Ti₃C₂T_x/Ni₅P₄/NiP₂ Double-Heterojunction Anodes With Fluoride-Free Interfacial Engineering for High-Rate and...

Transition metal phosphides (TMPs) are promising lithium-ion battery anodes but are hindered by severe volume expansion and poor cycling stability. To address these challenges, we report a fluoride-free strategy combining Lewis acidic molten salt etching and in situ phosphorization to grow biphasic Ni₅P₄/NiP₂ nanoparticles uniformly on Ti₃C₂T_x MXene, forming a Ti₃C₂T_x/Ni₅P₄/NiP₂ double-heterostructure. This approach avoids toxic HF, achieves simultaneous MXene exfoliation and active material anchoring, and establishes robust Ti-O-Ni/Ti-P interfacial bonds that are expected to facilitate intimate contact and efficient charge transfer, thereby effectively maintaining structural integrity during prolonged cycling and promoting the absorption and diffusion of lithium ions. As a result, the composite delivers outstanding rate capability (329.1 mAh g^-1 at 5.0 A g^-1) and long-term cycling stability (487.1 mAh g^-1 after 600 cycles at 1 A g^-1), significantly outperforming Ti₃C₂T_x/Ni₂P composite and pristine Ti₃C₂T_x. This work provides a fluorine-free and scalable route for MXene/TMP heterostructures, offering mechanistic insights into interface-engineered electrodes for next-generation energy storage systems.