Ultrafast Carbothermal Shock Synthesis of Wadsley–Roth Phase Niobium-Based Oxides for Fast-Charging Lithium-Ion Batteries

Abstract

Wadsley–Roth phase niobium-based oxides show potential as anode candidates for fast-charging lithium-ion batteries. Traditional synthesis methods, however, usually involve a time-consuming calcination process, resulting in poor production efficiency. Herein, a novel carbothermal shock (CTS) method that enables the ultra-fast synthesis of various Wadsley–Roth phase Nb-based oxides within seconds is introduced. The extremely rapid heating rates enabled by CTS alter the reaction mechanism from a sluggish solid-state process to a swift liquid-phase assisted one and drive the chemical reactions away from equilibrium, thereby generating abundant oxygen vacancies and dislocations. Theoretical calculations reveal that oxygen vacancies significantly lower the energy barrier for Li⁺ diffusion and enhance the intrinsic electronic conductivity. Moreover, dislocations help convert the surface tensile stress arising from Li⁺ intercalation into compressive stress, effectively improving the structural integrity during cycling. Notably, this approach can also be applied to synthesize LiFePO₄ cathode materials under ambient conditions, eliminating the requirement for inert atmospheres. Consequently, the CTS-synthesized Nb₁₄W₃O₄₄||LiFePO₄ battery demonstrates reversible structural evolution validated by in situ XRD and exceptional cycling ability (e.g., 0.0065% capacity decay per cycle at 4 A g⁻¹ over 3000 cycles). Importantly, the Nb₁₄W₃O₄₄||LiFePO₄ configuration also shows enhanced thermal stability in the Ah-level pouch cell nail penetration test, confirming its feasibility.