Slightly Li-enriched chemistry enabling super stable LiNiMnO cathodes under extreme conditions.

High voltage/high temperature operation aggravates the risk of capacity attenuation and thermal runaway of layered oxide cathodes due to crystal degradation and interfacial instability. A combined strategy of bulk regulation and surface chemistry design is crucial to handle these issues. Here, we present a simultaneous LiWO-coated and gradient W-doped 0.98LiNiMnO·0.02LiWO cathode through modulating the content of the exotic dopant and stoichiometric lithium salt during lithiation calcination. Benefiting from the slightly Li-enriched chemistry induced by the hetero-epitaxially grown LiWO surface, the 0.98LiNiMnO·0.02LiWO cathode demonstrates superior electrochemical performance to W-doped LiNiMnWO and WO coated 0.98LiNiMnO·0.02WO cathodes without a Li-enriched phase. Specifically, when cycled in the potential range of 2.7-4.5 V at 30 °C, the 0.98LiNiMnO·0.02LiWO cathode possesses a high discharge capacity of 199.2 and 156.5 mA h g at 0.1 and 5C and a capacity retention of 92.88% after 300 cycles at 1C. Even at a high cut-off voltage of 4.6 V, it still retains a capacity retention of 91.15% after 200 cycles at 1C and 30 °C. Compared with LiNiMnO, the enhanced performance of 0.98LiNiMnO·0.02LiWO can be attributed to its robust bulk and stable interface, inhibited lattice oxygen release, and improved Li transport kinetics. Our work emphasizes the significance of the slightly Li-enriched chemistry and bulk modulation strategy in stabilizing cathodes and hence unlocks vast possibilities for future cathode design.