Stabilizing Nickel Ions by Local Magnetic Order Modulation for Durable Ultrahigh-Nickel Cathode

We report successfully synthesized ultra-high-performance LiNi _0.95 Mn _0.05 O ₂ (NM) and its TiO ₂ -doped modified material Li[Ni _0.95 Mn _0.05 ] _{1− x} Ti _x O ₂ (0 ≤ x ≤ 0.1) (LNMTO) via a high-temperature solid-state method. The introduction of TiO ₂ as a dopant aims to stabilize the crystal structure, modulate the local magnetic order of nickel ions, reduce Ni/Li exchange and magnetic frustration, enhancing electrochemical stability. X-ray diffraction (XRD) results confirm successful TiO ₂ doping into the lattice, effectively increasing the interlayer spacing. Magnetic measurements reveal weakened average exchange interactions. The introduction of non-magnetic Ti ⁴⁺ ions significantly alters the low-temperature magnetic ordering state, indicating that Ti ⁴⁺ modulates the super-exchange interactions between TM layer, forming a more stable antiferromagnetic coupling network. Electrochemical testing confirms that at Ti ⁴⁺ doping concentration of 2.5%, the Li[Ni _0.95 Mn _0.05 ] _{1− x} Ti _x O ₂ (0 ≤ x ≤ 0.1) cathode material exhibits optimal capacity retention and cycling stability. After 40 cycles, the capacity retention increases from 70.5% to 95%, while the specific discharge capacity increased from 140 mAh g ^− 1 to 155 mAh g ^− 1 after stable cycling. This study reveals that TiO ₂ doping induced local magnetic ordering in LiNi _0.95 Mn _0.05 O ₂ is an effective strategy for stabilizing the crystal structure and enhancing the electrochemical stability of high-nickel cathode materials.