Binder-induced ultrafast PF₆⁻-intercalation toward a high-voltage, high-power and long-cycling zinc–graphite dual-ion battery

Metallic zinc is an ideal anode material owing to its high theoretical capacity (819 mAh·g⁻¹), eco-friendliness, low cost and high safety, which have driven fast development of Zn-ion batteries (ZIBs). However, the practical application of current ZIBs is significantly restricted by irregular dendrite growth of zinc anode and the low working voltage (usually < 2 V) of cathode materials. Herein, we report a high-voltage Zn-based dual-ion battery (DIB), which is constructed by a graphite cathode, a Zn anode, and 3 M LiPF₆ in the ethyl methyl carbonate (EMC) electrolyte. Under the corrosion interaction of Li⁺ ions, Zn²⁺ can be easily dissolved from Zn anode into the electrolyte to enable dendrite-free Zn²⁺ plating/stripping at the anode. Moreover, an aqueous carboxymethyl cellulose (CMC) binder is employed to generate a robust cathode electrolyte interface (CEI) layer on the graphite cathode, which renders ultrafast PF₆⁻-de-/intercalation into graphite. The resultant Zn–graphite DIB operates stably at a high cut off voltage of 3.2 V, corresponding to an average output voltage of 2.2 V. After 9000 cycles at 5 C, the high capacity retention of 95.9% can be achieved with ~ 100% Coulomb efficiency. Based on the mass of cathode material, our Zn–graphite battery exhibits ultrafast rate capability (60 C, a discharge time of 44 s) and high energy/power densities (208 Wh·kg⁻¹ at 214 W·kg⁻¹; 142 Wh·kg⁻¹ at 8692 W·kg⁻¹), which holds great promise for large-scale energy storage.