Building multifunctional Cu2Se@biomass carbon composite interfacial layer on zinc anode towards stable aqueous zinc-ion batteries

Abstract

Aqueous zinc ion batteries (AZIBs) become the most promising candidates for grid-scale energy storage applications due to their high safety, environmental benignity, low price, and high capacity. However, the uncontrolled Zn dendrite growth severely damages the stability of Zn anodes, which greatly hinders the practical application of AZIBs. Biomass carbon materials are of interest due to their wide range of sources, sustainability, low cost, and environmental friendliness. In recent years, biomass carbon has also been reported for zinc anode protection. In this study, a multifunctional interface layer of Cu2Se@biomass carbon (Cu2Se@BC) was first constructed to improve the structural stability of Zn anodes. First, the low bandgap of Cu2Se and the high conductivity of BC can promote formation of homogenous electric field and improve diffusion kinetics of zinc ions. Moreover, the (111) crystal plane of Cu2Se@BC exhibits the lowest adsorption energy and apparent charge transfer efficiency, revealing strong capturing zinc ions capacity, which is favorable for promoting homogenous zinc ion fluxes. Finally, it was demonstrated by a combination of experimental characterizations and theoretical calculations that the diffusion energy barrier of zinc ions towards the Zn(002) crystal plane is the lowest compared to the Zn(100) and Zn(101) crystal planes, which empowers Cu2Se@BC to be capable of inducing zinc ions to preferentially orientation at the Zn(002) crystal plane, therefore greatly inhibits the growth of Zn dendrites. Thanks to these advantages, the assembled symmetric cell containing Cu2Se@BC obtained a cycle life of to 2100 h at 1 mA cm−2 and 0.15 mAh cm−2, while exhibiting low voltage hysteresis. When this anode was assembled with the VO2 cathode, the full battery obtained capacity retention of 78.6% and coulomb efficiency (CE) close to 100% even after 4800 cycles at 5.0 A g−1. This work adequately promotes the promising application of Cu2Se@biomass carbon in protecting the stability of Zn anodes and provides a viable approach to achieve excellent electrochemical performance of AZIBs.