites, and significantly improve the cycle performance and safety performance of the lithium metal battery.

Claims

1. A negative electrode plate, comprising: a negative current collector and a piezoelectric layer, wherein a polarization electric field exists on the piezoelectric layer, and a direction of the polarization electric field is directed from the negative current collector to a surface of a negative electrode, and a material of the piezoelectric layer comprises at least one of a piezoelectric polymer, piezoelectric ceramic, piezoelectric monocrystal, or an inorganic piezoelectric material.

2. The negative electrode plate according to claim 1, wherein a room-temperature coercive field strength Ec of the material of the piezoelectric layer satisfies: 0 kV/mm<Ec<100 kV/mm.

3. The negative electrode plate according to claim 2, wherein a strength of the polarization electric field is 0.1 to 6 times the room-temperature coercive field strength Ec.

4. The negative electrode plate according to claim 1, wherein the material of the piezoelectric layer comprises the piezoelectric polymer and the piezoelectric polymer comprises polyvinylidene difluoride, a vinylidene difluoride-trifluoroethylene copolymer, a vinylidene difluoride-tetrafluoroethylene copolymer, a vinylidene dicyanide-vinyl acetate copolymer, a vinylidene dicyanide-vinyl benzoate copolymer, a vinylidene dicyanide-vinyl propionate copolymer, a vinylidene dicyanide-vinyl pivalate copolymer, a vinylidene dicyanide-methyl methacrylate copolymer, a vinylidene dicyanide-isobutylene copolymer, or a nylon-odd number piezoelectric polymer —(HN—(CH.sub.2).sub.x—CO—).sub.n—, wherein x is an even number within 2 to 10, and n is a positive integer within 90 to 400; the piezoelectric ceramic comprises at least one of barium titanate, lead titanate, lithium niobate, lithium tantalate, lead zirconate titanate PbZr.sub.yTi.sub.1-yO.sub.3, lead magnesium niobate PbMg.sub.zNb.sub.1-zO.sub.3, lead zinc niobate PbZn.sub.vNb.sub.1-vO.sub.3, or lead manganese antimonate PbMn.sub.wSb.sub.1-wO.sub.3 or Pb.sub.1-sM.sub.m(Zr.sub.tTi.sub.1-t).sub.1-(s/4)O.sub.3, wherein 0<y<1, 0<z<1, 0<v<1, 0<w<1, 0<s<1, 0<m<1, 0<t<1, and M is any one of rare earth elements; the piezoelectric monocrystal comprises quartz monocrystal, tellurium oxide crystal, bismuth germanate monocrystal, lithium iodate monocrystal, aluminum orthophosphate monocrystal, lanthanum gallium silicate monocrystal, barium titanate monocrystal, or lead zirconate titanate monocrystal PbZr.sub.eTi.sub.1-eO.sub.3, wherein, 0<e<1; and the inorganic piezoelectric material comprises at least one of zinc oxide, bismuth oxide, cobalt oxide, lead oxide, nickel oxide, chromium oxide, antimony oxide, aluminum nitride, aluminum gallium nitride, indium aluminum nitride, gallium nitride, indium gallium nitride, indium nitride, silicon carbide, or a trititanium aluminum-based or titanium-aluminum-based intermetallic compound.

5. The negative electrode plate according to claim 1, wherein the piezoelectric layer comprises a powder piezoelectric layer, and a thickness of the powder piezoelectric layer is 0.1 μm to 5 μm.

6. The negative electrode plate according to claim 5, wherein the material of the piezoelectric layer comprises a powder piezoelectric layer and the powder piezoelectric layer is formed of a powder piezoelectric material and a conductive material, a mass percent of the powder piezoelectric material is 50% to 100%, and a mass percent of the conductive material is 0% to 50%.

7. The negative electrode plate according to claim 6, wherein the powder piezoelectric material comprises at least one of powder of the piezoelectric polymer, powder of the piezoelectric ceramic, or powder of the piezoelectric monocrystal; and the conductive material comprises at least one of conductive carbon powder or conductive metal powder.

8. The negative electrode plate according to claim 1, wherein the piezoelectric layer comprises a thin film piezoelectric layer, and a thickness of the thin film piezoelectric layer is 5 μm to 200 μm.

9. The negative electrode plate according to claim 8, wherein the thin film piezoelectric layer comprises a thin film piezoelectric material, and the thin film piezoelectric material comprises at least one of a piezoelectric polymer film, a piezoelectric ceramic film, a piezoelectric monocrystal film, or an inorganic piezoelectric material film.

