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Lithium battery diaphragm for inhibiting expansion of silicon-carbon negative electrode and hot-pressing method of lithium battery cell containing diaphragm

A lithium battery diaphragm and negative electrode technology, which is applied in the direction of battery components, electrolyte storage battery manufacturing, non-aqueous electrolyte storage batteries, etc., can solve the problems of increased heat production, increased difficulty of battery production, and increased internal voids in batteries, etc.

Active Publication Date: 2021-09-10
WANXIANG 123 CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] For existing solutions using new binders, although the speed of battery expansion can be slowed down, due to the poor flexibility of the new binders used, the processability of the negative electrode slurry is affected, thereby increasing the difficulty of battery production
At the same time, in order to fully suppress the expansion of the negative electrode, the amount of binder is also high, which will increase the internal resistance of the lithium-ion battery and reduce the energy density of the battery.
In addition, the binder can only ensure the stable contact of the pole piece, but there is no bonding interface with the separator. After the battery has been cycled for a long time, due to repeated changes in battery thickness and internal side reactions, the gap between the pole piece and the separator inside the battery will be caused. Poor contact between the batteries increases the internal voids and destroys the structural integrity of the battery. These adverse phenomena will increase the internal resistance of the battery, increase heat generation during charging and discharging, damage the structure of the negative electrode sheet, and further lead to battery expansion.
[0004] For the existing solutions that use additives such as fluoroethylene carbonate in the electrolyte, although it can play a role in bonding silicon particles and SEI films, the decomposition of fluoroethylene carbonate will produce gases such as carbon dioxide, which will further lead to lithium Swelling of ion batteries

Method used

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  • Lithium battery diaphragm for inhibiting expansion of silicon-carbon negative electrode and hot-pressing method of lithium battery cell containing diaphragm
  • Lithium battery diaphragm for inhibiting expansion of silicon-carbon negative electrode and hot-pressing method of lithium battery cell containing diaphragm
  • Lithium battery diaphragm for inhibiting expansion of silicon-carbon negative electrode and hot-pressing method of lithium battery cell containing diaphragm

Examples

Experimental program
Comparison scheme
Effect test

preparation example Construction

[0046] The preparation method of garnet type modified LLZO solid electrolyte is:

[0047] A): with Li 2 CO 3 (purity 99.9%, add 5-15% excess Li 2 CO 3 to compensate for Li loss during sintering), La 2 o 3 (purity 99.9%), ZrO 2 (purity 99.9%), Ga 2 o 3 (purity 99.9%), Al 2 o 3 (purity 99.9%) as raw material, according to the required stoichiometric ratio into the three-dimensional high-energy vibration ball mill (the total doping amount of Ga and Al in LLZO is not more than 5wt%), the inner wall of the ball mill is made of zirconia, and the grinding balls are steel balls , tungsten carbide ball, polyaminopeptide ball, the ratio of ball to material is 20-50:40-80, ball milling at room temperature for 5-10 minutes, and sintering in air at 300-400°C for 1-3 hours to promote different Interfacial compatibility between raw materials, cooling to room temperature at a rate of 10-20°C / min, continue ball milling and mixing for 10-20 minutes, and anaerobic sintering at 900-1...

Embodiment 1

[0055] A lithium battery diaphragm that suppresses the expansion of a silicon-carbon negative electrode, comprising a polymer base film, an inorganic particle ceramic coating coated on both sides of the polymer base film, and an adhesive inorganic particle mixed coating coated on both sides of the inorganic particle ceramic coating layer. in:

[0056] The polymer base film is made of polyethylene with a thickness of 9 μm and a porosity of 45%.

[0057] The inorganic particles in the inorganic particle ceramic coating are boehmite, and the thickness of a single layer of the inorganic particle ceramic coating is 3 μm.

[0058] The adhesive and inorganic particle mixed coating includes adhesive and inorganic particles; the adhesive accounts for 30wt%, and the inorganic particles accounts for 70wt%; the thickness of a single layer of the adhesive and inorganic particle mixed coating is 1 μm. The adhesive is polyvinylidene fluoride. The inorganic particles in the adhesive inorga...

Embodiment 2

[0065] A lithium battery diaphragm that suppresses the expansion of a silicon-carbon negative electrode, comprising a polymer base film, an inorganic particle ceramic coating coated on both sides of the polymer base film, and an adhesive inorganic particle mixed coating coated on both sides of the inorganic particle ceramic coating layer. in:

[0066] The polymer base film is made of polyethylene with a thickness of 9 μm and a porosity of 45%.

[0067] The inorganic particles in the inorganic particle ceramic coating are boehmite, and the thickness of a single layer of the inorganic particle ceramic coating is 3 μm.

[0068] The adhesive-inorganic particle mixed coating includes adhesive and inorganic particles; the adhesive accounts for 50 wt%, and the inorganic particles account for 50 wt%; the single-layer thickness of the adhesive-inorganic particle mixed coating is 1 μm. The adhesive is polyvinylidene fluoride. The inorganic particles in the adhesive inorganic particle...

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Abstract

The invention relates to the field of lithium batteries, and discloses a lithium battery diaphragm for inhibiting expansion of a silicon-carbon negative electrode and a hot-pressing method of a lithium battery cell containing the diaphragm. The lithium battery diaphragm comprises a polymer base membrane, inorganic particle ceramic coatings coated on the two surfaces of the polymer base membrane, and adhesive inorganic particle mixed coatings coated on the two surfaces of the inorganic particle ceramic coatings. The hot-pressing method comprises the following steps: 1) performing primary hot-pressing on the battery cell; 2) carrying out secondary hot pressing on the battery cell; 3) standing; and 4) degassing. The diaphragm is matched with secondary hot pressing so that the diaphragm can be effectively bonded with positive and negative plates, the thickness of the battery is reduced, a gap between a negative electrode and the diaphragm caused by expansion of a silicon-carbon negative electrode material is avoided, the interface between the diaphragm and the positive and negative plates is improved, the effective contact area of the positive and negative electrodes is increased, the lithium ion transmission resistance is reduced, and a charge-discharge capacity is improved; and meanwhile, the hardness and smoothness of the batteries are ensured, the consistency of the batteries is improved, and convenience is provided for the process of assembling the batteries into a module.

Description

technical field [0001] The invention relates to the field of lithium batteries, in particular to a lithium battery diaphragm that suppresses the expansion of a silicon-carbon negative electrode and a hot pressing method for a lithium battery cell containing the diaphragm. Background technique [0002] In recent years, with the rapid development of new energy vehicles and other fields, the energy density requirements of lithium-ion batteries are getting higher and higher. Traditional graphite anode materials are difficult to meet the needs of high specific energy lithium-ion batteries. Silicon-carbon composite materials are used as anodes for lithium-ion batteries. Silicon with high specific capacity is used as an active material to provide more lithium storage capacity, and carbon is used as a dispersed matrix to buffer silicon particles. The volume change during delithiation maintains the integrity of the electrode structure and maintains electrical contact within the elect...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M50/457H01M50/451H01M50/443H01M50/46H01M10/058
CPCH01M50/457H01M50/451H01M50/443H01M50/46H01M10/058Y02P70/50Y02E60/10
Inventor 马子朋张睿成孟宪伟袁园许梦清李凡群
Owner WANXIANG 123 CO LTD
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