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D.
Matras
,
T. E.
Ashton
,
H.
Dong
,
M.
Mirolo
,
I.
Martens
,
J.
Drnec
,
J. A.
Darr
,
P. D.
Quinn
,
S. D. M.
Jacques
,
A. M.
Beale
,
A.
Vamvakeros
Abstract: Synchrotron X-ray diffraction computed tomography (XRD-CT) was employed to study a commercial 18650 cylindrical LiNi0.8Co0.15Al0.5O2 (NCA) battery under operating conditions and during seven cycles. The analysis of the spatially-resolved diffraction patterns revealed multiple chemical heterogeneities related to the lithium distribution in both the cathode and the anode. It is shown that during the charging of the battery, the anode exhibits different degrees of activity regarding the lithiation process. Explicitly, the following three regions were identified: a uniform/homogenous lithiation, a delayed lithiation and an inactive-to-lithiation region. The inactive-to-lithiation anode region was a result of the specific cell geometry (i.e. due to lack of cathode tape opposite these anode areas) and throughout the cycling experiments remained present in the form of LiC30-30+. The delayed lithiation region was seen to have a direct impact on the properties of NCA in its close proximity during the battery discharging, preventing its full lithiation. Further to this, the aluminum tab negatively affected the NCA in direct contact with it, leading to different lattice parameter a and c evolution compared to the rest of the cathode.
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Aug 2022
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I11-High Resolution Powder Diffraction
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Diamond Proposal Number(s):
[17433]
Abstract: Fast Li-ion conductivity at room temperature is a major challenge for utilization of all-solid-state Li batteries. Metal borohydrides with neutral ligands are a new emerging class of solid-state ionic conductors, and here we report the discovery of a new mono-methylamine lithium borohydride with very fast Li + conductivity at room temperature. LiBH 4 ∙CH 3 NH 2 crystallizes in the monoclinic space group P 2 1 / c , forming a two-dimensional unique layered structure. The layers are separated by hydrophobic –CH 3 moieties, and contain large voids, allowing for fast Li-ionic conduction in the interlayers, σ(Li+) = 1.24∙10 -3 S/cm at room temperature. The electronic conductivity is negligible, and the electrochemical stability is ~2.1 V vs Li. The first all-solid-state battery using a lithium borohydride with a neutral ligand as the electrolyte, Li-metal as the anode and TiS 2 as the cathode is demonstrated.
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Jun 2022
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B18-Core EXAFS
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Diamond Proposal Number(s):
[14239]
Open Access
Abstract: Rechargeable aqueous batteries are promising devices for large-scale energy storage applications because of their low-cost, inherent safety, and environmental friendliness. Among them, aqueous ammonium-ion (NH4+) batteries (AAIB) are currently emerging owing to the fast diffusion kinetics of NH4+. Nevertheless, it is still a challenge to obtain stable AAIB with relatively high output potential, considering the instability of many electrode materials in an aqueous environment. Herein, we report a cell based on a concentrated (5.8m) aqueous (NH4)2SO4 electrolyte, ammonium copper hexacyanoferrate (N-CuHCF) as the positiveelectrode (cathode), and 3,4,9,10-Perylene-bis(dicarboximide) (PTCDI) as the negative electrode (anode). The solvation structure, electrochemical properties, as well as the electrode-electrolyte interface and interphase are systematically investigated by the combination of theoretical and experimental methods. The results indicate for a remarkable cyling performance of the low-cost rocking-chair AAIB, which offers a capacity retention of around 72% after 1000 cycles and an average output potential of around 1.0 V.
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Jun 2022
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I11-High Resolution Powder Diffraction
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Diamond Proposal Number(s):
[26090]
Abstract: Solid-state inorganic magnesium batteries are considered as potential high energy storage devices for the future. Here we present a series of magnesium borohydride tetrahydrofuran (THF) composites, Mg(BH 4 ) 2 · x THF(−MgO), 0 ≤ x ≤ 3, as solid-state electrolytes for magnesium batteries. Three new monoclinic compounds were identified, Mg(BH 4 ) 2 ·2/3THF ( Cc ), α-Mg(BH 4 ) 2 ·2THF ( P2 1 /c ) and β-Mg(BH 4 ) 2 ·2THF ( C2 ), and the detailed structures of α− and β−Mg(BH 4 ) 2 ·2THF are presented. The magnesium ionic conductivity of composites formed by these compounds were several orders of magnitude higher than that of the distinct compounds, x = 0, 2/3, 2, and 3. The nanocomposite stabilized by MgO nanoparticles (~50 nm), Mg(BH 4 ) 2 ·1.5THF−MgO(75 wt%), displayed the highest Mg 2+ conductivity, σ(Mg 2+ ) ~10 -4 S cm -1 at 70 °C, a high ionic transport number of t ion = 0.99, and cyclic voltammetry revealed an oxidative stability of ~1.2 V vs. Mg/Mg 2+ . The electrolyte was stable towards magnesium electrodes, which allowed for stable Mg plating/stripping for at least 100 cycles at 55 °C with a current density of 0.1 mA cm -2 . Finally, a proof-of-concept rechargeable solid-state magnesium battery was assembled with a magnesium metal anode, a TiS 2 cathode providing a maximum discharge capacity of 94.2 mAh g -1 , which corresponds to y = 0.2 in Mg y TiS 2.
