Realization of a High-Voltage and High-Rate Nickel-Rich NCM Cathode Material for LIBs by Co and Ti Dual Modification

Nickel-rich Li(NixCoyMn1-x-yO2) (x >= 0.6) is considered to be a predominant cathode for next-generation lithium-ion batteries (LIBs) due to its towering specific energy density. Unfortunately, serious structural degradation causes rapid capacity degradation with the increase in nickel content. Herein, a Co and Ti co-modified LiNi0.8Co0.1Mn0.1O2 (NCM-811) cathode ameliorates the reversible capacity together with the rate capability by obviously alleviating the lattice structure degradation and microscopic intergranular cracks. Further studies show that the titanium doping effectively reduces the cation mixing and also stabilizes the crystal structure, while the spinel phase formed at the surface by a cobalt oxide coating is much stable than the layered phase at high voltage, which can alleviate the generation of micro-cracks. After 0.5% Co oxide coating and 1% Ti doping (T1Co0.5-NCM), a superior rate capability (121.75 mA h g(-1) at 20 C between 2.7 and 4.5 V) and predominant capacity retention (74.2%) are observed compared with the pristine NCM-811 (59.5%) after 400 cycles between 2.7 and 4.7 V. This work supplies an eminent design of high-voltage and high-rate layered cathode materials and has a huge application prospect in the next generation of high-energy LIBs.

Automated summary

The Co and Ti co-modified LiNi0.8Co0.1Mn0.1O2 (NCM-811) cathode effectively improves reversible capacity and rate capability by alleviating lattice structure degradation and microscopic intergranular cracks. Titanium doping reduces cation mixing and stabilizes crystal structure, while a cobalt oxide coating forms a stable spinel phase on the surface, reducing generation of micro-cracks. The T1Co0.5-NCM cathode demonstrates superior rate capability and capacity retention compared to pristine NCM-811, showing promise for high-energy LIBs.