Exploration of advanced solid electrolytes with good interfacial stability toward electrodes is a highly relevant research topic for all-solid-state batteries. Here, we report PCL/SN blends integrating with PAN-skeleton as solid polymer electrolyte prepared by a facile method. This polymer electrolyte with hierarchical architectures exhibits high ionic conductivity, large electrochemical windows, high degree flexibility, good flame-retardance ability, and thermal stability (workable at 80 °C). Additionally, it demonstrates superior compatibility and electrochemical stability toward metallic Li as well as LiFePO4 cathode. The electrolyte/electrode interfaces are very stable even subjected to 4.5 V at charging state for long time. The LiFePO4/Li all-solid-state cells based on this electrolyte deliver high capacity, outstanding cycling stability, and superior rate capability better than those based on liquid electrolyte. This solid polymer electrolyte is eligible for next generation high energy density all-solid-state batteries.Keywords: all-solid-state lithium-ion batteries; interfacial stability; poly(acrylonitrile); poly(ε-caprolactone); solid polymer electrolytes; succinonitrile;

•LiCoO2 powders are modified with glassy B2O3 through H3BO3 decomposition.•High-voltage (4.5 V) cycling stability and rate capability are greatly improved.•Lithium boron oxide (LBO) as major SEI part is formed on the surface after cycling.•B2O3-modification mitigates high-voltage induced interfacial side reactions.•The as-formed 3D glassy LBO enhances the kinetics of the electrode.In this work, commercial LiCoO2 is modified with a glassy B2O3 by solution mixing with H3BO3 followed by post-calcination in order to enhance its high-voltage electrochemical performance. The glassy B2O3 coating/additive is believed to serve as an effective physiochemical buffer and protection between LiCoO2 and liquid electrolyte, which can suppress the high-voltage induced electrolyte decomposition and active material dissolution. During the early cycling and due to the electrochemical force, the as-coated B2O3 glasses which have 3D open frameworks tend to accommodate some mobile Li+ and form a more chemically-resistant and ion-conductive lithium boron oxide (LBO) interphase as a major component of the solid electrolyte interphase (SEI), which consequently enables much easier Li+ diffusion/transfer at the solid-liquid interfaces upon further cycling. Due to the synergetic effects of B2O3 coating/modification, the high-voltage capacity and energy density of the B2O3-modified LiCoO2 cathode are promisingly improved by 35% and 30% after 100 cycles at 1 C within 3.0–4.5 V vs. Li/Li+. Meanwhile, the high-rate performance of the B2O3-modified electrode is even more greatly improved, showing a capacity of 105 mAh g−1 at 10 C while the bare electrode has dropped to no more than 30 mAh g−1 under this rate condition.

Type I clathrates are a promising thermoelectric (TE) material for waste heat recovery applications. However, the TE figure-of-merit of type I clathrates still needs further improvement. In this study, Yb-doped Ba8−xYbxNi0.1Zn0.54 Ga13.8Ge31.56 (0 ≤ x ≤ 0.5) type I clathrates were synthesized using a high-pressure technique. Energy dispersive spectrometry confirmed successful Yb doping. An increased Yb doping level reduces electrical resistivity and suppresses lattice thermal conductivity while keeping the Seebeck coefficient almost unchanged. TE figure-of-merit of Ba7.7Yb0.3Ni0.1Zn0.54Ga13.8Ge31.56 type I clathrate was improved by 15% (0.91) at the highest measured temperature (900 K) compared with a Yb-free sample.

Alloying with Se has been recently found to be an effective way to improve the cycling performance because the reduced-Se formations can act as a buffer matrix against the volume change of electrode for IVA materials or anchors S in Li-S batteries during cycling. In this paper, SnSe nanoparticles were dispersed within a carbon fiber matrix with ball milling and electrospinning methods. The uniform nano-architecture with SnSe nanoparticles homogeneously confined in the carbon matrix, which is revealed by X-ray powder diffraction and scanning electron microscope, provides a stable buffer and good electrical conductor for the lithiation/delithiation process. Moreover, Se-based phase acts as an additional stabilizer to alleviate Sn agglomeration during cycling. Such dual-buffered SnSe/C composites thus deliver large reversible capacity of 840 mAh/g with ultrastable cycling performance over 100 cycles and demonstrate good rate capacity.

•Sn-doped Nd0.6Fe2Co2Sb12p-type skutterudites were prepared.•Sn-doping for Sb increases the Nd filling fraction.•The in␣situ nanoinclusions were introduced by Sn-doping.•The thermal conductivity is intensively suppressed by 40% at room temperature.•ZT is significantly increased through Sn-doping.Nd0.6Fe2Co2Sb12−xSnx (0 ⩽ x ⩽ 0.6 nominal) skutterudite compounds were synthesized by traditional heat treatment method. Sn substitution on Sb (24g) site was verified by X-ray powder diffraction, energy dispersive spectrometry, and Raman spectroscopy. It was determined that substituting Sb with Sn increases the Nd filling fraction. Along with the in␣situ nanoinclusions introduced by Sn, the thermoelectric behavior of Sn in Nd0.6Fe2Co2Sb12−xSnx differs from those seen in CoSb3. Despite the increase of electrical resistivity, the enhanced Seebeck coefficient and suppressed lattice thermal conductivity resulted in a 30% improvement of ZT for Nd0.6Fe2Co2Sb11.6Sn0.4 compared with that of Sn-free sample. We hope our work can complement the knowledge of pnicogen-substituted p-type skutterudite family and demonstrate the ways to improve their properties through compositional modification as well as in␣situ formation of nanoinclusions.

•Anion-filled skutterudite IFexCo4−xSb12 was synthesized for the first time.•It had the lowest thermal conductivity among FexCo4−xSb12-based skutterudites.•The Fe-rich sample shows the lowest electrical resistivity and the largest Seebeck coefficient.•ZT for IFexCo4−xSb12 is twice that of ICo4Sb12 or iodine-free FexCo4-xSb12.Previously, we synthesized I-filled CoSb3 using a high-pressure synthesis (HPS) technique. This p-type skutterudite possessed an extraordinary low thermal conductivity but inferior power factor, thereby resulting in a fair thermoelectric performance. In this work, Fe atoms were introduced into the system to substitute Co atoms. The successful filling of I anions in FexCo4−xSb12 polycrystals was verified using X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), and specific heat measurements. Thermoelectric property investigation shows greatly enhanced electrical transport properties and slightly increased thermal conductivity with Fe substitution. Given the benefits caused by these factors, ZT for IFe0.7Co3.3Sb12 was enhanced more than 100% compared with those of previous ICo4Sb12 or I-free Fe0.65Co3.35Sb12.

•Iodine filled IyCo4Sb12 was synthesized for the first time.•The highest filling fraction ever reported in elemental filled CoSb3 materials.•Very strong phonon scattering effect for iodine fillers.•The lowest thermal conductivity among all skutterudites.p-Type iodine filled CoSb3 skutterudite, which is inaccessible under ambient pressure, was synthesized with high pressure synthesis technique. The successful filling of iodine into voids of CoSb3 crystal structure was verified by combined measurements including X-ray diffraction, Raman spectroscopy, and specific heat. The highest filling fraction of 0.79 was achieved for the sample with a nominal composition of I1.2Co4Sb12. Beneficial from such a high filling fraction of iodine and the strong phonon-scattering from iodine fillers, the thermal conductivity reached as low as 0.7 W m−1 K−1 for I0.79Co4Sb12, which is the lowest value among all elemental filled skutterudites. Introducing iodine fillers is thus a practical way to further suppress thermal conductivity for single- and multiple-filled skutterudites.