Enhancing Li+ Transportation at Graphite‐Low Concentration Electrolyte Interface Via Interphase Modulation of LiNO3 and Vinylene Carbonate

ABSTRACT The solvent‐rich solvent sheath in low‐concentration electrolytes (LCEs) not only results in high desolvation energy of Li + , but also forms organic‐rich solid electrolyte interface film (SEI) with poor Li + conductivity, which hinders Li + transport at the electrode‐electrolyte interface and greatly limits the application of LCEs. Here, the electrochemical performance of the LCEs is enhanced by dual interfacial modification with LiNO 3 and vinylene carbonate (VC) additives. Results show that LiNO 3 is preferentially reduced at about 1.65 V to form an inorganic‐rich but incomplete SEI inner layer. The formation of Li 3 N and LiN x O y inorganic components helps to achieve rapid Li + transport in the SEI film, and the bare electrode surface caused by the incomplete SEI inner layer provides a place for the subsequent decomposition of VC. Then, at a lower potential of about 0.73 V, VC is reduced to generate the poly(VC)‐rich SEI outer layer, which provides lithium‐philic sites and greatly weakens the interaction between Li + and ethylene carbonate (EC). The interaction modulates the Li + solvation structure at the interface and reduces the desolvation energy of Li + . This ingenious design of the bilayer SEI film greatly enhances Li + transport and inhibits the decomposition of traditional carbonate solvents and the swelling of graphite. As a result, the electrochemical performance of the battery using 0.5 M LiPF 6 EC/diethyl carbonate (DEC) + 0.012 M LiNO 3 + 0.5 vt% VC is improved to a higher level than the one using 1.0 M LiPF 6 EC/DEC electrolyte. This research expands the design strategy and promising applications of LCEs by constructing a favorable SEI to enhance Li + transport at the electrode‐electrolyte interface.