10. The negative electrode plate according to claim 1, wherein the piezoelectric layer is located on a surface of the negative current collector; or located between the negative current collector and a negative material layer, or located on an outer surface of the negative material layer: or the piezoelectric layer is mixed with the negative material layer and located on the surface of the negative current collector.

11. A lithium metal battery, comprising: a negative electrode plate, the negative electrode plate comprises a negative current collector and a piezoelectric layer, wherein a polarization electric field exists on the piezoelectric layer, and a direction of the polarization electric field is directed from the negative current collector to a surface of a negative electrode, and a material of the piezoelectric layer comprises at least one of a piezoelectric polymer, piezoelectric ceramic, piezoelectric monocrystal, or an inorganic piezoelectric material

12. The lithium metal battery according to claim 11, wherein a room-temperature coercive field strength Ec of the material of the piezoelectric layer satisfies: 0 kV/mm<Ec<100 kV/mm.

13. The lithium metal battery according to claim 12, wherein a strength of the polarization electric field is 0.1 to 6 times the room-temperature coercive field strength Ec.

14. The lithium metal battery according to claim 11, wherein the piezoelectric layer comprises a powder piezoelectric layer, and a thickness of the powder piezoelectric layer is 0.1 μm to 5 μm.

15. The lithium metal battery according to claim 11, wherein the piezoelectric layer comprises a thin film piezoelectric layer, and a thickness of the thin film piezoelectric layer is 5 μm to 200 μm.

16. An electronic device, comprising the lithium metal battery according to claim 11.

Description

DETAILED DESCRIPTION

[0037] To make the objectives, technical solutions, and advantages of this application clearer, the following describes this application in more detail with reference to embodiments. Evidently, the described embodiments are merely a part of but not all of the embodiments of this application. All other embodiments derived by a person of ordinary skill in the art based on the embodiments of this application fall within the protection scope of this application.

EMBODIMENTS

[0038] The implementations of this application are described below in more detail with reference to embodiments and comparative embodiments. Various tests and evaluations are performed in accordance with the following methods.

[0039] Test Methods and Devices:

[0040] Testing a Deposition Overpotential:

[0041] Assembling a lithium metal battery in which the positive electrode is lithium metal with a piezoelectric layer or a current collector with a piezoelectric layer, the negative electrode is pure lithium metal, and the separator and the electrolytic solution are the same as those in a battery intended for cycling. Discharging the lithium metal battery at a constant current at a current density of 0.3 mA/cm.sup.2 under 25° C., and recording a curve of time-varying voltage, where an absolute value difference between a peak voltage and a steady voltage is a lithium metal deposition overpotential.

[0042] Testing Cycle Performance:

[0043] Performing chemical formation on a lithium metal battery for one cycle at a charge rate and a discharge rate of 0.1 C under a temperature of 25° C., and then charging the battery at a constant current of 0.3 C under a temperature of 25° C. until the voltage reaches 4.3 V, and charging the battery at a constant voltage until the current reaches 0.05 C. Leaving the battery to stand for 5 minutes, and then discharging the battery at a current of 1 C until the voltage reaches 2.8 V. Using the capacity obtained in this step as an initial capacity, performing a cycle test in which the battery is charged at 0.3 C and discharged at 1 C. comparing the capacity obtained in each step with the initial capacity to obtain ratios, and obtaining a capacity attenuation curve based on the ratios. When the capacity retention rate reaches 80% in the cycle test under 25° C., recording the number of cycles as the room-temperature cycle performance of the lithium metal battery.

Embodiment 1

[0044] <Preparing a Negative Electrode Plate>

[0045] Dispersing PVDF powder and acetylene black (AB) at a mass ratio of 95:5 in NMP, blending the mixture into a slurry with a solid content of 12%, mixing the PVDF and the AB evenly by stirring, coating a surface of a 10 μm-thick negative current collector copper foil with the slurry by using a doctor blade, and drying the negative current collector in a vacuum oven at 80° C. to obtain a negative electrode plate with a 3 μm-thick powder piezoelectric layer.

[0046] Placing the prepared negative electrode plate in a parallel electric field to undergo air polarization, where the strength of the polarization electric field is 10 kV/mm, the polarization time is 30 minutes, the piezoelectric layer faces a negative voltage side, and the negative current collector faces a positive voltage side. After completion of the polarization, cutting the negative electrode plate into a size of 40 mm×60 mm for future use. The room-temperature coercive field strength Ec of the PVDF is 50 kV/mm.

