Browsing by Author "Adams, S"
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- ItemA database of ionic transport characteristics for over 29 000 inorganic compounds(Wiley, 2020-06-25) Zhang, LW; He, B; Zhao, Q; Zou, ZY; Chi, ST; Mi, PH; Ye, AJ; Li, YJ; Wang, D; Avdeev, M; Adams, S; Shi, STransport characteristics of ionic conductors play a key role in the performance of electrochemical devices such as solid-state batteries, solid-oxide fuel cells, and sensors. Despite the significance of the transport characteristics, they have been experimentally measured only for a very small fraction of all inorganic compounds, which limits the technological progress. To address this deficiency, a database containing crystal structure information, ion migration channel connectivity information, and 3D channel maps for over 29 000 inorganic compounds is presented. The database currently contains ionic transport characteristics for all potential cation and anion conductors, including Li+, Na+, K+, Ag+, Cu(2)+, Mg2+, Zn2+, Ca2+, Al3+, F−, and O2−, and this number is growing steadily. The methods used to characterize materials in the database are a combination of structure geometric analysis based on Voronoi decomposition and bond valence site energy (BVSE) calculations, which yield interstitial sites, transport channels, and BVSE activation energy. The computational details are illustrated on several typical compounds. This database is created to accelerate the screening of fast ionic conductors and to accumulate descriptors for machine learning, providing a foundation for large-scale research on ion migration in inorganic materials.© 1999-2021 John Wiley & Sons, Inc.
- ItemEffects of penta- and trivalent dopants on structure and conductivity of Li7La3Zr2O12(Elsevier, 2015-06-01) Gu, W; Ezbiri, M; Prasada Rao, R; Avdeev, M; Adams, SDue to their high ionic conductivity and stability versus metallic lithium, garnet-related Li7La3Zr2O12 (LLZ) are of interest as Li+ solid electrolytes. The correlation between structure and ion mobility in undoped, Ta5 +, Nb5 +, Ga3 + or Al3 + doped LLZ is studied combining molecular dynamics (MD) simulations and experimental characterisation. Neutron and in situ XRD powder diffraction are employed to analyse the Li and dopant distribution and temperature dependence of the structure. Pentavalent doping enhances ionic conductivity by increasing the vacancy concentration and reducing local Li ordering. Trivalent doping Al3 + or Ga3 + on the Li site is slightly less effective in enhancing conductivity. Ga3 + doping on the La3 + site only helps to retain the cubic phase, but does not affect the mobile charge carrier concentration. The cooling rate after sintering is found to strongly affect both the ionic conductivity and its hysteresis on subsequent thermal cycling in the low temperature range, which can be attributed to local Li ordering as manifested by non-linear variations of the lattice parameters. © 2015 Elsevier B.V.
- ItemFormation and conductivity studies of lithium argyrodite solid electrolytes using in-situ neutron diffraction(Elsevier, 2013-01-10) Rao, RP; Sharma, N; Peterson, VK; Adams, SLithium-ion conducting argyrodites Li6PS5X (X = Cl, Br, I) are a promising class of fast-ion conductors for all-solid state Li-ion batteries. To gain a deeper insight into the phase formation of Li6PS5Cl, in situ neutron diffraction studies are carried out on a stoichiometric ball-milled precursor mixture during thermal treatment. The evolution of the S2 −/Cl− anion disorder and its correlation with ionic conductivity are reported here. In contrast to earlier reports, an argyrodite phase is found to form between 80 and 150 °C, but the phase shows only moderate conductivity when crystallized at such low temperatures and further thermal treatment is required to access the highly conducting phase. The maximum room-temperature ionic conductivity of 1.1 × 10− 3 S/cm is observed for samples annealed at intermediate temperatures (250 °C). When ball-milled glass-ceramic precursors for Li6PS5Cl are crystallized with a constant slow heating rate, the initially formed argyrodite phase is found to be Li7PS6, which is then gradually converted into Li6PS5Cl at higher temperatures. The industrial requirements for minimizing cost by using lower annealing temperatures thus need to be balanced with the requirements of obtaining the highest conducting composition of the phase for performance in all-solid state batteries. © 2012, Elsevier B.V.
