Design Principles of Sodium/Potassium Protection Layer for High-Power High-Energy Sodium/Potassium-Metal Batteries in Carbonate Electrolytes: a Case Study of Na Te/K Te.

The sodium (potassium)-metal anodes combine low-cost, high theoretical capacity, and high energy density, demonstrating promising application in sodium (potassium)-metal batteries. However, the dendrites' growth on the surface of Na (K) has impeded their practical application. Herein, density functional theory (DFT) results predict Na Te/K Te is beneficial for Na /K transport and can effectively suppress the formation of the dendrites because of low Na /K migration energy barrier and ultrahigh Na /K diffusion coefficient of 3.7 × 10 cm s /1.6 × 10 cm s (300 K), respectively. Then a Na Te protection layer is prepared by directly painting the nanosized Te powder onto the sodium-metal surface. The Na@Na Te anode can last for 700 h in low-cost carbonate electrolytes (1 mA cm , 1 mAh cm ), and the corresponding Na V (PO ) //Na@Na Te full cell exhibits high energy density of 223 Wh kg at an unprecedented power density of 29687 W kg as well as an ultrahigh capacity retention of 93% after 3000 cycles at 20 C. Besides, the K@K Te-based potassium-metal full battery also demonstrates high power density of 20 577 W kg with energy density of 154 Wh kg . This work opens up a new and promising avenue to stabilize sodium (potassium)-metal anodes with simple and low-cost interfacial layers.