[0047] <Preparing a Positive Electrode Plate>

[0048] Mixing lithium iron phosphate (LiFePO.sub.4) as a positive active material, conductive carbon black (Super P) as a conductive agent, and PVDF as a binder at a mass ratio of 97.5:1.0:1.5, adding N-methyl-pyrrolidone (NIP) as a solvent, blending the mixture into a slurry with a solid content of 75%, and stirring the slurry evenly. Coating a 10 μm-thick positive current collector aluminum foil with the slurry evenly, and drying the slurry at a temperature of 90° C. to obtain a positive electrode plate coated with a positive active material layer on a single side, where the thickness of the positive active material layer is 100 μm. After completion of the coating, cutting the positive electrode plate into a size of 38 mm×58 mm for futureuse.

[0049] <Preparing an Electrolytic Solution>

[0050] Mixing dioxolane (DOL) and dimethyl ether (DME) at a volume ratio of DOL:DME=1:1 in a dry argon atmosphere to obtain a mixed solvent, adding lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) serving as a lithium salt into the mixed solvent, and letting the lithium salt be dissolved and mixed evenly to obtain an electrolytic solution in which a lithium salt concentration is 1 mol/L.

[0051] <Preparing a Lithium Metal Battery>

[0052] Using a 15 μm-thick polyethylene (PE) as a separator, placing the prepared negative electrode plate in the middle, placing one single-side-coated positive electrode plate as an upper layer and another as a lower layer, and placing a separator between each positive electrode plate and the negative electrode plate. After proper lamination, fixing four corners of the entire laminate structure by using adhesive tape, and then placing the laminate structure into an aluminum plastic film, and performing top-and-side sealing, electrolyte injection, and sealing to ultimately obtain a laminated lithium metal battery.

Embodiments 2-8

[0053] The steps of <Preparing a negative electrode plate>, <Preparing a positive electrode plate>, <Preparing an electrolytic solution>, and <Preparing a lithium metal battery> are the same as those described in Embodiment 1, and the changes in the relevant preparation parameters are shown in Table 1.

Embodiment 9

[0054] <Preparing a Negative Electrode Plate>

[0055] Putting 80 grams of PVDF powder into a round-bottom flask containing a mixed solvent of 180 mL of anhydrous ethanol and 120 mL of NMR and stirring at 70° C. for 2 hours. Then placing the mixed solvent into an ultrasonic cleaner, connecting a vacuum pump to the ultrasonic cleaner to ultrasonically pump air for 10 minutes, and thermally insulating the mixed solvent under 70° C. for 20 minutes to obtain a transparent and homogeneous solution. Leading the solution into a tape-casting machine equipped with polyester film tape, and preparing a PVDF film by tape-casting. Adjusting the width of a slit of the doctor blade, and stripping the prepared PVDF film of 10 μm in thickness from the polyester film tape.

[0056] Placing the PVDF film in a parallel electric field to undergo air polarization, where the strength of the polarization electric field is 10 kV/mm, the polarization time is 30 minutes, and the direction of the polarization electric field is constant. After completion of the air polarization, affixing an end that is of the polarized PVDF film and that interiorly carries a positive charge to the negative current collector copper foil side, so as to obtain a negative electrode plate with a 10 μm-thick thin film piezoelectric layer. Cutting the negative electrode plate into a size of 40 mm×60 mm for future use.

[0057] <Preparing a positive electrode plate>, <Preparing an electrolytic solution>, and <Preparing a lithium metal battery> are the same as those described in Embodiment 1.

Embodiments 10-15

[0058] The steps of <Preparing a negative electrode plate>, <Preparing a positive electrode plate>, <Preparing an electrolytic solution>, and <Preparing a lithium metal battery> are the same as those described in Embodiment 9, and the changes in the relevant preparation parameters are shown in Table 1.

Embodiment 16

[0059] <Preparing a Negative Electrode Plate>

[0060] Dispersing PVDF powder and acetylene black (AB) at a mass ratio of 95:5 in NMP, blending the mixture into a slurry with a solid content of 12%, mixing the PVDF and the AB evenly by stirring, coating the outer surface of the lithium metal of the negative material layer with the slurry by using a doctor blade, and drying the negative material layer in a vacuum oven at 80° C. for future use, so as to obtain a negative electrode plate with a 3 μm-thick powder piezoelectric layer.

