01
研究亮点
可穿戴电子产品的日益普及促进了具有高理论能量密度、高安全性和低成本的柔性锌空气电池的发展。然而，半放开的电池结构和高浓度的碱性水环境对于电解质材料的保液能力和锌负极的稳定性提出了挑战。基于此，天津大学钟澄课题组开发了一种超吸水淀粉基聚合物电解质，并将其成功应用于柔性锌空气电池领域，为新型聚合物电解质的设计与制备提供了新思路。超吸水淀粉基聚合物电解质的基体呈网络状，具有高的离子传导率（约166 mS cm–1）、电解质吸液和保液能力、强耐碱性和较好的锌负极稳定性。基于该电解质所组装的锌空气电池能够稳定循环300小时，约为常用聚乙烯醇基聚合物电解质所组装电池寿命的15倍。
02
主要内容
为推进智能时代的发展，水系柔性锌空气电池引起广泛关注。该电池体系具有理论能量密度高、安全性高、成本低，且环境友好的优势。为了避免传统电解液的泄露与挥发问题，水凝胶电解质具有介于液体和固体之间的形态，可有效缓解漏液，并且具有离子传导率高、机械柔性较好三维优点，是目前柔性锌空气电池中使用最为广泛的电解质体系。其中，聚乙烯醇（PVA）基聚合物是该领域报道最多的电解质基体之一，因为其具有高的化学和电化学稳定性、低成本和简单的制造工艺。然而，基于该电解质所组装的锌空气电池通常具有较短的充放电寿命，约为10–20小时。
鉴于此，本研究将农业中常用的土壤保水剂的概念引入锌空气电池中，以缓解半开放电池体系所导致水分易流失的问题。实验结合DFT理论模拟计算结果，揭示了超吸水淀粉基聚合物电解质提升电池性能的原因，证实了电解质中聚合物链上羧基官能团的重要性，有助于促进无枝晶界面层的生成，提高锌电极循环稳定性。该工作有助于启发聚合物电解质功能化设计新策略，强调了电解质材料对于电池性能的重要性，促进了长循环寿命、优异倍率性能、大功率输出的锌空气电池的发展。
▲Figure 1. (a) Schematics of the preparation process of the SSHPEs. Structure diagram of (b) PVA, (c) PAA, and (d) SSHPE.
▲Figure 2. (a) XRD spectrum of SSHPEs and PVA. (b) FTIR patterns of SSHPEs and starch. (c) XPS spectrum of C 1s and O 1s of the SSHPE. (d) SEM image and elemental mapping results of the SSHPE. (e) Liquid uptake behaviors of SSHPEs and PAA. (f) Ionic conductivity performances and (g) liquid retention abilities of SSHPEs, PAA, and PVA–KOH.
▲Figure 3. Electrochemical performances of ZABs with SSHPEs, PAA, and PVA–KOH. (a) Galvanostatic cycling curves with 30 min discharging and 30 min charging per cycle at 1 mA cm–2. (b) The galvanostatic discharging profiles at 1 mA cm–2. (c) Rate performances at 0.25, 0.5, 1, 2, 4 and 8 mA cm–2. (d) Polarization and corresponding power density curves. (e) Open circuit potential of the assembled ZAB. (f) Galvanostatic cycling curves of the ZAB at various bending states. Photographs of connected ZABs charging (g) an eye massager, and powering (h) a watch fan.
▲Figure 4. Zinc plating–stripping behavior of Zn//Zn symmetric cell with (a) SSHPEs and PVA–KOH at 1 mA cm–2 and 0.5 mAh cm–2, and (b) SSHPE-2 at 5 mA cm–2 and 2.5 mAh cm–2. (c) Cross-section SEM image and EDX element mapping results of the cycled zinc anode with SSHPE-2. (d–g) XPS spectrum of the cycled zinc anode with SSHPE-2. Cross-section SEM image and EDX element mapping results of (h) pure zinc and (i) the cycled zinc anode with PVA–KOH.
▲Figure 5. SEM images and corresponding EDX mapping results of the cycled zinc anode with (a–b) SSHPE-2 and (c) PVA–KOH. Schematic diagrams of the formation of (d–e) a steady interface on the surface of zinc anode with SSHPEs and (f) dendrites with PVA–KOH. (g) Differential charge density of the interface between the SSHPE and the zinc anode. (h–i) 2D slice of the SSHPE–Zn and PVA–Zn interfaces. (j–k) ICP testing battery configuration with the optical photo. (l) Zn(OH)42− crossover behavior through SSHPE after different duration of time.
03
文献信息
Xiayue Fan, Rui Zhang, Simi Sui, Xiaorui Liu, Jie Liu, Chunsheng Shi, Naiqin Zhao, Cheng Zhong, Wenbin Hu. Starch-Based Superabsorbent Hydrogel with High Electrolyte Retention Capability and Synergistic Interface Engineering for Long-Lifespan Flexible Zinc–Air Batteries. Angewandte Chemie International Edition. 2023, DOI: 10.1002/anie.202302640.
连接：https://onlinelibrary.wiley.com/doi/10.1002/anie.202302640
第一作者：范夏月
通讯单位：天津大学