Suri J.,Intel Corporation |
Shaw L.L.,Wanger Institute for Sustainable Energy Research |
Shaw L.L.,Illinois Institute of Technology
Ceramics International | Year: 2014
In this study, liquid phase sintering (LPS) of the nanostructured Si 3N4/SiC powder synthesized from silica fume is investigated. Two major processing parameters, one being the composition of the powder bed that surrounds the part to be liquid phase sintered and the other the volume fraction of the sintering aid, are studied. It is shown that both of these processing parameters are crucial in achieving high density Si 3N4/SiC nanocomposites and controlling their microstructure and thus their mechanical properties. With the proper powder bed composition and sufficient volume fraction of the sintering aid, dense Si 3N4/SiC composites composed of a bi-modal distribution of equiaxed and elongated Si3N4 grains along with nanoscale SiC particles can be formed via LPS, and such composites offer a good combination of hardness and toughness. The mechanisms via which the two processing parameters play their critical roles in controlling the densification and microstructure have been identified. © 2014 Elsevier Ltd and Techna Group S.r.l.
Wang C.,Materials and Aerospace Engineering |
Wang C.,Wanger Institute for Sustainable Energy Research |
Sawicki M.,Materials and Aerospace Engineering |
Sawicki M.,Wanger Institute for Sustainable Energy Research |
And 3 more authors.
Journal of the Electrochemical Society | Year: 2015
Na3MnCO3PO4 with a potential to deliver two-electron transfer reactions per formula via Mn2+/Mn3+ and Mn3+/Mn4+ redox reactions and a high theoretical capacity (191 mAh/g) can play an important role in Na-ion batteries. This study investigates the dependence of the electrochemical performance of Na3MnCO3PO4-based sodium-ion batteries on processing, structural defects and ionic conductivity. Na3MnCO3PO4 has been synthesized via hydrothermal process under various conditions with and without subsequent high-energy ball milling. Particle sizes, structural defects and ionic conductivity have been studied as a function of processing conditions. It is found that Na3MnCO3PO4 nanoparticles (20 nm in diameter) can be produced from hydrothermal synthesis, but the reaction time is critical in obtaining nanoparticles. Nanoparticles exhibit a higher ionic conductivity than agglomerated particles. Further, structural defects also have a strong influence on ionic conductivity which, in turn, affects the charge/discharge capacities of the Na3MnCO3PO4-based sodium-ion batteries. These results provide guidelines for rational design and synthesis of high capacity Na3MnCO3PO4 for Na-ion batteries in the near future. © The Author(s) 2015.
Guo Y.,Tianjin University of Technology |
Ma W.,Tianjin University of Technology |
Zhang F.,Materials and Aerospace Engineering |
Zhang F.,Wanger Institute for Sustainable Energy Research
Journal of Materials Science: Materials in Electronics | Year: 2016
In this work Pb(Sb1/2Nb1/2)O3–Pb(Ni1/3Nb2/3)O3–Pb(Zr, Ti)O3 (PSN–PNN–PZT) ceramics were prepared by a conventional mixed oxide method. The morphotropic phase boundaries (MPBs) of yPSN–0.3PNN–(0.7 − y)PZT (y = 0, 0.005, 0.01, 0.015 and 0.02) ceramics with a variable PSN were investigated. The MPB compositions, possessing high performances, were identified using X-ray diffraction and further confirmed by their piezoelectric/dielectric properties. The MPBs shifted to a PT-rich region as PSN increased. The optimal electric properties of 0.015PSN–0.3PNN–0.685PZT were found to be d33 = 660pC/N, kp = 0.68, ε33 T/ε0 = 4279, tan δ = 1.56 % for the MPB composition. The remanent polarizations and poling strain gradually increased and then decreased as the PSN content increased. The remanent polarizations (Pr) and poling strains of 0.015PSN–0.3PNN–0.685PZT ceramics at MPB were 33.5 μC/cm2 and 0.39 %, respectively. Furthermore, the electrical performances were also related to the cooling speed in the poling process, where the poling field was 3 kV/mm, the poling temperature was 120 °C and the poling time was 15 min. © 2015, Springer Science+Business Media New York.
Chen L.,Wanger Institute for Sustainable Energy Research |
Chen L.,Illinois Institute of Technology |
Liu Y.,Argonne National Laboratory |
Dietz-Rago N.,Argonne National Laboratory |
And 2 more authors.
Nanoscale | Year: 2015
Li2S with a high theoretical capacity of 1166 mA h g-1 and the capability to pair with lithium free anodes has drawn much attention for lithium sulfur (Li-S) battery applications. However, the fast battery decay and the low capacity retention due to dissolution of intermediate polysulfides in electrolytes limit its development. Designing a nanosized and nanostructured host for Li2S through facile techniques is one of the ways to alleviate the dissolution and improve Li-S battery performance; nevertheless, it is technically difficult to synthesize nanosized and nanostructured hosts for Li2S because Li2S is highly sensitive to moisture and oxygen. Herein, a novel technique, i.e., a bottom-up, hard template and scalable method, is proposed to engineer nanoLi2S composites with core-shell structures as cathodes of Li-S batteries. The size of the as-prepared nanostructured Li2S is around 100 nm. With the assistance of FETEM, HRTEM and EFTEM elemental mapping, an excellent core-shell structure has been confirmed and the outside carbon shell has a thickness of 20-50 nm, effectively retarding polysulfide outflow and dissolution. A high initial capacity of 915 mA h g-1 at 0.2 C has been achieved upon electrochemical cycling and the battery still has exceptional capacity retention after prolonged 200 cycles with a limited decay of 0.18% per cycle. Also, at 0.5 C the electrode exhibits 60% capacity retention with a long life of 300 cycles. We attribute these good performances to the nano-architecture constructed by the novel and facile method. © 2015 The Royal Society of Chemistry.
Liu C.,Wanger Institute for Sustainable Energy Research |
Liu C.,Illinois Institute of Technology |
Shamie J.S.,Wanger Institute for Sustainable Energy Research |
Shamie J.S.,Illinois Institute of Technology |
And 3 more authors.
ACS Applied Materials and Interfaces | Year: 2016
In this study, we have investigated the key factors dictating the cyclic performance of a new type of hybrid sodium-based flow batteries (HNFBs) that can operate at room temperature with high cell voltages (>3 V), multiple electron transfer redox reactions per active ion, and decoupled design of power and energy. HNFBs are composed of a molten Na-Cs alloy anode, flowing aqueous catholyte, and a Na-β′-Al2O3 solid electrolyte as the separator. The surface functionalization of graphite felt electrodes for the flowing aqueous catholyte has been studied for its effectiveness in enhancing V2+/V3+, V3+/V4+, and V4+/V5+ redox couples. The V4+/V5+ redox reaction has been further investigated at different cell operation temperatures for its cyclic stability and how the properties of the solid electrolyte membrane play a role in cycling. These fundamental understandings provide guidelines for improving the cyclic performance and stability of HNFBs with aqueous catholytes. We show that the HNFB with aqueous V-ion catholyte can reach high storage capacity (∼70% of the theoretical capacity) with good Coulombic efficiency (90% ± 1% in 2-30 cycles) and cyclic performance (>99% capacity retention for 30 cycles). It demonstrates, for the first time, the potential of high capacity HNFBs with aqueous catholytes, good capacity retention and long cycling life. This is also the first demonstration that Na-β′-Al2O3 solid electrolyte can be used with aqueous electrolyte at near room temperature for more than 30 cycles. © 2015 American Chemical Society.