[0061] Placing the negative electrode plate in a parallel electric field to undergo air polarization, where the strength of the polarization electric field is 50 kV/mm, the polarization time is 30 minutes, and the piezoelectric layer faces a negative voltage side. After completion of the polarization, cutting the negative electrode plate into a size of 40 mm×60 mm for future use.

[0062] <Preparing a positive electrode plate>, <Preparing an electrolytic solution>, and <Preparing a lithium metal battery> are the same as those described in Embodiment 1.

Embodiment 17

[0063] <Preparing a Negative Electrode Plate>

[0064] Dispersing PVDF powder and acetylene black (AB) at a mass ratio of 95:5 in NMR blending the mixture into a slurry with a solid content of 12%, mixing the PVDF and the AB evenly by stirring, coating the surface of the negative current collector copper foil with the slurry by using a doctor blade, and drying the negative current collector in a vacuum oven at 80° C. for future use, so as to obtain a modified current collector with a 3 μm-thick powder piezoelectric layer. Then, rolling the lithium metal of the negative material layer over the modified current collector under a pressure of 8 tons by using a roller press machine, so as to obtain a negative electrode plate.

[0065] Placing the negative electrode plate in a parallel electric field to undergo air polarization, where the strength of the polarization electric field is 50 kV/mm, the polarization time is 30 minutes, and the piezoelectric layer faces a negative voltage side. After completion of the polarization, cutting the negative electrode plate into a size of 40 mm×60 mm for future use.

[0066] <Preparing a positive electrode plate>, <Preparing an electrolytic solution>, and <Preparing a lithium metal battery> are the same as those described in Embodiment 1.

Embodiment 18

[0067] <Preparing a Negative Electrode Plate>

[0068] Dispersing PVDF powder and acetylene black (AB) at a mass ratio of 95:5 in NMR blending the mixture into a slurry with a solid content of 12%, mixing the PVDF and the AB evenly by stirring, coating the surface of the negative current collector copper foil with the slurry by using a doctor blade, and drying the negative current collector in a vacuum oven at 80° C. for future use, so as to obtain a modified current collector with a 3 μm-thick powder piezoelectric layer. Performing pre-replenishment of lithium electrochemically by using a 0.05 mm-thick lithium sheet as a lithium source. Selecting a 15 μm-thick PE separator, placing the modified current collector and the lithium metal on two sides of the separator respectively, with both the piezoelectric layer part and the lithium metal part facing the separator directly. In this way, a lithium replenishment battery is assembled for electrochemical replenishment of lithium, where the electrolytic solution is the same as the electrolytic solution described in <Preparing an electrolytic solution>, the lithium replenishment device is a LAND brand (model: CT2001A) of a 5 V and 5 mA specification, the lithium replenishment current is 0.2 mA/cm.sup.2, the discharge duration is 15.5 hours, and the amount of lithium replenishment is 3.1 mAh/cm.sup.2. After the pre-replenishment of lithium is completed, a negative electrode plate containing lithium metal is obtained.

[0069] Placing the negative electrode plate in a parallel electric field to undergo air polarization, where the strength of the polarization electric field is 50 kV/mm, the polarization time is 30 minutes, and the piezoelectric layer faces a negative voltage side. After completion of the polarization, cutting the negative electrode plate into a size of 40 mm×60 mm for future use.

[0070] <Preparing a positive electrode plate>, <Preparing an electrolytic solution>, and <Preparing a lithium metal battery> are the same as those described in Embodiment 1.

[0071] Relevant preparation parameters in Embodiments 16-18 are shown in Table 1.

Embodiment 19

[0072] <Preparing a Negative Electrode Plate>

[0073] Dispersing BaTiO.sub.3 piezoelectric ceramic powder and conductive carbon black (SP) at a mass ratio of 95:5 in NMP, blending the mixture into a slurry with a solid content of 12%, mixing the BaTiO.sub.3 and the SP evenly by stirring, coating the surface of the negative current collector copper foil with the slurry by using a doctor blade, and drying the negative current collector in a vacuum oven at 80° C. for future use, so as to obtain a negative electrode plate with a 3 μm-thick powder piezoelectric layer.

