Vertical Graphene Film Enables High-Performance Quasi-Solid-State Planar Zinc-Ion Microbatteries

With the advantages of low cost, high safety, and environmental friendliness, quasi-solid-state zinc-ion microbatteries (ZIMBs) have received widespread attention in the field of flexible wearable devices and on-chip integratable energy storage. However, hysteresis Zn-ion transport kinetics and inhomogeneous growth of the zinc anode result in the poor capacity reversibility and cycling stability. Herein, a quasi-solid-state planar zinc-ion cell was developed by employing a vertical graphene (VG) film as an effective conductive modification layer for both the cathode and anode. The VG distinctly induces uniform Zn deposition/stripping, accelerates the charge transport, and enhances the adhesion between the active materials and current collectors. As a result, planar Zn@VG//MnO₂@VG exhibits a high areal capacity of 159 μAh cm^-2, a remarkably high areal energy/power density of 201.5 μWh cm^-2/67.16 μW cm^-2, and a high capacity retention of 95.6% at a bending angle of 180°. The proposed facile strategy for electrode modification provides a new insight into the design of high-performance flexible and planar ZIMBs.