Lithium battery based on three-dimensional interpenetrating network structure and preparation method thereof
By constructing a three-dimensional interpenetrating network structure in lithium batteries, the problem of weak bonding between the electrode sheet and the separator was solved, achieving a synergistic improvement in mechanical strength and electrochemical performance, extending battery life and enhancing safety.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-23
- Publication Date
- 2026-04-21
AI Technical Summary
In existing lithium batteries, the interfacial bonding between the electrode sheet and the separator is weak, resulting in poor long-term cycle stability, uneven ion transport, and easy occurrence of lithium dendrite growth and capacity decay. Existing improvement schemes have failed to innovate the interfacial bonding from the microstructure.
A three-dimensional interpenetrating network structure is adopted. By forming a biomimetic porous layer on the surface of the membrane substrate and forming a gel network phase by using a thermosetting gel precursor solution in situ hot pressing-crosslinking process, a three-dimensional interpenetrating network structure between the negative electrode and the membrane is realized, which enhances mechanical strength and ion transport uniformity.
It significantly improves the interface peel strength, ensures ion flow uniformity, inhibits lithium dendrite growth, extends battery cycle life, and is compatible with existing processes for easy industrialization.
Smart Images
Figure CN121905930A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of lithium battery technology, and in particular to a lithium battery based on a three-dimensional interpenetrating network structure and its preparation method. Background Technology
[0002] As lithium batteries develop towards higher energy density and longer cycle life, the interfacial stability between their internal components becomes crucial, especially the interfacial stability between the electrode sheets and the separator. Traditional lithium battery manufacturing processes employ a "planar stacking-thermal pressing bonding" method, using physical pressure to bond the separator to the surface of the electrode sheets (especially the negative electrode sheet). This model has fundamental defects: (1) Weak bonding: It relies on limited surface contact and polymer melting bonding. Under the severe volume expansion / contraction of electrode active materials (such as silicon) and long-term immersion in electrolyte, the interface is prone to peeling, resulting in a surge in battery internal resistance and capacity decay; (2) Uneven ion transport: Simple surface contact is difficult to guarantee the uniformity of electrolyte distribution at the interface, which can easily cause local lithium ion flow disturbance, aggravate lithium dendrite growth, and bring safety hazards; (3) Limited solutions: In order to improve the interface, existing technologies mostly focus on coating the separator with inorganic ceramic coatings (such as Al2O3, SiO2) or optimizing hot pressing parameters. However, these improvements are still at the level of two-dimensional coating modification or process parameter adjustment, focusing on coating composition, particle size or hot pressing temperature / pressure range, etc., and have failed to innovate the essence of interface bonding from the microstructure.
[0003] Therefore, existing technologies have been limited to parameter optimization within traditional frameworks, and there is an urgent need to explore innovative solutions from the perspective of interface bonding mechanisms to achieve a synergistic leap in interface mechanical strength and electrochemical performance. Summary of the Invention
[0004] The purpose of this invention is to address the problems in existing lithium battery manufacturing processes, such as weak interfacial mechanical bonding, poor long-term cycle stability, and poor ion transport uniformity caused by the "planar contact-physical bonding" mode between the electrode sheet and the separator, which exacerbates lithium dendrite growth and capacity decay, and is easily limited by existing materials and processes. The invention provides a lithium battery based on a three-dimensional interpenetrating network structure and its manufacturing method.
[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a lithium battery based on a three-dimensional interpenetrating network structure, comprising a positive electrode, a negative electrode, and a separator located between the positive electrode and the negative electrode. The negative electrode comprises a current collector and a negative electrode active layer. The separator comprises a separator substrate and a biomimetic porous layer, wherein the biomimetic porous layer is located on at least one side of the separator substrate. A three-dimensional interpenetrating network structure is formed between the negative electrode active layer and the separator.
[0006] Preferably, the biomimetic porous layer and the negative electrode active layer are connected by a gel network, and the gel network penetrates through the pores of the biomimetic porous layer and fills the pores of the negative electrode active layer to form the three-dimensional interpenetrating network structure.
[0007] Preferably, the thickness of the biomimetic porous layer is 3~20μm.
