Cells were prepared by pressing 200 mg of electrolyte, 5 mg of cathode composite and 20 mg of anode composite with a pressure of 2 t for 90 sec using a pellet press inside an Ar-filled glovebox. The dimensions of the resulting pellet were approximately 1.3 mm in thickness and 7.3 mm in diameter. The pellets were spring-loaded into a modified air-tight Swagelok-type cell housing with the current collectors made of stainless steel shown in Figure . All the electrochemical cells were loaded, sealed and prepared for further handling inside the glovebox. The sealed cells were cycled outside the glovebox at 170 °C and the Swagelok-type cell housing was covered with glass wool to minimize temperature fluctuations. Battery testing was performed using a Biologic VSP300 potentiostat with charging and discharging currents of +8.29 µA and -4.05 µA respectively, which translates to rates of C/15 and C/30 for charge and discharge respectively with respect to the theoretical capacity of the active cathode material (~140 mAh g -1 for conversion to A2BO4F2). All the voltages are given as potential against the anode material. The mass of the active cathode material La2Ni0.75Co0.25O4.08 within the cell was ~ 1.5 mg, whereas the anode composite was used in large excess compared to the active cathode material, which helps to have the electrochemical curves being mainly dominated by the active cathode material. The discharge process was carried out directly after the charging process. Different cut-off capacities (20 / 40 / 60 / 140 mAh g -1 ) were tested.