Operando pressure measurements monitor the degradation of SiOx/C anode for Li-ion cells

Abstract

Monitoring on the degradation of the capacity is important to ensure the normal operation of the Li-ion cells. Herein, operando pressure measurement, an in-situ and real-time non-destructive method, is developed to monitor the degradation of SiOx/C anode. Combined with the potentials of the anode and cathode, the relationship between the cell pressure change and the internal reaction in cell is firstly established. Furthermore, the differential pressure (dP/dQ) possesses the ability to quantitatively distinguish the capacity of SiOx from total capacity, due to difference in volume change between SiOx and C during discharge. And then this powerful operando pressure method is used in the cells with two different binders, Carboxy Methyl Cellulose + Polymerized Styrene Butadiene Rubber (CMC + SBR) and Poly(Acrylic Acid)-based (PAA-based) binder, respectively. Based on the monitoring of the pressure and dP/dQ, the contribution and degradation of SiOx and C are clearly known in the cases of two binders, i.e., the capacity degradation of SiOx is only 1.7% for PAA-based binder after 500 cycles while 9.58% for CMC + SBR. Operando pressure method paves the wave for the in-situ and in real time monitoring the silicon-contained Li-ion cells.