[0074] Placing the prepared negative electrode plate in a parallel electric field to undergo air polarization, where the strength of the polarization electric field is 0.1 kV/mm, the polarization time is 30 minutes, and the piezoelectric layer faces a negative voltage side. After completion of the polarization, cutting the negative electrode plate into a size of 40 mm×60 mm for future use.

[0075] <Preparing a positive electrode plate>, <Preparing an electrolytic solution>, and <Preparing a lithium metal battery> are the same as those described in Embodiment 1.

Embodiments 20-25

[0076] The steps of <Preparing a negative electrode plate>, <Preparing a positive electrode plate>, <Preparing an electrolytic solution>, and <Preparing a lithium metal battery> are the same as those described in Embodiment 19, and the changes in the relevant preparation parameters are shown in Table 1.

Embodiment 26

[0077] <Preparing a Negative Electrode Plate>

[0078] Placing PbO, ZrO.sub.2, and TiO.sub.2 at a molar ratio of 5:3:2 into a high-energy planetary ball mill, adding 100 ml of ethanol as a ball-milling agent, and ball-milling at a speed of 250 r/min for 30 hours to obtain lead zirconate titanate PbZr.sub.0.6Ti.sub.0.4O.sub.3 powder. Dispersing the PbZr.sub.0.6Ti.sub.0.4O.sub.3 powder in NMP, stirring the NMP to disperse the PbZr.sub.0.6Ti.sub.0.4O.sub.3 powder evenly to obtain a slurry with a solid content of 12%. Coating the surface of the negative current collector copper foil with the slurry by using a doctor blade, and drying the negative current collector in a vacuum oven at 80° C. for future use, so as to obtain a negative electrode plate with a 3 μm-thick powder piezoelectric layer.

[0079] Placing the prepared negative electrode plate in a parallel electric field to undergo air polarization, where the strength of the polarization electric field is 3 kV/mm, the polarization time is 30 minutes, and the piezoelectric layer faces a negative voltage side. After completion of the polarization, cutting the negative electrode plate into a size of 40 mm×60 mm for future use.

[0080] <Preparing a positive electrode plate>, <Preparing an electrolytic solution>, and <Preparing a lithium metal battery> are the same as those described in Embodiment 1.

Embodiment 27

[0081] <Preparing a Negative Electrode Plate>

[0082] Growing a BaTiO.sub.3 monocrystal sheet by means of a cosolvent: mixing the BaTiO.sub.3 powder, a cosolvent KF, and an oxygenating agent Fe.sub.2O.sub.3 evenly, putting the mixture into a platinum crucible, heating up to 1175° C. in a high-temperature furnace, thermally insulating for 8 hours, slowly cooling down to 875° C., and then pouring out the molten KF, cooling the KF down to a room temperature at a speed of 10° C. per hour, and melting the remaining KF in the crucible by using hot water, thereby obtaining a BaTiO.sub.3 monocrystal sheet.

[0083] Placing the BaTiO.sub.3 monocrystal sheet in a parallel electric field to undergo air polarization, where the strength of the polarization electric field is 0.1 kV/mm, the polarization time is 30 minutes, and the direction of the polarization electric field is parallel to a thickness direction of the monocrystal sheet and remains constant. After completion of the air polarization, affixing a positively charged end of the polarized BaTiO.sub.3 monocrystal sheet to the negative current collector copper foil side, so as to obtain a negative electrode plate with a 10 μm-thick thin film piezoelectric layer. Cutting the negative electrode plate into a size of 40 mm×60 mm for future use.

[0084] <Preparing a positive electrode plate>, <Preparing an electrolytic solution>, and <Preparing a lithium metal battery> are the same as those described in Embodiment 1.

Embodiments 28-33

[0085] The steps of <Preparing a negative electrode plate>, <Preparing a positive electrode plate>, <Preparing an electrolytic solution>, and <Preparing a lithium metal battery> are the same as those described in Embodiment 32, and the changes in the relevant preparation parameters are shown in Table 1.

Embodiment 34

[0086] <Preparing a Negative Electrode Plate>

[0087] Placing a nylon-7 film of 10 μm in thickness (brand: Formosa Chemicals & Fibre Corporation; model: NP4000) into a parallel electric field to undergo air polarization, where the strength of the polarization electric field is 280 kV/mm, the polarization time is 30 minutes, and the direction of the polarization electric field is parallel to a thickness direction of the film and remains constant. After completion of the air polarization, affixing a positively charged end of the polarized nylon-7 film to the negative current collector copper foil side, so as to obtain a negative electrode plate with a 10 μm-thick thin film piezoelectric layer. Cutting the negative electrode plate into a size of 40 mm×60 mm for future use.

