Microfluidic high-throughput optimization enables scalable synthesis of high-entropy fluorophosphate cathode

Large-scale synthesis of high-entropy fluorophosphate cathode for high-rate sodium-ion batteries remains a huge challenge due to time-consuming conditional optimization and poor phase purity. Herein, for the first time, we overcome the bottlenecks of large-scale synthesis of high-entropy Na₃V_1.9M_0.1(PO₄)₂F₃ (HE-NVPF) cathode libraries by a microfluidic high-throughput optimization (MHO) strategy. Due to precise regulation and in situ monitoring of nucleation-growth kinetics, the microfluidic in situ Raman spectrometer achieves high iteration efficiency of conditional optimization with 400 times increase over traditional strategies. Consequently, kilogram-scale HE-NVPF with high phase purity is rapidly synthesized within 2 h, which delivers stable multielectron transfer, superior Na⁺ diffusion kinetics and negligible volume expansion/contraction, exhibiting reversible phase transition and excellent structural ruggedness. As a result, the representative Na₃V_1.9(Ca, Mg, Zr, Mn, Cr)_0.1(PO₄)₂F₃ cathode presents record-breaking rate capacity (108.6 mAh g^-1 at 50 C), large energy density (371.9 Wh kg^-1) and good cycling stability. This MHO strategy can be extended to synthesize other high-entropy Na₃V_1.9M_0.1(PO₄)₂F₃, such as M = (Mg, Zr, Co, Mn, Cr), (Zr, Ca, Fe, Mn, Cr), (Mg, Ca, Ni, Mn, Cr), (Zr, Cu, Mg, Mn, Cr) and (Ga, Zr, Ca, Mn, Cr). Our work provides a novel insight into machine intelligent synthesis of high-entropy materials and facilitates their industrialized process.