[0008] Preferably, the biomimetic porous layer is composed of polymer and inorganic nanoparticles, and the total porosity of the biomimetic porous layer is 40-85%. In the biomimetic porous layer, the mass fraction of inorganic nanoparticles is 30-70%.
[0009] Preferably, the polymer comprises one or more of polyvinylidene fluoride-hexafluoropropylene copolymer, polyacrylonitrile and polyimide, and the inorganic nanoparticles comprise one or more of nano-silica, nano-titanium dioxide and nano-alumina. The inorganic nanoparticles D 50 The wavelength range is 10~100nm.
[0010] Preferably, the gel network phase is formed by in-situ hot pressing and cross-linking of a thermosetting gel precursor solution, and the viscosity of the thermosetting gel precursor solution is 50~2000 mPa·s.
[0011] Preferably, the thermosetting gel precursor solution comprises a crosslinkable resin, a conductive lithium salt, and a solvent, wherein the mass fraction of the crosslinkable resin in the crosslinkable resin and the conductive lithium salt is 60-95%.
[0012] Preferably, the crosslinkable resin comprises one or more of epoxy resin systems, cyanate ester resin systems, and polyurethane prepolymers, and the conductive lithium salt comprises one or more of lithium bis(trifluoromethanesulfonyl)imide, lithium hexafluorophosphate, and lithium bisfluorosulfonylimide.
[0013] This invention also provides a method for fabricating a lithium battery based on a three-dimensional interpenetrating network structure, comprising the following steps: 1) A biomimetic porous layer is formed on the surface of the membrane substrate to obtain a composite membrane; 2) The thermosetting gel precursor solution is coated on the surface of the biomimetic porous layer and / or the surface of the negative electrode active layer, and then the positive electrode, composite separator and negative electrode are stacked and in-situ hot pressing-crosslinking is performed to obtain the battery cell. 3) After injecting electrolyte into the cell, it is packaged to obtain a lithium battery.
[0014] Preferably, the in-situ hot-press crosslinking pressure is 0.5~3MPa, the in-situ hot-press crosslinking temperature is 80~150℃, and the in-situ hot-press crosslinking time is 10~20min.
[0015] The beneficial effects of this invention are: 1) This invention abandons the traditional two-dimensional surface contact approach and constructs a "three-dimensional interpenetrating network structure" to achieve mechanical interlocking and chemical bonding between the negative electrode and the separator at the microscale. This increases the interfacial peel strength between the negative electrode and the separator by more than an order of magnitude, effectively buffering the volume change of the negative electrode and greatly extending the battery cycle life.
[0016] 2) A biomimetic porous layer with hierarchical pore size is constructed on the surface of the membrane substrate. A gel network phase formed by in-situ hot pressing and cross-linking of thermosetting gel precursor solution is used to penetrate the biomimetic porous layer, so that the biomimetic porous layer and the gel network phase work together to ensure highly uniform interfacial ion flow and effectively suppress lithium dendrites.
[0017] 3) Using the gel network phase as a temporary binder and the final structural phase, the thermosetting gel precursor solution is transformed from liquid to solid through a hot-pressed in-situ cross-linking process. The gel network phase penetrates the biomimetic porous layer and fills at least part of the pores of the negative electrode active layer, forming a stable integrated structure of three interwoven phases: "negative electrode active layer / gel network phase / biomimetic porous layer". This achieves interpenetration in the microstructure, realizing not only the functional integration of bonding and ion conduction, but also the synergistic improvement of interfacial mechanical strength and electrochemical performance based on the interfacial bonding mechanism.
[0018] 4) This invention is compatible with existing lamination hot pressing and winding processes, has a wide process window, and is easy to promote industrialization. Attached Figure Description
[0019] Figure 1 This is a schematic diagram of the three-dimensional interpenetrating network structure. Detailed Implementation
[0020] This invention provides a lithium battery based on a three-dimensional interpenetrating network structure, comprising a positive electrode, a negative electrode, and a separator located between the positive electrode and the negative electrode. The negative electrode comprises a current collector and a negative electrode active layer. The separator comprises a separator substrate and a biomimetic porous layer, wherein the biomimetic porous layer is located on at least one side of the separator substrate. A three-dimensional interpenetrating network structure is formed between the negative electrode active layer and the separator.
