An Asymmetric‐Electrolyte Zn−Air Battery with Ultrahigh Power Density and Energy Density

Abstract

ZnÀair batteries have attracted enormous research interest, driven by the promise for vehicle propulsion owing to their advantages of high-level safety, low cost, and high specific energy density. Here, we report an asymmetric-electrolyte ZnÀair battery with acid catholyte and alkaline anolyte separated by a bipolar membrane. We demonstrate that the asdesigned ZnÀair battery, thanks to the as-formed concentration cell, can deliver a maximum power density of 380 mW cm À2 and a specific energy density of 1522 Wh kg À1 with an open-circuit voltage of 2.25 V. The as-proposed ZnÀair battery performance is superior to the conventional ZnÀair battery in terms of these pivotal performance parameters.Energy crisis and environmental pollutions caused by the consumption of fossil fuels have stimulated great interests in developing renewable energy sources. Accordingly, a series of energy storage and conversion systems, such as rechargeable batteries, [1][2][3][4][5] fuel cells, [6][7][8][9] and capacitors, [10][11][12][13][14] have been developed successfully to fulfill application demands in diverse fields. Among them, Zn-air batteries powered by oxidizing zinc with oxygen have received intensive attentions due to their advantages of high theoretic energy density and specific capacity, low cost, and high efficiency. [15][16][17] In addition, the current yearly global zinc production is sufficient to produce enough Zn-air batteries, [18][19][20] which holds overwhelming advantages over the current limited production of lithium that is necessary source for the current dominant lithium ion batteries (LIBs). [21][22][23] Zn-air batteries are thus regarded as promising energy sources for the next generation electric vehicle battery and as a utility-scale energy storage system. [17,[24][25][26] However, the cell voltage for Zn-air batteries is theoretically capable 1.65 V and almost all practical devices are optimized for less than 1.4 or 1.3 V, less than half of that in LIBs. Moreover, the outputting energy density in the Zn-air batteries reported so far was less than theoretical estimates. For example, the peak power density and energy density are always behind 200 mW cm À2 and 1000 Wh kg À1 , respectively. In these regards, it is highly desirable to make further improvements in output voltage and energy density of Zn-air batteries. [17,[27][28][29] We here report a newly asymmetric-electrolyte Zn-air battery (AEZAB) with H 2 SO 4 as catholyte and NaOH as anolyte that are separated by a bipolar membrane (BPM), in which the commercial Pt/C is applied as the cathode catalyst to demonstrate such proof-of-concept. We demonstrate the as-designed Zn-air battery is capable of releasing an open circuit voltage of 2.25 V with a power density of 380 mW cm À2 , 1.90 times higher than that of the conventional ZAB and even beat that of the best ZAB ever reported. Moreover, the energy density of the AEZAB is as high as 1522 Wh kg À1 , 1.51 times higher than that of conventional ZAB, even far surpassing the theoretic energy density of ZAB. F...

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Ultrahigh voltage and energy density aluminum‐air battery based on aqueous alkaline‐acid hybrid electrolyte

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