Ultrafast Rechargeable Zinc Battery Based on High-Voltage Graphite Cathode and Stable Nonaqueous Electrolyte

Zinc-based battery chemistries have lately drawn great attention for grid-scale energy storage due to their material abundance and high safety. However, the low Coulombic efficiency (CE) and dendrite growth of zinc (Zn) anodes and the limited working voltage of current oxide cathodes are the major barriers hindering the development of rechargeable Zn-based batteries (RZBs). Here, we report an ultrafast and high-voltage Zn battery in a new cell configuration employing a graphite cathode, a Zn anode, and nonaqueous 1 M zinc bis(trifluoromethylsulfonyl)imide (Zn(TFSI)2) in acetonitrile (AN) electrolyte. This RZB operates through the (de)intercalation of TFSI– anions into the graphite and the electrochemical Zn2+ plating/stripping at the anode. The optimized Zn(TFSI)2/AN electrolyte features high reductive/oxidative stability, good ionic conductivity (∼28 mS cm–1), and low viscosity (∼0.4 mPa·s), enabling the unprecedented cycling stability (over 1000 h) of the Zn anode with a dendrite-free morphology, the ultrafast Zn plating/stripping with a high CE (>99%), and the good compatibility with the graphite cathode. Consequently, this RZB exhibits a high average output voltage (2.2 V), a high energy/power density (86.5 Wh kg–1 at 4400 W kg–1), and a long cycle life (97.3% capacity retention after 1000 cycles). The present work offers new insights and opportunities to the Zn-based electrochemistry.