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Jun 2022
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B18-Core EXAFS
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Open Access
Abstract: Layered oxides for Na-ion batteries containing Fe have attracted strong interest mainly due to their low cost. However, full oxidation of Fe3+ to Fe4+ is rarely seen before O-redox sets in and is typically accompanied by voltage and capacity fade on cycling. On charging P2-Na0.67[Fe0.5Mn0.5]O2, Fe3+ is oxidized to only ≈Fe3.3+ before the onset of O-redox. O-redox occurs when the Na content is sufficiently low (Na ≈0.3) to permit the transition from P-type to O-type stacking, thus enabling Fe3+ migration to the Na layer. Fe3+ migration generates cation vacancies in the transition metal layer, forming □-O-□ configurations, which trigger the onset of O-redox. In contrast, doping this material with Mg2+ to form P2-Na0.67[Fe0.25Mn0.6Mg0.15]O2 allows full oxidation of Fe3+ to Fe4+ before the Na content is low enough to favor O-type stacking. During O-redox, Mg2+ is displaced into the Na layers instead of Fe. Mg substitution enables greater reversibility of the Fe3+/Fe4+ redox couple and significantly suppresses Fe migration, which is responsible for the voltage and capacity fade observed for P2-Na0.67Fe0.5Mn0.5O2.
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Jun 2022
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B18-Core EXAFS
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Diamond Proposal Number(s):
[14239]
Open Access
Abstract: Garnet solid electrolytes, of the form Li7La3Zr2O12 (LLZO), remain an enticing prospect for solid-state batteries owing to their chemical and electrochemical stability in contact with metallic lithium. Dopants, often employed to stabilize the fast ion conducting cubic garnet phase, typically have no effect on the chemical stability of LLZO in contact with Li metal but have been found recently to impact the properties of the Li/garnet interface. For dopants more “reducible” than Zr (e.g., Nb and Ti), contradictory reports of either raised or reduced Li/garnet interfacial resistances have been attributed to the dopant. Here, we investigate the Li/LLZO interface in W-doped Li7La3Zr2O12 (LLZWO) to determine the influence of a “reducible” dopant on the electrochemical properties of the Li/garnet interface. Single-phase LLZWO is synthesized by a new sol–gel approach and densified by spark plasma sintering. Interrogating the resulting Li/LLZWO interface/interphase by impedance, muon spin relaxation and X-ray absorption spectroscopies uncover the significant impact of surface lithiation on electrochemical performance. Upon initial contact, an interfacial reaction occurs between LLZWO and Li metal, leading to the reduction of surface W6+ centers and an initial reduction of the Li/garnet interfacial resistance. Propagation of this surface reaction, driven by the high mobility of Li+ ions through the grain surfaces, thickens the resistive interphases throughout the material and impedes Li+ ion transport between the grains. The resulting high resistance accumulating in the system impedes cycling at high current densities. These insights shed light on the nature of lithiated interfaces in garnet solid electrolytes containing a reducible dopant where high Li+ ion mobility and the reducible nature of the dopant can significantly affect electrochemical performance.
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May 2022
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E02-JEM ARM 300CF
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Diamond Proposal Number(s):
[22479]
Open Access
Abstract: Li-rich metal oxides, such as Li1.2Ni0.13Mn0.54Co0.13O2, can deliver high specific capacities because of the redox of lattice O2− in addition to the cations. Observing oxygen distortions is key to understand the redox process. Electron ptychography is a phase-reconstruction method in 4D scanning transmission electron microscopy, providing atomic-resolution phase images with high signal-to-noise ratio and dose efficiency. Herein, we use electron ptychography to image the oxygen shift in Li1.2Ni0.13Mn0.54Co0.13O2 during the first cycle. The picometer-scale precision measurement shows distinct oxygen shifts in the bulk and surface after charging and compares with various theoretical anionic redox models. The shift after discharging is not seen to recover in the bulk accounting for voltage hysteresis; however, it recovers close to the surface, although with a phase change. We suggest that Li1.2Ni0.13Mn0.54Co0.13O2 proceeds distinct oxygen redox in the bulk and surface. The altered oxygen sublattice after first cycle potentially explains the changed voltage profiles of following cycles.
