Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, MD, USA.
Battery Science Branch, Energy Science Division, Sensor and Electron Devices Directorate, US Army Research Laboratory, Adelphi, MD, USA.
Nat Nanotechnol. 2021 Aug;16(8):902-910. doi: 10.1038/s41565-021-00905-4. Epub 2021 May 10.
Metallic zinc is an ideal anode due to its high theoretical capacity (820 mAh g), low redox potential (-0.762 V versus the standard hydrogen electrode), high abundance and low toxicity. When used in aqueous electrolyte, it also brings intrinsic safety, but suffers from severe irreversibility. This is best exemplified by low coulombic efficiency, dendrite growth and water consumption. This is thought to be due to severe hydrogen evolution during zinc plating and stripping, hitherto making the in-situ formation of a solid-electrolyte interphase (SEI) impossible. Here, we report an aqueous zinc battery in which a dilute and acidic aqueous electrolyte with an alkylammonium salt additive assists the formation of a robust, Zn-conducting and waterproof SEI. The presence of this SEI enables excellent performance: dendrite-free zinc plating/stripping at 99.9% coulombic efficiency in a Ti||Zn asymmetric cell for 1,000 cycles; steady charge-discharge in a Zn||Zn symmetric cell for 6,000 cycles (6,000 h); and high energy densities (136 Wh kg in a Zn||VOPO full battery with 88.7% retention for >6,000 cycles, 325 Wh kg in a Zn||O full battery for >300 cycles and 218 Wh kg in a Zn||MnO full battery with 88.5% retention for 1,000 cycles) using limited zinc. The SEI-forming electrolyte also allows the reversible operation of an anode-free pouch cell of Ti||ZnVOPO at 100% depth of discharge for 100 cycles, thus establishing aqueous zinc batteries as viable cell systems for practical applications.
金属锌是一种理想的阳极，因为它具有高的理论容量（820 mAh g）、低的氧化还原电位（相对于标准氢电极为-0.762 V）、丰富的储量和低的毒性。当用于水系电解液时，它还具有内在的安全性，但存在严重的不可逆性。这一点最好的例证是库仑效率低、枝晶生长和耗水。这被认为是由于在锌电镀和剥离过程中发生严重的析氢反应，迄今为止，使得无法原位形成固体电解质中间相（SEI）。在这里，我们报告了一种水系锌电池，其中含有烷基铵盐添加剂的稀酸性水系电解液有助于形成坚固的、导锌的和防水的 SEI。该 SEI 的存在使电池具有优异的性能：在 Ti||Zn 不对称电池中，锌的沉积/剥离效率高达 99.9%，库仑效率在 1000 次循环内无枝晶；在 Zn||Zn 对称电池中，6000 次循环（6000 h）稳定充放电；高能量密度（在 Zn||VOPO 全电池中为 136 Wh kg，保留率>6000 次循环为 88.7%，在 Zn||O 全电池中为 325 Wh kg，保留率>300 次循环为 218 Wh kg，在 Zn||MnO 全电池中为 88.5%，保留率为 1000 次循环），使用有限的锌。形成 SEI 的电解液还允许 Ti||ZnVOPO 的无阳极袋式电池在 100%深度放电下循环 100 次，从而确立了水系锌电池作为实际应用中可行的电池系统。
