Hydrated lithium nido-boranes for solid–liquid hybrid batteries. Issue 20 (12th September 2022)

• Record Type: Journal Article
• Authors: Souza, Diego H. P.; Humphries, Terry D.; Liu, Yu; Gradišek, Anton; D'Angelo, Anita M.; Buckley, Craig E.; Paskevicius, Mark
• Is Part Of: Sustainable energy & fuels. Volume 6:Issue 20(2022)
• Page Start: 4614
• Page End: 4625
• Publication Date: 2022-09-12
• Subjects: Renewable energy sources -- Periodicals; Fuel cells -- Periodicals; Electric batteries -- Periodicals; Electrochemistry -- Periodicals; 660.297
• DOI: 10.1039/d2se00843b
• Languages: English
• ISSNs: 2398-4902

Abstract

Abstract : Hydrated and anhydrous LiB11 H14 salts are prepared through a facile approach. Liquid-like Li + conductivity (10 −2 S cm −1 ) is observed for a-LiB11 H14 ·(H2 O) n at 60 °C. LiB11 H14 ·2H2 O is classified as a new class of ionic liquid as it melts near 70 °C. Abstract : Hydridoborate salts are considered as promising solid-state electrolyte candidates for the development of solid-state batteries (SSBs). The presence of coordinated water in the crystal structure may facilitate the migration of the cation, yielding compounds with high ionic conductivity. In the present study, two samples of hydrated LiB11 H14, here called LiB11 H14 ·2H2 O and a-LiB11 H14 ·(H2 O) n ( n < 2), demonstrate remarkably different properties as solid-state electrolytes. LiB11 H14 ·2H2 O is identified as a new class of ionic liquid, as it melts at ≈70 °C, whereas the sample a-LiB11 H14 ·(H2 O) n undergoes a polymorphic phase transition close to this temperature, reaching the liquid-like ionic conductivity of 3.2 × 10 −2 S cm −1 at 70 °C and an oxidative stability limit of 2.8 V against Li + /Li. Galvanostatic cycling and battery tests were conducted with a-LiB11 H14 ·(H2 O) n as the solid-state electrolyte (SSE) at 60 °C with the addition of traces of either the ionic liquid (IL) LiB11 H14 ·2H2 O or the liquid electrolyte (LE) 1.0 M LiPF6 EC/DMC (v/v = 50/50) at their interfaces. Galvanostatic experiments for the cell Li/IL/SSE/IL/Li showed an overpotential of only 21 mV after 9 days cycling (48 h at 25 μA cm −2 and 168 h at 50 μA cm −2 ), and the battery Li/LE/SSE/SSE + TiS2 retained 83% of its capacity shown in the first cycle at 0.4C after 50 cycles. LiB11 H14 ·2H2 O and 1.0 M LiPF6 EC/DMC work effectively as wetting agents to improve SSE/Li contact.