Cation Group‐Driven Dual‐Track Regulation Enables Dendrite‐Free and Low‐Temperature Zn‐Ion Hybrid Supercapacitors

Why It Matters

By eliminating dendrite formation and preserving ion mobility at sub‑zero temperatures, the technology makes zinc‑ion hybrid supercapacitors viable for extreme‑environment grid and mobility applications, accelerating commercialization of safe, low‑cost energy storage.

Key Takeaways

• PDAC hydrogel immobilizes Cl‑ anions, creating Zn²⁺ channels
• Zn²⁺ transference number reaches 0.87, enhancing ion selectivity
• Ionic conductivity 5.3 mS cm⁻¹ at –50 °C
• Dendrite‑free Zn plating yields 98 % reversibility at –40 °C
• ZHSCs retain 95 % capacity after 20 k cycles at –40 °C

Pulse Analysis

Zinc‑ion hybrid supercapacitors (ZHSCs) have attracted attention for their low cost and safety, yet their deployment is hampered by sluggish Zn²⁺ migration, parasitic side reactions, and dendrite growth—problems that intensify in cold climates. Traditional electrolyte designs focus almost exclusively on the cation, overlooking how anions can influence interfacial chemistry and ion transport pathways. The emerging dual‑track regulation concept leverages both cationic and anionic interactions to simultaneously address kinetic bottlenecks and morphological instability, opening a new design space for extreme‑temperature energy storage.

The core of this breakthrough is a poly(acryloyloxyethyl trimethyl ammonium chloride) (PDAC) hydrogel infused with ZnCl₂. Quaternary ammonium groups (─N⁺(CH₃)₃) electrostatically bind Cl⁻ anions, effectively removing them from the conduction pathway and establishing highly selective Zn²⁺ channels. This architecture boosts the Zn²⁺ transference number to 0.87 and sustains an ionic conductivity of 5.3 mS cm⁻¹ even at –50 °C, far surpassing conventional aqueous electrolytes. Concurrently, the cationic sites adsorb onto high‑energy zinc crystal facets, steering (002)‑oriented deposition that suppresses dendrite nucleation and enables 98 % reversible plating/stripping at –40 °C.

Performance data translate into practical advantages: ZHSCs equipped with the PDAC electrolyte maintain 95 % capacity after 20,000 cycles at –40 °C, showcasing durability required for grid‑scale storage in polar regions or electric vehicles operating in winter conditions. The dual‑track strategy is inherently scalable, relying on inexpensive polymer chemistry and common zinc salts, suggesting a clear pathway toward commercial adoption. Future work will likely explore electrolyte tuning for higher energy density, integration with solid‑state architectures, and broader temperature windows, positioning dendrite‑free zinc systems as a compelling alternative to lithium‑based technologies.