Interfacial design towards stable zinc metal-free zinc-ion batteries with high energy density

Zinc metal-free zinc-ion batteries hold promise for achieving higher energy densities by eliminating the need for dense zinc foil as the anode. However, the direct use of substrates like copper foil in these batteries results in poor cyclic stability due to dendrite growth. Herein, we propose a strategy to modulate the nucleation sites and growth dynamics of Zn. This is achieved by introducing a graphene coating on the copper substrate, which directs the initial nucleation of Zn to form hexagonal plates. Subsequently, the incorporation of positively polarized poly(vinylidene fluoride-trifluoroethylene) promotes growth along these hexagonal plates, resulting in uniform crystalline plates. As a result, the half-cell demonstrated a significant improvement in the cyclic life of 3000 cycles at a high current density of 10 mA cm-2 and capacity of 1 mA h cm-2. When paired with Zn-inserted MnO2 cathode, the full cell exhibited high cyclic stability (retaining 83% capacity after 500 cycles at 1 mA cm-2) and energy density of 378 W h kg-1 at 0.5 mA cm-2. This is notably higher than the conventional Zn ion battery based on a Zn anode (136 W h kg-1). To showcase its potential, we prepared a pouch cell that successfully powered the electric fan and LED lights, suggesting its promising application in high-performance Zn ion batteries. Graphene and positively polarized P(VDF-TrFE) assist in controlling Zn nucleation and growth on a Cu substrate, enabling high-performance zinc metal-free zinc-ion batteries.