Abstract
Single-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 Ni2+ and increases the degree of mixing of Li+ and Ni2+. Herein, for the first time, a method for short-time high-temperature sintering combined with low-temperature heat preservation is proposed to prepare LiNi0.6Co0.6Mn0.2O2 (NCM622) single crystal materials in a mixed molten salt system of LiOH and Li2CO3. 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 2.8–4.3 V. 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.
Published Version
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