实用大容量三电极方形锌空气电池

Developing high-capacity prismatic zinc-air batteries with tri-electrode configuration

锌空气电池具有高安全、大容量、低成本和低自放电等特性,因此获得广泛关注。可充电式锌空气电池在商业化过程中最重要的问题在于难以找到合适的双功能催化剂同时长时间实现氧还原反应(ORR)和析氧反应(OER),而三电极电池结构是一个有效解决此问题的方案。另外,大容量方形锌空气电池在商品化过程中的耐漏液性能极其重要。本文报道了一种可商业化的大容量三电极方形锌空气一次电池,该电池具4大创新特点:(1)放电性能优异,在合适的电流放电情况下锌粉利用率高达97.0%;(2)高耐漏液性能,其耐漏液性能比市面上的方形锌空气电池更好,经过高低温测试以及高温45℃储存1个月测试不会出现漏液现象;(3)比容量大,单电芯比容量可达356 A·h/kg,由此串并联而成的电池包放电能量密度达到405 W·h/kg;(4)结构新颖,采用双面ORR空气极的锌空气电池结构可大幅度增加空气催化有效面积,提高电池的放电功率,此外,其中一面ORR空气极未来可切换为OER空气极,电池变为三电极结构有助于推动可充式锌空气电池的发展。

Zinc-air batteries have attracted widespread attention for their excellent safety, high capacity, low cost, and low self-discharge performance. A critical problem in commercializing rechargeable zinc-air batteries is finding a suitable bifunctional catalyst, in which the oxygen reduction reaction(ORR) and oxygen evolution reaction(OER) can work consistently over a long period. Therefore, a zinc-air battery with a tri-electrode configuration is a solution.Nevertheless, antileakage performance is critical for commercial batteries. We report a highcapacity prismatic zinc-air battery using a novel tri-electrode configuration. We introduce a design assuring a better connection between the cathode current collector and tab and a better sealing configuration for antileakage. Four highlights of this work are as follows:(1) excellent discharge performance,(2) antileakage,(3) high capacity, and(4) novel structure. When the cell was loaded with small amounts of zinc gel, it showed a low voltage of 1.10 V when discharging because the small amount of zinc gel might not cover the current collector and separator completely. However, leakage after discharge was observed when the cell was loaded with excess zinc gel. The amount of zinc gel, while being antileakage, was optimized by filling the anode case cavity with a proper amount of zinc gel, i. e., 87%. When the cell was discharged under a high current, it incurred a low voltage problem. However, discharging under a low current took long, and the surrounding carbon dioxide can seriously deteriorate the cathode catalyst’s performance. Consequently, an optimal zinc loading as high as 97% in the zinc gel was used in an effective current discharge process. Moreover, the cell showed low voltage in a highly humid environment because of the high humidity affecting the active sites for the three-phase reaction. Notably, no leakage was detected even after the extreme conditioning test, i. e., the high-low temperature cycle test(70 ℃ to-20 ℃) and high-temperature storage(45 ℃) for one month test. The tests demonstrated excellent antileakage performance of our cells compared to other commercial zinc-air batteries. An impressively high capacity of 356 A·h/kg was obtained for a single Cell-14 under a 600 mA discharge current, whereas batteries packed with the Cell-14 connected in series and parallel possessed a high energy density of405 W·h/kg. Also, our optimized design strategies(the larger size anode cavity design,optimized zinc gel recipe, and improved catalyst performance) could theoretically be used to design a cell to obtain an energy density as high as 650 W·h/kg. The novel structure of a double-layered air cathode with tri-electrode configuration increases the effective air catalytic area, doubling the power density. Ultimately, our novel zinc-air battery with a unique trielectrode structure, combined with gel polymer electrolytes, can be used to develop and commercialize a rechargeable zinc-air battery in the future.