PNNL

Abstract

Cation disordered rocksalt (DRX) cathodes have recently emerged as a promising class of cobalt-free, high-capacity cathodes for lithium-ion batteries. To facilitate their commercialization, the development of scalable synthesis techniques providing control over composition and morphology is critical. To this end, we present a sol-gel synthesis route to prepare Mn-rich DRX cathodes with high capacities. Several compositions with varied Mn content and nominal F doping are successfully prepared using this technique. In-situ X-ray diffraction measurements demonstrate that DRX formation proceeds at moderate temperature (800 °C) when using sol-gel synthesis, which enables intimate mixing among reactive intermediate phases that form at lower temperature. All synthesized compositions possess cation short-range order, as evidenced by neutron pair distribution function and electron diffraction analysis. These DRX materials demonstrate promising electrochemical performance with reversible capacities up to 275 mAh/g. Compared to the baseline oxide (Li1.2Mn0.4Ti0.4O), the Mn-rich compositions exhibit improved cycling stability, with some even demonstrating an increase in capacity upon cycling. The current study demonstrates the feasibility of sol-gel based synthesis route for the preparing high capacity DRX cathodes, and points to the possibility for improved control over product morphology with further optimization of the synthesis procedure.