Heterogeneous nucleation of Li3VO4 regulated in dense graphene aerogel for lithium ion capacitors

Abstract

Achieving both high gravimetric and volumetric rate performances of the anode for lithium ion capacitors (LICs) is still a challenge. Herein, we propose a dense Li3VO4 (LVO)/graphene aerogel (GA) composite as the two active components anode, the crystalline and particle size of LVO can be regulated in the GA that provides abundant heterogeneous nucleation sites to prevent the agglomeration and preferred growth of LVO. The dense LVO/GA exhibits significantly improved electrochemical performances. The gravimetric/volumetric specific capacity can reach up to 84.4 mAh g−1 and 63.3 mAh cm−3 at the very high current density of 16 A g−1, as well as the 85% capacity retention after 5000 cycles at 8 A g−1. This superior performance is contributed from the facilitated diffusion rate of confined LVO clusters in GA, the accelerated electron transport offered by the three dimensional (3D) graphene skeleton that closely surrounds LVO, and the fast electrochemical kinetics boosted by the combined dense structure. The LICs exhibit excellent energy/power densities (maximum 122.2 W h kg−1, 8.8 kW kg−1). We believe that this two active components design demonstrates an unparalleled function that the single active material cannot realize, and provide a promising road propelling the development of high performance LICs.