Ternary Salt–Solvent Electrolytes for 5 V-Class Anode-less Li-Metal Batteries

The anode-less lithium-metal battery stands out, due to the lowest electrochemical reduction potential of lithium, high capacity, and lightweight nature, making it an optimal choice for constructing rechargeable metal batteries. We explored a distinctive ternary salt–solvent electrolyte formulation to demonstrate an anode-less 5 V Li-metal battery. Salt and solvent components were fine-tuned to synergistically alleviate aluminum dissolution and extend the oxidative stability up to 5.2 V (vs Li/Li+) with the Li-metal interface stabilization. In a 5 V-class cobalt-free LiNi0.5Mn1.5O4–Li anode-less cell, we attained 65 cycles within 20% capacity loss by keeping a 40% Li reserve, touted as a potential next-generation battery design. The dynamical behavior of lithium metal interfaces with cycling has been analyzed through a series of surface and bulk analysis techniques. We correlate the influence of salt formulation with the composition in the negative electrode and show that the LiF dense interface is the main cause of long cycle life.