Li-ion-conducting chloride solid electrolytes receive considerable attention due to their physicochemical characteristics such as high ionic conductivity, deformability and oxidative stability. However, the raw materials are expensive, and large-scale use of this class of inorganic superionic conductors seems unlikely. Here, a cost-effective chloride solid electrolyte, Li₂ZrCl₆, is reported. Its raw materials are several orders of magnitude cheaper than those for the state-of-the-art chloride solid electrolytes, but high ionic conductivity (0.81 mS cm^–1 at room temperature), deformability, and compatibility with 4V-class cathodes are still simultaneously achieved in Li₂ZrCl₆. Moreover, Li₂ZrCl₆ demonstrates a humidity tolerance with no sign of moisture uptake or conductivity degradation after exposure to an atmosphere with 5% relative humidity. By combining Li₂ZrCl₆ with the Li-In anode and the single-crystal LiNi_0.8Mn_0.1Co_0.1O₂ cathode, we report a room-temperature all-solid-state cell with a stable specific capacity of about 150 mAh g^–1 for 200 cycles at 200 mA g^–1.

To enable the development of all-solid-state batteries, an inorganic solid-state electrolyte should demonstrate high ionic conductivity (i.e., > 1 mS cm⁻¹ at 25 °C), compressibility (e.g., > 90% density under 250−350 MPa), and cost-effectiveness (e.g., < $50/kg). Here we report the development and preparation of Li_1.75ZrCl_4.75O_0.5 oxychloride solid-state electrolyte that demonstrates an ionic conductivity of 2.42 mS cm⁻¹ at 25 °C, a compressibility enabling 94.2% density under 300 MPa and an estimated raw materials cost of $11.60/kg. As proof of concept, the Li_1.75ZrCl_4.75O_0.5 is tested in combination with a LiNi_0.8Mn_0.1Co_0.1O₂-based positive electrode and a Li₆PS₅Cl-coated Li-In negative electrode in lab-scale cell configuration. This all-solid-state cell delivers a discharge capacity retention of 70.34% (final discharge capacity of 70.2 mAh g⁻¹) after 2082 cycles at 1 A g⁻¹, 25 °C and 1.5 tons of stacking pressure.

Polymer nanocomposites with nanoparticles dispersed in polymer matrices have attracted extensive attention due to their significantly improved overall performance, in which the nanoparticle-polymer interface plays a key role. Understanding the structures and properties of the interfacial region, however, remains a major challenge for polymer nanocomposites. Here, we directly observe the presence of two interfacial polymer layers around a nanoparticle in polar polymers, i.e., an inner bound polar layer (~10 nm thick) with aligned dipoles and an outer polar layer (over 100 nm thick) with randomly orientated dipoles. Our results reveal that the impacts of the local nanoparticle surface potential and interparticle distance on molecular dipoles induce interfacial polymer layers with different polar molecular conformations from the bulk polymer. The bilayer interfacial features lead to an exceptional enhancement in polarity-related properties of polymer nanocomposites at ultralow nanoparticle loadings. By maximizing the contribution of inner bound polar layer via a nanolamination design, we achieve an ultrahigh dielectric energy storage density of 86 J/cm³, far superior to state-of-the-art polymers and nanocomposites.

The development of energy-dense all-solid-state Li-based batteries requires positive electrode active materials that are ionic conductive and compressible at room temperature. Indeed, these material properties could contribute to a sensible reduction of the amount of the solid-state electrolyte in the composite electrode, thus, enabling higher mass loading of active materials. Here, we propose the synthesis and use of lithium titanium chloride (Li₃TiCl₆) as room-temperature ionic conductive (i.e., 1.04 mS cm⁻¹ at 25 °C) and compressible active materials for all-solid-state Li-based batteries. When a composite positive electrode comprising 95 wt.% of Li₃TiCl₆ is tested in combination with a Li-In alloy negative electrode and Li₆PS₅Cl/Li₂ZrCl₆ solid-state electrolytes, an initial discharge capacity of about 90 mAh g⁻¹ and an average cell discharge voltage of about 2.53 V are obtained. Furthermore, a capacity retention of more than 62% is attainable after 2500 cycles at 92.5 mA g⁻¹ and 25 °C with an applied external pressure of 1.5 tons. We also report the assembly and testing of a “single Li₃TiCl₆” cell where this chloride material is used as the solid electrolyte, negative electrode and positive electrode.