Progress in Lithium Battery Materials

Abstract

Although lithium batteries are a commercial reality, there is still room for further improvement of their performance. For instance, it would be greatly desirable to replace the present high cost and toxic LiCoO ₂ with more affordable and environmentally benign cathode materials. A convenient candidate is the phospho olivine LiFePO₄, which is cheap, disposable and characterized by a flat voltage profile. However, the performance of this material is controlled by diffusion kinetics of LiFePO₄ in part associated to its low electronic conductivity .The solution of the problem is provided by suitable modifications at the nanoscale level, e.g., dispersion of nanoparticle metals and/or advanced nanofibril morphologies. Among negative electrodes, lithium metal alloys and disordered carbons may be considered as alternatives to graphite. However these materials suffer of decay in capacity, both by initial irreversibility and by cycling decay. Interesting materials are spinel lithium titanium oxides which are characterized by a stable voltage and almost zero structural strain processes.Lithium iron phosphate and lithium titanium oxide may be combined in new types of polymer electrolyte lithium ion batteries which are characterized by a high level of safety and reliability.