Tracking Structural Changes of Carbon Nanotube Electrodes for Lithium–Air Batteries by Time-Resolved Operando Wide- and Small-Angle X-ray Scattering

Abstract

In this study, we prepared single-walled carbon nanotube electrodes for lithium–air batteries (LABs) to investigate the structural changes of the electrodes during the discharge–charge cycle coupled with the precipitation and decomposition of Li oxide. Wide-angle X-ray scattering (WAXS) and small-angle X-ray scattering (SAXS) were used for the structural analysis. A new test cell was designed and fabricated to perform these measurements under operando conditions. From the results of the WAXS measurements during discharge tests, diffraction peaks indicating crystalline oxides and a broad peak indicating amorphous components were observed. The intensities of these peaks increased rapidly in the later stages of the discharge. Moreover, the WAXS measurements showed that the peak of the amorphous component preferentially disappears during the charging process. Furthermore, the nanoscale structural changes associated with the precipitation and decomposition of Li oxide were analyzed using SAXS. The results suggest that the electrode expansion caused electrolyte depletion in the electrode. The post-test electrode thickness was also analyzed, and the results support interpreting the data obtained from WAXS and SAXS. We think that the structural analysis approach and the pore formation discovered in this study will enable LABs to be used more effectively in the future.

Advances in Electric Double-Layer Capacitor Research Using X-ray Scattering Techniques

“…3 and performing operando time-resolved SAXS measurements on organic electrolyte-type EDLC electrodes. 55,56 In this study, a single plate activated carbon with a stronger structure than a single plate and controlled macropores was used as the electrode, 15,18 and PC containing 1 mol dm -3 concentration of 5-Azoniaspiro [4.4]nonane Tetrafluoroborate (SBPBF4) was used as the electrolyte to construct the EDLC. 18,57 The SAXS experiments were performed using the apparatus at the BL-6A station of the Photon Factory (PF) operated at 2.5 GeV and 450 mA in the Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Tsukuba, Japan.…”

Recent advances in battery characterization using in situ XAFS, SAXS, XRD, and their combining techniques: From single scale to multiscale structure detection

“…The in situ combined WAXS/SAXS technique can provide simultaneously these-levels information on the structural changes of electrode materials during electrochemical charging and discharging. [123] However, the difficulty of this experiment lies in the need to design specific battery devices [124,125] that can be used for WAXS/SAXS combined testing when perform charging and discharging cycles. Designing and manufacturing a battery device that can be successfully applied to in situ SR tests is of great importance.…”

“…Designing and manufacturing a battery device that can be successfully applied to in situ SR tests is of great importance. Hatakeyama et al [125] designed a two-electrode cell of an Li-air battery for operando WAXS/SAXS measurements (Figure 8A). The main material of the test cell was stainless steel.…”

“…Hatakeyama et al. [ 125 ] designed a two‐electrode cell of an Li–air battery for operando WAXS/SAXS measurements (Figure 8A). The main material of the test cell was stainless steel.…”

“…Reproduced with permission. [ 125 ] Copyright 2022, American Chemical Society. (B) Sketch map of operando combined WAXS/SAXS measurements.…”