Enabling a high-performance saltwater Al-air battery via ultrasonically driven electrolyte flow

Huiyu Huang; Pengzhan Liu; Qiuxia Ma; Zihao Tang; Mu Wang; Junhui Hu

doi:10.1016/j.ultsonch.2022.106104

Enabling a high-performance saltwater Al-air battery via ultrasonically driven electrolyte flow

Ultrason Sonochem. 2022 Aug:88:106104. doi: 10.1016/j.ultsonch.2022.106104. Epub 2022 Jul 29.

Authors

Huiyu Huang¹, Pengzhan Liu¹, Qiuxia Ma¹, Zihao Tang¹, Mu Wang¹, Junhui Hu²

Affiliations

¹ State Key Lab of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China.
² State Key Lab of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China. Electronic address: ejhhu@nuaa.edu.cn.

Abstract

As an emerging battery technology, the Al-air flow battery (AAFB) exhibits high energy density due to the recycling of electrolytes, thus showing great potential as a type of clean and sustainable energy storage system. Conventionally, it employs an external mechanical pump to recycle the electrolyte. In this work, the saltwater AAFB in which the electrolyte is recycled by the ultrasonic capillary effect (rather than a mechanical pump) and the reaction chamber is agitated by ultrasonic vibration, is proposed and investigated. Our numerical simulations show that a travelling ultrasonic wave in the electrolyte flow system causes the capillary flow and agitation. The experimental results show that the percentage increase of the peak power density (relative to that with static electrolyte) can be up to about 7.5 times of that with the electrolyte flow driven by a mechanical pump, under the same electrolyte flow rate and concentration (3.3 ml min^-1 and 3 M NaCl). The optimal peak power density, which can be achieved by optimizing the reaction chamber thickness, electrolyte concentration and ultrasonic vibration velocity, is 43.88 mW cm^-2. This work illustrates that the acoustofluidic method can not only improve the discharge performance of the saltwater AAFB effectively, but also greatly decrease the energy consumption, weight and volume of the electrolyte driving unit of the AAFB. In addition, analyses based on experimental results show that the energy gain of a series/parallel battery system formed by multiple identical cells can be larger than one, if the number of cells in the system is large enough.

Keywords: Al-air battery; Electrolyte flow; Saltwater; Ultrasound.