Aqueous secondary batteries have garnered significant attention for their inherent safety, low cost, and environmental friendliness, making them strong contenders for next-generation energy storage systems. However, their practical applications are hindered by a narrow electrochemical stability window and relatively low energy density, which limit their scalability and performance in large-scale settings. These challenges highlight the urgent need for advanced electrolytes that can overcome these limitations and unlock the full potential of aqueous batteries for energy storage applications.
On December 31, 2024, researchers from the China University of Petroleum (East China) unveiled their findings (DOI: 10.26599/EMD.2024.9370050) in the journal Energy Materials and Devices . The team successfully synthesized a novel hydrogel electrolyte that, when paired with a Prussian blue cathode, achieves outstanding energy density and cyclability in sodium-zinc hybrid ion batteries. This innovation represents a significant leap forward in the field of aqueous battery technologies.
The newly developed hydrogel electrolyte, named Zn–SA–PSN, is built on a unique polymer network featuring interconnected amide chains and hydrophilic functional groups, which are key to its high performance. This advanced design delivers an impressive ionic conductivity of 43 mS·cm⁻¹, significantly surpassing traditional electrolytes, and an expanded electrochemical stability window of 2.5 V. The broader stability window supports higher voltage operations, critical for enhancing the energy density of batteries.
When paired with a Prussian blue cathode, the sodium-zinc hybrid battery demonstrates remarkable performance, achieving over 6000 cycles with a minimal capacity decay of just 0.0096% per cycle at a high current density of 25 C. This stability is attributed to the hydrogel electrolyte's ability to suppress side reactions and inhibit dendrite growth, which are common challenges in zinc anodes. Additionally, the battery achieves an impressive energy density of approximately 220 Wh·kg⁻¹ and outstanding rate performance, with capabilities of up to 5 C. The Zn–SA–PSN electrolyte's versatility extends its applications to other cathode materials, making it compatible with both aqueous sodium-zinc hybrid batteries and zinc-ion batteries. These findings highlight the transformative potential of hydrogel electrolytes in advancing battery technologies.
"Our hydrogel electrolyte represents a significant advancement in the field of aqueous batteries," said Dr. Linjie Zhi, lead researcher on the project. "Its ability to maintain high performance over thousands of cycles and at high current densities is a testament to its potential for practical applications in energy storage. This innovation addresses critical limitations in current battery technologies and opens new avenues for further development."
The development of the Zn–SA–PSN hydrogel electrolyte carries profound implications for the energy storage industry. Its ability to deliver high energy density and long-term stability could transform battery systems for grid-scale energy storage, electric vehicles, and other applications demanding efficiency and safety. Moreover, this breakthrough underscores the promise of hybrid ion batteries in meeting the growing need for sustainable, high-performance energy storage solutions. As the demand for reliable and environmentally friendly energy systems continues to rise, innovations like this hydrogel electrolyte pave the way for a more sustainable energy future.
This work was financially supported by National Key Research and Development Program of China (Grant No. 2022YFE0127400), Taishan Scholar Project of Shandong Province (Grant Nos. ts202208832 and tsqnz20221118), National Natural Science Foundation of China (Grant No. 52473285), Shandong Provincial Natural Science Foundation (Grant No. 21CX06028A).
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