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

Abstract

<jats:title>Abstract</jats:title><jats:p>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) ZrO<jats:sub>2</jats:sub>(-ACl)-A<jats:sub>2</jats:sub>ZrCl<jats:sub>6</jats:sub> (A = Li or Na) that demonstrate improved ionic conductivities at 30 °C, from 0.40 to 1.3 mS cm<jats:sup>−1</jats:sup> and from 0.011 to 0.11 mS cm<jats:sup>−1</jats:sup> for Li<jats:sup>+</jats:sup> and Na<jats:sup>+</jats:sup>, respectively, compared to A<jats:sub>2</jats:sub>ZrCl<jats:sub>6</jats:sub>, and improved compatibility with sulfide solid electrolytes. The mechanochemical method employing Li<jats:sub>2</jats:sub>O 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 <jats:sup>6</jats:sup>Li 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 Li<jats:sub>2</jats:sub>ZrCl<jats:sub>6</jats:sub>, the fluorinated ZrO<jats:sub>2</jats:sub>−2Li<jats:sub>2</jats:sub>ZrCl<jats:sub>5</jats:sub>F HNSE shows improved high-voltage stability and interfacial compatibility with Li<jats:sub>6</jats:sub>PS<jats:sub>5</jats:sub>Cl and layered lithium transition metal oxide-based positive electrodes without detrimentally affecting Li<jats:sup>+</jats:sup> conductivity. We also report the assembly and testing of a Li-In||LiNi<jats:sub>0.88</jats:sub>Co<jats:sub>0.11</jats:sub>Mn<jats:sub>0.01</jats:sub>O<jats:sub>2</jats:sub> all-solid-state lab-scale cell operating at 30 °C and 70 MPa and capable of delivering a specific discharge of 115 mAh g<jats:sup>−1</jats:sup> after almost 2000 cycles at 400 mA g<jats:sup>−1</jats:sup>.</jats:p>