Feasibility of an interpenetrated polymer network system made of Di-block copolymer composed of polyethylene oxide and polystyrene as the gel electrolyte for lithium secondary batteries

The feasibility of a di-block copolymer, composed of a polyethylene oxide (PEO) chain and a polystyrene (PS) chain covalently bonded, as the gel electrolyte for lithium secondary batteries was investigated. The PEO-PS di-block copolymer gel electrolyte showed a high ionic conductivity of∼ 1 mS/cm at room temperature. Moreover, it retained good mechanical strength within a co-continuous phase separated structure, and it suppressed the dendritic deposition of Li. Indications were that the interface between the electrolyte and the Li metal was chemically stable, as a result of the PEO phase fixed to PS by covalent bonding. In addition, it was indicated that the Li/PEO-PS di-block copolymer gel electrolyte/LiFeP0₄ cell had a high charge-discharge efficiency of∼99% during 30 cycles, while maintaining a discharge capacity of 124 mAh/g.