Propanediol Cyclic Sulfate as An Electrolyte Additive to Improve the Cyclic Performance of LiNi0.6Co0.1Mn0.3O2/Graphite Pouch-Cell at High Voltage

Abstract

By using Ni-rich material (LiNixCoyMnzO2, x+y+z=1) as cathode electrode, the energy density of lithium-ion batteries can be increased. However, the electrode/electrolyte interface instability of Ni-rich cathode at high voltage will adversely affect the cycle performance and limit its practical application. In this paper, propanediol cyclic sulfate (PCS) is proposed as a functional additive to improve the cycling stability of LiNi0.6Co0.1Mn0.3O2/graphite battery. After adding 3.0 wt.% PCS to the baseline electrolyte, the capacity retention of the batteries improves from 9.6 % to 86.5 % after 150 cycles at the voltages of 3.0–4.5 V. Based on the theoretical calculation and experimental result, the main reason for the improvement of electrochemical performance is that the PCS forms a highly stable sulfur-containing compound interface layer (SEI/CEI) on the electrode surface, which can not only inhibit electrolyte decomposition and interface impedance increase, but also reduce transition metal dissolution. This work has given some ideas for the practical utilization of high-voltage LiNi0.6Co0.1Mn0.3O2/graphite pouch-cells.