Organic/inorganic hybrid quaternary ionogel electrolyte with low lithium-ion association and uniform lithium flux for lithium secondary batteries

High-energy-density lithium secondary batteries require high-voltage electrolyte. Ionic liquids with wide elec-trochemical window have been regarded as promising electrolyte candidate for high-safety electrochemical devices. However, the solvation state of lithium ions severely restricts the conductivity due to the sluggish ki-netics of lithium-ion cluster. Moreover, the leakage risk also impedes its practical application. Here, we propose to mitigate the above issues by designing organic/inorganic hybrid quaternary ionogel electrolyte (PSIL). The key to our strategy is promoting the dissociation of Li (TFSI)(2)(- )cluster and increasing the percentage of free Li+ in the ionogel electrolyte. The amorphous matrix formed by PEO and SiO2 increases the interaction between Li+ and PEO, reducing the association of Li (TFSI)(2)(-) cluster. And then, the synergistic transportation of lithium ions by PEO and ionic liquid promises the high conductivity of PSIL. As a result, the ionogel electrolyte shows a high conductivity of 1.50 x10(-3) S.cm(-1) at 20 celcius. The impressive electrochemical performance with LiFePO4 cathode indicates the high compatibility with the electrode. The ex-situ SEM and molecular dynamic simulation both demonstrate the uniform transportation of lithium ions during the electrochemical process and indicate the successful design for the quaternary ionogel electrolyte.

Automated summary

By designing organic/inorganic hybrid ionogel electrolyte, the issues of high-energy-density lithium batteries can be addressed, leading to improved conductivity and safety.