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.