Synthesis of Cobalt‐Doped Tin‐Based Metal Phosphides/MXene Hybrids With Improved Sodium Storage Performance

ABSTRACT Tin phosphide (Sn ₄ P ₃ ) has emerged as a potential anode material for sodium‐ion batteries (SIBs) because of the exceptional theoretical capacity and favorable redox potential. However, the practical application of Sn ₄ P ₃ in SIBs has been hindered by significant challenges, including rapid capacity fading and inherently low electrical conductivity. To address the issue, we developed a novel CoSnP _x /MXene composite through a hydrothermal synthesis followed by phosphidation, which effectively incorporates cobalt‐doped Sn ₄ P ₃ nanoparticles into the MXene matrix. The combination of cobalt doping and the MXene conductive network effectively accommodates the volume expansion and prevents tin aggregation during sodiation /desodiation processes, while simultaneously enhancing ionic and electronic transport kinetics. As a result, the optimized CoSnP _x /MXene‐3:1 delivers exceptional reversible capacities of 473.9, 241.3, and 208.8 mAh g ⁻¹ at 0.1, 1.0, and 5.0 A g ⁻¹ , respectively. These findings demonstrate that appropriate cobalt doping coupled with MXene incorporation can significantly improve the rate capability and cycling stability of Sn ₄ P ₃ ‐based electrodes.