Boosting the interfacial superionic conduction of halide solid electrolytes for all-solid-state batteries

Abstract

Designing highly conductive and (electro)chemical stable inorganic solid electrolytes using cost-effective materials is crucial for developing all-solid-state batteries. Here, we report halide nanocomposite solid electrolytes (HNSEs) ZrO2(-ACl)-A(2)ZrCl(6) (A = Li or Na) that demonstrate improved ionic conductivities at 30 degrees C, from 0.40 to 1.3 mS cm(-1) and from 0.011 to 0.11 mS cm(-1) for Li+ and Na+, respectively, compared to A(2)ZrCl(6), and improved compatibility with sulfide solid electrolytes. The mechanochemical method employing Li2O for the HNSEs synthesis enables the formation of nanostructured networks that promote interfacial superionic conduction. Via density functional theory calculations combined with synchrotron X-ray and Li-6 nuclear magnetic resonance measurements and analyses, we demonstrate that interfacial oxygen-substituted compounds are responsible for the boosted interfacial conduction mechanism. Compared to state-of-the-art Li2ZrCl6, the fluorinated ZrO2-2Li(2)ZrCl(5)F HNSE shows improved high-voltage stability and interfacial compatibility with Li6PS5Cl and layered lithium transition metal oxide-based positive electrodes without detrimentally affecting Li+ conductivity. We also report the assembly and testing of a Li-In||LiNi0.88Co0.11Mn0.01O2 all-solid-state lab-scale cell operating at 30 degrees C and 70 MPa and capable of delivering a specific discharge of 115 mAh g(-1) after almost 2000 cycles at 400 mA g(-1). Compositional tuning is a standard procedure to improve the ionic conductivity of inorganic superionic conductors. Here, the authors report (electro)chemical stable composite halide solid electrolytes applying a nanostructure approach that promotes interfacial superionic conductivity.