Irreducible solid electrolytes (SEs), characterized by non-Li framework ions in their lowest oxidation states, offer intrinsic compatibility with low-reduction-potential, high-capacity negative electrodes, such as lithium metal and silicon. In these SE materials, disorder engineering and vacancy formation reduce lithium-ion diffusion barriers, achieving room-temperature ionic conductivities exceeding 0.1 mS cm^–1. Experiments and atomistic simulations confirm that irreducible SEs form decomposition-free interfaces with Li metal. Their limited oxidative stability can be addressed by pairing them with an electrolyte layer stable with practical cathodes yet demanding interface compatibility between the two electrolyte layers. Here we highlight key research directions to accelerate irreducible SE transition from laboratory to practical application, including expanding compositional diversity, optimizing interfaces with cathode-facing electrolytes, developing scalable thin-film processing, and exploring compatibility with other low working potential anodes like silicon. Addressing these challenges is essential to unlock the full potential of irreducible SEs for high-energy, long-life, all-solid-state batteries.

Solid-state batteries currently receive extensive attention due to their potential to outperform lithium-ion batteries in terms of energy density when featuring next-generation anodes such as lithium metal or silicon. However, most highly conducting solid electrolytes decompose at the low operating voltages of next-generation anodes leading to irreversible lithium loss and increased cell resistance. Such performance losses may be prevented by designing electrolytes which are thermodynamically stable at low operating voltages (anolytes). Here, we report on the discovery of a new family of irreducible (i.e., fully reduced) electrolytes by mechanochemically dissolving lithium nitride into the Li₂S antifluorite structure, yielding highly conducting crystalline Li_2+xS_1-xN_x phases reaching >0.2 mS cm^-1 at ambient temperature. Combining impedance spectroscopy experiments and ab initio density functional theory calculations we clarify the mechanism by which the disordering of the sulfide and nitride ions in the anion sublattice boosts ionic conductivity in Li_2+xS_1-xN_x phases by a factor 10⁵ compared to the Li₂S host structure. This advance is achieved through a novel theoretical framework, leveraging percolation analysis with local-environment-specific activation energies and is widely applicable to disordered ion conductors. The same methodology allows us to rationalize how increasing nitrogen content in Li_2+xS_1-xN_x antifluorite-like samples leads to both increased ionic conductivity and lower conductivity-activation energy. These findings pave the way to understanding disordered solid electrolytes and eliminating decomposition-induced performance losses on the anode side in solid-state batteries.

All-solid-state batteries receive ample attention due to their promising safety characteristics and energy density. The latter holds true if they are compatible with next-generation high-capacity anodes, but most highly ion-conductive solid electrolytes decompose at low operating potentials, leading to lithium loss and increased cell resistances. Here the dynamic stability of solid electrolytes that can improve all-solid-state battery performance is demonstrated. Halide electrolytes Li₃YCl₃Br₃ and Li₂ZrCl₆, considered unstable at low potentials, are found to exhibit structurally reversible redox activity beyond their electrochemical stability windows, increasing compatibility with anodes and contributing to capacity without compromising ionic conductivity. The benefit of this dynamic stability window is demonstrated with cost-effective red phosphorus anodes, resulting in high reversible capacities (2,308 mAh g⁻¹), high rate capacity retention (1,024 mAh g⁻¹ at 7.75 mA cm⁻²) and extended cycle life (61% retention after 1,780 cycles). Furthermore, high areal capacity (7.65 mAh cm⁻²) and stability (70% retention after 1,000 cycles) are achieved for halide-based full cells with red phosphorous anodes. The beneficial redox activity of halide electrolytes greatly expands their application scenarios and suggests valuable battery design principles to enhance performance.

Rotary motors play key roles in energy transduction, from macroscale windmills to nanoscale turbines such as ATP synthase in cells. Despite our abilities to construct engines at many scales, developing functional synthetic turbines at the nanoscale has remained challenging. Here, we experimentally demonstrate rationally designed nanoscale DNA origami turbines with three chiral blades. These DNA nanoturbines are 24–27 nm in height and diameter and can utilize transmembrane electrochemical potentials across nanopores to drive DNA bundles into sustained unidirectional rotations of up to 10 revolutions s⁻¹. The rotation direction is set by the designed chirality of the turbine. All-atom molecular dynamics simulations show how hydrodynamic flows drive this turbine. At high salt concentrations, the rotation direction of turbines with the same chirality is reversed, which is explained by a change in the anisotropy of the electrophoretic mobility. Our artificial turbines operate autonomously in physiological conditions, converting energy from naturally abundant electrochemical potentials into mechanical work. The results open new possibilities for engineering active robotics at the nanoscale.

Li₃YX₆(X = Cl, Br) materials are Li-ion conductors that can be used as solid electrolytes in all solid-state batteries. Solid electrolytes ideally have high ionic conductivity and (electro)chemical compatibility with the electrodes. It was proven that introducing Br to Li₃YCl₆increases ionic conductivity but, according to thermodynamic calculations, should also reduce oxidative stability. In this paper, the trade-off between ionic conductivity and electrochemical stability in Li₃YBr_xCl_6-xhalogen-substituted compounds is investigated. The compositions of Li₃YBr_1.5Cl_4.5and Li₃YBr_4.5Cl_1.5are reported for the first time, along with a consistent analysis of the whole Li₃YBr_xCl_6-x(x = 0-6) tie-line. The results show that, while Br-rich materials are more conductive (5.36 × 10^-3S/cm at 30 °C for x = 4.5), the oxidative stability is lower (∼ 3 V compared to ∼ 3.5 V). Small Br content (x = 1.5) does not affect oxidative stability but substantially increases ionic conductivity compared to pristine Li₃YCl₆(2.1 compared to 0.049 × 10^-3S/cm at 30 °C). This work highlights that optimization of substitutions in the anion framework provide prolific and rational avenues for tailoring the properties of solid electrolytes.

Flow-driven rotary motors such as windmills and water wheels drive functional processes in human society. Although examples of such rotary motors also feature prominently in cell biology, their synthetic construction at the nanoscale has remained challenging. Here we demonstrate flow-driven rotary motion of a self-organized DNA nanostructure that is docked onto a nanopore in a thin solid-state membrane. An elastic DNA bundle self-assembles into a chiral conformation upon phoretic docking onto the solid-state nanopore, and subsequently displays a sustained unidirectional rotary motion of up to 20 rev s⁻¹. The rotors harness energy from a nanoscale water and ion flow that is generated by a static chemical or electrochemical potential gradient in the nanopore, which are established through a salt gradient or applied voltage, respectively. These artificial nanoengines self-organize and operate autonomously in physiological conditions, suggesting ways to constructing energy-transducing motors at nanoscale interfaces.