[0021] In this invention, the biomimetic porous layer and the negative electrode active layer are preferably connected by a gel network, and the gel network penetrates through the pores of the biomimetic porous layer and fills the pores of the negative electrode active layer to form a three-dimensional interpenetrating network structure.
[0022] In this invention, the filling of the gel network phase in the negative electrode active layer is preferably at least partially filled; the three-dimensional interpenetrating network structure is specifically a network structure in which the three phases of "negative electrode active layer / gel network phase / biomimetic porous layer" are interwoven.
[0023] In this invention, the thickness of the biomimetic porous layer is preferably 3~20μm, more preferably 5~15μm, and even more preferably 8~12μm.
[0024] In this invention, the biomimetic porous layer is preferably composed of polymer and inorganic nanoparticles, and the total porosity of the biomimetic porous layer is preferably 40-85%, more preferably 50-80%, and even more preferably 60-70%. In the biomimetic porous layer, the mass fraction of inorganic nanoparticles is preferably 30-70%, more preferably 40-60%, and even more preferably 50%. The biomimetic porous layer has a three-dimensional network structure and a hierarchical interconnected pore structure, which includes macropores, mesopores, and micropores. The macropores have a diameter of 1-10 μm and are used to store electrolyte; the mesopores have a diameter of 50-500 nm and are used to construct rapid ion transport channels; the micropores have a diameter of <50 nm and are used to provide a high specific surface area to enhance mechanical anchoring and interfacial stability.
[0025] In this invention, the polymer preferably comprises one or more of polyvinylidene fluoride-hexafluoropropylene copolymer, polyacrylonitrile, and polyimide, and the inorganic nanoparticles preferably comprise one or more of nano-silica, nano-titanium dioxide, and nano-alumina. The inorganic nanoparticles D 50 Preferably, the particle size is 10~100nm, more preferably 20~80nm, and even more preferably 30~60nm. Inorganic nanoparticles with too small a particle size are prone to agglomeration, while those with too large a particle size are not conducive to the formation of fine micropores.
[0026] In this invention, the gel network phase is preferably formed by in-situ hot pressing and cross-linking of a thermosetting gel precursor solution. The viscosity of the thermosetting gel precursor solution is preferably 50~2000 mPa·s, more preferably 200~1500 mPa·s, and even more preferably 500~1000 mPa·s.
[0027] In this invention, the thermosetting gel precursor solution preferably comprises a crosslinkable resin, a conductive lithium salt, and a solvent. The mass fraction of the crosslinkable resin in the crosslinkable resin and the conductive lithium salt is preferably 60-95%, more preferably 65-90%, and even more preferably 70-85%.
[0028] In this invention, the crosslinkable resin preferably comprises one or more of epoxy resin systems, cyanate ester resin systems, and polyurethane prepolymers, and the conductive lithium salt preferably comprises one or more of lithium bis(trifluoromethanesulfonyl)imide, lithium hexafluorophosphate, and lithium bisfluorosulfonylimide. The crosslinkable resin has an elongation at break of >5% after curing.
[0029] In this invention, the epoxy resin system preferably comprises epoxy resin and a curing agent.
[0030] In this invention, the solvent preferably comprises one or more of carbonate solvents, ether solvents, and N-methylpyrrolidone. The solvent must not cause harmful side reactions with the active material of the electrode.
[0031] This invention also provides a method for fabricating a lithium battery based on a three-dimensional interpenetrating network structure, comprising the following steps: 1) A biomimetic porous layer is formed on the surface of the membrane substrate to obtain a composite membrane; 2) The thermosetting gel precursor solution is coated on the surface of the biomimetic porous layer and / or the surface of the negative electrode active layer, and then the positive electrode, composite separator and negative electrode are stacked and in-situ hot pressing-crosslinking is performed to obtain the battery cell. 3) After injecting electrolyte into the cell, it is packaged to obtain a lithium battery.
[0032] In this invention, the method for forming the biomimetic porous layer in step 1) preferably includes phase separation, template method, or electrospinning combined with sol-gel method.
