Enhanced cycleability and dendrite-free lithium deposition by addition of sodium ion in electrolyte for lithium metal batteries

Highlights: • Na⁺ addition to electrolyte significantly improves the morphology and cycleability of Li metal anode. • Explanation of the functions and mechanism of Na⁺ addition to the electrolyte. • Demonstration of Li–Na co–deposition and co–stripping processes occur during cycles. The effects of adding sodium (Na) ion into lithium (Li) ion containing organic electrolyte on the cycle behaviors of Li deposition–stripping on Li₂₂Sn₅ substrate are investigated. The functions and mechanism of Na⁺ addition to the electrolyte are evaluated through scanning electron microscopy, inductively coupled plasma-atomic emission spectrometry, element mapping, energy dispersive spectrometer, electrochemical impedance spectroscopy, and cyclic voltammetry analyses. The results show that Li–Na co–deposition and co–stripping processes occur during cycles. Utilizing Li–Na co–deposition/stripping reactions to replace the reactions of single Li in organic electrolyte is an effective way to inhibit Li dendrite growth and improve the cycling performance of Li anode in Li metal batteries.