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

Abstract

Aqueous zinc-ion batteries (AZIBs) have become the most promising candidates for grid-scale energy storage applications due to their high safety, environmental benignity, low price, and high capacity. However, uncontrolled Zn dendrite growth severely damages the stability of Zn anodes, which greatly hinders the practical application of AZIBs. Biomass carbon materials are of great 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 interfacial layer of Cu₂Se@biomass carbon (Cu₂Se@BC) was constructed for the first time to improve the structural stability of Zn anodes. First, the low bandgap of Cu₂Se and the high conductivity of BC can promote the formation of a homogeneous electric field and improve the diffusion kinetics of zinc ions. Moreover, the (111) crystal plane of Cu₂Se@BC exhibits the lowest adsorption energy and the highest apparent charge transfer efficiency, revealing a strong zinc-ion capturing capacity, which is favorable for promoting homogeneous zinc-ion fluxes. Finally, it was demonstrated by a combination of experimental characterization and theoretical calculations that the diffusion energy barrier of zinc ions towards the Zn(002) crystal plane is lower than that of the Zn(100) and Zn(101) crystal planes, which empowers Cu₂Se@BC to be capable of inducing zinc ions to preferentially orient on the Zn(002) crystal plane, therefore greatly inhibiting the growth of Zn dendrites. Thanks to these advantages, the assembled symmetric cell containing Cu₂Se@BC exhibited a cycle life of up to 2100 h at 1 mA cm⁻² and 0.15 mA h cm⁻² while exhibiting low-voltage hysteresis. When this anode was assembled with a VO₂ cathode, the full battery exhibited a capacity retention of 78.6% and a coulombic 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 maintaining the stability of Zn anodes and provides a viable approach for achieving excellent electrochemical performance of AZIBs.