Additive engineering for a hydrophilic/zincophilic polymeric layer towards dendrite-free zinc anode

Aqueous zinc batteries are an emerging candidate for large-scale energy storage applications, but the Zn anode still suffers from poor reversibility due to the serious side reactions and dendrite growth. Here, a polymeric protective layer has been insitu built on Zn anode by using silk fibroin (SF) as additives. Specifically, the SF additive could preferentially adsorb on Zn surface and then undergo a self-phase transition process to yield a polymeric layer. Owing to the abundant polar groups, this polymeric layer features high hydrophilicity and zincophilicity, which could promote the Zn2+ transfer while guiding the homogenous redistribution of Zn2+, thus promising a dendrite-free Zn anode. Remarkably, by adding 0.2 g/L SF into 2 M ZnSO4, the Zn–Zn cell stably cycles for 3000 h at 2 mA/cm2 with 2 mAh/cm2, and the Zn–V2O5·nH2O cell also shows high stability during the whole 1500 cycles at 1 A/g. This work demonstrates a new paradigm for in situ constructing polymeric coatings from electrolyte additives, opening a powerful way to address common challenges faced by various metal anodes. [Display omitted] •A hydrophilic/zincophilic polymeric layer has been in situ built on Zn anode by using silk fibroin as additives.•The growth mechanism of the silk fibroin-based polymeric layer has been comprehensively analyzed.•The reasons why this silk fibroin-based polymeric layer can effectively stabilize the Zn anode are revealed.•A silk fibroin-modified electrolyte that could greatly improve the reversiblity of the Zn anode is developed.