Search Results

You searched for all publications:

with publication states 'Published (Approved)'

Search Again...

These results only include publications that have been reviewed and processed by Diamond Light Source. To also view papers that have not yet been processed click here.

You can use the folder icon under Actions to collate papers as required. You can then click on View Folder in the left-hand navigation to review and/or download your folder.

Exact matches
Related results

3 items found (0 items not approved), displaying all items.1

Instruments / Technical Area	Publication Details	Published
I15-1-X-ray Pair Distribution Function (XPDF)	Structural and electrochemical properties of type VIII Ba8Ga16−δSn30+δ clathrate (δ ≈ 1) during lithiation Andrew Dopilka , Amanda Childs , Alexander Ovchinnikov , Ran Zhao , Svilen Bobev , Xihong Peng , Candace Chan Acs Applied Materials & Interfaces DOI: 10.1021/acsami.1c07240 Diamond Proposal Number(s): [22209] Open Access Show Abstract ▼ Abstract: The clathrate was prepared in a Sn flux using conditions that favor the type VIII over type I clathrate structure as described previously and the composition was confirmed by single-crystal X-ray diffraction (XRD). More details can be found in the Supporting Information. Slurries containing the active material (type VIII clathrate or commercially obtained β-Sn powder), carbon black, and binder were prepared and coated onto the copper foil (see the Supporting Information). These composite electrodes were then lithiated galvanostatically in half-cells with lithium metal and then extracted for ex situ measurements. Synchrotron X-ray pair distribution (PDF) measurements were conducted at Diamond Light Source (Didcot, U.K.) at the I15-I dedicated PDF beamline with λ = 0.161669 Å. The atomic PDF, G(r), as defined by Billinge et al., was generated from the total scattering data using PDFgetx3 within the xPDF suite software package. The first-principles density functional theory (DFT) calculations were performed in a similar manner to our previous work and are described in more detail in the Supporting Information. The Gibbs free-energy change, average lithiation voltage, and formation energy were calculated as described previously. The climbing image nudged elastic band (NEB) method was used to calculate the Li migration barriers.	Sep 2021
I15-1-X-ray Pair Distribution Function (XPDF)	Electrochemical lithium alloying behavior of guest-free type II silicon clathrates Andrew Dopilka , Amanda Childs , Svilen Bobev , Candace Chan The Journal Of Physical Chemistry C DOI: 10.1021/acs.jpcc.1c04020 Diamond Proposal Number(s): [22209] Open Access Show Abstract ▼ Abstract: The guest-free type II Si clathrate (Si136) is an open framework polymorph of Si that displays unique electrochemical reactions with Li. Li ions are first topotactically inserted into the vacant clathrate cages, followed by an alloying reaction that forms an amorphous lithium silicide phase. The alloying reaction voltage is higher than those seen in other Si electrodes, suggesting that there are structural differences in the formed amorphous phases. Synchrotron X-ray total scattering measurements and pair distribution function analysis are employed to characterize the amorphous phases formed after lithiation. The results show that the clathrate becomes completely amorphous at an earlier stage of lithiation when compared to diamond cubic Si, forming a phase with comparatively larger amounts of Si–Si bonding. The initial insertion of Li into the clathrate cages establishes important Li diffusion paths that kinetically enable the formation of an amorphous phase with lower Li content than typically seen in other silicon-based electrodes. After the initial crystalline-to-amorphous conversion reaction, lithiation takes place via solid-solution alloying. These results demonstrate how the topotactic insertion of Li into an alloying host can kinetically enable modified reaction pathways leading to more homogeneous lithiation throughout the electrode, which is beneficial for Li-ion battery applications.	Aug 2021
I15-1-X-ray Pair Distribution Function (XPDF)	Understanding the amorphous lithiation pathway of the type I Ba8Ge43 clathrate with synchrotron X-ray characterization Andrew Dopilka , Amanda Childs , Svilen Bobev , Candace Chan Chemistry Of Materials DOI: 10.1021/acs.chemmater.0c03641 Diamond Proposal Number(s): [21467, 22209] Open Access Show Abstract ▼ Abstract: Tetrel (Tt = Si, Ge, and Sn) clathrates have highly tunable host–guest structures and have been investigated as novel electrode materials for Li-ion batteries. However, there is little understanding of how the clathrate structure affects the lithiation processes and phase evolution. Herein, the electrochemical lithiation pathway of type I clathrate Ba8Ge43 is investigated with synchrotron X-ray diffraction (XRD) and pair distribution function (PDF) analyses and compared to the lithiation of germanium with a diamond cubic structure (α-Ge). The results confirm previous laboratory XRD studies showing that Ba8Ge43 goes through a solely amorphous phase transformation, which contrasts with the crystalline phase transformations that take place during lithiation of micrometer-sized α-Ge particles. The local structure of framework-substituted clathrate Ba8Al16Ge30 after lithiation is found to proceed through an amorphous phase transformation similar to that in Ba8Ge43. In situ PDF and XRD during heating show that the amorphous phases derived from lithiation of Ba8Ge43 are structurally related to various Li–Ge phases and crystallize at low temperatures (350–420 K). We conclude that the Ba atoms inside the clathrate structure act to break up the long-range ordering of Li–Ge clusters and kinetically prevent the nucleation and growth of bulk crystalline phases. The amorphous phase evolution of the clathrate structure during lithiation results in electrochemical properties distinct from those in α-Ge, such as a single-phase reaction mechanism and lower voltage, suggesting possible advantages of clathrates over elemental phases for use as anodes in Li-ion batteries.	Oct 2020

Publications Database

Search Results

You searched for all publications:

Search Again...

Subject Areas (check all that apply) select all

Instruments used to collect data (check all that apply) select all

Collaborations involved (check all that apply) select all

Diamond Offline Facilities used

Relevant Technical Areas (check all that apply) select all

Menu for Anonymous User