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Abstract A thin solid electrolyte with a high Li+conductivity is used to separate the metallic lithium anode and the cathode in an all‐solid‐state Li‐metal battery. However, most solid Li‐ion electrolytes have a small electrochemical stability window, large interfacial resistance, and cannot block lithium‐dendrite growth when lithium is plated on charging of the cell. Mg2+stabilizes a rhombohedral NASICON‐structured solid electrolyte of the formula Li1.2Mg0.1Zr1.9(PO4)3(LMZP). This solid electrolyte has Li‐ion conductivity two orders of magnitude higher at 25 °C than that of the triclinic LiZr2(PO4)3.7Li and6Li NMR confirm the Li‐ions in two different crystallographic sites of the NASICON framework with 85% of the Li‐ions having a relatively higher mobility than the other 15%. The anode–electrolyte interface is further investigated with symmetric Li/LMZP/Li cell testing, while the cathode–electrolyte interface is explored with an all‐solid‐state Li/LMZP/LiFePO4cell. The enhanced performance of these cells enabled by the Li1.2Mg0.1Zr1.9(PO4)3solid electrolyte is stable upon repeated charge/discharge cycling.
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This content will become publicly available on November 20, 2026
Critical Role of Li + ··· Li + Distance and Anion Restriction in Conductivity and Lithium‐Ion Transference Number of Molecular Crystals for Solid State Electrolytes
Abstract Insights into structure‐conductivity mechanisms are investigated for a series of six (dinitrile)2LiPF6 molecular crystals with varied alkyl chain lengths, N≡C─(CH2)n─C≡N, n = 2, 3, 4, 5, 6, and 2Me‐glutaronitrile. The molecular crystals have separate Li+ and channels, with the Li+ions weakly coordinated by four ─C≡N groups. The following correlations are observed: i) shorter Li+⋯ Li+ hopping distances (5.72–8.08 Å) increase ionic conductivity (3.1 × 10−4–0.15 × 10−4 S cm−1 at 25 °C) for all (dinitrile)2LiPF6; ii) when there are unrestricted anion channels, the lithium ion transference number increases ( = 0.39–0.62) as the void volume (565–250 Å3) and Li+⋯ Li+ hopping distance (7.15–5.72 Å) decrease, since a greater fraction of the charge is contributed by the Li+ions; this correlates with n= 2, 4, 5, 6; iii) the exceptions are Gln (n = 3) and 2Me‐Gln, where there are restricted channels for anion migration, and in this case: iv) conductivity decreases (0.57–0.15 × 10−4 S cm−1 at 25 °C), since contributions to the conductivity from anion migration decrease, but v) increases (0.64–0.7) since a greater fraction of the charge is carried by the Li+ ions.
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- Award ID(s):
- 2215854
- PAR ID:
- 10651252
- Publisher / Repository:
- Wiley
- Date Published:
- Journal Name:
- Advanced Energy Materials
- ISSN:
- 1614-6832
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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