Interfacial high-concentration electrolyte for stable lithium metal anode: Theory, design, and demonstration

Lithium metal anodes hold great potential for high-energy-density secondary batteries. However, the uncontrollable lithium dendrite growth causes poor cycling efficiency and severe safety concerns, hindering lithium metal anode from practical application. Electrolyte components play important roles in suppressing lithium dendrite growth and improving the electrochemical performance of long-life lithium metal anode, and it is still challenging to effectively compromise the advantages of the conventional electrolyte (1 mol·L⁻¹ salts) and high-concentration electrolyte (> 3 mol·L⁻¹ salts) for the optimizing electrochemical performance. Herein, we propose and design an interfacial high-concentration electrolyte induced by the nitrogen- and oxygen-doped carbon nanosheets (NO-CNS) for stable Li metal anodes. The NO-CNS with abundant surface negative charges not only creates an interfacial high-concentration of lithium ions near the electrode surface to promote charge-transfer kinetics but also enables a high ionic conductivity in the bulk electrolyte to improve ionic mass-transfer. Benefitting from the interfacial high-concentration electrolyte, the NO-CNS@Ni foam host presents outstanding electrochemical cycling performances over 600 cycles at 1 mA·cm⁻² and an improved cycling lifespan of 1,500 h for symmetric cells.