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

High Resolution Image Download MS PowerPoint Slide 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.