Design Principles of Sodium/Potassium Protection Layer for High-Power High-Energy Sodium/Potassium-Metal Batteries in Carbonate Electrolytes: a Case Study of Na2Te/K2Te

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 Na2Te/K2Te 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 x 10(-10) cm(2) s(-1)/1.6 x 10(-10) cm(2) s(-1) (300 K), respectively. Then a Na2Te protection layer is prepared by directly painting the nanosized Te powder onto the sodium-metal surface. The Na@Na2Te anode can last for 700 h in low-cost carbonate electrolytes (1 mA cm(-2), 1 mAh cm(-2)), and the corresponding Na3V2 (PO4)(3)//Na@Na2Te full cell exhibits high energy density of 223 Wh kg(-1) at an unprecedented power density of 29687 W kg(-1) as well as an ultrahigh capacity retention of 93% after 3000 cycles at 20 C. Besides, the K@K2Te-based potassium-metal full battery also demonstrates high power density of 20 577 W kg(-1) with energy density of 154 Wh kg(-1). This work opens up a new and promising avenue to stabilize sodium (potassium)-metal anodes with simple and low-cost interfacial layers.

Automated summary

The study demonstrates that Na2Te/K2Te can improve Na+/K+ transport and suppress dendrite formation, offering a promising way to stabilize sodium (potassium)-metal anodes.