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Stackable bipolar pouch cells with corrosion-resistant current collectors enable high-power aqueous electrochemical energy storage

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Abstract

A critical bottleneck in the development of aqueous electrochemical energy storage systems is the lack of viable complete cell designs. We report a metal-free, bipolar pouch cell designed with carbon black/polyethylene composite film (CBPE) current collectors as a practical cell architecture. The light-weight, corrosion-resistant CBPE provides stable operation in a variety of aqueous electrolytes over a ∼2.5 V potential range. Because CBPE is heat-sealable, it serves simultaneously as both the pouch cell packaging and seal in addition to its use as a current collector. Although this non-metallic composite has a low electrical conductivity relative to metal foils, current travels only a short distance in the through-plane direction of the current collector in the bipolar cell configuration. This shorter path length lowers the effective electrical resistance, making the design suitable for high-power applications. We test the cell architecture using an aqueous ZnBr2 battery chemistry and incorporate tetrabutylammonium cations to improve the intrinsic low Coulombic efficiency and fast self-discharge of non-flow ZnBr2 cells. These devices demonstrate a cell-level energy density of 50 W h L−1 at a 10C rate (0.5 kW L−1), with less than 1% capacity loss over 500 cycles. A large-area (>6 cm2) 4-cell stack is built to illustrate that the pouch cells are scalable to practical dimensions and stackable without sacrificing performance. The device operates in the range of 6–7 V and has an internal self-balancing mechanism that prevents any individual cell in the stack from overcharging. The results thus demonstrate both a conceptually new cell architecture that is broadly applicable to many aqueous electrolyte chemistries and a specific high-performance example thereof.

Graphical abstract: Stackable bipolar pouch cells with corrosion-resistant current collectors enable high-power aqueous electrochemical energy storage

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Publication details

The article was received on 17 Feb 2018, accepted on 25 May 2018 and first published on 14 Jun 2018


Article type: Paper
DOI: 10.1039/C8EE00546J
Citation: Energy Environ. Sci., 2018, Advance Article
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    Stackable bipolar pouch cells with corrosion-resistant current collectors enable high-power aqueous electrochemical energy storage

    B. Evanko, S. J. Yoo, J. Lipton, S. Chun, M. Moskovits, X. Ji, S. W. Boettcher and G. D. Stucky, Energy Environ. Sci., 2018, Advance Article , DOI: 10.1039/C8EE00546J

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