Browsing by Author "Brant, WR"
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- ItemIn situ neutron powder diffraction using custom-made lithium-ion batteries(Jove, 2014-011-10) Brant, WR; Schmid, S; Du, GD; Brand, G; Pang, HEA; Peterson, VK; Guo, ZP; Sharma, NLi-ion batteries are widely used in portable electronic devices and are considered as promising candidates for higher-energy applications such as electric vehicles.1,2 However, many challenges, such as energy density and battery lifetimes, need to be overcome before this particular battery technology can be widely implemented in such applications.3 This research is challenging, and we outline a method to address these challenges using in situ NPD to probe the crystal structure of electrodes undergoing electrochemical cycling (charge/discharge) in a battery. NPD data help determine the underlying structural mechanism responsible for a range of electrode properties, and this information can direct the development of better electrodes and batteries. We briefly review six types of battery designs custom-made for NPD experiments and detail the method to construct the ‘roll-over’ cell that we have successfully used on the high-intensity NPD instrument, WOMBAT, at the Australian Nuclear Science and Technology Organisation (ANSTO). The design considerations and materials used for cell construction are discussed in conjunction with aspects of the actual in situ NPD experiment and initial directions are presented on how to analyze such complex in situ data.
- ItemInfluence of synthesis routes on the crystallography, morphology, and electrochemistry of Li2MnO3(American Chemical Society, 2020-02-05) Menon, AS; Ojwang, DO; Wilhammar, T; Peterson, VK; Edström, K; Gomez, CP; Brant, WRWith the potential of delivering reversible capacities of up to 300 mAh/g, Li-rich transition-metal oxides hold great promise as cathode materials for future Li-ion batteries. However, a cohesive synthesis–structure–electrochemistry relationship is still lacking for these materials, which impedes progress in the field. This work investigates how and why different synthesis routes, specifically solid-state and modified Pechini sol–gel methods, affect the properties of Li2MnO3, a compositionally simple member of this material system. Through a comprehensive investigation of the synthesis mechanism along with crystallographic, morphological, and electrochemical characterization, the effects of different synthesis routes were found to predominantly influence the degree of stacking faults and particle morphology. That is, the modified Pechini method produced isotropic spherical particles with approximately 57% faulting and the solid-state samples possessed heterogeneous morphology with approximately 43% faulting probability. Inevitably, these differences lead to variations in electrochemical performance. This study accentuates the importance of understanding how synthesis affects the electrochemistry of these materials, which is critical considering the crystallographic and electrochemical complexities of the class of materials more generally. The methodology employed here is extendable to studying synthesis–property relationships of other compositionally complex Li-rich layered oxide systems. © 2020 American Chemical Society
- ItemRapid lithium insertion and location of mobile lithium in the defect perovskite Li0.18Sr0.66Ti0.5Nb0.5O3(Wiley-V C H Verlag GMBH, 2012-06-18) Brant, WR; Schmid, S; Kuhn, A; Hester, JR; Avdeev, M; Sale, M; Gu, QFFast and fancy: Lithium that was originally disordered within the structure of the perovskite Li0.18Sr0.66Ti0.5Nb0.5O3 can be induced into ordering within the yellow region of the unit cell by low temperatures and treatment with n-butyl-lithium. The fast kinetics of lithium insertion, in connection with a color change, make this nontoxic, air-stable material a suitable candidate for use in electrochromic systems or lithium-storage batteries. © 2012, Wiley-VCH Verlag GmbH & Co. KGaA
- ItemA simple electrochemical cell for in-situ fundamental structural analysis using synchrotron X-ray powder diffraction(Elsevier Science BV, 2013-12-15) Brant, WR; Schmid, S; Du, GD; Gu, QF; Sharma, NA simple in-situ cell design is formulated based on the various in-situ electrochemical cells developed over the last three decades. The cell is targeted at those researchers who are not necessarily in the field of lithium ion battery research but are interested in synthesising and performing fundamental structural analyses of compounds that cannot be made via any other route. Therefore, this design uses only components that are routinely available and can be machined in-house. The effectiveness of the initial cell design is demonstrated through kinetic analysis of the lithium insertion reaction for the Li0.18Sr0.66Ti0.5Nb0.5O3 defect perovskite using data obtained from hundreds of diffraction patterns. Within the first discharge it has been possible to identify three regions with different rates of crystal lattice expansion. These regions extend from 1.01 to 1.47 V, 1.47-1.58 V and 1.58-2.07 V with rates of crystal lattice expansion determined to be 1.765(6) x 10(-5) angstrom min(-1), 1.44(5) x 10(-5) angstrom min(-1) and 2.47(1) x 10(-5) angstrom min(-1), respectively. These three regions correlate with three distinct regions in the electrochemical profile, between 1.00 and 1.36 V, 1.36-1.55 V and 1.55-1.80 V. © 2013, Elsevier Ltd.
- ItemSynthetic pathway determines the nonequilibrium crystallography of Li- and Mn-rich layered oxide cathode materials(American Chemical Society, 2021-02-10) Menon, AS; Ulusoy, S; Ojwang, DO; Riekehr, L; Didier, C; Peterson, VK; Salazar-Alvarez, G; Svedlindh, P; Edström, K; Gomez, CP; Brant, WRLi- and Mn-rich layered oxides show significant promise as electrode materials for future Li-ion batteries. However, an accurate description of its crystallography remains elusive, with both single-phase solid solution and multiphase structures being proposed for high performing materials such as Li1.2Mn0.54Ni0.13Co0.13O2. Herein, we report the synthesis of single- and multiphase variants of this material through sol–gel and solid-state methods, respectively, and demonstrate that its crystallography is a direct consequence of the synthetic route and not necessarily an inherent property of the composition, as previously argued. This was accomplished via complementary techniques that probe the bulk and local structure followed by in situ methods to map the synthetic progression. As the electrochemical performance and anionic redox behavior are often rationalized on the basis of the presumed crystal structure, clarifying the structural ambiguities is an important step toward harnessing its potential as an electrode material. Copyright © 2021 The Authors. Published by American Chemical Society.
- ItemTemperature and composition dependent structural investigation of the defect perovskite series Sr1−xTi1−2xNb2xO3, 0≤x≤0.2(Elsevier, 2010-09) Brant, WR; Schmid, S; Gu, QF; Withers, RL; Hester, JR; Avdeev, MThe crystal structure of the defect perovskite series Sr1−xTi1−2xNb2xO3 has been investigated over a range of temperatures using high-resolution synchrotron X-ray diffraction, neutron diffraction and electron diffraction. Three distinct regions were observed: 00.2 Sr0.8Ti0.6Nb0.4O3 and Sr3TiNb4O15 formed a two phase region. The cubic structure for Sr0.8Ti0.6Nb0.4O3 was stable over the temperature range 90–1248 K and the thermal expansion co-efficient was determined to be 8.72(9)×10−6 K−1. Electron diffraction studies revealed diffuse scattering due to local scale Ti/Nb displacements and slightly enhanced octahedral rotations that did not lead to long range order. The octahedral rotations were observed to ‘lock-in’ at temperatures below ~75 K resulting in a tetragonal structure (I4/mcm) with anti-phase octahedral tilting about the c-axis. © 2010, Elsevier Ltd.