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May 2022
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B18-Core EXAFS
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Diamond Proposal Number(s):
[14239]
Open Access
Abstract: Sodium layered oxides showing oxygen redox activity are promising positive electrodes for sodium‑ion batteries (SIBs). However, structural degradation typically results in limited reversibility of the oxygen redox activity. Herein, the effect of Zn‑doping on the electrochemical properties of P3-type sodium manganese oxide, synthesised under air and oxygen is investigated for the first time. Air‑Na 0.67 Mn 0.9 Zn 0.1 O 2 and Oxy‑Na 0.67 Mn 0.9 Zn 0.1 O 2 exhibit stable cycling performance between 1.8 and 3.8 V, each maintaining 96% of their initial capacity after 30 cycles, where Mn 3+ /Mn 4+ redox dominates. Increasing the voltage range to 1.8‑4.3 V activates oxygen redox. For the material synthesised under air, oxygen redox activity is based on Zn, with limited reversibility. The additional transition metal vacancies in the material synthesised under oxygen result in enhanced oxygen redox reversibility with small voltage hysteresis. These results may assist the development of high‑capacity and structurally stable oxygen redox‑based materials for SIBs.
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Apr 2022
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B18-Core EXAFS
E01-JEM ARM 200CF
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Zhangxiang
Hao
,
Jie
Chen
,
Xuekun
Lu
,
Liqun
Kang
,
Chun
Tan
,
Ruoyu
Xu
,
Lixia
Yuan
,
Dan J.l.
Brett
,
Paul R.
Shearing
,
Feng Ryan
Wang
,
Yunhui
Huang
Diamond Proposal Number(s):
[19072, 19246]
Open Access
Abstract: Despite progress of functionalized separator in preventing the shuttle effect and promoting the sulfur utilization, the precise and non-destructive investigation of structure-function-performance associativity remains limited so far in Li-S batteries. Here, we build consecutive multiscale analysis via combining X-ray absorption fine structure (XAFS) and X-ray computational tomography (CT) techniques to precisely visit the structure-function-performance relationship. XAFS measurement offers the atomic scale changes in the chemical structure and environment. Moreover, a non-destructive technique of X-ray CT proves the functionalized separator role for microscopic scale, which is powerful chaining to bridge the chemical structures of the materials with the overall performance modulation of cells. Benefiting from this consecutive multiscale analysis, we report that the uniform doping of Sr2+ into the perovskite LaMnO3-δ material changes the Mn oxidation states and conductivity (chemical structure), leading to effective lithium polysulfide trapping and accelerated sulfur redox (separator function), and resulting in outstanding cell performance.
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Apr 2022
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I12-JEEP: Joint Engineering, Environmental and Processing
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Chun
Huang
,
Matthew
Wilson
,
Kosuke
Suzuki
,
Enzo
Liotti
,
Thomas
Connolley
,
Oxana
Magdysyuk
,
Stephen
Collins
,
Frederic
Van Assche
,
Matthieu N
Boone
,
Matthew C.
Veale
,
Andrew
Lui
,
Rhian-Mair
Wheater
,
Chu Lun Alex
Leung
Diamond Proposal Number(s):
[23400]
Open Access
Abstract: The performance of Li+ ion batteries (LIBs) is hindered by steep Li+ ion concentration gradients in the electrodes. Although thick electrodes (≥300 µm) have the potential for reducing the proportion of inactive components inside LIBs and increasing battery energy density, the Li+ ion concentration gradient problem is exacerbated. Most understanding of Li+ ion diffusion in the electrodes is based on computational modeling because of the low atomic number (Z) of Li. There are few experimental methods to visualize Li+ ion concentration distribution of the electrode within a battery of typical configurations, for example, coin cells with stainless steel casing. Here, for the first time, an interrupted in situ correlative imaging technique is developed, combining novel, full-field X-ray Compton scattering imaging with X-ray computed tomography that allows 3D pixel-by-pixel mapping of both Li+ stoichiometry and electrode microstructure of a LiNi0.8Mn0.1Co0.1O2 cathode to correlate the chemical and physical properties of the electrode inside a working coin cell battery. An electrode microstructure containing vertically oriented pore arrays and a density gradient is fabricated. It is shown how the designed electrode microstructure improves Li+ ion diffusivity, homogenizes Li+ ion concentration through the ultra-thick electrode (1 mm), and improves utilization of electrode active materials.
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Apr 2022
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