A zincophobic interface engineering achieving crystal-facet manipulation for ultra-long-life zinc-based flow batteries

Zinc-based flow batteries (ZFBs) have attracted considerable attention due to their high energy density, high safety, and low cost. However, the notorious dendrite problem is universally recognized as a bottleneck limiting the commercial application of ZFBs. This work proposes a zincophobic interface engineering strategy based on electrostatic repulsion to achieve uniform distribution of zincate ions along the membrane-electrode interface, where the carboxymethyl cellulose (CMC) is introduced for customized optimization of membrane surface charge. Such interface engineering successfully realizes crystal-facet manipulation that contributes to a 33.76% increase in the exposure of preferential crystallographic orientation ((002) plane), as evidenced by molecular scale characterization techniques, in-situ dynamic observation and density functional theory study. Moreover, the good wettability of hydrophilic CMC and the positive impact of its abundant –OH functional groups on the transport dynamics of charge carrier (OH−) synergistically enable the prepared membrane delivering high ion conductivity. Consequently, the battery employing the as-prepared membrane achieves stable operation for over 3000 cycles at 80 mA cm−2 with an average energy efficiency of ∼80%. This study provides a new solution for metal dendrite problem by crystal-facet manipulation, and so as to facilitate the commercialization of ZFBs in long-term energy storage.