Solid Electrolyte Based on Succinonitrile and LiBOB

Abstract

This paper reports physical and electrochemical properties of a solid electrolyte for lithium batteries formed by doping a plastic crystal solvent, succinonitrile, with lithium bioxalato borate (LiBOB)(LiBOB) . Thermal properties, solubility limits, conductivity, compatibility with lithium, and range of electrochemical stability have been studied. Succinonitrile doped with 4mol%4mol% LiBOBLiBOB is a solid at room temperature and melts near 50°C50°C . Electrochemical cells employing either LiFePO4LiFePO4 or Li1.2Mn0.4Ni0.3Co0.1O2Li1.2Mn0.4Ni0.3Co0.1O2 as the active cathode material and lithium metal as the anode were evaluated. This solid electrolyte showed excellent performance when combined with a LiFePO4LiFePO4 cathode, delivering a reversible discharge capacity of ∼142mAhg−1∼142mAhg−1 with very good capacity retention. However, with the Li1.2Mn0.4Ni0.3Co0.1O2Li1.2Mn0.4Ni0.3Co0.1O2 cathode, the cell’s capacity retention was not as good exhibiting a discharge capacity that decreased from 194mAhg−1194mAhg−1 in the first cycle to 149mAhg−1149mAhg−1 at 20th cycle.