Growth mechanism of grand spherical Al-doped Co3O4 precursors via optimized in-situ precipitation method for high-voltage LiCoO2 cathode

Due to its high energy density and superior stability, LiCoO2 is widely applied in the field of digital devices. Currently, to satisfy the rising demand of LiCoO2, enhancing the cut-off voltage offers an enticing strategy to effectively improve the volumetric energy density, which become a common hotspot both in the academic and industry. It is confirmed that elemental doping is the main strategy for modification, which is adopted during the high-temperature sintering process, easily resulting in the uneven distribution of dopants. In fact, the precursors Co3O4 plays a vital role in the high-voltage performance of LiCoO2, which is often overlooked by many researchers. Therefore, the microstructure control and doping uniformity of Co3O4 precursor remain challenging. Herein, the limitation of grand spherical precursors synthesis and the morphology regulatory mechanisms of doping optimization are systematically investigated. On the one hand, the growth mechanism is comprehensively explored to synthesize grand spherical Co3O4 precursors. On the other hand, Al-doping mechanism is logically analyzed by thermodynamic theory. Therefore, an optimized in-situ precipitation method is designed to avoid the segregation of Al and achieve uniform distribution as anticipated. The modified LiCoO2 cathode derived from uniform Al-doping exhibits improved high-voltage electrochemical performance. It can display the high reversible capacity of 167.3 mAh g−1, with retention rates of 90.0 % after 100 cycles at 0.5C in the high-voltage of 3–4.55 V. This work not only comprehensively elucidates the precursor growth mechanism, but also provides an efficacious and up-scalable strategy for the LiCoO2 production.