[0033] In this invention, after stacking the positive electrode, composite separator, and negative electrode in step 2), it is preferable to first pre-press until there is no obvious liquid aggregation, and then perform in-situ hot pressing-crosslinking; the pre-pressing pressure is preferably 0.1~0.5MPa, more preferably 0.2~0.4MPa, and more preferably 0.3MPa; the pre-pressing temperature is preferably ≤60℃, more preferably ≤55℃; the pre-pressing time is preferably 5~60s, more preferably 10~50s, and more preferably 20~40s. Pre-pressing enables the thermosetting gel precursor solution to fully wet the pores of the electrode sheet and the biomimetic porous layer.
[0034] In this invention, the pressure of the in-situ hot-pressing-crosslinking is preferably 0.5~3 MPa, more preferably 1~2.5 MPa, and even more preferably 1.5~2 MPa; the temperature of the in-situ hot-pressing-crosslinking is preferably 80~150℃, more preferably 90~130℃, and even more preferably 100~120℃; the time of the in-situ hot-pressing-crosslinking is preferably 10~20 min, more preferably 12~18 min, and even more preferably 15 min. During the in-situ hot-pressing-crosslinking process, the pressure promotes the thermosetting gel precursor solution to penetrate deep into the pores of the biomimetic porous layer and the negative electrode active layer, and causes the crosslinkable resin to undergo a crosslinking reaction at a specific temperature. During the in-situ curing process, a three-dimensional interpenetrating network structure of "negative electrode active layer / gel network phase / biomimetic porous layer" is formed.
[0035] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.
[0036] The positive electrode used in the embodiments and comparative examples of the present invention is an aluminum foil coated with lithium cobalt oxide (LiCoO2) with an areal capacity of 4.0 mAh / cm².
[0037] Example 1
[0038] Polyvinylidene fluoride-hexafluoropropylene copolymer and nano-silica (20 nm particle size) were dispersed in N-methylpyrrolidone (polyvinylidene fluoride-hexafluoropropylene copolymer and N-methylpyrrolidone in a mass ratio of 1 g:9 mL) at a 1:1 mass ratio to obtain a mixture. Using a 12 μm thick polyethylene membrane as the membrane substrate, a biomimetic porous layer with a thickness of 8 μm and a total porosity of 65% was formed on the surface of the membrane substrate using a solvent-free (water) induced phase separation method with the mixture.
[0039] E-51 epoxy resin and curing agent D230 were mixed according to a stoichiometric ratio, and lithium bis(trifluoromethanesulfonyl)imide was added. The mixture was then dispersed in an organic solvent (ethylene carbonate and dimethyl carbonate in a 1:1 volume ratio) to obtain a thermosetting gel precursor solution with a viscosity of 800 mPa·s. The lithium bis(trifluoromethanesulfonyl)imide comprised 20% of the total solids in the thermosetting gel precursor solution. The thermosetting gel precursor solution was uniformly coated onto the surface of a biomimetic porous layer. Silicon-carbon anode and cathode sheets with an areal capacity of 3.5 mAh / cm² were then stacked. Pre-pressing was performed at 0.2 MPa and 60 °C for 1 min to allow the thermosetting gel precursor solution to penetrate the pores of the silicon-carbon anode sheet and the biomimetic porous layer. Subsequently, hot-pressing was performed at 120 °C and 1.0 MPa for 10 min to cure the epoxy resin and form a gel network phase, resulting in the battery cell. A 2032-type coin cell was assembled by injecting a 1 mol / L lithium hexafluorophosphate (LiPF6) solution (the electrolyte being ethylene carbonate EC, diethyl carbonate DEC, and methyl ethyl carbonate EMC in a volume ratio of 1:1:1) into the cell.
[0040] Example 2
[0041] The difference from Example 1 is as follows: Polycaprolactone diol and isophorone diisocyanate were reacted at a mass ratio of 1:1.05 to obtain a polyurethane prepolymer. The polyurethane prepolymer and chain extender 1,4-butanediol (BDO) were mixed at a mass ratio of 100:8 (prepolymer: chain extender), and lithium difluorosulfonyl imide was added. Then, the mixture was dispersed in N-methylpyrrolidone to obtain a thermosetting gel precursor solution with a viscosity of 1200 mPa·s. The mass of lithium difluorosulfonyl imide accounted for 30% of the total solids in the thermosetting gel precursor solution. The thermosetting gel precursor solution was uniformly coated on the surface of a biomimetic porous layer, and then silicon-carbon anode and cathode sheets with an areal capacity of 3.5 mAh / cm² were stacked. The mixture was then pre-compressed at 0.2 MPa and 60°C for 1 min to allow the thermosetting gel precursor solution to enter the pores of the silicon-carbon anode sheet and the biomimetic porous layer. Subsequently, the polyurethane prepolymer was hot-pressed at 100℃ and 0.8MPa for 15 minutes to solidify and form a gel network phase, thus obtaining the battery cell. A 1mol / L lithium hexafluorophosphate solution (LiPF6) was injected into the battery cell (the electrolyte being ethylene carbonate EC, diethyl carbonate DEC, and methyl ethyl carbonate EMC in a volume ratio of 1:1:1) to assemble a 2032-type coin cell lithium battery.
