IDENTIFICATION OF CATHODE MATERIALS FOR LITHIUM BATTERIES GUIDED BY FIRST-PRINCIPLES CALCULATIONS

Lithium batteries have the highest energy density of all rechargeable batteries and are favoured in applications where low weight or small v olume are desired - for example, laptop computers, cellular telephones and electric vehicles(1). One of the limitations of present commercia l lithium batteries is the high cost of the LiCoO2 cathode material. S earches for a replacement material that, Like LiCoO2, intercalates lit hium ions reversibly have covered most of the known lithium/transition -metal oxides, but the number of possible mixtures of these(2-5) is al most limitless, making an empirical search labourious and expensive. H ere we show that first-principles calculations can instead direct the search for possible cathode materials. Through such calculations we id entify a large class of new candidate materials in which non-transitio n metals are substituted for transition metals. The replacement with n on-transition metals is driven by the realization that oxygen, rather than transition-metal ions, function as the electron acceptor upon ins ertion of Li. For one such material, Li(Co,Al)O-2, we predict and veri fy experimentally that aluminium substitution raises the cell voltage while decreasing both the density of the material and its cost.