Achieving Long-Life Ni-Rich Cathodes with Improved Mechanical-Chemical Properties Via Concentration Gradient Structure

The irreversible deterioration of electrochemical performance in Ni-rich cathode materials, attributed to crack propagation and undesired side reactions, poses a critical barrier to the further development of high-energy power batteries for electrical vehicles (EVs). Herein, a concentration gradient strategy is proposed for synthesizing a Ni-rich cathode with enhanced mechanical and electrochemical stability to address the issues related to the irreversible structural deterioration. Notably, the concentration gradient structure contributes to superior mechanical strength in secondary particles due to the radially orientated primary particles resulted from Mn composition grading, which effectively alleviate the internal strain caused by structural changes and fatigue destruction during successive cycling. Moreover, the Mn-rich surface minimizes the parasitic side reactions at the electrode-electrolyte interface. Benefitting from the above, the concentration gradient sample can deliver approximate to 180.1 mA h g-1 at 1 C and retain 96.2% of its initial discharge capacity after 100 cycles. This work demonstrates that the concentration gradient structure can simultaneously improve the mechanical and chemical stabilities of Ni-rich cathode and offers a feasible way for designing stable lithium-ion batteries with high energy density. Here a concentration gradient structure strategy in Ni-rich layered oxide (NCMs) cathodes is proposed to enhance mechanical and chemical stability. In this way, spoke-like microstructure is formed, leading to the higher mechanical properties and Mn-rich shell reduces the parasitic reactions. Thus, the reversibility of the structure and the capacity retention are significantly improved. image