[0088] <Preparing a positive electrode plate>, <Preparing an electrolytic solution>, and <Preparing a lithium metal battery> are the same as those described in Embodiment 1.

Embodiment 35

[0089] <Preparing a Negative Electrode Plate>

[0090] Place a 10 μm-thick tellurium oxide monocrystal sheet (brand: Physcience Opto-electronics Co., Ltd., Beijing: model: TEO2) into a parallel electric field to undergo air polarization, where the strength of the polarization electric field is 3 kV/mm, the polarization time is 30 minutes, and the direction of the polarization electric field is parallel to a thickness direction of the monocrystal sheet and remains constant. After completion of the air polarization, affixing a positively charged end of the polarized tellurium oxide monocrystal sheet to the negative current collector copper foil side, so as to obtain a negative electrode plate with a 10 μm-thick thin film piezoelectric layer. Cutting the negative electrode plate into a size of 40 mm×60 mm for future use.

[0091] <Preparing a positive electrode plate>, <Preparing an electrolytic solution>, and <Preparing a lithium metal battery> are the same as those described in Embodiment 1.

Comparative Embodiment 1

[0092] The negative electrode plate is a negative current collector copper foil. The steps of <Preparing a positive electrode plate>, <Preparing an electrolytic solution>, and <Preparing a lithium metal battery> are the same as those described in Embodiment 1.

Comparative Embodiments 2˜5

[0093] The steps of <Preparing a negative electrode plate>, <Preparing a positive electrode plate>, <Preparing an electrolytic solution>, and <Preparing a lithium metal battery> are the same as those described in Embodiment 1.

Comparative Embodiments 6˜7

[0094] The steps of <Preparing a negative electrode plate>, <Preparing a positive electrode plate>, <Preparing an electrolytic solution>, and <Preparing a lithium metal battery> are the same as those described in Embodiment 9.

Comparative Embodiments 8˜9

[0095] The steps of <Preparing a negative electrode plate>, <Preparing a positive electrode plate>, <Preparing an electrolytic solution>, and <Preparing a lithium metal battery> are the same as those described in Embodiment 19.

Comparative Embodiments 10˜11

[0096] The steps of <Preparing a negative electrode plate>, <Preparing a positive electrode plate>, <Preparing an electrolytic solution>, and <Preparing a lithium metal battery> are the same as those described in Embodiment 32.

Comparative Embodiment 12

[0097] The negative electrode plate is lithium metal. The steps of <Preparing a positive electrode plate>, <Preparing an electrolytic solution>, and <Preparing a lithium metal battery> are the same as those described in Embodiment 1.

[0098] The changes in the relevant preparation parameters in each of the foregoing comparative embodiments are shown in Table 1.

[0099] Table 1 shows performance parameters of a lithium metal battery assembled with the negative electrode plate prepared in each embodiment and comparative embodiment.

