An Anode-Free Zn-Graphite Battery.

Abstract

The anode-free battery concept is proposed to pursue the aspiration of energy-dense, rechargeable metal batteries, but this has not been achieved with dual-ion batteries. Herein, the first anode-free Zn-graphite battery enabled by efficient Zn plating-stripping onto a silver-coated Cu substrate is demonstrated. The silver coating guides uniform Zn deposition without dendrite formation or side reaction over a wide range of electrolyte concentrations, enabling the construction of anode-free Zn cells. In addition, the graphite cathode operates efficiently under reversible bis(trifluoromethanesulfonyl)imide anion (TFSI^- ) intercalation without anodic corrosion. An extra high-potential TFSI^- intercalation plateau is recognized at 2.75 V, contributing to the high capacity of graphite cathode. Thanks to efficient Zn plating-stripping and TFSI^- intercalation-deintercalation, an anode-free Zn-graphite dual-ion battery that exhibits impressive cycling stability with 82% capacity retention after 1000 cycles is constructed. At the same time, a specific energy of 79 Wh kg^-1 based on the mass of cathode and electrolyte is achieved, which is over two times higher than conventional Zn-graphite batteries (<30 Wh kg^-1 ).