Current‐Controlled Inactive Aluminum Loss: Quantification, Mechanism, and Mitigation via Stack Pressure for Long‐Cycle Al‐Ion Batteries
Yaoyao Liu, Yushuang Yang, Haichen Huang, Haoying Qi, Xianglin Yin, Xingmin Yu, Shuhua Wang, Jian‐Jun Wang, Yuanhua Sang, Peihua Zhu, Hong Liu, Weijia Zhou, Hao ChenABSTRACT
Aluminum‐ion batteries are a promising energy storage technology for high resource abundance, safety, and cost‐effectiveness advantages, but practical implementation is hindered by two degradation mechanisms in Al metal anode: electrically isolated metallic aluminum (iAl 0 ) and electrochemical side‐reaction products (iSEI Al 3+ ). Precise quantification of these inactive species and relationships with cycling reversibility have rarely been established, limiting rational anode design. Here, we develop a basic titration gas chromatography technology to accurately quantify iAl 0 and iSEI Al 3+ , revealing a current density‐dependent Al loss mechanism: iSEI Al 3+ loss dominates at low current, while metallic iAl 0 loss prevails at high current. We discover that an inorganic‐dominated interphase favors significant suppression of inactive Al formation. Applying an optimal stack pressure strategy (780 kPa) constructs tip‐localized stack pressure/electric field, effectively reducing inactive Al loss by 81.99% and prolonging battery cycling life by ≥500%. These advancements offer fundamental theory and techniques for Al anode reaction mechanism research and provide design principles for high‐performance aluminum‐ion battery.