Lithium trapping induced memory effect of Gr/SiOx blend anodes in lithium-ion batteries subjected to repeated partial cycling

The use of silicon-based secondary anode materials in blend anodes alongside graphite is becoming increasingly prevalent in commercial lithium-ion batteries also used more and more in automotive applications. In addition to the accelerated degradation of silicon due to its significant volume expansion, the crystalline phase transition of fully lithiated silicon results in alterations to the voltage profile during discharging. This study examines the impact of this phase transition on the operation and state estimation of battery cells using such silicon-containing graphite/SiOx blend anodes. A memory effect of trapping lithium in the crystalline phase occurs when the cell is subjected to partial cycling without being fully discharged. However, this effect can be cancelled out by a single deep discharge. To gain further insights, a variation in cycle numbers, state of charge range during cycling, charge and discharge current, and the operation temperature is conducted. In order to validate the findings, a variety of commercial and automotive cells and blend anode half-cells are analyzed.