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

Abstract

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 ≈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.

The future nickel metal supply for lithium-ion batteries

“…Currently, some novel methods are used to prepare single-crystal materials such as molten NaCl salt flux method, 61 microfluidic technology, 62 and all-dry solid-phase synthesis. 63 The concentration gradient structure and core–shell structure is to provide high capacity with nickel-rich material as the core, and ensure structural and thermal stability with nickel-short material as the shell, such as concentration gradient LiNi 0.8 Co 0.1 Mn 0.1 O 2 , 64 LiNi 0.9 Co 0.05 Mn 0.05 O 2 core and LiNi 0.6 Co 0.2 Mn 0.2 O 2 shell, 65 and LiNi 0.9 Mn 0.05 Co 0.05 O 2 core and LiNi 1/3 Mn 1/3 Co 1/3 O 2 shell by a rational control of local stoichiometry. 66 Elemental doping is an effective method by introducing small amounts of foreign atoms into a crystal lattice to improve the stability of cathode materials.…”