Decomposition of Li2O2 as the Cathode Prelithiation Additive for Lithium-Ion Batteries without an Additional Catalyst and the Initial Performance Investigation

Abstract

Compared to the graphite anode, Si and SiOx-containing anodes usually have a larger initial capacity loss (ICL) due to more parasitic reactions. The higher ICL of the anode can cause significant Li inventory loss in a full cell, leading to a compromised energy density. As one way to mitigate such Li inventory loss, Li2O2 can be used as the cathode prelithiation additive to provide additional lithium. However, an additional catalyst is usually needed to lower its decomposition potential. In this work, we investigate the use of Li2O2 as the cathode prelithiation additive without the addition of a catalyst. Li2O2 decomposition is first demonstrated in coin half-cells with a calculated capacity of 1180 mAh g−1 obtained from Li2O2 decomposition. We then further demonstrate successful Li2O2 decomposition in single-layer pouch (SLP) full cells and evaluate the initial electrochemical performance. Despite its moisture sensitivity, Li2O2 showed reasonable compatibility with dry-room handling. After dry-room handling, Li2O2 decomposition was observed with an onset potential of 4.29 V vs SiOx anode in SLP cells. With Li2O2 addition, the utilization of the Li inventory from cathode active material was improved by 12.9%, and discharge DCR was reduced by 7% while the cells still delivered similar cell capacities. Cycle performance is not evaluated in this paper due to the high cutoff voltage used, but the factors affecting the cycle performance are discussed. Strategies to further improve the practical use of Li2O2 are also discussed.