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Diaphragn additive for lithium secondary cell and lithium secondary cell diaphragm

A lithium secondary battery and diaphragm technology, applied in the field of diaphragm additives, can solve the problems of good electrical properties of the diaphragm, and achieve the effects of easy dispersion, enhancement and change of surface properties, high conductivity and safety

Inactive Publication Date: 2008-05-14
ZHEJIANG UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] In order to overcome the disadvantages that the separator in the prior art cannot have high strength and good electrical performance at the same time, the invention provides a separator additive for lithium secondary batteries

Method used

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  • Diaphragn additive for lithium secondary cell and lithium secondary cell diaphragm
  • Diaphragn additive for lithium secondary cell and lithium secondary cell diaphragm
  • Diaphragn additive for lithium secondary cell and lithium secondary cell diaphragm

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0024] Add 4g of polymethylmethacrylate (PMMA) crosslinked polymer particles (CPMB) with an average particle size of 0.5μm as a crosslinking agent of polymethylmethacrylate (PMMA) into a solution of 100g of PVDF, 800g of tetrahydrofuran and 100g of glycerin, and mix, and Stir at a constant temperature of 50°C for 2 hours, and ultrasonically treat for 20 minutes to obtain a viscous solution. Use a 0.6mm notch spatula to coat the smooth glass. Put the coated film together with the glass into a 5°C water bath to remove the solvent. With the non-solvent, take it out after half an hour to obtain a smooth and flat microporous CPMB composite PVDF film. The film is dried in an oven at 45°C for 24 hours, and the thickness after drying is about 50 μm. Take PVDF microporous membrane without CPMB for comparison. The results are shown in Table 1 below.

Embodiment 2

[0026] Replace the cross-linked polymer particles (CPMB) in Example 1 with 4g CPMB of polyacrylonitrile (PAN) with an average particle size of 0.8 μm and dicyclopentadiene as the cross-linking agent. Others are the same as in Example 1. The results are shown in the table 1 shows:

[0027] Table 1

[0028]

[0029] The above results indicate that the microporous membrane with CPMB has better liquid absorption and tensile strength.

Embodiment 3

[0031] 5kg of acrylonitrile copolymer CPMB with divinylbenzene with an average particle size of 0.6μm as the crosslinking agent was melt blended with 95kg of polypropylene (S1004), extruded through a T-die to form a 35μm thick film, and then annealed and stretched. For the battery separator, the annealing and stretching process is detailed in US Patent No. 5,480,945; No. 5,691,047; No. 5,691,077; No. 5,667,416; No. 5,952,120; No. 6,602,593. The comparative example is without CPMB, and the related performance of the test is shown in Table 2 below:

[0032] Table 2

[0033]

[0034]

[0035] The above results indicate that the microporous membrane with CPMB has greater porosity, hardness and tensile strength.

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Abstract

The additive is cross-linked polymer particulate (CPMB) in mean grin size of 10-2000nm. The diaphragm includes at least one layer of micro porous membrane made from polyolefine. 0.2-15úÑ mass portion of cross-linked polymer particulate in mean grin size of 10-2000nm is dispersed in micro porous membrane made from polyolefine. The disclosed membrane with additive dispersed into reinforces and changes surface performance, maintains high intensity, as well as possesses larger absorbency and capability of preserving liquid. Lithium secondary battery made from the disclosed diaphragm possesses high conductivity and safety. Comparing with inorganic filling material of fine grain, the disclosed additive is cheap and easy to be dispersed in plastic fused mass or solution. The preparation method is simple and easy to be generalized in practical application.

Description

(1) Technical field [0001] The invention relates to a diaphragm additive for a lithium secondary battery, and also relates to a lithium secondary battery diaphragm added with the additive. (2) Background technology [0002] Lithium-ion batteries are mainly composed of positive and negative electrode materials, electrolytes and diaphragms. The preparation methods of lithium ion battery separators mainly include melt stretching (MSCS) and thermally induced phase separation (TIPS). For details, see US Patent No. 5,480,945; No. 5,691,047; No. 5,691,077; No. 5,667,416; No. 5,952,120; No. 6,602,593. Lithium-ion battery diaphragm is the main component of lithium-ion battery. The performance of the diaphragm determines the interface structure of the battery and the internal resistance of the battery, which in turn affects the battery’s capacity, cycle performance, charge and discharge current density and other key characteristics. It can be seen that the performance A good separator play...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M2/16C08L23/00C08L75/00H01M50/411H01M50/417H01M50/443H01M50/457H01M50/491H01M50/497
CPCY02E60/12Y02E60/10
Inventor 邬润德童筱莉
Owner ZHEJIANG UNIV OF TECH