CuSO₄·5H₂O was used as an additive for paste Fe₃O₄ electrode by a simple physical mixing method. The results of cyclic voltammetry and energy dispersive spectroscopy tests confirm that during the initial charge, copper sulfate could be converted to metallic Cu with uniform distribution in the electrode and stable during normal charge–discharge cycles. Compared with the electrode without the additive, the discharge capacity of the one with 5‐wt% CuSO₄·5H₂O increases from 483 to 513 mAh·g⁻¹ at a current density of 90 mAh·g⁻¹ and from 147 to 221 mAh·g⁻¹ at a current density of 900 mAh·g⁻¹, respectively. After 50 cycles at a current density of 225 mAh·g⁻¹, its capacity retention rate is 85.7%, but it is only 42.4% for the electrode without the additive. Combined with the results of powder X‐ray diffraction and scanning electron microscopy tests, the improvement in high‐power and cycle performance of the Fe₃O₄ electrodes might be due to the obvious depassivation caused by metallic Cu.

中文翻译：

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硫酸铜作为可充电镍铁电池中Fe3O4电极的添加剂

通过简单的物理混合方法，将CuSO ₄ ·5H ₂ O用作糊状Fe ₃ O ₄电极的添加剂。循环伏安法和能量色散光谱测试的结果证实，在初次充电过程中，硫酸铜可以转变为金属Cu，在电极中分布均匀，并且在正常的充放电循环中稳定。与没有添加剂的电极中，一个与5重量％的CuSO的放电容量相比，₄ ·5H _2个O将增加从483至513毫安·克^-1在90毫安的电流密度·克^-1和从147至221毫安·^克-1在900毫安的电流密度·^克-1， 分别。在电流密度为225 mAh·g ^{-1的条件下}进行50次循环后，其容量保持率是85.7％，但是对于没有添加剂的电极，其容量保持率仅为42.4％。结合粉末X射线衍射和扫描电子显微镜测试的结果，Fe ₃ O ₄电极在高功率和循环性能方面的改进可能是由于金属Cu引起的明显的钝化作用。