Synergistical Stabilization of Li Metal Anodes and LiCoO₂ Cathodes in High-Voltage Li∥LiCoO₂ Batteries by Potassium Selenocyanate (KSeCN) Additive

Dramatic growth of lithium (Li) dendrite and structural deterioration of LiCoO2 (LCO) lead to rapid failure of a high-voltage Li∥LCO battery. The nitrile group (−C≡N) is beneficial to maintain the integrity of the LCO lattice due to its strong affiliation to Co ions, whereas the −C≡N bond is incompatible with the Li metal anode, leading to form a deleterious solid electrolyte interphase (SEI) film. Herein, a dual-functional electrolyte additive potassium selenocyanate (KSeCN) is introduced to construct stable and dense SEI/cathode electrolyte interphase (CEI) films by synergistic effects with −Se and −C≡N groups, resulting in uniform Li deposition and a stabilized LCO lattice during cycling. With a trace amount of KSeCN (0.1 wt %) in conventional carbonated electrolyte, the Li∥LCO battery exhibits promoted cycling performance at high charge cutoff 4.6 V. This work provides a strategic guidance for rational design of electrolyte to construct stable SEI and CEI films, to achieve a high-energy-density Li∥LCO battery with great performance.