A wide temperature 10 V solid-state electrolyte with a critical current density of over 20 mA cm−2

Abstract

The use of solid-state electrolytes in all-solid-state batteries is a technology with prospects for increasing energy densities. However, poor oxidative stability and issues with dendrite growth significantly hamper their applicability. LiBH₄ is considered as one of the most promising candidates due to the thermodynamic stability of Li. Herein, an in situ melting reaction is proposed to generate covalently bonded coordination on the particle surfaces of electrolytes to resolve these issues. This coordination thermodynamically shuts down the electronic exchanges during the anionic oxidation decomposition by covalently bonding the local high-concentration electrons on the anions, and it kinetically blocks electronic percolation on the particle surfaces of electrolytes; this phenomenon leads to an unprecedented voltage window (0–10 V) with a peak oxidation current that is 97.2 times lower and an electronic conductivity that is 3 orders of magnitude lower than that of the counterpart at 25 °C. The coordination can act as a binder to bond electrolyte particles, achieving a remarkable Young's modulus of 208.45 GPa; this modulus is twice as high as that of the counterpart. The remarkable mechanical property of the coordination is capable of adapting the sustained stress–strain release in Li plating and stripping. With these merits, the electrolyte displays a record-breaking critical current density of 21.65 mA cm⁻² at 25 °C (twice the best-reported data in Li-ion solid-state electrolytes), cycling stabilities at 10.83 mA cm⁻² for 6000 h and under 10 V for 1000 h, and an operational temperature window of −30 to 150 °C. The Li–LiCoO₂ cells exhibit superior reversibility at high voltage. Our findings illuminate a clear direction for oxidative stability and dendrite suppression in solid-state electrolytes, making tremendous progress in high-voltage lithium batteries.