TABLE-US-00001 TABLE 1 Room- temperature Mass ratio of coercive field Strength of piezoelectric strength Ec polarization material to Piezoelectric of material electric field Conductive conductive material (kV/mm) (kV/mm) material material Embodiment 1 PVDF 50 10 AB 95:5 Embodiment 2 PVDF 50 50 AB 95:5 Embodiment 3 PVDF 50 100 AB 95:5 Embodiment 4 PVDF 50 200 AB 95:5 Embodiment 5 PVDF 50 50 AB 95:5 Embodiment 6 PVDF 50 50 AB 95:5 Embodiment 7 PVDF 50 50 AB 95:5 Embodiment 8 PVDF 50 50 AB  50:50 Embodiment 9 PVDF 50 10 / / Embodiment 10 PVDF 50 50 / / Embodiment 11 PVDF 50 100 / / Embodiment 12 PVDF 50 200 / / Embodiment 13 PVDF 50 50 / / Embodiment 14 PVDF 50 50 / / Embodiment 15 PVDF 50 50 / / Embodiment 16 PVDF 50 50 AB 95:5 Embodiment 17 PVDF 50 50 AB 95:5 Embodiment 18 PVDF 50 50 AB 95:5 Embodiment 19 BaTiO.sub.3 1 0.1 SP 95:5 Embodiment 20 BaTiO.sub.3 1 1 SP 95:5 Embodiment 21 BaTiO.sub.3 1 3 SP 95:5 Embodiment 22 BaTiO.sub.3 1 5 SP 95:5 Embodiment 23 BaTiO.sub.3 1 3 SP 95:5 Embodiment 24 BaTiO.sub.3 1 3 SP 95:5 Embodiment 25 BaTiO.sub.3 1 3 SP 95:5 Embodiment 26 Lead zirconate 0.7 3 SP 95:5 titanate PbZr.sub.0.6Ti.sub.0.4O.sub.3 Embodiment 27 BaTiO.sub.3 1 0.1 / / monocrystal sheet Embodiment 28 BaTiO.sub.3 1 1 / / monocrystal sheet Embodiment 29 BaTiO.sub.3 1 3 / / monocrystal sheet Embodiment 30 BaTiO.sub.3 1 5 / / monocrystal sheet Embodiment 31 BaTiO.sub.3 1 3 / / monocrystal sheet Embodiment 32 BaTiO.sub.3 1 3 / / monocrystal sheet Embodiment 33 BaTiO.sub.3 1 3 / / monocrystal sheet Embodiment 34 Nylon-7 97 280 / / Embodiment 35 Tellurium 1.2 3 / / oxide crystal Comparative / / / / / Embodiment 1 Comparative PVDF 50 0 AB 95:5 Embodiment 2 Comparative PVDF 50 −100 AB 95:5 Embodiment 3 Comparative PVDF 50 −10 AB 95:5 Embodiment 4 Comparative PVDF 50 −50 AB 95:5 Embodiment 5 Comparative PVDF 50 0 / / Embodiment 6 Comparative PVDF 50 −50 / / Embodiment 7 Comparative BaTiO.sub.3 1 0 SP 95:5 Embodiment 8 Comparative BaTiO.sub.3 1 −3 SP 95:5 Embodiment 9 Comparative BaTiO.sub.3 1 −3 / / Embodiment 10 monocrystal sheet Comparative BaTiO.sub.3 1 0 / / Embodiment 11 monocrystal sheet Comparative / / / / / Embodiment 12 Thickness of Deposition piezoelectric Type of Location of overpotential layer piezoelectric piezoelectric Quantity (0.3 mA/ (μm) layer layer of cycles cm.sup.2)/mV Embodiment 1 3 Powder Surface of negative 28 17 piezoelectric current collector layer Embodiment 2 3 Powder Surface of negative 46 8 piezoelectric current collector layer Embodiment 3 3 Powder Surface of negative 45 6 piezoelectric current collector layer Embodiment 4 3 Powder Surface of negative 45 7 piezoelectric current collector layer Embodiment 5 0.1 Powder Surface of negative 42 8 piezoelectric current collector layer Embodiment 6 1 Powder Surface of negative 45 10 piezoelectric current collector layer Embodiment 7 5 Powder Surface of negative 40 16 piezoelectric current collector layer Embodiment 8 3 Powder Surface of negative 30 12 piezoelectric current collector layer Embodiment 9 10 Thin film Surface of negative 30 18 piezoelectric current collector layer Embodiment 10 10 Thin film Surface of negative 40 10 piezoelectric current collector layer Embodiment 11 10 Thin film Surface of negative 42 9 piezoelectric current collector layer Embodiment 12 10 Thin film Surface of negative 38 12 piezoelectric current collector layer Embodiment 13 5 Thin film Surface of negative 39 8 piezoelectric current collector layer Embodiment 14 50 Thin film Surface of negative 36 16 piezoelectric current collector layer Embodiment 15 200 Thin film Surface of negative 31 18 piezoelectric current collector layer Embodiment 16 3 Powder Outer surface 117 / piezoelectric of negative layer material layer Embodiment 17 3 Powder between negative 126 / piezoelectric current collector layer and negative material layer Embodiment 18 3 Powder The piezoelectric 121 / piezoelectric layer is mixed layer with the negative material layer and located on the surface of the negative current collector Embodiment 19 3 Powder Surface of negative 32 16 piezoelectric current collector layer Embodiment 20 3 Powder Surface of negative 56 9 piezoelectric current collector layer Embodiment 21 3 Powder Surface of negative 62 6 piezoelectric current collector layer Embodiment 22 3 Powder Surface of negative 60 8 piezoelectric current collector layer Embodiment 23 0.1 Powder Surface of negative 58 9 piezoelectric current collector layer Embodiment 24 1 Powder Surface of negative 60 8 piezoelectric current collector layer Embodiment 25 5 Powder Surface of negative 53 15 piezoelectric current collector layer Embodiment 26 3 Powder Surface of negative 57 9 piezoelectric current collector layer Embodiment 27 10 Thin film Surface of negative 35 14 piezoelectric current collector layer Embodiment 28 10 Thin film Surface of negative 48 12 piezoelectric current collector layer Embodiment 29 10 Thin film Surface of negative 52 9 piezoelectric current collector layer Embodiment 30 10 Thin film Surface of negative 50 9 piezoelectric current collector layer Embodiment 31 5 Thin film Surface of negative 45 10 piezoelectric current collector layer Embodiment 32 50 Thin film Surface of negative 41 13 piezoelectric current collector layer Embodiment 33 200 Thin film Surface of negative 38 15 piezoelectric current collector layer Embodiment 34 10 Thin film Surface of negative 52 15 piezoelectric current collector layer Embodiment 35 10 Thin film Surface of negative 48 11 piezoelectric current collector layer Comparative / / / 16 17 Embodiment 1 Comparative 3 Powder Surface of negative 15 20 Embodiment 2 piezoelectric current collector layer Comparative 3 Powder Surface of negative 15 26 Embodiment 3 piezoelectric current collector layer Comparative 3 Powder Surface of negative 18 20 Embodiment 4 piezoelectric current collector layer Comparative 3 Powder Surface of negative 16 24 Embodiment 5 piezoelectric current collector layer Comparative 10 Thin film Surface of negative 16 27 Embodiment 6 piezoelectric current collector layer Comparative 10 Thin film Surface of negative 12 30 Embodiment 7 piezoelectric current collector layer Comparative 3 Powder Surface of negative 16 18 Embodiment 8 piezoelectric current collector layer Comparative 3 Powder Surface of negative 12 20 Embodiment 9 piezoelectric current collector layer Comparative 10 Thin film Surface of negative 12 26 Embodiment 10 piezoelectric current collector layer Comparative 10 Thin film Surface of negative 15 24 Embodiment 11 piezoelectric current collector layer Comparative / / / 86 / Embodiment 12 Note: “/” in Table 1 indicates that there is no corresponding preparation parameter.

