A computational investigation on the electrochemical properties of spinel-like LiCoAsO4 as positive electrode for lithium-ion batteries

The electrochemical properties of spinel-LiCoAsO4, recently reported, as potential electrode materials for rechargeable lithium batteries has been investigated from first principles calculations and compared to those of the ambient pressure polymorph olivine-LiCoAsO4. The predicted lithium deinsertion voltage of this material, 4.75 V towards lithium metal, is promising. From the optimized crystalline structures of lithiated (As[LiCo]O4) and delithiated (As[Co]O4) materials it is inferred that major structural rearrangements would occur upon lithium deinsertion. The calculated electronic structure indicates that spinel-like LiCoAsO4 is an insulating compound, suggesting that efficient lithium removal would be hindered by a very poor intrinsic electronic conductivity. The ionic mobility of lithium ions in the octahedral sites of the spinel structure is also expected to be low. Therefore, in spite of the promising insertion voltage, structural and electrical considerations rule out the effective utilization of the spinel-like As[LiCo]O4 as positive electrode for lithium cells. While predicting lithium insertion voltages by first principles methods is a powerful screening tool in the search for novel electrode materials, the electronic and crystalline information obtained from the calculation should not be overlooked to evaluate the potential interest of an electrode material.

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