A novel cobaltocenium-containing polybenzimidazole polymer was used for alkaline anion exchange membranes.

In order to develop a high-performance and longterm stable anion exchange membrane (AEM), ether-bond-free poly(biphenyl bromohexyl indole) (PPHIN) was prepared and explored as a highly alkaline stable polymer backbone. Combining two alkyl chain modification strategies, a series of flexible doublecationic side chains with different lengths of extender chains were grafted onto the PPHIN backbone to improve the hydrophilic/ hydrophobic microphase separation, ionic conductivity, and alkaline stability of the AEM. The resulting PPHIN-N1C possessed a high hydroxide conductivity of 136 mS/cm at 80 °C due to the well-developed microphase separation. Furthermore, the PPHIN-N8C with a long extender chain exhibited high ionic conductivity (103 mS/cm), a low swelling ratio, and excellent alkaline stability. The ionic conductivity of PPHIN-N8C only decreased by 13% after soaking in 2 M NaOH at 80 °C for 1000 h, which was attributed to the steric hindrance of the extender hydrophobic alkyl chain. The single cell using the PPHIN-N8C membrane has a maximum peak power density of 216 mW/cm 2 at a current density of 472 mA/cm 2 at 80 °C. The results suggest that this type of PPHIN-based AEM is promising in anion exchange membrane fuel cell application.

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Aqueous Zn-ion batteries (AZBs) have been considered as one of the most promising large-scale energy storage systems, owing to the advantages of raw material abundance, low cost, and eco-friendliness. However, the severe growth of Zn dendrites leads to poor stability and low Coulombic efficiency of AZBs. Herein, to effectively inhibit the growth of Zn dendrites, a new strategy has been proposed, i.e., tuning the surface energy of the Zn anode. This strategy can be achieved by in situ doping of Sn heteroatoms in the lattice of metallic Zn via codeposition of Sn and Zn with a small amount of the SnCl2 electrolyte additive. Density functional theory calculations have suggested that Sn heteroatom doping can sharply decrease the surface free energy of the Zn anode. As a consequence, driven by the locally strong electric field, metallic Sn tends to deposit at the tips of the Zn anode, thus decreases the surface energy and growth of Zn at the tips, resulting in a dendrite-free Zn anode. The positive effect of the SnCl2 additive has been demonstrated in both the Zn∥Zn symmetric battery and the Zn/LFP and Zn/HATN full cell. This novel strategy can light a new way to suppress Zn dendrites for long life span Zn-ion batteries.