[0100] As can be seen from Embodiments 1-4, 9-12, 19-22, and 27-30, when lithium metal batteries with the same type of piezoelectric layer are selected, the deposition overpotential and the cycle performance of the batteries vary with the strength of the polarization electric field. After the negative electrode plate is polarized by using the strength and direction of the polarization electric field within the range specified in this application, the deposition overpotential can be effectively reduced, and the cycle performance of the lithium metal battery can be enhanced.

[0101] Generally, the thickness of the piezoelectric layer also affects the deposition overpotential and cycle performance of the lithium metal battery. As can be seen from Embodiments 2, 5-7, 10, 13-15, 21, 23-25, 29, and 31-33, when the thickness of the piezoelectric layer falls within the range specified in this application, the lithium metal battery of a low deposition overpotential and excellent cycle performance can be obtained.

[0102] As can be seen from Embodiments 1-15, 19-25, 27-33 and Comparative Embodiment 1, the lithium metal battery containing the piezoelectric layer according to this application achieves cycle performance significantly higher than the cycle performance of a lithium metal battery containing no piezoelectric layer. As can be seen from Embodiments 16-18 and Comparative Embodiment 12, when the negative electrode plate further includes a negative material layer, the lithium metal battery containing the piezoelectric layer according to this application also achieves cycle performance significantly higher than the cycle performance of a lithium metal battery containing no piezoelectric layer. The piezoelectric layer disposed in the negative electrode plate and falling within the range specified in this application can significantly improve the cycle performance of the lithium metal battery.

[0103] Taking all the above analysis into account, the negative electrode plate according to this application includes a negative current collector and a piezoelectric layer in which a polarization electric field exists. A direction of the polarization electric field is directed from the negative current collector to a surface of a negative electrode. A material of the piezoelectric layer includes at least one of a piezoelectric polymer, piezoelectric ceramic, piezoelectric monocrystal, or an inorganic piezoelectric material. The negative electrode plate can control lithium deposition sites, effectively suppress the growth of lithium dendrites, and significantly improve the cycle performance and safety performance of the lithium metal battery.

[0104] The foregoing descriptions are merely preferred embodiments of this application, but are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application fall within the protection scope of this application.