New insights into the pre-lithiation kinetics of single-crystalline Ni-rich cathodes for long-life Li-ion batteries

Abstract

Developing single-crystalline Ni-rich cathodes is an effective strategy to improve the safety and cycle life of Li-ion batteries (LIBs). However, the easy-to-loss of Li and O in high-temperature lithiation results in unsatisfactory ordered layered structure and stoichiometry. Herein, we demonstrate the synthesis of highly-ordered and fully-stoichiometric single-crystalline LiNi0.83Co0.12Mn0.05O2 (SC-NCM83) cathodes by the regulation of pre-lithiation kinetics. The well-balanced pre-lithiation kinetics have been proved to greatly improve the proportion of layered phase in the intermediate by inhibiting the formation of metastable spinel phase, which promoted the rapid transformation of the intermediate into highly-ordered layered SC-NCM83 in the subsequent lithiation process. After coating a layer of Li2O–B2O3, the resultant cathodes deliver superior cycling stability with 90.9% capacity retention at 1C after 300 cycles in pouch-type full batteries. The enhancement mechanism has also been clarified. These findings exhibit fundamental insights into the pre-lithiation kinetics process for guiding the synthesis of high-quality single-crystalline Ni-rich cathodes.

Keywords

• Single-crystalline cathode
• Ni-rich oxides
• Pre-lithiation
• Li-ion batteries
• Surface modification