Weakening solvent polarity enables shuttle-effect-free and temperature-independent lithium-organic batteries

Abstract

Lithium-organic batteries feature transition-metal-free cathode, resource sustainability and low cost, showing great potential to be substitutes for lithium-ion batteries that greatly depend on scarce natural resources. However, lithium-organic batteries are plagued by the shuttle effect and unstable Li metal anodes, especially under extreme operating conditions. High-concentration or localized high-concentration electrolytes may mitigate these problems, but at the expense of high-cost and environmental concerns. Herein, we propose a standard-concentration electrolyte that shows excellent compatibility with both organic active materials (shuttle-effect-free) and Li metal anodes (Coulombic efficiency ∼ 99.52%) by weakening the solvent polarity. It demonstrates that the introduction of the nonpolar n-heptane can simultaneously inhibit the dissolution of perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) and restrain side reactions between electrolyte solvents and Li metal, as well as weaken the affinity between solvents and Li+. The PTCDA|Li batteries retain 98.2% capacity after 200 cycles with an average Coulombic efficiency of 99.97%, and also show high cycling stability from −40 to +60 °C. With the replacement of traditional electrolyte by our electrolyte, the energy density of PTCDA|Li pouch-cells increases by 13.9% under identical conditions. Furthermore, our electrolyte can be extended to other (Li-sulfur, Li-FeS) batteries encountering the dilemma of the shuttle effect and unstable Li anodes.