To determine the structural stability of LaSrMnO4 after cycling, ex-situ XRD (Figure ) was performed after 100 cycles in the fluorinated (charged) state. No significant changes were observed, and the lattice parameters were similar to those of the cell charged once up to 1.2 V (Table ). This confirms that the LaSrMnO4 remains highly structurally stable over 100 cycles and indicates that carbon degradation might be the predominant cause for reduced cycling stability. active material. Figure shows the charging/discharging curves of the cells operated at 140 °C. The charging capacity was ~ 53 mAh/g and the discharge capacity was ~ 40 mAh/g, resulting in a coulombic efficiency of ~ 66 % for the first cycle which is lowered compared to 84 % obtained at 170 °C (see Section 3.3). In the second cycle, the charging and discharging capacities are similar at ~38 mAh/g, with the discharge capacity remaining consistent over 60 cycles, resulting in close to 100 % coulombic efficiency. This increased stability implies that reducing the temperature may reduce the extent of undesirable side reactions during the charging process, resulting in improved cycling performance, although at the cost of a reduced overall cell capacity.