锂离子电池用离子塑性晶体-离子液体聚合物全固态电解质

Novel ionic plastic crystal-polymeric ionic liquid all-solid-state electrolytes for lithium ion batteries

离子塑性晶体作为一类新型的固态电解质材料,近年来受到研究人员的极大关注。本文合成了一种新型离子塑性晶体:N,N-二甲基吡咯双氟磺酰亚胺(P11FSI),并将其与吡咯阳离子离子液体聚合物-聚二甲基二烯丙基铵双氟磺酰亚胺(PILFSI)和锂盐(LiFSI)复合制备了P_(11)FSI-PILFSI-LiFSI全固态电解质。采用差示扫描量热法、热重分析、阻抗测试、线性扫描伏安法及对称锂电池测试等一系列表征技术对全固态电解质的热性能和电化学性能进行了系统研究。所制备的电解质膜具有好的柔韧性和热稳定性,高的离子电导率和电化学稳定性,以及与金属锂良好的界面相容性。将全固态电解质应用于Li/LiFePO_4电池中,在50℃、0.2 C充放电倍率时,电池放电比容量在60次循环后仍可达151.1 mA·h/g,容量保持率为96.8%;且在0.5 C、1.0 C倍率下放电比容量仍然高达138.1mA·h/g和128.1mA·h/g,展现出高的放电比容量,好的循环性能和倍率性能,有望应用于全固态锂离子电池中。

As a kind of new solid electrolyte materials, ionic plastic crystals have received much attention in recent years. In this paper, a novel ionic plastic crystal N, N-dimethylpyrrolidinium bis（fluorosulfonyl）imide （P11FSI） was firstly synthesized, and blended with pyrrolidinium-based polymeric ionic liquid （PILFSI） and lithium salt （LiFSI） to obtain a series of new solid electrolytes.The thermal and electrochemical properties of as-prepared solid electrolytes are investigated by differential scanning calorimeter, thermogravimetric analysis, impedance spectroscopy measurements, linear sweep voltammetry and symmetrical lithium cell test. The as-prepared solid electrolytes exhibit good flexibility and thermal stability, high ionic conductivity and electrochemical stability, as well as good compatibility with the lithium metal. Particularly, Li/LiFePO4 cells assembled with as-obtained solid electrolytes present high discharge capacity （151.1 mA.h.g 1）, good cycle life and rate performance. This finding indicates that the solid electrolyte system obtained in our work has great potential for use in all-solid-state lithium ion batteries.