A soft co-crystalline solid electrolyte for lithium-ion batteries
Alternative solid electrolytes are the next key step in advancing lithium batteries with better thermal and chemical stability. A soft solid electrolyte, (Adpn) 2 LiPF 6 (Adpn, adiponitrile), is synthesized and characterized that exhibits high thermal and electrochemical stability and good ionic con...
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Veröffentlicht in: | Nature materials 2023-05, Vol.22 (5), p.627-635 |
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Sprache: | eng |
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Zusammenfassung: | Alternative solid electrolytes are the next key step in advancing lithium batteries with better thermal and chemical stability. A soft solid electrolyte, (Adpn)
2
LiPF
6
(Adpn, adiponitrile), is synthesized and characterized that exhibits high thermal and electrochemical stability and good ionic conductivity, overcoming several limitations of conventional organic and ceramic materials. The surface of the electrolyte possesses a liquid nano-layer of Adpn that links grains for a facile ionic conduction without high pressure/temperature treatments. Further, the material can quickly self-heal if fractured and provides liquid-like conduction paths via the grain boundaries. A substantially high ion conductivity (~10
−4
S cm
–1
) and lithium-ion transference number (0.54) are obtained due to weak interactions between ‘hard’ (charge dense) Li
+
ions and the ‘soft’ (electronically polarizable) –C≡N group of Adpn. Molecular simulations predict that Li
+
ions migrate at the co-crystal grain boundaries with a (preferentially) lower activation energy
E
a
and within the interstitial regions between the co-crystals with higher
E
a
values, where the bulk conductivity is a smaller but extant contribution. These co-crystals establish a special concept of crystal design to increase the thermal stability of LiPF
6
by separating ions in the Adpn solvent matrix, and also exhibit a unique mechanism of ion conduction via low-resistance grain boundaries, which contrasts with ceramics or gel electrolytes.
Alternative solid electrolytes with enhanced thermal and chemical stability are key for advancing lithium batteries. A soft solid electrolyte with improved stability and ionic conductivity, overcoming several limitations of conventional materials, is now reported. |
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ISSN: | 1476-1122 1476-4660 |
DOI: | 10.1038/s41563-023-01508-1 |