Enhancing LiNiO2 stability via phase transition suppression: The critical role of bulk Hf doping enabled by coprecipitation

초록

Addressing the critical instability of LiNiO2 (LNO) cathodes is paramount for advancing high-energy batteries. This study presents a significant advancement by demonstrating the crucial role of synthesis strategy in hafnium (Hf) doping efficacy. Our novel contribution lies in the direct, multi-technique comparison of coprecipitation versus solid-state methods, revealing that only coprecipitation facilitates the essential homogeneous bulk Hf integration required for effective stabilization. Comprehensive characterization provides compelling evidence that this bulk doping dramatically suppresses H2-H3 phase transitions and Ni migration, unlike the less effective surface-dominant doping via solid-state reaction. The significance is demonstrated by the markedly superior cycling stability and sustained Li-ion diffusion kinetics of coprecipitated Hf-doped LNO. This work fundamentally highlights the necessity of achieving bulk dopant integration through optimized synthesis, offering a vital blueprint for developing robust, next-generation Ni-rich cathode materials.

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