Circular in situneutron powder diffraction cell for study of reaction mechanism in electrode materials for Li-ion batteries

Abstract

The study of reaction mechanisms in materials for Li-ion batteries mainly involves localization of lighter elements like Li, O, or even H in the structure. Thus, in order to facilitate in situ localization of lighter elements and in situ study of structural evolution in the electrode materials, a circular in situ neutron diffraction cell capable of cycling small amounts of electrode materials (0.2-0.3 g) was developed for primary use at the D20 beamline at ILL, Grenoble, France. The circular cell design was tested using LiFePO 4 and graphite as the model electrode materials. The effect of using deuterated electrolyte versus protonated electrolyte on the quality of the in situ neutron diffraction data was also investigated. First in situ neutron powder diffraction measurements at ILL, Grenoble, were successfully conducted where each neutron diffraction pattern was recorded in only 24 min, delivering very good time resolution. It was also found that a circular cell design holding only a small amount of material soaked in deuterated electrolyte was best to perform quantitative analysis using the Rietveld method over the complete 2 theta range. The pattern shows no apparent anisotropic absorption of the diffracted neutron beams.

In Situ Powder Diffraction Studies of Electrode Materials in Rechargeable Batteries

“…However,i nb othc ases, the main drawbacki st he Kapton- Figure 6. The battery designs presented by a) Rosciano et al, [23] b) Godbole et al, [33] c) Bianchini et al, [31] and d) Vadlamanietal. [47] These figures have beenr eproducedf rom Ref.…”

“…[47] These figures have beenr eproducedf rom Ref. [33] with permission from The Royal Society of Chemistry,IUCr,a nd reprintedwith permissionf rom Refs. [31,47].Copyright2 013 and 2014, The ElectrochemicalS ociety.…”

In situ methods for Li-ion battery research: A review of recent developments

“…A remaining issue is however the presence of many cell components in the pathway of the neutron beam. This results in additional undesired Bragg reflections and increased background intensity [90]. Also the different electrochemical equilibrium phases that are generally present lead to overlapping spectra of anode and cathode.…”

“…Consequently, a relatively high amount of electrode material is necessary for a proper measurement, which can be challenging for laboratoryscale batteries [90,91]. However, due to this large penetration depth of the neutrons, measurements can be performed on unmodified commercial cells and diffraction patterns of the anode and cathode can be obtained simultaneously [92].…”

“…At this moment in time it remains challenging to obtain high-quality full pattern Rietveld refinements of in situ neutron diffraction data [91]. In an effort to resolve the aforementioned issues, several promising new battery cells for in situ neutron diffraction measurements have recently been proposed [90,91,94,96,98].…”