In-situ constructing surface intergranular carbonaceous conductive frameworks and protective layers of Ni-rich layered oxide cathodes

Surface chemistry instability of Ni-rich layered oxides triggers rapid performance degradation and severe safety concerns of Li-ion batteries. Herein we report a transformative approach using free-radical reaction to in-situ build protective conductive carbon frameworks within the surface intergranular of layered oxide cathodes. Typically, a mild reaction between carbon tetrachloride (CCl₄) and N,N-dimethylformamide (DMF) at 200 °C achieves the direct deposition of amorphous carbon within surface intergranular of LiNi_0.8Co_0.1Mn_0.1O₂, forming dense protective layers and conductive highways, and also eliminating surface residual alkalis and other impurities. With the enhancement in the surface phase purity, chemistry stability and electrical properties, this cathode surface architecture enables much improved electrochemical performance, exhibiting high cycling retention of 87.7 % after 100 cycles at 0.1 C and 82.5 % after 150 cycles at 1.0 C in 2.80–4.35 V. Notably, the present synthetic methodology provides an efficient carbonaceous modification method for Ni-rich layered oxides, overcoming major constraints of traditional thermal carbonization coating technologies. It may shift the design paradigm of carbothermic sensitive metal oxide materials. Moreover, this facile and scalable fabrication strategy makes them potentially viable for commercialization in Li-ion batteries.