Hydroborate Solid-State Lithium Battery with High-Voltage NMC811 Cathode

Abstract

Hydroborate solid electrolytes offer high ionic conductivity and are stable in contact with alkali metal anodes but are challenging to integrate into batteries with high-voltage cathodes. Here, we demonstrate stable dis-/charge cycling of solid-state Li batteries combining a Li 3 (CB 11 H 12 ) 2 (CB 9 H 10 ) hydroborate electrolyte with a 4 V-class LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NMC811) cathode, exploiting the enhanced kinetic stability of the LiCB 11 H 12 -rich and LiCB 9 H 10 -poor electrolyte composition. Cells with Li metal and InLi anodes achieve a discharge capacity at C/10 of ∼145 mAh g −1 at room temperature and ∼175 mAh g −1 at 60 °C. InLi cells retain 98% of their initial discharge capacity after 100 cycles at C/5 and 70% after 1000 cycles at C/2. Capacity retentions of 97% after 100 cycles at C/5 and 75% after 350 cycles at C/2 are also achieved with a graphite anode without any excess Li. The energy density per cathode composite weight of 460 Wh kg −1 is on par with the best solid-state batteries reported to date.

Lithium salt of a pro-mesogenic [closo-CB11H12]− derivative: anisotropic Li+ ion transport in liquid crystalline electrolytes

“…Particularly interesting in this context are closo -borate anions, which are weakly coordinating, inorganic, three-dimensional, σ-aromatic boron hydrides. 30–33 closo -Borate anions have recently received significant attention as new solid electrolyte systems, 34–43 owing to their high ionic conductivity 44 and superior chemical/electrochemical stability. 44–49…”