Solid-state lithium ion composite electrolyte membrane and preparation method thereof

Abstract

The invention relates to a solid-state lithium ion composite electrolyte membrane and a preparation method thereof, in particular to the field of all-solid-state lithium ion batteries. A volatilization method is adopted, methanol is used as a solvent, an organic metal framework ZIF-67 material with high crystallinity and uniform morphology is synthesized and the material is used as a filling material to be mixed with PEO and LITFSI to form composite electrolyte membrane slurry. ZIF-67/PEO/LITFSI composite electrolyte membranes with different components are prepared by using a casting method. When the mass percentage of ZIF-67 in (ZIF-67 + PEO) is 3wt%, the composite electrolyte membrane has the optimal room-temperature conductivity, and the numerical value of the optimal room-temperature conductivity is 1.51 * 10 <-5 > S/cm and is about 5 times of the conductivity of a PEO/LITFSI electrolyte.

Description

technical field [0001] The invention belongs to the research field of lithium ion batteries, and in particular relates to a solid lithium ion composite electrolyte membrane and a preparation method thereof. Background technique [0002] With the rise of large-scale battery fields such as electric vehicles and large-scale energy storage, the dependence on lithium batteries with high energy density, long life, and high safety has increased, especially the safety of batteries. Traditional lithium-ion batteries are due to overshoot, Internal short circuit and other reasons will lead to overheating of the organic electrolyte, which is prone to safety accidents such as fire and even explosion. These problems have brought serious challenges to traditional liquid electrolyte lithium-ion batteries. Compared with liquid electrolytes, inorganic solid electrolytes are non-flammable. At the same time, they can avoid internal short circuit and electrolyte leakage problems. The use of inor...

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Problems solved by technology

PEO polymer electrolyte is one of the most commonly used solid-state electrolytes. It has good flexibility and processability, and is suitable for practical applications. The conductive principle of PEO-based electrolytes is mainly Li + Continuously complex-decomplex with the ether oxygen on the PEO chain, and realize Li through the chain segment movement of PEO + The transfer, therefore, the free Li + The ionic conductivity of the PEO-based polymer electrolyte is determined by the number of PEO segments and the mobility of the PEO chain segment. However, since PEO is easy to crystallize at room temperature, the solubility of lithium salts in the amorphous phase is low, and the carrier concentration is low. Lithium ions The transfer number is small, which leads to the low room temperature ionic conductivity of PEO-based electrolytes, which limits the improvement of the energy density of all-solid-state lithium-ion batteries

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