Stability analysis for 5V high energy density pouch batteries of Si anode and SL/EMC electrolytes

Currently, the effective way to improve energy density of lithium ion batteries may include choosing active materials that could guarantee both high voltage and high capacity. Herein, a pouch cell of 4.8 V was assembled by stacking several layers of (−) SiOC || LiNi0.5Mn1.5O4 (LNMO) (+) electrodes. Under wide voltage windows, the stability of the non-aqueous electrolyte is a great challenge. Ethylene carbonate (EC) are commonly used in LIBs, as the electrolyte can hardly withstand the high voltage above 4.5 V, but the sulfone (SL) solvent can keep stable under such condition. Even so, the structural stability of Si-based anode has to been considered in such batteries owing to the well-known volume expansion. The FEC additive was to improve the SEI formation for Si materials, and it was added into the SL-based electrolyte to study the compatibility of full cell for the first time. For pouch cell, the tri-electrode curves were measured during discharge process. And the volume changes and gas composition were recorded by a special equipment with respect to the charge voltage and cycling. Then, a failure mechanism and gas generation of the SiOC||LNMO system in both electrolytes was deduced, and the study of full (pouch) cells can guide the practical application.