PNNL

Abstract

Lithium (Li)-rich transition metal oxide cathodes with cation disordered rock salt structure (DRX) are increasingly gaining popularity for advanced Li batteries as they offer high capacity and cost benefits over the commonly used layered lithium transition metal oxide cathodes. However, the performance of DRX cathodes and their applications are limited by severe side reactions between the cathode and the state-of-the-art carbonate-based electrolytes, transition metal dissolution and structural instability of the cathode particles. In this work, an advanced localized high-concentration electrolyte (LHCE) is developed to form a stable cathode-electrolyte interphase and mitigate structural instability of Li1.2Mn0.6Ti0.2O2 (LMTO) DRX during electrochemical cycling. Li||LMTO half cells with the developed LHCE demonstrate increased capacity, cycling stability and superior rate capabilities compared with cells with the conventional electrolyte. For instance, the Li||LMTO cells cycled in LHCE show higher initial capacity of 205.2 mAh g?1, and a capacity retention of 72.5 % in contrast to an initial capacity of 187.7 mAh g?1 and a capacity retention of 19.9 % observed in Li||LMTO cells with the conventional electrolyte after 200 cycles at a current density of 20 mAh g?1. This work paves the way for the development of practical DRX cathode-based high-energy Li batteries.