Could K+‐Based Electrolytes Be the Reliable Environmental‐Friendly Alternative to Li+ in Gr//LMO Battery We Searched for?

Manganese oxide LiMn2O4 (LMO) is one of the most promising cathode materials because it benefits from the low cost and availability of manganese, a high electrochemical stability, and a neutral environmental impact. In the same vein, the full or partial replacement of lithium salt in electrolyte by a more available and less expensive potassium salt contributes to reducing the environmental impact of batteries. Herein, the impact of the partial or total replacement of LiPF6 by KPF6 in a binary mixture of alkyl carbonate (EC/EMC) for LMO/graphite full battery is reported. The physicochemical properties of the electrolyte and its consequence on the kinetic and thermodynamic intercalation controls of each cation on cyclability are explored. Without protection with an additive, at a high current density (1 C), the nonselective intercalation of the two cations induces an optimum observed with an equimolar salt composition (0.5 m LiPF6 + 0.5 m KPF6), whereas in the presence of 5% of fluoroethylene (FEC), the replacement of part of the lithium is achievable without significant loss of performance. However, LMO/Gr cycling seems to depend on the discharge current density. Herein, the impact of the partial replacement of LiPF6 by KPF6 in LMO//Gr full battery as well as comparative properties of K/Li electrolytes and their consequences on cyclability is covered. It shows the kinetic/thermodynamic control of Li+ and K+ cation intercalation in LMO and emphasizes the dependence of LMO/Gr performance on the electrodes surface protection by fluoroethylene.