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 LiNi0.5Mn1.5O4 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 LiNi0.5Mn1.5O4 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.