CN-121983577-A - Gradient piezoelectric buffer layer, preparation method and solid-state battery

CN121983577ACN 121983577 ACN121983577 ACN 121983577ACN-121983577-A

Abstract

The invention relates to a gradient piezoelectric buffer layer, a preparation method and a solid-state battery, wherein the gradient piezoelectric buffer layer comprises a sodium bismuth titanate nanoparticle coating layer, a lithium phosphate conducting layer and a PVDF-ZnO composite electrolyte layer which are arranged in a stacked mode, and the preparation raw materials of the sodium bismuth titanate nanoparticle coating layer comprise a sodium source, a bismuth source, a titanium source, a mineralizer and a ternary anode material. According to the invention, by constructing a three-layer structure of the piezoelectric buffer layer, the ion conducting layer and the piezoelectric composite electrolyte, the volume change of the electrode is dynamically compensated by utilizing the inverse piezoelectric effect of the piezoelectric material, and the stress regulation and the ion transmission are synchronously realized. Compared with the traditional passive buffer strategy, the invention can reduce interface impedance and remarkably improve cycle stability, and provides technical support for industrialization of high-energy-density (more than or equal to 400 Wh/kg) solid-state batteries.

Inventors

XU KAIHUA
LIU HAI
WANG YANING
ZHANG KUN
WU YULOU
CHEN HUANHUI
ZHOU ZHICONG
Zhang Zhuolun
LIANG LI

Assignees

格林美股份有限公司
格林美(深圳)超级绿色技术研究中心有限公司

Dates

Publication Date: 20260505
Application Date: 20260226

Claims (10)

1. The gradient piezoelectric buffer layer is characterized by comprising a sodium bismuth titanate nanoparticle coating layer, a lithium phosphate ion conducting layer and a PVDF-ZnO composite electrolyte layer which are arranged in a laminated mode; the preparation raw materials of the bismuth sodium titanate nanoparticle coating layer comprise a sodium source, a bismuth source, a titanium source, a mineralizer and a ternary anode material.
2. The gradient piezoelectric buffer layer according to claim 1, wherein the thickness of the sodium bismuth titanate nanoparticle coating layer is 20 nm-60 nm; And/or the thickness of the lithium phosphate ion conducting layer is 20 nm-40 nm; and/or the thickness of the PVDF-ZnO composite electrolyte layer is 40 nm-60 nm.
3. The gradient piezoelectric buffer layer of claim 1 or 2 wherein the molar ratio of sodium in the sodium source, bismuth in the bismuth source, and titanium in the titanium source is 0.5:0.5:1; And/or the PVDF-ZnO composite electrolyte layer is prepared from PVDF, znO and LiTFSI.
4. The preparation method of the gradient piezoelectric buffer layer is characterized by comprising the following steps of: (1) The preparation method comprises the steps of dissolving a calculated amount of bismuth source and sodium source in a mixed solvent containing ethanol and acetic acid, sequentially and slowly adding a titanium source and a ternary positive electrode material under the action of strong stirring to obtain precursor slurry, slowly adding a mineralizer solution into the precursor slurry, carrying out hydrothermal reaction to uniformly nucleate the surface of the ternary positive electrode material to grow into nano particles, naturally cooling to room temperature after the reaction, and carrying out annealing treatment in a protective atmosphere after the product is sufficiently washed and dried to obtain a bismuth sodium titanate nano particle coating material, wherein the bismuth sodium titanate nano particle coating material is prepared into slurry, and is coated on the surface of an aluminum foil to obtain a bismuth sodium titanate nano particle coating layer; (2) The surface of the bismuth sodium titanate nanoparticle coating layer is subjected to magnetron sputtering to form a lithium phosphate ion conducting layer; (3) And a PVDF-ZnO composite electrolyte layer is arranged on the surface of the lithium phosphate ion conducting layer, so that the gradient piezoelectric buffer layer in any one of claims 1-3 is obtained.
5. The preparation method of claim 4, wherein the volume ratio of ethanol to acetic acid in the step (1) is 1 (1-3); and/or, the particle diameter D50 of the ternary positive electrode material in the step (1) is 3-8 mu m; And/or, in the precursor slurry in the step (1), the mass percentage of the ternary positive electrode material is 15-25 wt%.
6. The method according to claim 4 or 5, wherein the hydrothermal reaction in step (1) is carried out at a temperature of 140 ℃ to 180 ℃; and/or, the hydrothermal reaction time in the step (1) is 6-18 h; And/or, in the hydrothermal reaction in the step (1), stirring at 500-1000 rpm; and/or after the hydrothermal reaction in the step (1), washing the product to be neutral by using deionized water and ethanol alternately, and then drying the product for 12-18 hours at 60-80 ℃; And/or, the temperature of the annealing treatment in the step (1) is 500-650 ℃; and/or, the heat preservation time of the annealing treatment in the step (1) is 2-5 h.
7. The method according to any one of claims 4 to 6, wherein the substrate temperature during the magnetron sputtering in the step (2) is 90 ℃ to 110 ℃; and/or the deposition rate of the magnetron sputtering in the step (2) is 1 nm/min-1.5 nm/min.
8. The preparation method of the PVDF-ZnO composite electrolyte layer according to any one of claims 4 to 7, wherein the method for arranging the PVDF-ZnO composite electrolyte layer in the step (3) comprises the steps of dissolving PVDF, znO and LiTFSI in a solvent to form uniform slurry, casting the slurry into a film, and drying the film in vacuum to obtain the PVDF-ZnO composite electrolyte layer.
9. The method of claim 8, wherein the PVDF content of the homogeneous slurry is 10wt% to 15wt%; And/or the content of ZnO in the uniform slurry is 12-18 wt%; And/or the LiTFSI content in the uniform slurry is 5-10 wt%; And/or the solvent in the uniform slurry is DMF.
10. A solid-state battery, characterized in that the solid-state battery comprises the gradient piezoelectric buffer layer according to any one of claims 1 to 3, or comprises the gradient piezoelectric buffer layer prepared by the preparation method according to any one of claims 4 to 9.

