Stable wide-temperature and low volume expansion Al batteries: Integrating few-layer graphene with multifunctional cobalt boride nanocluster as positive electrode

To achieve stable positive electrode for promoting the overall electrochemical performance of Al batteries (ABs), here novel cobalt boride (CoB) nanoclusters are synthesized to construct composite electrodes with few-layer graphene (FLG). Due to the presence of amorphous channels in the employed CoB nanoclusters, the ABs with FLG/CoB composite positive electrodes exhibit high rate capability and both mechanical and electrochemical stability in the ABs. With assistance of in situ scanning electron microscopy (SEM), the observation results suggest that the positive electrode of CoB nanoclusters holds almost ignorable volume variation upon electrochemical processes, which substantially alleviates the massive electrode expansion induced by the anion intercalation in the composite positive electrode. Interestingly, the composite positive electrodes provide stable reversible energy storage capability within a broadened temperature range (-30-60 °C), promising a novel strategy to design advanced ABs positive electrodes with enhanced overall energy storage performance.