CN-122026001-A - Lithium battery electrode-diaphragm complex based on micro-nano interlocking and in-situ chemical bonding and preparation method thereof

Abstract

The invention belongs to the technical field of batteries, provides a lithium battery electrode-diaphragm complex based on micro-nano interlocking and in-situ chemical bonding and a preparation method thereof, and solves the problems that in the existing lithium battery electrode plate-diaphragm thermal compounding technology, interface impedance is high, high-temperature stability is poor, and mechanical bonding strength and electrochemical performance cannot be cooperatively optimized due to dependence on a single physical bonding mechanism. The method comprises the steps of carrying out structural treatment on the surface of an electrode to obtain an electrode plate with a three-dimensional micro-nano structure, coating a precursor solution on the surface of a substrate diaphragm to obtain a coating diaphragm, and carrying out hot pressing after the three-dimensional micro-nano structure surface of the electrode plate with the three-dimensional micro-nano structure is attached to the coating surface of the coating diaphragm. The invention innovatively provides a new interface strengthening mechanism of double synergies of micro-nano scale mechanical interlocking and in-situ heat-induced chemical bonding, and a set of brand-new materials and process systems are designed according to the new mechanism.

Inventors

• ZHOU YONGBING
• DI YANPING
• JIANG ZHONGLEI
• XU SHENGWANG
• XIAO HAIYAN

Assignees

• 惠州赣锋锂电科技有限公司

Dates

Publication Date

20260512

Application Date

20260312

Claims (10)

1. 1. The preparation method of the lithium battery electrode-diaphragm complex based on micro-nano interlocking and in-situ chemical bonding is characterized by comprising the following steps: (1) Carrying out structural treatment on the surface of the electrode to obtain an electrode plate with a three-dimensional micro-nano structure; (2) Coating the precursor solution on the surface of a matrix diaphragm to obtain a coated diaphragm; (3) And (3) bonding the three-dimensional micro-nano structure surface of the three-dimensional micro-nano structure electrode plate and the coating surface of the coating diaphragm, and then performing hot pressing to obtain the lithium battery electrode-diaphragm complex based on micro-nano interlocking and in-situ chemical bonding.
2. 2. The preparation method of the lithium battery electrode-membrane composite based on micro-nano interlocking and in-situ chemical bonding, which is disclosed in claim 1, is characterized in that in the step (1), the three-dimensional micro-nano structure is one or more of pits, grooves, bulges and honeycomb networks, the relative height of the three-dimensional micro-nano structure and the electrode surface is 0.05-20 mu m, and the aspect ratio of the three-dimensional micro-nano structure is more than or equal to 1.
3. 3. The method for preparing a lithium battery electrode-separator composite based on micro-nano interlocking and in-situ chemical bonding according to claim 2, wherein the precursor solution in step (2) comprises a polymer matrix, a filler and a solvent; the polymer matrix is thermoplastic resin with active reactive groups; The reactive group comprises one or more of epoxy group, carboxyl group, hydroxyl group, amino group and isocyanate group; the glass transition temperature of the polymer matrix is 30-80 ℃.
4. 4. The method for preparing the lithium battery electrode-diaphragm composite based on micro-nano interlocking and in-situ chemical bonding according to claim 3, wherein the filler is one or more of nano silicon dioxide, aluminum oxide and lithium bistrifluoromethylsulfonimide; the solvent is one or more of N-methyl pyrrolidone, acetone and water.
5. 5. The method for preparing the lithium battery electrode-diaphragm composite based on micro-nano interlocking and in-situ chemical bonding according to claim 4, wherein the mass of the filler is 0-5% of the mass of the polymer matrix.
6. 6. The method for preparing the lithium battery electrode-membrane composite based on micro-nano interlocking and in-situ chemical bonding according to claim 5, wherein the solid content of the precursor solution is 10-40%.
7. 7. The method for preparing the lithium battery electrode-membrane composite based on micro-nano interlocking and in-situ chemical bonding according to claim 6, wherein in the step (2), the matrix membrane is one or more of a PE membrane, a PP membrane, a ceramic membrane and a non-woven membrane; And (3) the coating thickness of the coating diaphragm in the step (2) is 1-15 mu m.
8. 8. The method for preparing a lithium battery electrode-membrane composite based on micro-nano interlocking and in-situ chemical bonding according to claim 7, wherein the hot pressing temperature in the step (3) is 0.65-0.9 Tm, wherein Tm is the melting point of the matrix membrane.
9. 9. The method for preparing the lithium battery electrode-membrane composite body based on micro-nano interlocking and in-situ chemical bonding according to claim 8, wherein the hot pressing pressure in the step (3) is 2-10 MPa, and the dwell time is 30-180 s.
10. 10. The lithium battery electrode-membrane composite based on micro-nano interlocking and in-situ chemical bonding prepared by the preparation method of the lithium battery electrode-membrane composite based on micro-nano interlocking and in-situ chemical bonding of any one of claims 1-9.

