Polyvinildene difluoride copolymer gel state electrolyte film and its preparation technology

Abstract

The invention discloses a method to made polyvinylidene fluoride copolymer gel state electrolyte membrane. It includes adhering said membrane on the electrode pole piece and mixing one portion weight poly-winylidene fluoride copolymer with 6-8 portions weight solution and coating on the electrode pole piece to form polyvinylidene fluoride copolymer membrane, pouring the electrode liquid to form the material. The manufacturing process includes: making polyvinylidene fluoride copolymer solution, coating the solution onto the electrode pole piece, laying for 20-30 hours in room temperature and drying for 20-30 hours in vacuum, taking rolling hot joint, septum stacking and encasing into aluminum mold packaging film. The invention has good conductivity.

Description

technical field [0001] The invention relates to a gel-state electrolyte membrane for lithium ion batteries and a preparation process thereof, in particular to a polyvinylidene fluoride copolymer gel-state electrolyte membrane and a preparation process thereof. Background technique [0002] Lithium-ion batteries are the leading products in the domestic and foreign battery markets. At present, most of the electrolytes used in lithium-ion batteries are organic liquid electrolytes. This electrolyte has the advantages and characteristics of high conductivity and large lithium ion migration number. However, liquid electrolytes used in lithium-ion batteries also have the following disadvantages: [0003] 1. The electrolyte is an organic solution of lithium salt, so it is easy to decompose and generate gas when it is high-voltage or overcharged, which will cause the battery to expand and deform. Under extreme conditions, it will burn or even cause an explosion. The manufacturing qu...

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Problems solved by technology

[0003] 1. The electrolyte is an organic solution of lithium salt, so it is easy to decompose and generate gas when it is high-voltage or overcharged, which will cause the battery to expand and deform. Under extreme conditions, it will burn or even cause an explosion. The manufacturing qualification rate of products has dropped significantly;

[0004] 2. For lithium-ion batteries using aluminum-plastic film flexible packaging, due to the difference in the electrode sheets, the electrolyte absorption is incomplete, and a small amount of free electrolyte may be drawn out during the packaging process, thereby affecting the sealing of the battery and the product qualification rate;

[0005] 3. The organic solvent of the electrolyte is unstable to the thermodynamic properties of lithium or even carbon electrodes, and the electrode surface passivation phenomenon is serious. In addition, when the positive and negative electrodes are overcharged or the positive and negative electrodes do not match, LiC dendrites will grow on the surface of the negative electrode, thereby increasing the internal density of the battery. danger of short circuit

Therefore, for traditional gel-state electrolytes, it is necessary to organically combine the mechanical strength of the polymer with the amount of plasticizer. There are too many factors to be controlled, which causes a lot of trouble to the actual production control, and the production efficiency and pass rate are relatively low. Low, the quality stability of the product is poor, and there are few practical applications, and it will significantly increase the internal resistance of the battery and affect the high-rate discharge performance

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