Artificial Solid-Electrolyte Interphase Enabled High-Capacity and Stable Cycling Potassium Metal Batteries

Secondary batteries based on earth-abundant potassium metal anodes are attractive for stationary energy storage. However, suppressing the formation of potassium metal dendrites during cycling is pivotal in the development of future potassium metal-based battery technology. Herein, a promising artificial solid-electrolyte interphase (ASEI) design, simply covering a carbon nanotube (CNT) film on the surface of a potassium metal anode, is demonstrated. The results show that the spontaneously potassiated CNT framework with a stable self-formed solid-electrolyte interphase layer integrates a quasi-hosting feature with fast interfacial ion transport, which enables dendrite-free deposition of potassium at an ultrahigh capacity (20 mAh cm(-2)). Remarkably, the potassium metal anode exhibits an unprecedented cycle life (over 1000 cycles, over 2000 h) at a high current density of 5 mA cm(-2) and a desirable areal capacity of 4 mAh cm(-2). Dendrite-free morphology in carbon-fiber and carbon-black-based ASEI for potassium metal anodes, which indicates a broader promise of this approach, is also observed.