The quiescent electrolyte causes serious concentration polarization and dendrite problems during the charging and discharging of the battery, which restricts the development of metal secondary batteries and flow batteries. Herein, we report a new concept of ion motors, with which the directional driving and uniformity of the electrolyte are realized to eliminate the concentration polarization and dendritic phenomenon for secondary metal batteries and flow batteries without additional external energy. In this study, a dendrite-free secondary metal battery with ion motors is constructed to eliminate a considerable concentration polarization voltage by a tiny induced counter electromotive force generated by Lorentz force, significantly improving the output power and energy efficiency of the battery. An actual pump-free flow battery with an ion motor is also assembled, which overcomes the problems of low energy efficiency and the complex structure caused by the traditional flow battery requiring 1−2 pumps to drive the electrolyte. The efficiency of ion motors to drive the electrolyte is hundreds of times higher than that of the mechanical pump. Therefore, the ion motor provides a universal strategy for designing more pump-free flow batteries and metal secondary batteries without the risk of dendrites in the future.

The hydrometallurgical technology provides an efficient and sustainable green lead recovery process from lead acid batteries. Methanesulfonic acid has been widely considered as a green solvent for lead electrolytic recovery. However, the competitive precipitation of PbO2 at anode and higher overpotential for OER limit the lead recovery efficiency. In this work, an anodic oxygen evolution reaction (OER) catalyst with a low Ir mass fraction of 7.2% is obtained by electroplating iridium on carbon cloth (CC), exhibiting a lower overpotential of 256 mV, longer lifetime of 10 h, and better stability in the 0.5 M MSA solution. When CC-Ir is used as an anodic catalyst for lead recovery in the lead methanesulfonate electrolyte, only a lesser Pb precipitation product with Pb atom mass fraction of 1.42% is found after electrolysis of 10 h, demonstrating the suppression effect of CC-Ir for a PbO2 side reaction. This work proves that the anodic catalyst plays an important role in the lead electrolytic recovery process, which can inhibit the side reaction, reduce the energy consumption, and increase recovery efficiency.

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