Thermally Controlled Synthesis of Cr₂(NCN)₃/CrN Heterostructured Composite Anodes for High-Performance Li-Ion Batteries

Cr₂(NCN)₃ features high specific capacity and fast electrical conductivity, making it a promising anode candidate for Li-ion batteries. However, inherent chemical and structural metastability severely restrict its capacity output and cycle life, resulting in unsatisfactory battery performance. Here we use its thermal instability characteristic and propose a thermal controlled structural coordination strategy to in-situ construct a Cr₂(NCN)₃/CrN heterostructure. Systematic studies reveal the thermodynamic structural evolution of Cr₂(NCN)₃ under precise temperature regulation, as well as the essential relevancy between electrochemical properties and crystalline structures. An optimal Cr₂(NCN)₃/CrN heterostructural composite obtained at 690 °C features uniform two-phase recombination with abundant grain boundaries enables promising electrochemical performance, exhibiting a high reversible discharge capacity (760 mAh g⁻¹) and a good cycle performance (75 % retention after 100 cycles). It is worth noting that the above performance is significantly improved over unmodified pure transition metal carbodiimides or metal nitride anodes. This study provides a simple and universal structural regulation strategy for transition metal carbodiimides that utilizes their thermal sensitivity to synchronously construct synergistic transition metal carbodiimides/transition metal nitrides heterostructures, promoting their potential applications in Li-ion batteries.