[0042] Example 3
[0043] The difference from Example 1 is that polyacrylonitrile and nano-titanium dioxide (50 nm particle size) were dispersed in N-methylpyrrolidone (polyacrylonitrile and N-methylpyrrolidone in a mass ratio of 1 g:8 mL) at a mass ratio of 6:4 to obtain a mixture. Using a 12 μm thick polyethylene membrane as the membrane substrate, a 10 μm thick biomimetic porous layer with a total porosity of 70% was formed on the surface of the membrane substrate using a solvent-free (water) induced phase separation method with the mixture.
[0044] Comparative Example 1
[0045] A 12μm thick polyethylene film was used as the separator, and silicon-carbon negative and positive electrodes with an area capacity of 3.5 mAh / cm² were stacked on top. The cells were hot-pressed at 90℃ and 1.0MPa for 10 min to obtain the battery cells. A 1mol / L lithium hexafluorophosphate solution (LiPF6) was injected into the battery cells as the electrolyte (the electrolyte solvent was ethylene carbonate EC, diethyl carbonate DEC, and methyl ethyl carbonate EMC in a volume ratio of 1:1:1) to assemble them into 2032 coin cell lithium batteries.
[0046] Comparative Example 2
[0047] A 4μm thick Al2O3 coating was applied to the surface of a 12μm thick polyethylene separator. Polyvinylidene fluoride (PVDF) was dispersed in N-methylpyrrolidone to obtain a 10% (w / w) binder solution. This binder solution was then coated onto the Al2O3 coating surface. Silicon-carbon negative and positive electrode sheets with an areal capacity of 3.5 mAh / cm² were then stacked and hot-pressed at 90℃ and 1.0 MPa for 10 min to melt and bond the PVDF, resulting in a battery cell. A 1mol / L lithium hexafluorophosphate (LiPF6) solution was injected into the battery cell (the electrolyte consisted of ethylene carbonate EC, diethyl carbonate DEC, and methyl ethyl carbonate EMC in a 1:1:1 volume ratio) to assemble a 2032 coin cell lithium battery.
[0048] A universal testing machine was used to test the interfacial peel strength between the negative electrode and the separator in the coin lithium batteries of Examples 1-3 and Comparative Examples 1-2 at a peel angle of 180° and a speed of 50 mm / min.
[0049] The thermosetting gel precursor solutions prepared in Examples 1-3 and the binder solution prepared in Comparative Example 2 were respectively prepared into gel films, sandwiched between stainless steel blocking electrodes, and the bulk resistance was measured by electrochemical impedance spectroscopy (EIS) to calculate the ionic conductivity at room temperature (25°C).
[0050] The coin-type lithium batteries prepared in Examples 1-3 and Comparative Examples 1-2 were tested for discharge capacity at 0.2C and 2C rates, respectively, and the capacity retention rate at 2C rate relative to 0.2C rate was calculated. Constant current charge-discharge cycles were performed at 0.5C rate, and the capacity retention rate after the 200th cycle was recorded. After 200 cycles, the batteries were disassembled, and the uniformity of lithium deposition on the negative electrode surface was observed using SEM. The test results are shown in Table 1.
[0051] Table 1 Performance Test Results
[0052] As can be seen from Table 1, the interfacial peel strength of Examples 1-3 is significantly improved compared with Comparative Examples 1 and 2, which is attributed to the three-dimensional interpenetrating network structure at the interface. The thermosetting gel precursor solutions of Examples 1-3 have high ionic conductivity, which ensures excellent rate performance, effectively stabilizes the electrode / electrolyte interface, maintains extremely high capacity retention during long-term cycling, and induces uniform lithium deposition, which fundamentally improves battery safety and extends the cycle life of the battery.
