Gel-state polymer lithium-ion battery adaptable to high and low temperature environment and preparation method thereof

Abstract

The invention relates to a polymer lithium-ion battery and a preparation method thereof. The invention is made by stacking the positive and negative pole pieces and the diaphragm produced by the Bellcore process into an electric core, which is extracted, welded, packaged, and chemically formed. The active material of the positive electrode sheet is LiCoO2 with a D50 of 5-10um; the active material of the negative electrode sheet is graphite; the diaphragm is a polyethylene film made by a dry process; Organic solvents and additives are uniformly mixed and prepared. The preparation method of the present invention is to stack the positive and negative electrodes and the diaphragm to form a cell, and after extraction, welding and packaging, place it in a flexible packaging film to seal the three sides of the flexible packaging film; inject high and low temperature electrolyte into the In the above cell, the fourth side of the film is sealed by vacuum packaging, and the chemical formation process is carried out. Compared with the prior art, the invention realizes the low-temperature discharge performance of the battery.

Description

Technical field: [0001] The invention relates to a polymer lithium ion battery and a preparation method thereof, in particular to a gel state polymer lithium ion battery suitable for high and low temperature environments and a preparation method thereof. The polymer lithium-ion battery can reach more than 80% of the rated capacity at -40°C ultra-low temperature discharge, and more than 98% of the rated capacity at 60°C high temperature discharge, and the expansion rate is less than 5% when stored at 75°C for 4 hours. [0002] Background technique: [0003] Energy and the environment are extremely important material foundations for the survival and development of human society. Since the formation of energy systems based on fossil fuels such as oil, coal and natural gas, countries around the world have greatly promoted the prosperity, progress and development of human society; however, with the various unfortunate disasters encountered by countries in the world today With th...

AI Technical Summary

Problems solved by technology

[0005](1) Liquid lithium-ion batteries are prone to electrolyte leakage and lead to battery failure due to the liquid electrolyte

[0006](2) During the process of dropping, impacting, shaking, etc., the liquid battery is likely to cause short circuit within the misalignment of the pole piece, and even cause fire and explosion, which poses a safety hazard

[0007] (3) Storage at high temperature is prone to a large amount of gassing, mainly because the low boiling point substances in the liquid electrolyte are easy to gasify, resulting in flatulence

[0008](4) Due to the mismatch between electrolyte and graphite, the reversible capacity of graphite decreases during charge and discharge, and the battery cycle performance is poor

However, the boiling point of EC is 248°C under normal pressure, and the melting point is 36-39°C under normal pressure; the melting point is high, and after simply adding linear carbonate and lithium salt, the melting point drops limited, which limits the low-temperature application range of lithium-ion batteries; propylene carbonate (PC) has a boiling point of 242°C and a melting point of -49°C under normal pressure, so it has excellent low-temperature performance, but PC is prone to co-intercalation in graphitized electrodes, and the decomposition potential of PC is lower than the corresponding reduction potential of solvated lithium ions, so This binary intercalation compound is unstable. PC decomposes on the surface of the graphite negative electrode to produce propylene, which leads to the exfoliation of the graphite electrode, which leads to a decrease in the reversible capacity of graphite. Therefore, a single solvent PC is not suitable for using graphite as an organic negative electrode active material Electrolyte solvent, need to add additives to PC

Images