Modified bacterial cellulose lithium-sulfur battery diaphragm

A technology of bacterial cellulose membrane and bacterial cellulose, which is applied in the field of modified bacterial cellulose lithium-sulfur battery diaphragm, can solve the problems of affecting battery cycle stability, poor electrolyte absorption rate, unfavorable high current charging and discharging, etc. It achieves the effect of enhancing the rate cycle performance, reducing the risk of combustion and explosion, and avoiding coating peeling off

Pending Publication Date: 2020-12-08
荣晓晓
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] At present, the commonly used separators in the market are polyolefin separators. Due to the lyophobic surface, low surface energy and low porosity of polyolefin materials, the separator has poor wettability to the electrolyte, which hinders the migration of lithium ions. High current charging and discharging; thermal stability is poor; when the temperature is too high, the diaphragm will undergo severe thermal shrinkage, resulting in short circuit of the battery; in addition, in lithium-sulfur batteries, since the positive electrode sulfur is gradually reduced to a Dissolved polysulfides, dissolved polysulfides react with the lithium negative electrode to cause corrosion of the lithium negative electrode and affect the cycle stability of the battery; therefore, the research solves the problem of dissolution and diffusion of polysulfides, and inhibits the "shuttle effect" of lithium-sulfur batteries. It is expected to improve the comprehensive performance of lithium-sulfur batteries
[0005] Bacterial cellulose is a kind of extracellular cellulose produced by bacteria. As a kind of biological nanofiber, it has a cross-linked nano-network structure and good mechanical strength. It also has high liquid absorption and water retention. It is used in battery separators. The field has received extensive attention. The current research on bacterial cellulose separators has low ionic conductivity. Drying causes the pores of the separator to become smaller and the liquid absorption rate of the electrolyte is not good, and the reduction in mechanical strength limits its application in the field of battery separators.

Method used

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  • Modified bacterial cellulose lithium-sulfur battery diaphragm
  • Modified bacterial cellulose lithium-sulfur battery diaphragm
  • Modified bacterial cellulose lithium-sulfur battery diaphragm

Examples

Experimental program
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Effect test

Embodiment 1

[0023] Preparation of bacterial cellulose membrane

[0024] Take the activated strain of Gluconacetobacter xylinum and inoculate it in the fermentation medium for dynamic culture. After culturing for 60 hours at 30°C, add silicon dioxide to the fermentation medium, and then ferment for 11 days at 30°C. , to obtain the fermentation broth, take out the bacterial cellulose film on the upper layer of the fermentation broth, wash the cellulose film with alkaline solution, then wash it to neutrality, place it in a freeze-drying box and dry it to obtain a spongy bacterial cellulose film; bacterial cellulose The thickness of the membrane is 30-40μm; the diameter of the bacterial fiber is 200-500nm;

[0025] The composition of the fermentation medium is that 1L medium contains 45g of sucrose, 15g of beef extract, 4.5g of disodium hydrogen phosphate, 0.8g of citric acid, and 8g of ethanol; 10%-12% of mass;

[0026] Preparation of Boric Acid Modified Silica

[0027] Disperse 100g of s...

Embodiment 2

[0032] A modified bacterial cellulose lithium-sulfur battery diaphragm, which is prepared by culturing sulfate-reducing bacteria with bacterial cellulose membrane as a carrier, and then coating the surface with boric acid-modified silicon dioxide; the preparation method is specific Include the following steps: ;

[0033] (1) Immerse the spongy bacterial cellulose membrane (prepared in Example 1) in the nutrient solution of sulfate-reducing bacteria, ferment and cultivate it at 30°C for 6 days in a closed environment, and take out the bacterial fibers loaded with sulfate-reducing bacteria after cultivation Plain film; Wherein, the composition of described sulfate-reducing bacteria culture solution is to contain 11g ferrous ammonium sulfate, 7g ferric citrate, 25g guar gum, 18g polyethylene glycol, 10g cysteine ​​in 1L deionized water; Sulfuric acid The quality of salt-reducing bacteria accounts for 13% of the culture solution;

[0034] (2) 100g boric acid modified silica No. 2...

Embodiment 3

[0036]The preparation method of the diaphragm of embodiment 3 is basically the same as that of embodiment 2, the difference is that: the content of other components in the fermentation broth of sulfate-reducing bacteria is controlled to be constant, the content of cysteine ​​is adjusted, and the obtained diaphragm is successively recorded as BCM-L1, BCM-L2, BCM-L3, BCM-L3, BCM-L4, BCM-L5, BCM-L6, BCM-L7, BCM-L8, BCM-L9, BCM-L10, BCM-L11, and the performance of the diaphragm At the same time, the diaphragm was assembled into a lithium-sulfur battery, and the rate performance and cycle performance of the battery were tested respectively. The test method used the method described in the specification below, and the test results are recorded in Table 1.

[0037] Table 1

[0038]

[0039]

[0040] From the data in Table 1, it can be seen that with the increase of cysteine ​​content in the fermentation broth, the tensile strength, porosity, ion conductivity, average value of s...

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Abstract

The invention discloses a modified bacterial cellulose lithium-sulfur battery diaphragm which is prepared by taking bacterial cellulose as a carrier to culture sulfate reducing bacteria and then coating boric acid modified silicon dioxide on the surface of the sulfate reducing bacteria. The diaphragm has high porosity, high liquid absorption rate, high ionic conductivity and good thermal shrinkageresistance; the diaphragm is applied to a lithium-sulfur battery diaphragm, and the shuttle effect of polysulfide in the cycle process of a lithium-sulfur battery can be effectively inhibited; the diaphragm is expected to be applied to the lithium-sulfur battery diaphragm and the charge-discharge rate cycle performance and the service life of the battery can be effectively improved.

Description

technical field [0001] The invention belongs to the field of lithium-sulfur battery materials, and in particular relates to a modified bacterial cellulose lithium-sulfur battery diaphragm. Background technique [0002] Lithium-sulfur battery has high theoretical specific capacity (1672mAh / g) and energy density (2600Wh / kg), and its active material sulfur has the advantages of abundant resources, low price and environmental friendliness, as a battery with good application prospects The system has received extensive attention in the field of new energy. [0003] The separator is an important part of the lithium-sulfur battery, which is used to block the positive and negative electrodes and prevent the short circuit caused by direct contact between the two electrodes. The diaphragm allows lithium ions to pass through and prevents electrons from flowing through, completing the transmission of lithium ions between the positive and negative electrodes during charge and discharge; ...

Claims

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Application Information

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IPC IPC(8): H01M2/14H01M2/16H01M10/052
CPCH01M10/052Y02E60/10
Inventor 荣晓晓
Owner 荣晓晓
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