High-capacity and long-life lithium storage boosted by pseudocapacitance in three-dimensional MnO-Cu-CNT/graphene...

Boosting the lifespan of MnO-based materials for future lithium ion batteries is one of the primary challenges due to the intrinsic low ionic conductivity and volume expansion during the conversion process. Herein, superior lithium storage in a new quaternary MnO-Cu-CNT/graphene composite has been demonstrated, which is boosted by pseudocapacitance benefitting from the three-dimensional CNT/graphene and nanosized Cu additives. Such architecture offers highly interpenetrated porous conductive networks in intimate contact with MnO-Cu grains and abundant stress buffer space for effective charge transport upon cycling. The ternary MnO-Cu-graphene electrode contributes an ever-increasing reversible capacity of 938.3 mA h g^-1 after 800 cycles at 0.8 A g^-1. In particular, the quaternary MnO-Cu-CNT/graphene electrode demonstrates a high specific capacity of 1334 mA h g^-1 at 0.8 A g^-1 after 800 cycles and long lifetimes of more than 3500 cycles at 5 A g^-1 with a capacity of 557.9 mA h g^-1 and close-to-100% Coulombic efficiency. The boosted pseudocapacitive lithium storage together with the simple material fabrication method in a MnO-Cu-CNT/graphene hybrid could pave the way for the development of high-capacity and long-life energy storage devices.