Lithium-ion Battery Research And Development Of Porous Polymer Electrolyte

Gel polymer lithium batteries (GPLB) not only have the excellent performance of liquid lithium battery, but also can resolve the possible problems of leakage and blast owing to no free liquid electrolyte in GPLB. It is also very convenient to design the shape at will. Now the ion conductivity of gel polymer electrolyte (GPE) can reach the magnitude of 10^-3S/cm, which can satisfy the practical request. However, it is still lower than that of liquid electrolyte (10^-2S/cm), which causes the fall of high rate discharge and low temperature performance of lithium battery. Now the main method of preparing GPLB is to fabricate a GPE film through solution casting first, and then assemble the battery. The cost of the process is very high and it is difficult to treat with the disused solvents, therefore, it is difficult for most liquid lithium battery manufactures to transfer to produce GPLB.Focusing on the preparation process of lithium battery and GPE membrane, by optimizing the component of the gel electrolyte, the paper intends to resolve some of the key problems mentioned above and to prepare a porous GPE with good performance.Firstly, a series of P(HEA-AN) copolymers were synthesized by free radical solvent polymerization. The formation and construction of copolymer were confirmed by FT-IR.Secondly, a phase inversion method as the preparation process of porous GPE is introduced, and then the process is optimized. The heat performance and characterization of porous membranes were confirmed by TGA, SEM.Finally, the GPE membranes were produced by dipping porous membrane into liquid electrolyte. The electrochemical performance can be measured by electrochemical work station. The sorts and weights of the components of the gel electrolyte are optimized, and a GPE with excellent performance is prepared, whose ion conductivity reaches 4.08mS/cm, and it is electrochemically stable up to about 5.5V versus Li/Li⁺, which means the GPEs have suitable electrochemical stability to allow the use of high-voltage electrode couples such as LiCoO₂, LiNiO₂ and so on positive electrode.