High-energy density, portable and safe energy storage remains one of the most prevalent issues in modern society. Lithium-ion batteries (LIB) are amongst the most promising options but are far from achieving their theoretical performance . Maximal energy density of lithium batteries can only be achieved by use of Li metal anodes, which enable the highest theoretical capacity (3860 mA h g -1 ) and the lowest electrochemical potential (-3.04 V vs. the standard hydrogen electrode) of all anode materials . However, current LIB electrolytes (usually LiPF6 dissolved in a ethylene carbonate/dimethyl carbonate ) are incompatible with Li metal, present with safety concerns and an inability to accommodate high V cathode materials. Hence, electrolyte optimisation, or replacement, is paramount .