“Design and in-situ construction of hydrogel electrolytes and manganese dioxide cathodes toward simplified, stable, and wide-temperature aqueous zinc-ion batteries.”

Dept: Electrical & Computer Engineering

Chair: Petru Andrei, Ph.D.

Abstract

Aqueous zinc-ion batteries have emerged as promising candidates for safe, low-cost, and sustainable energy storage; however, their practical development remains hindered by complex electrode fabrication and interfacial instability. A new method for fabricating AZIB full cells, including pouch cells, is proposed by leveraging the sol–gel transition of the PVANF hydrogel electrolyte in combination with a conventionally prepared MnO2 cathode. The PVANF hydrogel exhibited a high ionic conductivity of 19.7 mS cm–1 and enabled stable Zn plating/stripping for over 1000 h, owing to its optimized network structure and balanced composition. The full cell with MnO2 cathode delivered a high capacity and retained 50 mAh g–1 after 3500 cycles at 10C, demonstrating excellent rate capability and long-term stability. Furthermore, we developed a simplified and efficient strategy that integrates in-situ hydrogel electrolyte formation with in-situ MnO2 electrodeposition to streamline the assembly process and enhance battery performance. A dual-network ANF-PxA hydrogel (aramid nanofiber reinforced poly(acrylamide-co-acrylic acid)) was designed as a quasi-solid electrolyte, featuring high ionic conductivity, robust mechanical strength, and stable Zn plating/stripping behavior over 800 h even at –30 °C. The incorporation of DMSO as a cosolvent improved low-temperature tolerance and maintained interfacial stability. For the cathode, MnO2 was directly electrodeposited on current collectors via a one-step constant-current and constant-voltage activation during the initial charge. In this way, conventional slurry preparation, coating, and drying steps can be eliminated. By systematically optimizing Mn2+ concentration and deposition time, a well-interconnected MnO2 nanoflake film with superior electrochemical performance was achieved. The resulting Zn/MnO2 full cells exhibited high reversibility, superior rate performance and extended cycle life. This integrated in-situ fabrication approach not only simplifies electrode assembly but also ensures strong electrode/electrolyte interfacial contact, thereby enhancing structural integrity and electrochemical efficiency. Overall, this study provides a practical route toward scalable, high-performance AZIBs and highlights the potential of in-situ material formation for next-generation aqueous battery technologies.