【摘要】 以钒渣钠化焙烧水浸液为含钒原料，亚硫酸钠（Na₂SO₃）为还原剂，通过还原、沉淀、酸溶和结晶工艺制备了硫酸氧钒（VOSO₄）。系统探究了还原与沉淀条件对钒回收率的影响，并对中间产物和VOSO₄产品进行表征。结果表明，在还原pH为2.5、还原温度70℃、还原时间60 min、沉淀pH为6.0、沉淀温度20℃、沉淀时间10 min、Na₂SO₃与V的质量比m（S）∶m（V）=0.5的条件下制备VOSO₄，钒回收率达到最大值97.08%。还原沉淀中间产物VO（OH）₂为非晶态，酸溶结晶所得VOSO₄晶体由直径1～3μm的块状晶体组成。浸出液中杂质Cr离子对VOSO₄纯度影响较大。电化学性能测试表明，该VOSO₄电解液在循环稳定性和扩散速率方面表现优异，但需进一步降低杂质含量并提升稳定性。研究结果为钒资源利用提供了一种高效的新途径，同时也为钒电池电解液的开发提供了重要参考。更多还原

【Abstract】 Vanadyl sulfate（VOSO₄） is a key active material for all-vanadium redox flow batteries（VRFBs）, but traditional preparation processes rely on high-purity V₂O₅ as raw material, featuring long flow, high energy consumption and high production cost. To achieve efficient and low-cost utilization of vanadium resources, a shortprocess technology for in-situ preparation of VOSO₄ was proposed using sodium roasting-water leaching solution of vanadium slag（vanadium concentration: 16.5 g/L, Cr concentration: 0.66 g/L） as the vanadium source and sodium sulfite（Na₂ SO₃） as the reducing agent. The process includes four steps: reduction, precipitation, acid dissolution and crystallization. The effects of reduction parameters(pH value, temperature, time, mass ratio of S to V（m（S）/m（V）） and precipitation parameters（pH value, temperature, time） on vanadium recovery rate were systematically investigated. A variety of material characterization techniques were employed to analyze the phase composition, chemical structure, and micro-morphology of the intermediate product VO（OH）₂ and the final VOSO₄ product, while electrochemical testing methods were used to evaluate the electrochemical performance of the VOSO₄ electrolyte. The results show that the maximum vanadium recovery rate of 97.08% is obtained under the optimal process conditions including reduction pH value of 2.5, reduction temperature of 70 ℃, reduction time of 60 min, m（S）/m（V）=0.5, precipitation pH value of 6.0, precipitation temperature of 20 ℃, and precipitation time of 10 min. X-ray diffraction（XRD） and Fourier transform infrared spectroscopy（FTIR） analyses confirm that the intermediate product VO（OH）₂ is amorphous, and washing with ethanol and deionized water effectively reduces the Na⁺ content from 0.66 g/L to 0.03 g/L without significant loss of V⁴⁺（maintained at about 16.3 g/L）. Scanning electron microscopy（SEM） observations reveal that the synthesized VOSO₄ consist of blocky crystals with a diameter of 1–3 μm, and XRD results indicate it is a mixture of VOSO₄· 3H₂O and VOSO₄· 2H₂O. Energy dispersive spectroscopy（EDS） and impurity detection show that trace Cr impurities exist in the product, with a Cr content of 2 836 mg/L, which affect the product purity. Electrochemical test results demonstrate that after 10 cyclic voltammetry（CV） cycles（scan rate: 10 mV/s, potential range from –0.2 V to 1.5 V）, the VOSO₄ electrolyte exhibites a reduction peak potential of 0.49 V and an oxidation peak potential of 1.17 V, with a peak potential difference（ΔE_p） of 0.68 V and an oxidation-reduction peak current ratio of 11. The peak current has a good linear relationship with the square root of the scan rate, indicating the electrochemical reaction is controlled by vanadium ion diffusion. The limiting diffusion current density fitted from the steady-state polarization curve is 0.516 mA/cm². Electrochemical Impedance Spectroscopy（EIS） tests show that the electrolyte impedance is 26.9 Ω after the first cycle and increases to 55.7 Ω after 10 cycles due to the formation of a stable solid electrolyte interphase（SEI） film, while the charge transfer resistance in the high-frequency region decreases, leading to improved conductivity. This study provides a feasible technical route for the efficient utilization of vanadium slag resources and the development of VRFB electrolytes. Future work should focus on reducing Cr impurity content to further enhance the electrochemical performance and industrial application value of VOSO₄ products.更多还原