The effect of Sr2+ and thermal treatment conditions on electrochemical characteristics of Li3OCl solid electrolyte in batteries

Lithium-rich oxychloride anti-perovskite solid electrolytes have the potential to be promising for the next generation of batteries. Here, the influence of Sr2+ doping and heat treatment regime on the structure evolution, microstructure, and electrochemical properties of Li3-2xSrxOCl prepared by the hydrothermal route was reported. This research shows that both strategies of doping Sr2+ and the thermal treatment conditions lead to increase ionic conductivity. The lithium-ion conductivity increased with doping Sr2+ content and reached a maximum by x = 0.007 substitution of Sr2+ for Li+. A novel sintering approach is employed with ceramic elements for faster heat treatment that provids more homogeneity with a lower penetration barrier for lithium ions to diffuse in comparison with regular sintering in a furnace. Through this technique, the Li3-2x0.007Sr0.007OCl composition shows a high ionic conductivity of 0.38 x 10  3 S cm  1 at 60 degrees C. According to differential scanning calorimetry (DSC) measurements, the secondary hydroxide phases were found to have been transformed into the Li3-2xSrxOCl phase upon the first heat treatment cycle. Furthermore, the chemical stability of the Li/Li3-2x0.007Sr0.007OCl/Cu electrochemical cell was verified by cyclic voltammetry at 130 degrees C during lithiation/delithiation in a wide potential window ( 1 to 8 V). The total impedance of the interfaces (RB) and the impedance of the bulk electrolyte (RA) in Li/ Li3-2x0.007Sr0.007OCl /NCM half-cell were obtained at 3690 and 723 & omega;, respectively. The electrochemical stability of the Li3-2x0.007Sr0.007OCl electrolyte in contact with lithium metal is confirmed by chronopotentiometry test during charge/discharge conducted for 216 h at 60 degrees C. Moreover, the charge/discharge performance of Li/ Li3-2x0.007Sr0.007OCl/NCM half-cell showed an initial discharge capacity of 163 mAh/g and a discharge efficiency of 80 % after 20 cycles.