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A solid electrolyte material comprises Li, T, X and A wherein T is at least one of P, As, Si, Ge, Al, and B; X is one or more halogens or N; A is one or more of S and Se. The solid electrolyte material has peaks at 17.8°±0.75° and 19.2°±0.75° in X-ray diffraction measurement with Cu-Kα(1,2)=1.5418 Å and may include glass ceramic and/or mixed crystalline phases.
The solid-electrolyte interphase (SEI) is pivotal in stabilizing lithium metal anodes for rechargeable batteries. However, the SEI is constantly reforming and consuming electrolyte with cycling. The rational design of a stable SEI is plagued by the failure to control its structure and stability. In this article, we report a molecular-level SEI design using a reactive polymer composite, which effectively suppresses electrolyte consumption in the formation and maintenance of the SEI. The SEI layer consists of a polymeric lithium salt, lithium fluoride nanoparticles, and graphene oxide sheets, as evidenced by cryo-TEM, AFM, and surface-sensitive spectroscopies. This structure is different from that of a conventional electrolyte-derived SEI and has excellent passivation properties, homogeneity, and mechanical strength. The use of the polymer-inorganic SEI enables high-efficiency Li deposition and stable cycling of 4V Li|LiNi 0.5 Co 0.2 Mn 0.3 O 2 cells under lean electrolyte, limited Li excess, and high capacity conditions. The same approach was also applied to design stable SEI layers for sodium and zinc anodes.
We consider near-field heat transfer with nonzero chemical potential for photons, as can occur between two semiconductor bodies, held at different temperatures with at least one of the bodies under external bias.We show that the dependence of radiative heat flux on chemical potential enables electronic control of both the direction and magnitude of near-field heat transfer between the two bodies. Moreover such a configuration can operate as a solid-state cooling device whose efficiency can approach the Carnot limit in the ideal case. Furthermore, significant cooling can also be achieved in the presence of inherent nonidealities including Auger recombination and parasitic phonon-polariton heat transfer.
Intermediate temperature solid oxide fuel cells (IT-SOFCs) are cost-effective and efficient energy conversion systems. Here, the sluggish oxygen reduction reaction (ORR) and the degradation of cathodes are critical challenges to the commercialization of IT-SOFCs. Here, a highly efficient multiphase (MP) catalyst coating, consisting of Ba 1–x Co 0.7 Fe 0.2 Nb 0.1 O 3–δ (BCFN) and BaCO 3 , to enhance the ORR activity and durability of the state-of-the-art lanthanum strontium cobalt ferrite (La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3–δ , LSCF) cathode is reported. The conformal MP catalyst-coated LSCF cathode shows a polarization resistance (R p ) of 0.048 Ω cm 2 at 650 °C, about one order of magnitude smaller than that of the bare LSCF. In an accelerated Cr-poisoning test, the degradation rate of the catalyst-coated LSCF electrode is 10 –3 Ω cm 2 h –1 (0.59% h –1 ) over 200 h, only one fifth of the degradation rate of the bare LSCF electrode at 750 °C. In addition, anode-supported single cells with the MP catalyst-coated LSCF cathode show a dramatically enhanced peak power density (1.4 W cm –2 vs 0.67 W cm –2 at 750 °C) and increased durability against Cr and H 2 O. Both experimental results and density functional theory-based calculations indicate that the BCFN phase improves the ORR activity while the BaCO 3 phase enhances the stability of the LSCF cathode.
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The thermal expansion (TE) coefficients of the lithium-stable lithium-ion conducting garnet lithium lanthanum zirconium oxide (LLZ) and the effect of aluminum substitution were measured from room temperature up to 700 °C by a synchrotron-based X-ray diffraction. The typical TE value measured for the most reported composition (LLZ doped with 0.3 wt.% or 0.093 mol% aluminum) was 15.498 × 10-6 K-1, which is approximately twice the value reported for other garnet-type structures. As the Al(III) concentration has been observed to strongly affect the structure observed and the ionic conductivity, we also assessed its role on thermal expansion and noted only a small variation with increasing dopant concentration. The materials implications for using LLZ in a solid state battery are discussed.
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In situ high energy X-ray diffraction (HEXRD) and in situ X-ray absorption near edge spectroscopy (XANES) were carried out to understand the soild state synthesis of Na x MnO 2 , with particular interest on the synthesis of P2 type Na 2/3 MnO 2 . It was found that there were multi intermediate phases formed before NaMnO 2 appeared at about 600 °C. And the final product after cooling process is a combination of O'3 NaMnO 2 with P2 Na 2/3 MnO 2 . A P2 type Na 2/3 MnO 2 was synthesized at reduced temperature (600 °C). The influence of Na 2 CO 3 impurity on the electrochemical performance of P2 Na 2/3 MnO 2 was thoroughly investigated in our work. It was found that the content of Na 2 CO 3 can be reduced by optimizing Na 2 CO 3 /MnCO 3 ratio during the solid state reaction or other post treatment such as washing with water. Lastly, we expected our results could provide a good guide for future development of high performance cathode materials for sodium-ion batteries.