The electronic conductivity of the positive electrode was evaluated at temperatures 15 °C, 20 °C, 25 °C, 30 °C, and 35 °C using a four-point probe (Ossila Instruments). The positive electrode coating was delaminated using liquid gallium to dissolve the aluminium current collector and obtain the electrode coating undamaged. Small quantities of 1 mol dm -3 hydrochloric acid and deionised water were used to remove the gallium alloy. This methodology has been described in detail previously. To measure the electronic conductivity of the positive electrode a target current of 100 µA was used, the voltage was stepped by 0.1 V until the target current had been reached.