▎ 摘　　要

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 Co3O4@graphene (Co3O4@G) composite is prepared via a simple hydrothermal method and first evaluated at subzero temperatures. Benefitting from the especially suitable lithiation/delithiation potentials of Co3O4, ingenious nanostructure and high conductivity of graphene, the Co3O4@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 degrees 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 degrees C. Furthermore, very high capacities of similar to 920.4 mAh g(-1) (0.2 A g(-1)) can be maintained at 30 degrees C, and similar to 450.2 mAh g(-1) (0.5 A g(-1)) can be remained at -20 degrees C during alternating cycling. This work demonstrates that conversion-type Co3O4@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.