Novel Slurry Electrolyte Containing Lithium Metasilicate for High Electrochemical Performance of a 5 v Cathode

We report a novel slurry electrolyte with ultrahigh concentration of insoluble inorganic lithium metasilicate (Li₂SiO₃) that is exploited for lithium ion batteries to combine the merits of solid and liquid electrolytes. The safety, conductivity, and anodic and storage stabilities of the eletrolyte are examined, which are all enhanced compared to a base carbonate electrolyte. The compatibility of the elecrolyte with a LiNi_0.5Mn_1.5O₄ cathode is evaluated under high voltage. A discharge capacity of 173.8 mAh g^-1 is still maintained after 120 cycles, whereas it is only 74.9 mAh g^-1 in the base electrolyte. Additionally, the rate capability of the LiNi_0.5Mn_1.5O₄ cathode is also improved with reduced electrode polarization. TEM measurements indicate that the electrode interface is modified by Li₂SiO₃ with a thinner solid electrolyte interphase film. Density functional theory computations demonstrate that LiPF₆ is stabilized against its decomposition by Li₂SiO₃. A possible path for the reaction between PF₅ and Li₂SiO₃ is also proposed by deducing the transition states involved in the process using the DFT method.