Elevated temperature performance of high voltage Li1+yMn1.5Ni0.5O4−xFx spinel in window-shifted Li-ion cells

Although the LiMn1.5Ni0.5O4 spinel operating at 4.7 V presents some beneficial characteristics over more traditional positive electrode materials, instability issues at elevated temperature have limited its practical use so far. While we previously proposed Li1+yMn1.5Ni0.5O4−xFx (LMNOF) spinel that is intrinsically stable at elevated temperatures in Li-excess half-cell configuration, we investigate herein fixed, non-excess Li-content window-shifted Li-ion systems. By utilizing Li4Ti5O12 (LTO) or TiS2 negative electrodes stable in broad electrolyte compositions instead of carbonaceous electrodes, we aim at limiting the Li-consuming side reactions such as the formation of solid-electrolyte interphase and enable a focus on the exploration of electrolyte compositions including additives. Utilizing such an approach, excellent fundamental stability of LMNOF in a fixed Li-content Li-ion environment is demonstrated at 55 °C with the use of relatively common electrolyte components. •Li1+yMn1.5Ni0.5O4−xFx shows good 55 °C cycling in Li-ion window-shifted systems.•LMNOF/TiS2 achieves 80% capacity after 500 cycles at 55 °C in carbonate electrolytes.•LiBF4 salt improves 55 °C cycling of LMNOF/LTO cells compared to LiPF6 in carbonates.•Poly(2-vynilpyridine) additive boots LMNOF/LTO cycling at 55 °C in LiBF4 electrolyte.•TiS2-system further enhances cycling stability at 55 °C over LTO with LMNOF.