Toward high stability single crystal material by structural regulation with high and low temperature mixing sinter

S ingle-crystal cathode materials are a potential research focus for high-nickel ternary cathode materials owing to their high compaction density and good electrochemical stability. However, in the traditional sintering process, lithium is lost because of the long-time and higher-temperature sintering, which reduces the migration energy barrier of Ni 2+ and increases the degree of mixing of Li + and Ni 2+ . Herein, for the first time, a method for short-time high-temperature sintering combined with low-temperature heat preservation is proposed to prepare LiNi 0.6 Co 0.6 Mn 0.2 O 2 (NCM622) single crystal materials in a mixed molten salt system of LiOH and Li 2 CO 3 . In analyses of morphology, structure and electrochemical properties, the prepared NCM622 exhibits excellent cycling stability owing to an ordered layered structure and low cation mixing degree. The single-crystal material shows an excellent capacity retention of 93.19% (150.49–140.24mAh·g −1 ) after 100 cycles at 1 C in the voltage range of 2.8–4.3V. The single crystal particles exhibit reliable stability after long cycling without microcracks in the cycled particles. Furthermore, the preparation cost could be significantly reduced with a closed loop of the flux salt. The short-time high-temperature combined with the low-temperature holding sintering method may provide an effective strategy for the synthesis of other single-crystal materials with excellent electrochemical properties.