Self-assembly of MoS₂ nanoflakes contributing to continuous porous hydrogel for high-rate flexible zinc battery

Hydrogel can be ideal electrolyte material for flexible devices because of its excellent mechanical flexibility and good ion transport ability. Here, we added a small amount of MoS2 into the hydrogel to produce polyvinyl alcohol/sodium alginate/polyethylene glycol-MoS2 (PVA/SA/PEG-MoS2) hydrogel by freeze-thaw method, followed by soaking in 6 M KOH + 0.2 M ZnAC aqueous solution to obtain the hydrogel electrolyte for flexible zinc battery. The mechanical properties of the hydrogel can be improved by building the multi-network through hydrogen bonding among polymers and MoS2 nanoflakes, and the performance of the hydrogel at low temperature can be improved by PEG. Interestingly, MoS2 nanoflakes within the hydrogel self-assemble and further crystallize after soaking in KOH/ZnAc solution, and the hydrogel electrolyte exhibits continuous porous structure, which is ideal for ionic diffusion. The hydrogel added with 0.75 wt% MoS2 showed a stress strain performance of 9.956 MPa, 525 %, and the hydrogel electrolyte also showed a stress strain performance of 4.1 MPa, 1087.61 %. The fabricated flexible zinc battery using the PVA/SA/PEG-MoS2-0.75-E electrolyte exhibits a high capacity of 139.72 mAh g(-1) at room temperature and 100.08 mAh g(-1) at -20 degrees C. Especially, benefiting from the high ionic conductivity, the flexible zinc battery shows similar rate performances compared with liquid device.