An Interphase-enhanced Liquid Na-K Anode for Dendrite-free Alkali Metal Batteries Enabled by SiCl4 Electrolyte Additive

Abstract

Thanks to the high theoretical capacity and low redox potential, alkali metals (Li, Na, K) show great superiority as anodes for high-energy-density rechargeable batteries. However, practical application of alkali metal battery (AMB) is limited due to its formidable dendrite growth. Liquid Na-K alloy is a promising choice to fulfill long-term cyclability of AMB due to its liquid characteristics. Nevertheless, the instability of electrolyte/liquid Na-K interface is still a challenge for the dendrite-free deposition/stripping. In this work, a stable organic/inorganic hybrid interface beneficial to improving the charge-transfer kinetics is formed on the liquid alloy with the assistance of SiCl4 electrolyte additive. The symmetric cell using interface-modified Na-K alloy electrode maintains an overpotential below 200 mV over 2000 h at 1mA cm−2 with 1mAh cm−2 for each cycle. The Na3V2(PO4)3 cathode coupled with interface-modified Na-K alloy shows a capacity of 91.5 mAh g−1 at 30 C, and remains 103.6 mAhg−1 after 1000 cycles at 2 C with nearly no capacity loss per-cycle. This work presents a facile approach for developing dendrite-free liquid alloy anodes and possesses potential application in liquid metal (LM)-related battery system with high energy density.