Accelerated Development of High Voltage Li-Ion Cathodes

摘要

High voltage cathodes are attractive for high energy density Li-ion batteries.However, candidates such as LiCoPO_4 have presented numerous challengesstemming from poor electronic/ionic conductivities such that typical solutionsinvolving nanosizing result in extremely poor cycling performance.Here, high-throughput methods are applied to develop near-micron sizedcarbon-coated LiCoPO_4 with improved energy density and capacity retention.In total, 1300 materials with 46 different substituents are synthesizedand characterized. A number of substituents show greatly improved capacity(e.g., 160 mAh g~(?1) for 1 indium (In) substitution vs 95 mAh g~(?1) for thepristine). However, co-doping is required to improve extended cycling.Li_(1–3x)Co_(1–2x)In_xMo_xPO_4 is found to be particularly effective with dramaticallyimproved cycling (as high as 100 after 10 cycles, vs ≈50 in unsubstituted).While In improves the electronic conductivity of the carbon-coated materials,molybdenum (Mo) co-doping gives larger particles. DFT calculations showthat Mo impedes the formation of Li/Co antisite defects.