Concerted Influence of HO and CO: Moisture Exposure of Sulfide Solid Electrolyte LiSnS.

Although moisture-induced deterioration mechanisms in sulfide solid electrolytes to enhance atmospheric stability have been investigated, the additional impact of CO exposure remains unclear. This study investigated the generation of HS from LiSnS under HO and CO exposure. LiSnS was exposed to Ar gas at a dew point of 0 °C with and without 500 ppm of CO, and its ion conductive properties were evaluated.

Elucidating the Reductive Decomposition Mechanism in Sulfide Solid Electrolyte LiSnS.

The sulfide solid electrolyte LiSnS has garnered considerable interest due to its exceptional moisture durability, which is attributed to its stable hydrated state. However, a major limitation of certain sulfide solid electrolytes, including LiSnS, is their low reduction durability, which limits their application in the negative electrodes of all-solid-state batteries and impedes qualitative material development assessments. In this study, we introduced a quantitative and straightforward method for evaluating the reductive decomposition of LiSnS to better understand its degradation mechanism.

Improvement of the rate capability of all-solid-state cells with Fe-based polysulfide positive electrode materials by modifying the microstructure.

We successfully prepared an Fe- and Li-containing polysulfide positive electrode material (LiFeS-LiFeS composite) that shows a high specific capacity (>500 mA h g) with improved rate capability in all-solid-state cells. High-resolution TEM analysis indicated the coexistence of small crystallites of high-conductivity LiFeS and FeS, as well as low-crystallinity LiS, in the composite, and this microstructure is responsible for the improved battery performance.

Anion Redox in an Amorphous Titanium Polysulfide.

Amorphous transition-metal polysulfides are promising positive electrode materials for next-generation rechargeable lithium-ion batteries because of their high theoretical capacities. In this study, sulfur anion redox during lithiation of amorphous TiS (a-TiS) was investigated by using experimental and theoretical methods. It was found that a-TiS has a variety of sulfur valence states such as S, S, and S.

Mechanochemical synthesis of air-stable hexagonal LiSnS-based solid electrolytes containing LiI and LiPS.

Sulfide solid electrolytes with high ionic conductivity and high air stability must be developed for manufacturing sulfide all-solid-state batteries. LiGePS-type and argyrodite-type solid electrolytes exhibit a high ionic conductivity of ∼10 S cm at room temperature, while emitting toxic HS gas when exposed to air. We focused on hexagonal LiSnS prepared by mechanochemical treatment because it comprises air-stable SnS tetrahedra and shows higher ionic conductivity than orthorhombic LiSnS prepared by solid-phase synthesis.

A Reversible Rocksalt to Amorphous Phase Transition Involving Anion Redox.

The charge-discharge capacity of lithium secondary batteries is dependent on how many lithium ions can be reversibly extracted from (charge) and inserted into (discharge) the electrode active materials. In contrast, large structural changes during charging/discharging are unavoidable for electrode materials with large capacities, and thus there is great demand for developing materials with reversible structures. Herein, we demonstrate a reversible rocksalt to amorphous phase transition involving anion redox in a LiTiS electrode active material with NaCl-type structure.

A Monte-Carlo simulation of ionic conductivity and viscosity of highly concentrated electrolytes based on a pseudo-lattice model.

Simulating three transport phenomena-ionic conductivity, viscosity, and self-diffusion coefficient-in a common Monte-Carlo framework, we discuss their relationship to the intermolecular interactions of electrolyte solutions at high concentrations (C/mol l ∼ 1). The simulation is predicated on a pseudolattice model of the solution. The ions and solvents (collectively termed "molecules") are considered dimensionless points occupying the lattice sites.

Indigo carmine: an organic crystal as a positive-electrode material for rechargeable sodium batteries.

Using sodium, instead of lithium, in rechargeable batteries is a way to circumvent the lithium's resource problem. The challenge is to find an electrode material that can reversibly undergo redox reactions in a sodium-electrolyte at the desired electrochemical potential. We proved that indigo carmine (IC, 5,5'-indigodisulfonic acid sodium salt) can work as a positive-electrode material in not only a lithium-, but also a sodium-electrolyte.

From metal-organic framework to nanoporous carbon: toward a very high surface area and hydrogen uptake.

In this work, with a zeolite-type metal-organic framework as both a precursor and a template and furfuryl alcohol as a second precursor, nanoporous carbon material has been prepared with an unexpectedly high surface area (3405 m(2)/g, BET method) and considerable hydrogen storage capacity (2.77 wt % at 77 K and 1 atm) as well as good electrochemical properties as an electrode material for electric double layer capacitors. The pore structure and surface area of the resultant carbon materials can be tuned simply by changing the calcination temperature.