Synergistic effect of Co Mn co-doping on enhancing the stability and electrochemical performance of nickel-based layered double hydroxides

The development of high-performance cathode materials is crucial for advancing zinc-ion batteries (ZIBs), yet challenges such as structural instability and capacity fading persist in the promising candidate of Ni-based layered double hydroxides (LDHs). However, common single-element doping strategies are plagued by fundamental limitations, often resulting in inevitable trade-offs between electrical conductivity, specific capacity, and structural stability. Herein, we propose a novel Mn/Co co-doping strategy to synergistically enhance the electrochemical performance and structural stability of Ni-based LDHs. Through first-principles calculations, the effects of varying Mn/Co ratios on Jahn-Teller (J-T) distortion, electronic structure, ion adsorption, and diffusion kinetics were systematically investigated. The results reveal that NiMn 0.16 Co 0.16 is the most stable configuration. This enhanced stability arises from Co doping, which modulates Mn e g orbital occupancy, strengthens the Mn O bonds and promotes charge transfer. These effects collectively suppress J-T distortion, thereby reinforcing the structural stability. Furthermore, this configuration demonstrates superior Zn 2+ adsorption energy, a low diffusion barrier (0.34 eV), and a high theoretical Zn 2+ -storage capacity (up to four Zn 2+ per unit), while effectively inhibiting H + co-intercalation. This work provides deep atomic-level insights into the synergistic mechanisms of multi-element doping and offers a rational design strategy for high-performance ZIBs cathode. • Mn/Co ratio critically modulates the Jahn-Teller (J-T) effect, with 1:1 stoichiometry exhibiting minimal J-T distortion. • Co doping modulates the overlap between Mn-d and O-p orbital centers in LDHs, thereby suppressing J-T effect. • Mn and Co interact synergistically: Co doping strengthens the Mn–O bond and enhances structural stability. • NM 0.16 C 0.16 has highest Zn 2+ adsorption (-4.73 eV), lowest migration barrier (0.34 eV), and maximum Zn 2+ intercalation (4).