Hygroscopic dough-type Zn-air battery capable of dry operation with high power density
International Conference on Advadced Materials and Devices, Jeju, Korea(2023)
Ok Sung Jeon, Yunju La, Yong Bin Bang, Ji Hye Lee, Ye Rim Kim, Yong Yeol Park, Hyeon Seo Yang, Gyeong Hun Lee, So Yeon Han, Young Joon Yoo, Sang Yoon Park
Abstract
Zn-air battery (ZAB) is a promising next-generation energy storage device to be grafted onto the wearable electronics. Due to the half-open cathode configuration to use air as a fuel, drying out of water in an electrolyte is inevitable. Researchers focused on enhancing the water retention in the hydrogel. However, it is not practical solution to widen the scope of use in low relative humidity (RH) environment at 30% or less. To find a breakthrough in this issue, it is necessary to apply a new concept which can simultaneously obtain and retain water content. In addition, hydrophobic property of the cathode in contact with the aqueous electrolyte to avoid flooding phenomenon exerts significant influence on the number of active sites such as triple phase boundary (TPB). An immobilized solid-state electrolyte also suffers from poor contact at the interface between electrolyte and cathode.
Hence, our group has successfully fabricated novel type of electrolyte as dough-type which was able to absorb moisture at low RH as 30% or less by deliquescent property of KOH, and be tightly attached to the cathode with the porous structure retained. This dough-type electrolyte can be mass-manufactured on a large area as 10 cm × 10 cm due to the facile kneading preparation method, and crafted into desired shapes. The developed dough had high ionic conductivity of 248 mS cm-1 and superb water retention of 90.3% at RH 30% for 170 h. The dough-type ZABs showed a noticeable maximum power density of 160.1 mW cm-2, a specific capacity of 632 mAh gZn-1 and stability for 60 h at RH 30% and 120 h even at a low temperature of -20 oC, producing reasonable output though the pristine aqueous electrolyte-based ZAB shows only maximum power density of 45.84 mW cm-2 and stability of 14 h at RH 30%.