Lithium-ion batteries (LiBs) remain the most widely used rechargeable batteries worldwide, due to their light weight, high energy densities and their short charging times. Energy engineers have been trying to identify new materials and strategies that could help to further boost the energy stored by LiBs, while also extending their lifespan (i.e., the period for which they can be used reliably).
LiBs work by moving charged lithium atoms (i.e., ions) between a positive electrode (i.e., cathode) and a negative electrode (i.e., anode). When lithium ions enter and leave these materials, they can experience significant structural changes.
These changes include the sudden shrinkage of the spacing between the materials’ horizontal layers, which can be experimentally monitored through the crystal’s c-lattice parameter. This phenomenon, referred to as c-collapse, can deform the material, crack the particles and in turn shorten the life of batteries.
Researchers at Stanford University, SLAC National Accelerator Laboratory, Korea Institute of Science and Technology (KIST) and other institutes recently showed that by electrochemically tuning a Ni-rich cathode they could suppress c-collapse. Their approach, outlined in a paper published in Nature Energy, could help to increase the lifespan of LiBs, without compromising their energy capacity.
“It has long been recognized that the anisotropic strain in layered cathode is the original culprit that limits the lifetime of lithium-ion batteries,” Zhelong Jiang, co-first author of the paper, told Tech Xplore.
“Our primary objective is to identify a viable approach to produce lithium cathode materials free of such deleterious chemical strains. However, the origin of this anisotropic strain is rooted in the basic thermodynamics of the cathode materials.”
To address this well-documented issue, Jiang and his colleagues set out to identify a strategy to change the arrangement of atoms inside cathode active materials. Specifically, they wished to change how these transition-metal and lithium atoms are stacked along consecutive layers within the material.
Building on earlier work to improve LiB cathodes
The researchers previously performed extensive analyses exploring how structural and electronic properties of cathode materials influenced the performance of LiBs. The results of these analyses led them to the realization that atoms in a cathode’s crystal structure should not be perfectly layered, as this makes them more prone to chemical strain and c-collapse.
“Identifying a practical and reliable way to produce materials with these non-typical crystal structures is challenging, especially if we want to preserve the basic chemical formula of the cathodes that has stood the test of industry,” said Jiang.
“The breakthrough introduced in our paper stemmed from our team’s cumulative knowledge with the study of the effects of anion redox in lithium-ion cathodes.”
Earlier studies have highlighted the link between anion redox reactions (i.e., chemical reactions via which negatively charged ions gain or lose electrons) and the migration of positively charged ions (i.e., cations) from the sites that they normally occupy in the crystal structure. This relationship was most observed in Li- and Mn- rich (LMR) cathode materials.
“Cation migration is undesirable, and huge efforts have been put into either decreasing the extent of cation migration or decreasing the irreversibility of the migration,” explained Jiang.
“As part of our study, we sought the opposite and tried to take advantage of this traditionally negative effect. We looked for substantial and irreversible cation migrations coupled with anion redox, as a means of inducing imperfections in the crystal structure.”
Ultimately, the researchers found that Ni-rich materials were particularly promising for prompting changes in the arrangement of atoms. Conveniently, Ni-rich cathodes are also known to yield the highest energy densities for LiBs.
“We produced a new imperfect crystal structure, which we call disordered layered cathode (DL), in these materials,” said Jiang. “LiBs based on cathodes with this structure were found to exhibit both large capacity and high cycle life, due to the lack of anisotropic strain.”
Performance gains of stabilized cathodes
This recent work by Jiang and his colleagues demonstrates the potential of electrochemically tuning the Ni-rich materials to adapt their atomic structure in a fashion that suppresses c-collapse. As part of their study, they specifically changed the crystal structure of LiNi?.?Mn?.?O?, yet their approach could eventually be applied to other Ni-rich materials.
“Electrochemistry has the potential of making many forms of chemical and crystallographic imperfections inaccessible by other synthetic methods, and these new forms of materials can exhibit unique properties suitable for many technological applications,” said Jiang.
“I think we have only touched the tip of the iceberg here, and I expect many new forms of materials with different modes of crystal imperfections will emerge following electrochemical treatment.”
The results of the initial tests performed by the researchers were highly promising, as LiBs based on their improved cathode exhibited high capacities, a longer lifespan and a minimal reduction in voltage over time. Other researchers could soon draw inspiration from this study and devise similar strategies to limit c-collapse in LiB cathodes.
“In the future, we hope to formulate a more comprehensive understanding of the coupling and causality between the chemical composition, kinetics of structural change, and structural imperfection,” added Jiang.
“We are identifying both similarities and differences between the consequences of anion redox in Mn-rich and Ni-rich cathode systems. We hope to one day arrive at a unified theory and understanding pertaining to the fate of anion-redox battery cathodes with different chemistries.”
Written for you by our author Ingrid Fadelli, edited by Gaby Clark, —this article is the result of careful human work. We rely on readers like you to keep independent science journalism alive.
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More information:
Junghwa Lee et al, Eliminating lattice collapse in dopant-free LiNi?.?Mn?.?O? cathodes via electrochemically induced partial cation disorder, Nature Energy (2025). DOI: 10.1038/s41560-025-01910-w.
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