Boosting the Temperature Adaptability of Lithium Metal Batteries via a Moisture/Acid‐Purified, Ion‐Diffusion Accelerated Separator

• Published in: Advanced energy materials 2022-08, Vol.12 (32), p.n/a
• Main Authors: Zhang, Min, Liu, Kexin, Gan, Yichen, Wang, Helin, Liu, Fu, Bai, Miao, Tang, Xiaoyu, Wang, Zhiqiao, Li, Shaowen, Shao, Ahu, Zhou, Kefan, Wang, Tianyu, Wang, Zhuyi, Yuan, Shuai, Ma, Yue
• Format: Article
• Language: English
• Subjects: Asymmetry; Cathodes; Cycles; Electric potential; Electrodes; Electrolytes; Foils; high energy density; High temperature; Hydrofluoric acid; impurity scavenging; Ion diffusion; isotropic Li deposition; Janus‐faced separators; Lithium batteries; Melamine; Moisture effects; Molecular sieves; Optimization; Polyethylenes; Prototyping; Separators; temperature adaptability; Voltage
• ISSN: 1614-6832; 1614-6840
• DOI: 10.1002/aenm.202201390

The reliable operation of Li metal batteries suffers from cathode collapse due to high‐voltage cycling, interfacial reactivity of the Li deposits, self‐discharge at the elevated temperatures, as well as the power output deterioration in low‐temperature scenarios. In contrast to the individual electrode optimization, herein, a hetero‐layered separator with an asymmetric functional coating on polyethylene is proposed in response to the aforementioned issues: On the face‐to‐cathode side, the hybrid layer of the molecular sieve and sulfonated melamine formaldehyde can scavenge the hydrofluoric acid and moisture residues from the carbonate electrolyte, maintaining the cathode robustness in both the high‐voltage cycling or high‐temperature storage scenarios; while the pre‐coated Ag2S layer in situ generates the Li10Ag3‐Li2S composite matrix in contact with the Li foil, promoting interfacial ion diffusion and isotropic Li deposition. The as‐constructed LiNi0.8Co0.1Mn0.1O2/Li pouch cell (3.2 Ah) with the hetero‐layered separator can achieve a high energy density of 400.6 Wh kg−1 on the cell level, as well as a wider temperature adaptability (0–75 °C). This asymmetric separator strategy enables facile energy‐dense cell prototyping with the commercial electrode/electrolyte. A Janus‐faced separator is proposed to stabilize bi‐electrode structures: On the face‐to‐cathode side, a hybrid layer of a molecular sieve and sulfonated melamine formaldehyde can scavenge hydrofluoric acid and moisture from the carbonate electrolyte, suppressing transition metal dissolution of the cathode; while the pre‐coated Ag2S layer in situ generates an Li10Ag3‐Li2S interphase layer in contact with Li foil, promoting fast and isotropic ion diffusion.