[0053] As can be seen from the above embodiments, the present invention provides a lithium battery based on a three-dimensional interpenetrating network structure, comprising a positive electrode, a negative electrode, and a separator located between the positive and negative electrode. The negative electrode comprises a current collector and a negative electrode active layer. A biomimetic porous layer with hierarchical pore sizes is formed on the surface of the separator substrate. Through in-situ hot pressing and crosslinking, a thermosetting gel precursor solution enters the pores of the negative electrode active layer and permeates the pores of the biomimetic porous layer, forming a gel network phase. Finally, a stable integrated structure of "negative electrode active layer / gel network phase / biomimetic porous layer" is formed, which ensures highly uniform interfacial ion flow and effectively suppresses lithium dendrites. The lithium battery based on the three-dimensional interpenetrating network structure of the present invention has significantly improved interfacial peel strength and rate performance, ensures safety, and extends cycle life.
[0054] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A lithium battery based on a three-dimensional interpenetrating network structure, comprising a positive electrode, a negative electrode, and a separator located between the positive and negative electrode, wherein the negative electrode comprises a current collector and a negative electrode active layer, characterized in that, The diaphragm comprises a diaphragm substrate and a biomimetic porous layer, wherein the biomimetic porous layer is located on at least one side of the diaphragm substrate; A three-dimensional interpenetrating network structure is formed between the negative electrode active layer and the separator.
2. The lithium battery according to claim 1, characterized in that, The biomimetic porous layer and the negative electrode active layer are connected by a gel network. The gel network penetrates the pores of the biomimetic porous layer and fills the pores of the negative electrode active layer to form the three-dimensional interpenetrating network structure.
3. The lithium battery according to claim 1, characterized in that, The thickness of the biomimetic porous layer is 3~20μm.
4. The lithium battery according to any one of claims 1 to 3, characterized in that, The biomimetic porous layer is composed of polymer and inorganic nanoparticles, and the total porosity of the biomimetic porous layer is 40-85%. In the biomimetic porous layer, the mass fraction of inorganic nanoparticles is 30-70%.
5. The lithium battery according to claim 4, characterized in that, The polymer comprises one or more of polyvinylidene fluoride-hexafluoropropylene copolymer, polyacrylonitrile and polyimide, and the inorganic nanoparticles comprise one or more of nano-silica, nano-titanium dioxide and nano-alumina. The inorganic nanoparticles D 50 The wavelength range is 10~100nm.
6. The lithium battery according to claim 5, characterized in that, The gel network phase is formed by in-situ hot pressing and cross-linking of a thermosetting gel precursor solution, and the viscosity of the thermosetting gel precursor solution is 50~2000 mPa·s.
7. The lithium battery according to claim 6, characterized in that, The thermosetting gel precursor solution comprises a crosslinkable resin, a conductive lithium salt, and a solvent, wherein the mass fraction of the crosslinkable resin in the crosslinkable resin and the conductive lithium salt is 60-95%.
8. The lithium battery according to claim 7, characterized in that, The crosslinkable resin comprises one or more of epoxy resin systems, cyanate ester resin systems, and polyurethane prepolymers, and the conductive lithium salt comprises one or more of lithium bis(trifluoromethanesulfonyl)imide, lithium hexafluorophosphate, and lithium bisfluorosulfonylimide.
9. The method for preparing a lithium battery based on a three-dimensional interpenetrating network structure according to any one of claims 1 to 8, characterized in that, It includes the following steps: 1) A biomimetic porous layer is formed on the surface of the membrane substrate to obtain a composite membrane; 2) The thermosetting gel precursor solution is coated on the surface of the biomimetic porous layer and / or the surface of the negative electrode active layer, and then the positive electrode, composite separator and negative electrode are stacked and in-situ hot pressing-crosslinking is performed to obtain the battery cell. 3) After injecting electrolyte into the cell, it is packaged to obtain a lithium battery.
10. The preparation method according to claim 9, characterized in that, The in-situ hot-press crosslinking pressure is 0.5~3MPa, the in-situ hot-press crosslinking temperature is 80~150℃, and the in-situ hot-press crosslinking time is 10~20min.