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1. Studies of Functional Defects for Fast Na‐Ion Conduction in Na _{3− y} PS _{4− x} Cl _x with a Combined Experimental and Computational Approach

   https://doi.org/10.1002/adfm.201807951  

   Feng, Xuyong; Chien, Po‐Hsiu; Zhu, Zhuoying; Chu, Iek‐Heng; Wang, Pengbo; Immediato‐Scuotto, Marcello; Arabzadeh, Hesam; Ong, Shyue_Ping; Hu, Yan‐Yan (January 2019, Advanced Functional Materials)

   Abstract All‐solid‐state rechargeable sodium (Na)‐ion batteries are promising for inexpensive and high‐energy‐density large‐scale energy storage. In this contribution, new Na solid electrolytes, Na_3−yPS_4−xCl_x, are synthesized with a strategic approach, which allows maximum substitution of Cl for S (x= 0.2) without significant compromise of structural integrity or Na deficiency. A maximum conductivity of 1.96 mS cm⁻¹at 25 °C is achieved for Na_3.0PS_3.8Cl_0.2, which is two orders of magnitude higher compared with that of tetragonal Na₃PS₄(t‐Na₃PS₄). The activation energy (E_a) is determined to be 0.19 eV. Ab initio molecular dynamics simulations shed light on the merit of maximizing Cl‐doping while maintaining low Na deficiency in enhanced Na‐ion conduction. Solid‐state nuclear magnetic resonance (NMR) characterizations confirm the successful substitution of Cl for S and the resulting change of P oxidation state from 5+ to 4+, which is also verified by spin moment analysis. Ion transport pathways are determined with a tracer‐exchange NMR method. The functional detects that promote Na ‐ion transport are maximized for further improvement in ionic conductivity. Full‐cell performance is demonstrated using Na/Na_3.0PS_3.8Cl_0.2/Na₃V₂(PO₄)₃with a reversible capacity of ≈100 mAh g^‐1at room temperature. 

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2. Adverse Effects of Trace Non-polar Binder on Ion Transport in Free-standing Sulfide Solid Electrolyte Separators

   https://doi.org/10.1149/1945-7111/aced24  

   Mills, Anna; Yang, Guang; Tsai, Wan-Yu; Chen, X. Chelsea; Sacci, Robert L.; Armstrong, Beth L.; Hallinan, Daniel T.; Nanda, Jagjit (August 2023, Journal of The Electrochemical Society)

   Sulfide solid-state electrolyte (SE) possesses high room-temperature ionic conductivity. However, fabrication of the free-standing, sheet-type thin sulfide SE film electrolyte to enable all-solid-state batteries to deliver high energy and power density remains challenging. Herein we show that argyrodite sulfide (Li₆PS₅Cl) SE can be slurry cast to form free-standing films with low (≤5 wt%) loadings of poly(isobutylene) (PIB) binder. Two factors contribute to a lower areal specific resistance (ASR) of the thin film SEs benchmarked to the pristine powder pellet SSE counterparts: i) 1–2 orders reduced thickness and ii) reasonably comparable ionic conductivity at room temperature after the isostatic pressing process. Nevertheless, an increasing polymer binder loading inevitably introduced voids in the thin film SEs, compromising anode/electrolyte interfacial ion transport. Our findings highlight that electrolyte/electrode interfacial stability, as well as the selection of slurry components, including sulfide SE, binder, and solvent, play essential roles in thin film sulfide electrolyte development. 

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3. Operando EDXRD Study of All‐Solid‐State Lithium Batteries Coupling Thioantimonate Superionic Conductors with Metal Sulfide

   https://doi.org/10.1002/aenm.202002861  

   Sun, Xiao; Stavola, Alyssa_M; Cao, Daxian; Bruck, Andrea_M; Wang, Ying; Zhang, Yunlu; Luan, Pengcheng; Gallaway, Joshua_W; Zhu, Hongli (December 2020, Advanced Energy Materials)

   Abstract Sulfide solid‐state electrolytes have remarkable ionic conductivity and low mechanical stiffness but suffer from relatively narrow electrochemical and chemical stability with electrodes. Therefore, pairing sulfide electrolytes with the proper cathode is crucial in developing stable all‐solid‐state Li batteries (ASLBs). Herein, one type of thioantimonate ion conductor, Li_6+xGe_xSb_1−xS₅I, with different compositions is systematically synthesized and studied, among these compositions, an outstanding ionic conductivity of 1.6 mS cm⁻¹is achieved with Li_6.6Ge_0.6Sb_0.4S₅I. To improve the energy density and advance the interface compatibility, a metal sulfide FeS₂cathode with a high theoretical capacity (894 mAh g⁻¹) and excellent compatibility with sulfide electrolytes is coupled with Li_6.6Ge_0.6Sb_0.4S₅I in ASLBs without additional interface engineering. The structural stabilities of Li_6.6Ge_0.6Sb_0.4S₅I and FeS₂during cycling are characterized by operando energy dispersive X‐ray diffraction, which allows rapid collection of structural data without redesigning or disassembling the sealed cells and risking contamination by air. The electrochemical stability is assessed, and a safe operating voltage window ranging from 0.7≈2.4 V (vs. In–Li) is confirmed. Due to the solid confinement in the ASLBs, the Fe⁰aggregation and polysulfides shuttle effects are well addressed. The ASLBs exhibit an outstanding initial capacity of 715 mAh g⁻¹at C/10 and are stable for 220 cycles with a high capacity retention of 84.5% at room temperature. 

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4. Solution Synthesis of Sb ₂ S ₃ and Na ₃ SbS ₄ Solid-State Electrolyte

   https://doi.org/10.1149/1945-7111/ac3752  

   Vaselabadi, Saeed Ahmadi; Smith, William H.; Wolden, Colin A. (November 2021, Journal of The Electrochemical Society)

   Sodium thioantimonate (Na 3 SbS 4 ) is an attractive solid-state electrolyte for sodium-ion batteries due to its high ionic conductivity and stability in protic solvents. Herein, we describe solution-based routes for its synthesis. First, we demonstrate the synthesis of the Sb 2 S 3 precursor via thermodynamically favorable metathesis between Na 2 S and SbCl 3 . This solution-based approach is further extended to couple the resulting Sb 2 S 3 with Na 2 S for the synthesis of Na 3 SbS 4 . It is shown that ethanol is a superior solvent to water for solution-based synthesis of Na 3 SbS 4 with respect to yield, morphology, and performance. Amorphous Sb 2 S 3 synthesized from low-temperature metathesis produced highly crystalline Na 3 SbS 4 with a room temperature Na + conductivity of 0.52 mS cm −1 and low activation energy, comparable to leading values reported in the literature. 

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5. Transforming Li ₃ PS ₄ Via Halide Incorporation: a Path to Improved Ionic Conductivity and Stability in All‐Solid‐State Batteries

   https://doi.org/10.1002/adfm.202309656  

   Poudel, Tej_P; Deck, Michael_J; Wang, Pengbo; Hu, Yan‐Yan (October 2023, Advanced Functional Materials)

   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. 

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