Zeng Weikang, Zhang Shaobo, Lan Jiaqi, Lv You, Zhu Guoqing, Huang Haotian, Lv Wei, Zhu Yuan
School of Microelectronics, Southern University of Science and Technology, Shenzhen 518055, China.
School of Environment, Harbin Institute of Technology, Harbin 150090, China.
ACS Nano. 2024 Sep 13. doi: 10.1021/acsnano.4c09879.
Gel electrolytes hold promise for stabilizing zinc-ion batteries (ZIBs), but achieving both high ionic conductivity and strong mechanical properties remains challenging. This work presents a double network gel electrolyte based on poly(-hydroxymethyl acrylamide) (PNMA) and sodium alginate (SA), overcoming this trade-off. The PNMA network provides mechanical strength and water retention, while the SA network facilitates rapid zinc-ion (Zn) diffusion through tailored solvation. This double network gel exhibits a tensile strength of up to 838 kPa, significantly higher than previous reports. The SA network provides ion channels for rapid transport of hydrated Zn, enhancing the ionic conductivity to a ground-breaking 33.1 mS cm. This value is even higher than the liquid electrolytes. The growth of Zn dendrites is also suppressed due to the mechanical constraint and rapid ion conduction. In symmetrical cells, the PNMA/SA gel demonstrates exceptional cycling stability (>2000 h). Characterizations show this is because of reduced free water amount, hindering cathode material dissolution. The full cells with sodium vanadate cathode manifest a high capacity (364.8 mA h g at 0.5 A g) and excellent capacity retention (83% after 2500 cycles at 10 A g). This double network design offers a way to achieve high-performance and stable ZIBs.
凝胶电解质有望稳定锌离子电池（ZIBs），但同时实现高离子电导率和强机械性能仍具有挑战性。这项工作提出了一种基于聚（羟甲基丙烯酰胺）（PNMA）和海藻酸钠（SA）的双网络凝胶电解质，克服了这种权衡。PNMA网络提供机械强度和保水性，而SA网络通过定制溶剂化促进锌离子（Zn）的快速扩散。这种双网络凝胶的拉伸强度高达838 kPa，显著高于先前的报道。SA网络为水合锌的快速传输提供离子通道，将离子电导率提高到创纪录的33.1 mS/cm。这个值甚至高于液体电解质。由于机械约束和快速离子传导，锌枝晶的生长也受到抑制。在对称电池中，PNMA/SA凝胶表现出出色的循环稳定性（>2000小时）。表征表明，这是因为游离水量减少，阻碍了阴极材料的溶解。具有钒酸钠阴极的全电池表现出高容量（在0.5 A/g时为364.8 mA h/g）和出色的容量保持率（在10 A/g下2500次循环后为83%）。这种双网络设计为实现高性能和稳定的锌离子电池提供了一种方法。
