Electrolyte design for Li metal-free Li batteries
- Univ. of Maryland, College Park, MD (United States). Dept. of Chemical and Biomolecular Engineering
- Army Research Lab., Adelphi, MD (United States). U.S. Army Combat Capabilities Development Command. Sensors and Electron Devices Directorate. Energy and Biomaterials Division. Battery Science Branch
- Univ. of Maryland, College Park, MD (United States). Dept. of Chemical and Biomolecular Engineering; Univ. of Maryland, College Park, MD (United States). Dept. of Chemistry and Biochemistry
Li metal, with the lowest thermodynamically achievable negative electrochemical potential and the highest specific capacity (3860 mAh g-1), is the ultimate anode choice for Li batteries. However, the highest reported Li plating/stripping Coulombic efficiency (CE) of 99.5% after extensive efforts is still too low for the Li metal-free (all the Li metal in cycling comes from cathode, without anode pre-lithiation) Li metal batteries. The low CE is attributed to both non-uniform Li plating/stripping on the lithiophobic Cu current collector and Li dendrite growth through lithiophilic organic–inorganic solid electrolyte interphase (SEI) formed in carbonate electrolytes. Here, we use a lithiophilic Bismuth graphite blend (Bi–Gr) substrate to replace lithiophobic Cu current collector to seed a uniform Li nucleation, and form a lithiophobic LiF-rich SEI rather than lithiophilic organic-rich SEI to suppress Li dendrite growth. Molecular dynamics simulations reveal the preferential reduction of anions in 2.0 M LiPF6 in tetrahydrofuran/2-methyl tetrahydrofuran (2.0 M LiPF6–mixTHF) electrolyte to generate LiF-rich SEI on plated Li. Bi–Gr substrate and 2.0 M LiPF6–mixTHF electrolyte enable the Li anodes to achieve a record high CE of 99.83% at a high capacity of 1.0 mAh cm-2 and current of 0.5 mA cm-2. The Bi particles serve as dispersed nucleation centers that promote uniform Li deposition with strong adhesion to the substrate to avoid dead Li, while the lithiophobic LiF-rich SEI promotes lateral Li growth and suppresses the vertical Li dendrite growth even at a high current density of 3.0 mA cm-2 and high areal capacities of 3.0 mAh cm-2. The regulation of Li nucleation and growth enables the Li metal-free LiFePO4 full cells to achieve 100 cycles at a practical areal capacity of >2.0 mAh cm-2. This article highlights the benefits of simultaneous substrate design to improve Li nucleation and electrolyte design to promote lithiophobic SEI growth, enabling a promising and practical route Li metal-free Li metal batteries.
- Research Organization:
- Univ. of Maryland, College Park, MD (United States)
- Sponsoring Organization:
- USDOE Office of Energy Efficiency and Renewable Energy (EERE)
- Grant/Contract Number:
- EE0008202
- OSTI ID:
- 1848707
- Alternate ID(s):
- OSTI ID: 1690298
- Journal Information:
- Materials Today, Vol. 39, Issue C; ISSN 1369-7021
- Publisher:
- ElsevierCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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