- ItemHigh-throughput screening platform for solid electrolytes combining hierarchical ion-transport prediction algorithms(Springer Nature, 2020-05-21) He, B; Chi, ST; Ye, AJ; Mi, PH; Zhang, LW; Pu, B; Zou, Z; Ran, YB; Zhao, Q; Wang, D; Zhang, WQ; Zhao, JT; Adams, S; Avdeev, M; Shi, SThe combination of a materials database with high-throughput ion-transport calculations is an effective approach to screen for promising solid electrolytes. However, automating the complicated preprocessing involved in currently widely used ion-transport characterization algorithms, such as the first-principles nudged elastic band (FP-NEB) method, remains challenging. Here, we report on high-throughput screening platform for solid electrolytes (SPSE) that integrates a materials database with hierarchical ion-transport calculations realized by implementing empirical algorithms to assist in FP-NEB completing automatic calculation. We first preliminarily screen candidates and determine the approximate ion-transport paths using empirical both geometric analysis and the bond valence site energy method. A chain of images are then automatically generated along these paths for accurate FP-NEB calculation. In addition, an open web interface is actualized to enable access to the SPSE database, thereby facilitating machine learning. This interactive platform provides a workflow toward high-throughput screening for future discovery and design of promising solid electrolytes and the SPSE database is based on the FAIR principles for the benefit of the broad research community. © 2020, The Author(s)
- ItemA highly efficient and informative method to identify ion transport networks in fast ion conductors(Elsevier, 2021-01-15) He, B; Mi, PH; Ye, AJ; Chi, ST; Jiao, Y; Zhang, LW; Pu, BW; Zou, Z; Zhang, WQ; Avdeev, M; Adams, S; Zhao, JT; Shi, SHigh-throughput analysis of the ion transport pathways is critical for screening fast ion conductors. Currently, empirical methods, such as the geometric analysis and bond valence site energy (BVSE) methods, are respectively used for the task. Geometric analysis method can only extract geometric and topological pathway properties without considering the interatomic interactions, while the BVSE method alone does not yield a geometric classification of the sites and interstices forming the pathway. Herein, we propose a highly efficient and informative method to identify interstices and connecting segments constructing an ion transport network by combining topological pathway network and BVSE landscape, which enables to obtain both the geometry and energy profiles of nonequivalent ion transport pathways between adjacent lattice sites. These pathways can be further used as the input for first-principles nudged elastic band calculations with automatically generated chains of images. By performing high-throughput screening of 48,321 Li-, Na-, Mg- and Al-containing ionic compounds from the Inorganic Crystal Structure Database based on the filter combining geometric analysis and BVSE methods, we obtain 1,270 compounds with connected ionic migration pathways of suitable sizes and low migration energy barriers, which include both previously reported fast ion conductors, and new promising materials to be explored further. © 2020 Acta Materialia Inc. Published by Elsevier Ltd.
- ItemIn situ neutron diffraction monitoring of Li7La3Zr2O12 formation: towards a rational synthesis of garnet solid electrolytes(American Chemical Society, 2015-04-01) Rao, RP; Gu, W; Sharma, N; Peterson, VK; Avdeev, M; Adams, SThe favorable combination of fast-ionic conductivity and high electrochemical stability of Li-stuffed garnet type Li7La3Zr2O12 (LLZ) makes this material a promising candidate for applications as a solid-state electrolyte in high-energy-density batteries. However, a widespread technical use of LLZ is impeded by difficulty in reliable formation and densification of the pure fast-ion conducting phase. The present study of the phase-formation process enables rational fabrication procedures to be devised based on a thorough understanding of the complex phase formation of LLZ. In situ neutron powder diffraction monitoring of the phase formation revealed an influence of the partial melting of precursors on the formation of the fast-ion conducting phase, indicating that in the typical synthesis route LLZ is not formed in a solid-state reaction but from a partial carbonate melt that decomposes on further heating. The cooling rate critically influences lithium ordering and ionic conductivity. © 2015 American Chemical Society
- ItemRevisiting the layered Na3Fe3 (PO4) 4 phosphate sodium insertion compound: structure, magnetic and electrochemical study(IOP Publishing, 2019-11-18) Shinde, GS; Gond, R; Avdeev, M; Ling, CD; Rao, RP; Adams, S; Barpanda, PLayered sodium iron phosphate phase [Na3Fe3(PO4)4] was synthesized by solution combustion synthesis method, marking the first attempt of solvothermal synthesis of this phase. Its crystal structure was verified by synchrotron and neutron powder diffraction. Rietveld analyses proved the phase purity and formation of monoclinic framework with C2/c symmetry. It undergoes an antiferromagnetic ordering ~27 K. This combustion prepared nanoscale Na3Fe3(PO4)4 compound was found to be electrochemically active with a stepwise voltage profile involving an Fe3+/Fe2+ redox activity centred at 2.43 V vs. Na/Na+. Despite various cathode optimization, only 1.8 Na+ per formula unit could be reversibly inserted into the Na3Fe3(PO4)4 framework leading to capacity close to 50 mAh g−1. This limited electrochemical activity can be rooted to (i) relatively large diffusion barrier (ca. 0.28 eV) as per Bond valence site energy (BVSE) calculations and (ii) possible structural instability during (de)sodiation reaction. © 2019 The Author(s). CC-BY licence - Published by IOP Publishing Ltd
- ItemScreening of the alkali-metal ion containing materials from the Inorganic Crystal Structure Database (ICSD) for high ionic conductivity pathways using the bond valence method(Elsevier Science BV, 2012-10-04) Avdeev, M; Sale, M; Adams, S; Rao, RPHigh ionic conductivity is one of the key characteristics of electrolytes and electrode materials directly affecting performance of electrochemical devices in which they are used. In the case of inorganic crystalline solid electrolytes and insertion cathodes the topology and geometry of crystal structure essentially defines ionic conductivity and charge–discharge rates. We employed the bond valence method to identify materials with crystal structures featuring infinite networks of pathways of suitable size that is a prerequisite for fast ion transport. Taking advantage of the method low computational cost, we carried out exhaustive analysis of similar to 13,000 entries of the Inorganic Crystal Structure Database and ranked the materials based on the fraction of crystal structure space with low bond-valence mismatch. The results may be used as a guide for further theoretical and experimental studies of promising compositions. © 2012, Elsevier Ltd.
