An O2 Electrode for a Rechargeable Lithium Battery

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Energy storage has an important role to play in addressing global warming. It is vital to develop a number of storage technologies. One of the most promising is the rechargeable lithium battery. Such batteries are the technology of choice for hybrid electrical vehicles (some 30% of CO2 emissions arise from transport) and they can make a critical contribution to the storage of clean energy, including for micro-grid and off-grid applications.Currently rechargeable lithium batteries are composed of a graphite negative electrode, an organic electrolyte and LiCoO2 as the positive electrode. Li is removed from the layered intercalation compound LiCoO2 on charging and re-inserted on discharge. Energy storage is limited by the LiCoO2 electrode (0.5 Li/Co, 130 mAhg-1). All the research taking place worldwide aimed at improving the positive intercalation electrode can only hope to double the energy storage to 1 Li/Tm (300 mAhg-1). We propose a step change in rechargeable lithium batteries by replacing the LiCoO2 electrode with a porous carbon electrode and allowing Li+ and e- in the cell to react with O2 from the air. The capacity to store energy can be raised by 5-10 times compared with LiCoO2, supply of O2 is in-effect infinite and the cost is reduced significantly (LiCoO2 is the most expensive component of current batteries). Our preliminary studies have shown that the O2 cell is rechargeable and can sustain cycling. The proposal addresses a number of the materials issues necessary to realise this radically new high energy storage battery based on a non-aqueous O2 electrode.