Effect of Organic Electrolyte on the Performance of Solid Electrolyte for Solid-Liquid Hybrid Lithium Batteries

The interface problem caused by the contact between the electrodes and the solid electrolyte was the main factor hindering the development of solid-state batteries. To enhance the electrode|solid electrolyte interface property, we designed a hybrid electrolyte, the combination of x vol % Li_1.3Al_0.3Ti_1.7(PO₄)₃ (LATP) inorganic solid electrolyte and 1 - x vol % liquid organic electrolyte (LE). In this work, the 1 - x vol % LE was dropped between the electrode and the solid electrolyte, and it is found that the electrochemical performance of the LiFePO₄|Li solid-liquid hybrid battery is significantly improved. At the current density of 0.1 and 0.5 C, the LATP with 15% liquid organic electrolyte could deliver a specific capacity of 160.5 and 124.3 mAh g^-1, respectively; moreover, the specific discharge capacity remained as high as 111 mAh g^-1 at 0.5 C after 100 cycles, indicating that the larger interface impedance was eliminated. The LE may have three functions: (1) forming a solid-liquid electrolyte interphase on the surface of the LATP particles to prevent further reduction of LATP, (2) wetting the electrode and solid electrolyte to reduce the interface resistance, and (3) improving interfacial Li-ion transport.