Flux-free synthesis of single-crystal LiNi0.8Co0.1Mn0.1O2 boosts its electrochemical performance in lithium batteries

The single-crystal cathode materials exhibit better cyclic stability, enhanced compaction density, and improved safety than polycrystalline cathode materials. They, therefore, are ideal cathode material candidates for lithium-ion batteries. Introducing hetero materials, excessive sintering temperature and tedious steps during the synthesis of the single-crystal cathode materials, however, limit their large-scale application. In this work, we adopt the spray pyrolysis method to prepare the hybrid oxides NiO–MnCo2O4–Ni6MnO8. This kind of hybrid oxides is considered to be an ideal precursor for the single-crystal Ni-rich cathode materials owing to its fine particle size and porous structure. Subsequently, high-temperature lithiation synthesises the submicron single-crystal LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode material. The synthesis temperature of the submicron single-crystal NCM811 is significantly lowered when LiNO3 is selected as the lithium source and serves as the flux agent taking advantage of its fusibility. Consequently, the as-synthesized submicron single-crystal NCM811, compared with conventional polycrystalline NCM811, exhibits long lifetime applications, improved thermal stability and micro-crack immunity. The synthetic strategy in this work also demonstrates that the crystal crushing process, flux adding, and repeated sintering are not indispensable in the synthesis of single-crystal cathode materials.