1 Department of Energy Conversion and Storage, Technical University of Denmark2 Atomic scale modelling and materials, Department of Energy Conversion and Storage, Technical University of Denmark3 Risø National Laboratory for Sustainable Energy, Technical University of Denmark4 Department of Chemistry, Technical University of Denmark
The charge and discharge performance of an all-solid-state lithium battery with the LiBH4-LiI solid solution as an electrolyte is reported. Lithium titanate (Li4Ti5O12) was used as the positive electrode and lithium metal as the negative electrode. The performance of the all-solid-state cell is compared with a cell with an identical electrode setup but a liquid electrolyte (1 M LiPF6 in EC:DMC). All measurements were carried out at a temperature of 60°C. For the all-solid-state cells, 81% of the theoretical discharge capacity is reached for a discharge rate of 10 μA, but a capacity fade of 1.6% per charge-discharge cycle is observed. The electrochemical stability of the LiBH4-LiI solid solution was investigated using cyclic voltammetry and is found to be limited to 3 V. The impedance of the battery cells was measured using impedance spectroscopy. A strong correlation is found between the change in the discharge capacity of the cells and changes in the cell impedance over 200 charge-discharge cycles. This is expectedly due to the possible formation of passivating areas in the cell and/or loss of contact area between the electrolyte and the electrodes.
Journal of the Electrochemical Society, 2014, Vol 161, Issue 9