From Gems to Lithium Battery Electrodes: The Significance of the Diamond, Ruby (Sapphire), Spinel and Peridot Structures

The materials batteries have host compositional range. used for the negative and positive electrodes of rechargeable “lithium-ion” structures that can accommodate and release lithium over a wide In these batteries, carbon and intermetallic compounds have been widely exploited as the negative electrodes, and transition metal oxides as the positive electrodes. For a lithium-ion battery to perform adequately, the structural integrity of the electrode host structures must be maintained throughout discharge and charge for many hundreds of cycles. Nature provides many examples of stable compounds that can be produced under variable conditions of temperature and pressure. As such, the mineral world can be used as a guide for the selection of materials in technological applications. This paper highlights the structural relationships that exist between precious and semi-precious gems such as diamond, ruby (sapphire), spinel and peridot and insertion electrodes for lithium batteries. Introduction Lithium-ion batteries operate by an electrochemical reaction during which lithium ions are extracted from one host electrode structure and inserted into another with concomitant oxidation and reduction occurring at the two electrodes, respectively. In order to achieve high electrode capacities and good cycle life, as much lithium as possible must be inserted into and