Rechargeable Electrochemical Cells having Electrolyte Generated in situ from an All Solid State Assembly

摘要

Research on improving state of the art lithium ion batteries is focussed on three main issues. These are cost reduction, safety in larger units and higher energy / power density. Sulphur dioxide has been used as a low cost major constituent for both cathode and electrolyte in primary batteries for nearly three decades. No satisfactory solution has yet emerged for a rechargeable system based on sulphur oxides. This paper discloses the results of cyclic voltammetry on cathodes consisting of lithium sulphite and admixtures with a transition metal oxide. Lithium reversibility in this type of cathode has been demonstrated but utilisation of the active materials needs to be increased. Extended cycling shows that if organic carbonate solvents are present in the electrolyte, an unacceptable degree of degradation occurs. Recent research has focussed on elimination of such solvents and their replacement by a solid electrolyte. Starting with a solid state assembly, an optimum amount of sulphur dioxide is electrochemically generated on the first charge. The results presented show a significant improvement, and it is expected that with further development, high rate rechargeable batteries can be produced more economically and with much lower fire risk than the lithium batteries now sold.