Search for: All records

Abstract All‐solid‐state potassium batteries emerge as promising alternatives to lithium batteries, leveraging their high natural abundance and cost‐effectiveness. Developing potassium solid electrolytes (SEs) with high room‐temperature ionic conductivity is critical for realizing efficient potassium batteries. In this study, we present the synthesis of K_2.98Sb_0.91S_3.53Cl_0.47, showcasing a room‐temperature ionic conductivity of 0.32 mS/cm and a low activation energy of 0.26 eV. This represents an increase of over two orders of magnitude compared to the parent compound K₃SbS₄, marking the highest reported ionic conductivity for non‐oxide potassium SEs. Solid‐state³⁹K magic‐angle‐spinning nuclear magnetic resonance on K_2.98Sb_0.91S_3.53Cl_0.47reveals an increased population of mobile K⁺ions with fast dynamics. Ab initio molecular dynamics (AIMD) simulations further confirm a delocalized K⁺density and significantly enhanced K⁺diffusion. This work demonstrates diversification of the anion sublattice as an effective approach to enhance ion transport and highlights K_2.98Sb_0.91S_3.53Cl_0.47as a promising SE for all‐solid‐state potassium batteries. 

Abstract Polyanion rotations are often linked to cation diffusion, but the study of multiple polyanion systems is scarce due to the complexities in experimentally determining their dynamic interactions. This work focuses on BH₄‐based argyrodites, synthesized to achieve a high conductivity of 11 mS cm⁻¹. Advanced tools, including high‐resolution X‐ray diffraction, neutron pair distribution function analysis, and mutinuclear magic‐angle‐spinning nuclear magnetic resonance (NMR) spectroscopy and relaxometry, along with theoretical calculations, are employed to unravel the dynamic intricacies among the dual polyanion lattice and active charge carriers. The findings reveal that the anion sublattice of Li_5.07PS_4.07(BH₄)_1.93affords an even temporal distribution of Li among PS₄³⁻and BH₄⁻, suggesting minimal trapping of the charge carriers. Moreover, the NMR relaxometry unveils rapid BH₄⁻rotation on the order of ∼GHz, affecting the slower rotation of neighboring PS₄³⁻at ∼100 MHz. The PS₄³⁻rotation synchronizes with Li⁺motion and drives superionic transport. Thus, the PS₄³⁻and BH₄⁻polyanions act as two‐staged dual motors, facilitating rapid Li⁺diffusion. 

Abstract To enhance Li⁺transport in all‐solid‐state batteries (ASSBs), harnessing localized nanoscale disorder can be instrumental, especially in sulfide‐based solid electrolytes (SEs). In this investigation, the transformation of the model SE, Li₃PS₄, is delved into via the introduction of LiBr.³¹P nuclear magnetic resonance (NMR)unveils the emergence of a glassy PS₄³⁻network interspersed with Br⁻.⁶Li NMR corroborates swift Li⁺migration between PS₄³⁻and Br⁻, with increased Li⁺mobility indicated by NMR relaxation measurements. A more than fourfold enhancement in ionic conductivity is observed upon LiBr incorporation into Li₃PS₄. Moreover, a notable decrease in activation energy underscores the pivotal role of Br⁻incorporation within the anionic lattice, effectively reducing the energy barrier for ion conduction and transitioning Li⁺transport dimensionality from 2D to 3D. The compatibility of Li₃PS₄with Li metal is improved through LiBr incorporation, alongside an increase in critical current density from 0.34 to 0.50 mA cm⁻², while preserving the electrochemical stability window. ASSBs with 3Li₃PS₄:LiBr as the SE  showcase robust high‐rate and long‐term cycling performance. These findings collectively indicate the potential of lithium halide incorporation as a promising avenue to enhance the ionic conductivity and stability of SEs.