Description

Lithium battery electrode-diaphragm complex based on micro-nano interlocking and in-situ chemical bonding and preparation method thereof Technical Field The invention relates to the technical field of batteries, in particular to a lithium battery electrode-diaphragm complex based on micro-nano interlocking and in-situ chemical bonding and a preparation method thereof. Background The continuous improvement of the energy density of the lithium ion battery and the continuous expansion of the application scene bring out unprecedented high requirements on the reliability, interface stability and safety of the internal structure of the battery. In the traditional battery manufacturing process, the positive plate and the diaphragm are assembled in a simple physical stacking mode, the interface bonding force of the positive plate and the diaphragm is weak, and relative sliding or stripping is easy to occur under long-term circulation, thermal shock or mechanical abuse. The interface failure can lead to rapid increase of contact resistance and uneven current distribution, thereby accelerating battery capacity attenuation and possibly causing serious safety problems such as local overheating and even internal short circuit. In order to improve the integration degree and reliability of the battery, industry begins to explore a thermal compounding technology of the diaphragm and the pole piece, and aims to solidify the diaphragm and the pole piece into a whole through a layer of bonding material. However, current mainstream technology routes are generally focused on designing macroscopic patterns of polymer bonding layers (e.g., PVDF) in an effort to improve stress distribution. Such schemes have the following fundamental limitations: The function is single, the traditional bonding layer material (such as PVDF and SBR) is an insulator of ions and electrons, and the introduction of the bonding layer material can provide certain physical bonding force, but can inevitably block or greatly increase the transmission path of lithium ions at the interface, so that the overall interface impedance of the battery is increased, and the quick charge and the power performance are seriously restricted. The durability and the safety are insufficient, and the thermal stability and the mechanical strength of the existing polymer adhesive are limited. When the battery is abnormally warmed (such as 120 ℃), the bonding layer is easy to soften, shrink and even melt, so that bonding failure is caused, and the shrinkage of the diaphragm can be possibly caused, and the risk of thermal runaway is increased. The performance synergy difficulty is that the inherent material contradiction exists between the high bonding strength and the low interface impedance and the excellent thermal stability. The prior art has difficulty in breaking through the bottleneck through morphology fine tuning, and falls into the dilemma that the marginal effect of performance improvement is rapidly reduced. Therefore, there is a need for an innovative solution from the source of the bonding mechanism and material system that achieves a high strength, durable interface bond without sacrificing or even improving the electrochemical transport properties and thermal safety boundaries of the interface. Disclosure of Invention The invention aims to solve the core technical problems that in the existing lithium battery pole piece-diaphragm thermal composite technology, the interface impedance is high, the high-temperature stability is poor, and the mechanical bonding strength and the electrochemical performance cannot be cooperatively optimized due to the dependence on a single physical bonding mechanism. In order to achieve the above object, the present invention provides the following technical solutions: The invention provides a preparation method of a lithium battery electrode-diaphragm complex based on micro-nano interlocking and in-situ chemical bonding, which comprises the following steps: (1) Carrying out structural treatment on the surface of the electrode to obtain an electrode plate with a three-dimensional micro-nano structure; (2) Coating the precursor solution on the surface of a matrix diaphragm to obtain a coated diaphragm; (3) And (3) bonding the three-dimensional micro-nano structure surface of the three-dimensional micro-nano structure electrode plate and the coating surface of the coating diaphragm, and then performing hot pressing to obtain the lithium battery electrode-diaphragm complex based on micro-nano interlocking and in-situ chemical bonding. Preferably, in the step (1), the three-dimensional micro-nano structure is one or more of pits, grooves, bulges and honeycomb networks, the relative height of the three-dimensional micro-nano structure and the electrode surface is 0.05-20 mu m, and the depth-to-width ratio of the three-dimensional micro-nano structure is more than or equal to 1. Preferably, the precursor solution in step (2) comprises a poly