Operando structural study of non-aqueous Li–air batteries using synchrotron-based X-ray diffraction

Abstract

Non-aqueous lithium-air batteries (LABs) attract attention as a candidate technology for next-generation energy storage devices. It is crucial to understand how the discharge product Li 2 O 2 is formed and decomposed by the electrochemical reactions to improve the cycle performance and decrease the charge voltage, which are the most important subjects for LAB development. Here, operando X-ray diffraction with high-brilliant X-rays in a transmission mode was used to observe the intensity and structural changes of crystalline Li 2 O 2 in an operating non-aqueous LAB in real time, and the Li-O 2 electrochemical reaction involving Li 2 O 2 formation and decomposition was clearly demonstrated. The electrochemically formed Li 2 O 2 , which had an anisotropic domain size of 10 nm in the c-direction and 40-70 nm in the ab-plane, grew due to the increase of the number of domains during the discharge process. No other reaction products with a crystalline phase such as LiOH were found in either the cathode or anode of the LAB, whereas the accelerated decomposition rate of the domains was accompanied with the change of the domain shape and lattice constant of the c-axis in the latter half of the charge process with voltage higher than 4 V.

Lab‐Scale In Situ X‐Ray Diffraction Technique for Different Battery Systems: Designs, Applications, and Perspectives

“…That may be attributed to the oxidation of byproducts at the beginning of charge process. And the same phenomenon is further proved through in situ synchrotron‐based XRD by observing the intensity and structural changes of crystalline Li 2 O 2 . In addition, Kang and co‐workers synthesized an antioxidant mediator of 2,6‐di‐tert‐butyl‐hydroxytoluene (BHT) to improve the electrochemical performance of Li–O 2 batteries .…”

First-Principles Study of the Surfaces and Equilibrium Shape of Discharge Products in Li–Air Batteries

“…However, these SEM images do not allow us to identify the shape of the single crystallites. Indeed, X-ray diffraction (XRD) studies , have shown that their shape is strongly anisotropic in a disc- or platelet-like fashion.…”

Real time monitoring of generation and decomposition of degradation products in lithium oxygen batteries during discharge/charge cycles by an online cold trap pre-concentrator-gas chromatography/mass spectroscopy system

“…[11][12][13] To improve the cyclability, it is essential to clarify the LOB degradation mechanism by analysing reaction products and intermediates produced during the discharge/ charge processes. [13][14][15][16][17][18][19][20] Among many techniques to examine these reaction products and intermediates such as X-ray diffraction, 14,15 Raman spectroscopy, 16,17 and mass spectroscopy (MS), [18][19][20] MS provides the most direct information of the products and intermediates in real time.…”