Highly zincophilic-hydrophobic polyzwitterionic hydrogel electrolyte with strong electronegative sulfobetaine-carboxyl motifs for ultrastable zinc-ion batteries.

Polyzwitterionic hydrogel electrolytes with good anionic affinity and a well-aligned Zn2+ deposition effect are regarded as potential alternatives for propelling zinc-ion batteries (ZIBs). However, their hydrophilic molecular chains show relatively low zincophility and easily transfer H2O molecules to the Zn surface, resulting in interfacial Zn corrosion and dendrites. Here we design highly zincophilic-hydrophobic polyzwitterionic hydrogel electrolyte (SC-PAM) via the crosslinking of zwitterionic sulfobetaine and carboxyl-rich carboxylated chitosan for ultrastable ZIBs. The zincophilic -SO3 - motifs of zwitterionic sulfobetaine in SC-PAM afford highly Zn2+-selective migration channels and homogenize Zn2+ flux with a high transference number of 0.90. Meanwhile, strong electronegative carboxyl groups (C[double bond, length as m-dash]O) in carboxylated chitosan strongly anchor H2O molecules via rich H-bonding interactions to establish a hydrophobic interfacial layer, which shields direct contact between H2O solvent and the Zn anode to avoid Zn corrosion. As a consequence, the Zn‖SC-PAM‖Cu cell exhibits a high average coulombic efficiency of 99.7% during 7600 cycles, while the Zn‖SC-PAM‖Zn cell shows ultrastable cycling exceeding 7500 hours. Significantly, SC-PAM can be further leveraged to design a state-of-the-art Zn‖SC-PAM‖V2O5 full battery with high capacity (372 mAh g-1), large-current tolerance (15 A g-1), and ultralong cycle life (5000 cycles). This work extends the structural engineering landscape of zincophilic-hydrophobic polyzwitterionic hydrogel electrolytes for advanced ZIBs.