As the global electric vehicle market continues to grow, the recycling of Li-ion battery (LIB) becomes more important worldwide and the resynthesis of cathode materials would be the most value-added recycling approach taking into account limited metal resources. Although resynthesized homogenous LiNixCoyMnzO2 (NCM) from spent LIB leachate shows comparable battery performance to pristine NCM from virgin materials, there is general concern in its cycling performance. Here, we synthesize core–shell (CS) Ni-rich NCM, which consists of Ni-rich NCM as the core and NCM derived from the original or purified leachate of spent LIBs as the shell. Resynthesized CS Ni-rich NCM exhibits improved rate capability resulting from expanded interslab thickness in the NCM structure. CS Ni-rich NCM from purified LIB leachate shows improvement in cycling performance and thermal stability. It specifically delivers a capacity retention of 86.6% at a high temperature after 80 cycles compared to that (75.0%) of pristine CS Ni-rich NCM. These improvements are caused by a relatively high Mg content on the shell and the widespread distribution of Al through the CS structure. CS Ni-rich NCM derived from spent LIB leachate provides a new alternative approach to conventional LIB recycling methods, which would utilize efficiently limited metal resources for the sustainable LIB production.