Electrochemical performance of all-solid-state Li batteries based LiMn0.5Ni0.5O2 cathode and NASICON-type electrolyte

LiNi_0.5Mn_0.5O₂ thin films have been deposited on the NASICON-type glass ceramics, Li_1+x+yAl_xTi_2−xSi_yP_3−yO₁₂ (LATSP), by radio frequency (RF) magnetron sputtering followed by annealing. The films have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Raman spectroscopy. All-solid-state Li/PEO₁₈-Li(CF₃SO₂)₂N/LATSP/LiNi_0.5Mn_0.5O₂/Au cells are fabricated using the LiNi_0.5Mn_0.5O₂ thin films and the LATSP electrolyte. The electrochemical performance of the cells is investigated by galvanostatic cycling, cyclic voltammetry (CV), potentiostatic intermittent titration technique (PITT) and electrochemical impedance spectroscopy (EIS). Interfacial reactions between LiNi_0.5Mn_0.5O₂ and LATSP occur at a temperature as low as 300 °C with the formation of Mn₃O₄, resulting in an increased obstacle for Li-ion diffusion across the LiNi_0.5Mn_0.5O₂/LATSP interface. The electrochemical performance of the cells is limited by the interfacial resistance between LATSP and LiNi_0.5Mn_0.5O₂ as well as the Li-ion diffusion kinetics in LiNi_0.5Mn_0.5O₂ bulk.