Improving the Performance\nof LiNi<sub>0.925</sub>Co<sub>0.065</sub>Mn<sub>0.01</sub>O<sub>2</sub> via Ti<sup>4+</sup>&\nNb<sup>5+</sup> Co-Modifications

Ni-rich layer-structured materials are some of the most\npromising\ncathodes owing to their attractive reversible capacity and cost-effectiveness.\nWhen the Ni content is increased to 90% and higher, mechanical deterioration\nbecomes serious and leads to accelerated cyclic degradation, since\nremovable Li<sup>+</sup> is ∼0.85, accompanied by large lattice\nvariation during operation. Here, we investigate the influences of\nTi<sup>4+</sup> bulky substitution, Nb<sup>5+</sup> surface treatment,\nand their coutilization on the behavior of LiNi<sub>0.925</sub>Co<sub>0.065</sub>Mn<sub>0.01</sub>O<sub>2</sub> (NCM92). In contrast to\nthe limited positive effects of monousage, the coutilization of Ti<sup>4+</sup> and Nb<sup>5+</sup> obviously suppresses particles’\npulverization, relying on their synergistic effects of the shape of\nlattice variation and the protection of a tough shell layer. As a\nresult, Ti & Nb-LiNi<sub>0.925</sub>Co<sub>0.065</sub>Mn<sub>0.01</sub>O<sub>2</sub> (TiNb-NCM92) presents the best capacity retention,\nas high as 90.2% after 300 cycles, much higher than NCM92 (49.0%),\nTi-NCM92 (76.3%), and Nb-NCM92 (72.4%). Our approaches demonstrate\nthat the serious mechanical challenges of ultrahigh nickel cathodes\ncould be alleviated by various remedies coutilized together.