Cryo-SEM observation of electrolyte wetting phenomena in a lithium-air battery and elucidation of high-performance electrode structure

2023 Fiscal Year Final Research Report

• Project/Area Number: 21H01255
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 19020:Thermal engineering-related
• Research Institution: Hokkaido University
• Principal Investigator: Uemura Suguru 北海道大学, 工学研究院, 准教授 (70515163)
• Co-Investigator(Kenkyū-buntansha): 田部 豊 北海道大学, 工学研究院, 教授 (80374578)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: リチウム空気電池

Outline of Final Research Achievements

In this study, the effects of electrode structure and electrolyte wetting behavior on the discharge performance were investigated with the aim of improving oxygen transport efficiency in the cathode of lithium-air batteries. Discharge tests were conducted by changing the contact angle of the electrolyte to the reaction surface of a flat cathode. The results showed that the smaller the contact angle, the better the discharge performance. It is considered that the thinner the electrolyte thickness covering the reaction surface, the lower the oxygen transport resistance to the reaction surface, and the higher the current density. Discharge tests with different distribution of the electrolyte in the porous cathode showed that the discharge performance was improved by partially wetting the electrolyte to keep an oxygen transport path from the air, rather than by expanding the reaction area by saturating all the pore in the cathode.

Free Research Field

熱工学

Academic Significance and Societal Importance of the Research Achievements

従来の研究では放電に伴って生じる析出物への対処のため，正極の比表面積を増加させる研究成果が多数見られたが，本研究ではリチウム空気電池の高出力化に向けて，正極の多孔質構造と正極内における電解液の分布（濡れ）が重要な因子であることを示した．また，リチウム空気電池はその理論容量の大きさから，電気自動車用の重要な電源となるだけでなく，再生可能エネルギーの利用・普及に向けた，大容量かつ安全な蓄電デバイスとしても重要な役割が果たせる．さらに本研究で対象とする水系リチウム空気電池では従来の有機電解液を用いたリチウムイオン電池のような，短絡時の火災リスクも大幅に低減できる．