Defect and structural evolution under high-energy ion irradiation informs battery materials design for extreme environments

Abstract

Understanding defect evolution and structural transformations constitutes a prominent research frontier for ultimately controlling the electrochemical properties of advanced battery materials. Herein, for the first time, we utilize in situ high-energy Kr ion irradiation with transmission electron microscopy to monitor how defects and microstructures evolve in Na- and Li-layered cathodes with 3d transition metals. Our experimental and theoretical analyses reveal that Li-layered cathodes are more resistant to radiation-induced structural transformations, such as amorphization than Na-layered cathodes. The underlying mechanism is the facile formation of Li-transition metal antisite defects in Li-layered cathodes. The quantitative mathematical analysis of the dynamic bright-field imaging shows that defect clusters preferentially align along the Na/Li ion diffusion channels (a-b planes), which is likely governed by the formation of dislocation loops. Our study provides critical insights into designing battery materials for extreme irradiation environments and understanding fundamental defect dynamics in layered oxides.

Heterogeneous, Defect-Rich Battery Particles and Electrodes: Why Do They Matter, and How Can One Leverage Them?

“…15 Our further study discovered that high-energy ion radiation can create dislocations controllably in both density and distribution in Li-and Na-layered cathodes. 20 We expect that controlling structural defects through high-energy ion radiation can offer an effective path toward tailoring electrochemical properties of battery materials. In addition, a Ni−Li antisite defect is universally observed in layer oxide cathodes during synthesis and electrochemical cycling, which hinders Li transport and reduces capacity.…”

“…10 We also observed the evolution of microstructural defects in Li-and Na-layered cathodes under Kr ion irradiation and concluded that structural defects can be manipulated using a high-energy ion irradiation. 20 Therefore, manipulating the chemical and structural properties of electrode materials at the mesoscale can be an effective and promising approach to modulating battery performance. However, it is not trivial to characterize electrode properties at nanoscale or microscale, especially under operando/in situ conditions.…”

The In Situ Ion Irradiation Toolbox: Time-Resolved Structure and Property Measurements

“…8 Ion beams can also be used for implantation, 9 waveguide formation, 10 functionalization of interfaces and surfaces, or emulation of exposure to extreme radiation environments, such as outer space or nuclear reactors. [11][12][13][14] Post-irradiation examination (PIE) is typically conducted to examine the impact of irradiation on materials. Evaluating post-irradiation microstructural evolution can be done with a variety of microscopies from optical to electron, through compositional analysis with surface and bulk spectroscopies, and through a wide range of property testing platforms.…”

Chemical Modulation of Local Transition Metal Environment Enables Reversible Oxygen Redox in Mn-Based Layered Cathodes

“…One such hurdle is the irreversible oxygen redox, which often leads to many unwanted phenomena such as electrolyte decomposition and gas evolution . The gas evolution can cause the collapse of the crystal structure leading to the formation of cation dense phase. , Alkali/alkaline ions in the transition metal layer that are responsible for triggering oxygen redox, play a dominant role in determining the oxygen redox reversibility. Bruce and co-workers have shown that Li loss from the transition metal layer of Na x Li y Mn 1– y O 2 at high states of charge leads to the formation of underbonded oxygen ions causing O 2 and CO 2 evolution .…”