Nanostructured Co-Free Layered Oxide Cathode that Affords Fast-Charging Lithium-Ion Batteries for Electric Vehicles

摘要

The development of Co-free Li[NixMn1?x]O2 cathodes for lithium-ion batteries (LIBs) that can supersede Co-containing Li[Ni_xCo_yMn_(1?x?y)]O_2 and Li[Ni_xCo_yMn_(1?x?y)]O_2 cathodes is considered a priority as Co is associated with price volatility, environmental concerns, and human rights violations. However, the complete removal of Co from cathodes for LIBs is difficult because Co-free cathodes suffer from structural instability and inferior capacity. In this study, a morphology-engineering approach is used to develop a Cofree Li[Ni_xCo_yMn_(1?x?y)]O_2 cathode with a Ni-rich core–Mn-rich shell structure to overcome the limitations of Co-free Li[Ni_xMn_(1?x)]O_2 cathodes. The engineered morphology of the Co-free Li[Ni_(0.9)Mn_(0.1)]O_2 cathode particles effectively dissipates internal strain caused by state-of-charge heterogeneity and fracture toughening the cathode. Owing to the effective dissipation of internal strain and chemical protection provided by the Mn-rich shell, the Co-free cathode demonstrates excellent long-term cycling stability; it retains 78.5% of its initial capacity after 2000 cycles at 1 C charge and 0.8 C discharge rates, and retains an unprecedented 79.5% after 1000 cycles under fast-charging conditions (3 C charge and 1 C discharge). The proposed Co-free layered oxide cathode represents a next-generation cathode that affords fast-charging and durable LIBs, which are more cost effective than LIBs featuring commercial Co-containing cathodes.