Stable Lithium Storage at Subzero Temperatures for High‐capacity Co 3 O 4 @graphene Composite Anodes

Achieving high energy density and long‐term stability at subzero temperatures remains one of the main challenges for the development of lithium‐ion batteries. Shortcomings in energy density and stability mainly highlight on the increase in internal resistance and electrode polarization at subzero temperatures, which greatly affect the reversible capacities of lithium‐ion batteries. In this work, a conversion type Co 3 O 4 @graphene (Co 3 O 4 @G) composite is prepared via a simple hydrothermal method and first evaluated at subzero temperatures. Benefitting from the especially suitable lithiation/delithiation potentials of Co 3 O 4 , ingenious nanostructure and high conductivity of graphene, the Co 3 O 4 @G anode exhibits much higher capacity retentions than intercalation‐ and alloying‐type anodes at subzero temperatures, with 58.4% of room‐temperature capacity retention at −30 °C for initial cycle and a highly stable reversible capacity of 605.0 mAh g −1 (0.5 A g −1 ) for 600 cycles at −10 °C. Furthermore, very high capacities of ∼920.4 mAh g −1 (0.2 A g −1 ) can be maintained at 30 °C, and ∼450.2 mAh g −1 (0.5 A g −1 ) can be remained at −20 °C during alternating cycling. This work demonstrates that conversion‐type Co 3 O 4 @G composites have superior extreme temperature lithium storage capabilities and can be viable Li‐ion anode materials with fast and highly efficient ion/electron transport capacity at subzero operating temperatures.