The discovery of liquid battery electrolytes that facilitate the formation of stable solid electrolyte interphases (SEIs) to mitigate dendrite formation is imperative to enable lithium anodes in next‐generation energy‐dense batteries. Compared to traditional electrolyte solvents, tetrahydrofuran (THF)‐based electrolyte systems have demonstrated great success in enabling high‐stability lithium anodes by encouraging the decomposition of anions (instead of organic solvent) and thus generating inorganic‐rich SEIs. Herein, by employing a variety of different lithium salts (i.e., LiPF6,LiTFSI, LiFSI, and LiDFOB), it is demonstrated that electrolyte anions modulate the inorganic composition and resulting properties of the SEI. Through novel analytical time‐of‐flight secondary‐ion mass spectrometry methods, such as hierarchical clustering of depth profiles and compositional analysis using integrated yields, the chemical composition and morphology of the SEIs generated from each electrolyte system are examined. Notably, the LiDFOB electrolyte provides an exceptionally stable system to enable lithium anodes, delivering >1500 cycles at a current density of 0.5 mAh g−1and a capacity of 0.5 mAh g−1in symmetrical cells. Furthermore, Li//LFP cells using this electrolyte demonstrate high‐rate, reversible lithium storage, supplying 139 mAh g(LFP)−1at C/2 (≈0.991 mAh cm−2, @ 0.61 mA cm−2) with 87.5% capacity retention over 300 cycles (average Coulombic efficiency >99.86%).
Resources used in lithium‐ion batteries are becoming more expensive due to their high demand, and the global cobalt market heavily depends on supplies from countries with high geopolitical risks. Alternative battery technologies including magnesium‐ion batteries are therefore desirable. Progress toward practical magnesium‐ion batteries are impeded by an absence of suitable anodes that can operate with conventional electrolyte solvents. Although alloy‐type magnesium‐ion battery anodes are compatible with common electrolyte solvents, they suffer from severe failure associated with huge volume changes during cycling. Consequently, achieving more than 200 cycles in alloy‐type magnesium‐ion battery anodes remains a challenge. Here an unprecedented long‐cycle life of 1000 cycles, achieved at a relatively high (dis)charge rate of 3 C (current density: 922.5 mA g−1) in Mg2Ga5alloy‐type anode, taking advantage of near‐room‐temperatures solid–liquid phase transformation between Mg2Ga5(solid) and Ga (liquid), is demonstrated. This concept should open the way to the development of practical anodes for next‐generation magnesium‐ion batteries.
more » « less- Award ID(s):
- 1840672
- NSF-PAR ID:
- 10459584
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Energy Materials
- Volume:
- 9
- Issue:
- 45
- ISSN:
- 1614-6832
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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