The electro-reduction of magnetite is important for many different industries. For example, it relates to the extraction of iron from iron ore and the charging of iron-based batteries. The sluggish electro-reduction reaction of magnetite affects the energy efficiency of iron extraction or the charge rate of iron-based batteries. However, what factors affecting the reduction rate is not well understood. In this study, electrochemical analysis, XRD, SEM, EDS mapping and XPS techniques are adopted to analyze the reaction, and it is proved that two factors determine the electro-reduction rate of magnetite electrode: O²⁻ diffusion inside the particles determines the electro-reduction rate of a single particle, and the electrical resistivity of electrode determines how many magnetite particles are involved in electro-reduction simultaneously. Contact resistance between particles is the dominant part of the electrical resistance of the magnetite electrode. The function mechanism of sulfide in the reaction is also revealed: a sulfide additive can react with magnetite to form amorphous or crystal FeS at different potentials. These compounds, especially crystal FeS, coat onto the surface of magnetite particles, and bond them together. The coating and bonding can decrease contact resistance significantly, thus enhancing the electro-reduction rate of magnetite to one order of magnitude.

磁铁矿的电解还原对于许多不同的行业都很重要。例如，它涉及从铁矿石中提取铁以及对铁基电池进行充电。磁铁矿的缓慢还原反应会影响铁提取的能量效率或铁基电池的充电率。但是，影响降低率的因素尚不十分清楚。本研究采用电化学分析，XRD，SEM，EDS作图和XPS技术对反应进行了分析，结果证明，决定磁铁矿电极电还原速率的两个因素是O ²⁻粒子内部的扩散决定了单个粒子的电还原率，电极的电阻率决定了同时进行电还原的磁铁矿粒子数。颗粒之间的接触电阻是磁铁矿电极电阻的主要部分。还揭示了硫化物在反应中的作用机理：硫化物添加剂可与磁铁矿反应，形成不同电位的非晶或结晶FeS。这些化合物，尤其是晶体FeS，涂覆在磁铁矿颗粒的表面，并将它们结合在一起。涂层和粘结可显着降低接触电阻，从而将磁铁矿的电还原速率提高一个数量级。