Description

Gradient piezoelectric buffer layer, preparation method and solid-state battery Technical Field The invention belongs to the technical field of batteries, and relates to a solid-state battery, in particular to a gradient piezoelectric buffer layer, a preparation method and a solid-state battery. Background Lithium ion batteries are used as main stream energy storage technologies and are widely applied to the fields of consumer electronics, electric automobiles and energy storage, however, potential safety hazards such as electrolyte leakage and thermal runaway exist in the traditional liquid lithium batteries, the energy density is close to the theoretical limit, the solid-state batteries adopt nonflammable solid-state electrolytes, the theoretical energy density can reach more than 500Wh/kg, and the lithium ion batteries have the advantages of wide temperature range operation, ultra-long cycle life and the like and are recognized as the core direction of the next generation energy storage technology. The core bottleneck of the current solid-state battery industrialization is electrode-electrolyte interface failure, which is characterized in that firstly, volume mismatch stress is generated, the volume expansion rate of a high-nickel positive electrode in a 4.3V charging state is as high as 6% -8%, and the volume expansion rate of LLZO and other rigid solid-state electrolytes is less than 0.5%, so that interface microcracks are caused, secondly, interface impedance is increased rapidly, interface contact loss after charge and discharge cycles causes impedance to be increased to be more than 200Ω cm 2 from the initial 50Ω·cm 2, thirdly, lithium dendrite penetration risk is generated, and negative electrode side stress is concentrated to induce dendrite growth, so that the service life of the battery is shortened. The elastic adhesive adopted by CN119253079A can only passively buffer, can not dynamically respond to voltage change, can reduce ionic conductivity when the cut-in addition amount is more than 3%, can not solve the problem of stress accumulation though the wettability of an in-situ polymerization interface layer adopted by CN117525633A is improved, and can not inhibit interface delamination caused by cyclic stress accumulation although the transmission dynamics can be improved by adopting the ionic/electronic dual-phase filler in CN 116706064A. Therefore, the limitation of the prior art must be broken through, an innovative strategy capable of cooperatively solving the mechanical mismatch, the dynamic degradation of the interface and the dendrite inhibition is developed, the long-term stability of the mechanical-electrochemical performance is realized, and the commercialized application of the all-solid-state battery is promoted. Disclosure of Invention Aiming at the defects existing in the prior art, the invention aims to provide a gradient piezoelectric buffer layer, a preparation method and a solid-state battery, according to the invention, by constructing a three-layer structure of the piezoelectric buffer layer, the ion conducting layer and the piezoelectric composite electrolyte, the volume change of the electrode is dynamically compensated by utilizing the inverse piezoelectric effect of the piezoelectric material, and the stress regulation and the ion transmission are synchronously realized. Compared with the traditional passive buffer strategy, the invention can reduce interface impedance and remarkably improve cycle stability, and provides technical support for industrialization of high-energy-density (more than or equal to 400 Wh/kg) solid-state batteries. In order to achieve the aim of the invention, the invention adopts the following technical scheme: In a first aspect, the invention provides a gradient piezoelectric buffer layer, which comprises a sodium bismuth titanate nanoparticle coating layer, a lithium phosphate ion conducting layer and a PVDF-ZnO composite electrolyte layer which are arranged in a stacked manner; the preparation raw materials of the bismuth sodium titanate nanoparticle coating layer comprise a sodium source, a bismuth source, a titanium source, a mineralizer and a ternary anode material. According to the invention, by constructing a three-layer structure of the piezoelectric buffer layer, the ion conducting layer and the piezoelectric composite electrolyte, the volume change of the electrode is dynamically compensated by utilizing the inverse piezoelectric effect of the piezoelectric material, and the stress regulation and the ion transmission are synchronously realized. Compared with the traditional passive buffer strategy, the invention can reduce interface impedance and remarkably improve cycle stability, and provides technical support for industrialization of high-energy-density (more than or equal to 400 Wh/kg) solid-state batteries. In some embodiments of the present invention, the thickness of the bismuth sodium titanate nanoparticle coating layer is 20n