Hybrid Solid Electrolyte Interphases Enabled Ultralong Life Ca‐Metal Batteries Working at Room Temperature

• Published in: Advanced materials (Weinheim) 2021-01, Vol.33 (2), p.e2006141-n/a
• Main Authors: Song, Huawei, Su, Jian, Wang, Chengxin
• Format: Article
• Language: English
• Subjects: Batteries; Calcium ions; calcium–metal batteries; Carbon fibers; Electrochemistry; Electrolytes; hybrid electrolyte interphase; Lithium; Materials science; Metal surfaces; Oxidation; rechargeable batteries; relay extraction, relay insertion; Room temperature; Solid electrolytes
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.202006141

Currently, the application of calcium metal anodes is challenged by rapidly degenerated plating/stripping electrochemistry without suitable solid electrolyte interphases (SEIs) capable of fast Ca2+ transport kinetics and superior ability to resist anion oxidation. Here, through in situ evolved Na/Ca hybrid SEIs, symmetrical Ca//Ca batteries readily remain stable for more than 1000 h deposition–dissolution cycles (versus less than 60 h for those with pure Ca SEIs under the same condition). Coupled with a specially designed freestanding lattice‐expanded graphitic carbon fiber membrane and tailored operation voltages, the proof‐of‐concept Ca‐metal batteries reversibly run for almost 1900 cycles with ≈83% capacity retention and a high average discharge voltage of 3.16 V. The good performance not only benefits from the stable SEIs at the Ca metal surface which affords free Ca2+ transports and prohibits out‐of‐control fluridation of Ca (forming CaF2 ion‐/electron‐insulating layer) but is also attributed to reversible relay insertion/extraction electrochemistry in the cathode. This work sheds new light on durable metal battery technology. A stable Ca plating/stripping process for more than 1000 h is realized through a Na/Ca hybrid SEI strategy. This enables an ultralong life and high operation voltage, up to 4.5 V, for room‐temperature Ca‐metal batteries.