- ItemStructural evolution of NASICON-type Li1+xAlxGe2−x(PO4)3 using in situ synchrotron x-ray powder diffraction(Royal Society of Chemistry, 2016-04-04) Safanama, D; Sharma, N; Rao, RP; Brand, HEA; Adams, SFast Li-ion conducting Li1+xAlxGe2-x(PO4)3 or LAGP ceramics are the most commonly used anode-protecting membranes in new generation Li-air batteries. The electrochemical properties of this solid membrane (electrolyte) are highly dependent on the purity of the phase and the actual amount of Al incorporated into the structure which often deviates from the synthetic inputs for different annealing conditions. Hence, optimizing the annealing temperature range is of great importance to achieve desirable phases and therefore optimized properties. Here in situ synchrotron X-ray diffraction is carried out during the synthesis of LAGP. Starting with ball-milled and calcined LAGP glass powders we observe the structural evolution during the glass to ceramic transition. Sequential Rietveld refinements show that the dominant Al-poor LGP phase transforms into an Al-incorporated LAGP structure at temperatures higher than 800 °C. The c lattice parameter is found to be highly dependent on the temperature and also the amount of Al incorporated into the structure. The relationship between the c lattice parameter and Al concentration in LAGP is evaluated and the correlation can be used to allow the estimation of Al doping. Thus this work allows the lattice parameter to "fingerprint" the dopant concentration. © 2016 The Royal Society of Chemistry.
- ItemTime-dependent in-situ neutron diffraction investigation of a Li(Co0.16Mn1.84)O4 cathode(American Chemical Society, 2011-11-03) Sharma, N; Reddy, MV; Du, GD; Adams, S; Chowdari, BVR; Guo, ZP; Peterson, VKReal-time in-situ neutron diffraction data reveal for the first time that the Li(Co0.16Mn1.84)O4 cathode undergoes current-free discharge. We find that current-free discharge occurs in a partially charged Li(Co0.16Mn1.84)O4 cathode during its first charge cycle over a period of 11 h resulting in a 44(2)% expansion of the crystal lattice. The rate of change in the lattice parameter during the current-free discharge process is half the rate and more linear than for an applied-current discharge of ?0.5 mA. The origins of current-free discharge are discussed along with the implications of nonequilibrium relaxation processes in in-situ neutron and X-ray diffraction studies. We show that the lattice does not return to the predischarge values after either current-applied or current-free discharge, indicating a limited ability for Li reinsertion (capacity loss) in partially charged Li(Co0.16Mn1.84)O4 batteries. © 2011, American Chemical Society
- ItemVariation in structure and Li+-ion migration in argyrodite-type Li6PS5X (X = Cl, Br, I) solid electrolytes(Springer, 2012-05-01) Rayavarapu, PR; Sharma, N; Peterson, VK; Adams, SAll-solid-state rechargeable lithium-ion batteries (AS-LIBs) are attractive power sources for electrochemical applications due to their potentiality in improving safety and stability over conventional batteries with liquid electrolytes. Finding a solid electrolyte with high ionic conductivity and compatibility with other battery components is a key factor in raising the performance of AS-LIBs. In this work, we prepare argyrodite-type Li(6)PS(5)X (X = Cl, Br, I) using mechanical milling followed by annealing. X-ray diffraction characterization reveals the formation and growth of crystalline Li(6)PS(5)X in all cases. Ionic conductivity of the order of 7 x 10(-4) S cm(-1) in Li(6)PS(5)Cl and Li(6)PS(5)Br renders these phases suitable for AS-LIBs. Joint structure refinements using high-resolution neutron and laboratory X-ray diffraction provide insight into the influence of disorder on the fast ionic conductivity. Besides the disorder in the lithium distribution, it is the disorder in the S(2-)/Cl(-) or S(2-)/Br(-) distribution that we find to promote ion mobility, whereas the large I(-) cannot be exchanged for S(2-) and the resulting more ordered Li(6)PS(5)I exhibits only a moderate conductivity. Li(+) ion migration pathways in the crystalline compounds are modelled using the bond valence approach to interpret the differences between argyrodites containing different halide ions. © 2012, Springer.