image: (a) Schematic representation of the in situ ring-opening polymerization of DOL-based electrolyte initiated by Sn(OTf)2. (b) Optical images of DS–LE and DS–QSPE. (c) 1H-NMR and (d) 13C-NMR spectra of DOL and DS–QSPE. (e) FTIR spectra of DOL, DS–LE, and DS–QSPE.
Credit: Energy Materials and Devices, Tsinghua University Press
Sodium-sulfur (Na-S) batteries are recognized for their high energy density and cost-effectiveness, positioning them as strong candidates for large-scale energy storage. However, their widespread use has been hampered by several technical barriers. The inherent low electrical conductivity of sulfur and its sodium polysulfide derivatives lead to poor electrochemical performance. Additionally, the dissolution and shuttling of sodium polysulfides cause capacity fade and efficiency loss over time. Compounding these issues, the formation of sodium dendrites poses significant safety risks and further limits the battery's cycle life. To overcome these challenges, researchers have focused on developing advanced electrolytes that can stabilize the electrode/electrolyte interfaces and effectively control the movement of polysulfides.
A team of researchers from Fujian Normal University, led by Junxiong Wu and Yuming Chen, have made a significant breakthrough in this area. Their study (DOI: 10.26599/EMD.2024.9370051), published on December 31, 2024, in the Energy Materials and Devices journal, presents a dual salt-based quasi-solid polymer electrolyte (DS-QSPE) that effectively stabilizes the electrode/electrolyte interfaces and suppresses the polysulfide shuttle effect in room-temperature Na-S batteries. Through in situ polymerization, this electrolyte enables significant performance improvements, making Na-S batteries more viable for practical applications.
The DS-QSPE developed by the researchers achieves an impressive ionic conductivity of 4.8 × 10−4 S·cm−1 at 25°C and a sodium-ion transference number of 0.73, both of which significantly enhance the battery's electrochemical performance. The electrolyte forms an interconnected network within the sulfurized polyacrylonitrile (SPAN) cathode, providing a stable, seamless interface for electrochemical reactions. This structure not only facilitates efficient and uniform ion transport but also supports a high capacity of approximately 327.4 mAh·g−1 after 200 cycles at 0.2 A·g−1, retaining 81.4% of its initial capacity. Molecular dynamics simulations and density functional theory calculations reveal that the DS-QSPE works by enhancing the coordination of Na+ ions with the polydioxolane chain and promoting the dissociation of sodium salts. These factors contribute to mitigating the polysulfide shuttle effect and stabilizing the electrode/electrolyte interfaces, ultimately prolonging the battery's lifespan.
Junxiong Wu, lead researcher of the study, shared his thoughts on the significance of the research: "Developing a quasi-solid polymer electrolyte that can effectively address the interfacial challenges in Na-S batteries is a critical step forward in energy storage technology. Our DS-QSPE offers a reliable and scalable solution that enhances both the performance and stability of room-temperature Na-S batteries." The DS-QSPE not only addresses existing barriers but also offers a pathway to realizing the full potential of Na-S batteries for large-scale energy storage.
This advancement in quasi-solid polymer electrolytes holds broad implications for the energy storage industry. By overcoming critical challenges such as interface voids and the polysulfide shuttle effect, this new electrolyte technology could lead to more efficient and reliable energy storage systems. It has the potential to accelerate the adoption of renewable energy sources by providing a stable, cost-effective means of storing energy, thus contributing to the development of a more sustainable energy future. As research in this field continues, the DS-QSPE represents a significant step toward the realization of large-scale energy storage solutions that are both efficient and durable.
This work is granted by the National Natural Science Foundation of China (Grant Nos. 22209027, 22179022, and 22109023), the FuXiaQuan National Independent Innovation Demonstration Zone Collaborative Innovation Platform (Grant No. 2022-P-027), the Hundred Talents Plan of Fujian Province, the Top Young Talents of Young Eagle Program of Fujian Province, the Youth Innovation Fund of Fujian Province (Grant Nos. 2022J05046 and 2021J05043), the Award Program for Fujian Minjiang Scholar Professorship, and the Talent Fund Program of Fujian Normal University.
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Journal
Energy Materials and Devices
Article Title
In situ polymerized quasi-solid polymer electrolytes enabling void-free interfaces for room-temperature sodium–sulfur batteries
Article Publication Date
31-Dec-2024