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Computational study of ion conduction in lithium-ion batteries

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In a paper published in the journal Nature Materials, Prof. Arun Venkatnathan’s group at IISER Pune studied the properties of lithium-ion battery materials at a molecular level using powerful computer simulation techniques. This work was carried out in collaboration with researchers from Temple University, USA.

Batteries are primarily composed of three main components, the anode, the cathode and an electrolyte. The materials that make up each of these components determine the physical and chemical properties of a battery and eventually the utility of a battery as an energy storing device.

In their earlier work, Prof. Michael Zdilla and Prof. Stephanie Wunder’s research groups at Temple University had synthesised and characterised several soft co-crystalline electrolytes for batteries. In the current paper, they have synthesised a more stable version of the soft-solid electrolyte with good interfacial contact with electrodes. This electrolyte is referred to as (Adpn)2LiPF6 in the paper.

With a PhD student Prabhat Prakash (now a postdoctoral researcher at CalTech, USA), Prof. Arun Venkatnathan from IISER Pune collaborated with the Temple University team to study the material properties of soft-solid electrolytes at an atomic and molecular level.

Photo taken in 2020 of Prof. Venkatnathan's research group: (left to right) Prabhat Prakash, Rakesh Pant, Arun Venkatnathan, S. Ardhra, Anna Varughese. The then PhD student Prabhat Prakash (far left) and Prof. Venkatnathan (third from left) were involved in the research work described in this article. (Photo Courtesy: Prof. Arun Venkatnathan)

Using various computational models such as classical Molecular Dynamics simulations, the Venkatnathan group examined characteristics such as thermal stability, surface effects, ion-ion and ion-solvent interactions and ion dynamics of (Adpn)2LiPF6.

Through this in-depth study, the team sought to understand why grain boundaries (the boundaries between two crystals of the electrolyte) were more conductive than the crystals themselves and through what mechanism is the ion conduction taking place.

Modeling the ion conduction mechanism in these co-crystals proved non-trivial as it posed a formidable technical challenge to the team. With an educated guess that conduction could be higher at the boundaries, the team came up a model where two grains of the cocrystals are solvated in excess solvent, adiponitrile in this case.

After long equilibration, this model predicted two diffusive patterns of Li+ ions: highly diffusive in the boundary layers and inter-grain regions, and sub-diffusive in the crystalline region. Their prediction was consistent with experimental measures of conductivity.  Thus the team now has insights into the possible molecular-level view of the grain boundaries.

Read here a “Behind the paper” article in Materials Community, where Prabhat Prakash describes how this work developed, the technical challenges that it posed, and the team’s approach that takes one into a molecular level detail of the electrolyte in action obtained through modeling and simulation.

“Results from our work are expected to spur new experiments to search for similar alternatives to the conventional battery electrolyte materials,” said Prof. Venkatnathan speaking on the broad prospects this work has opened up towards understanding ion conduction and thereby enabling one to work towards better battery electrolytes.

This work was supported by research grants from the National Science Foundation, the Department of Science and Technology’s Nanomission, and the Scientific and Engineering Research Board (SERB). The authors acknowledge the role of several high-performance computing clusters including the National Supercomputing Mission ‘PARAM Brahma’ at IISER Pune that enabled this work.


Article Citation

Prabhat Prakash, Birane Fall, Jordan Aguirre, Laura A. Sonnenberg, Parameswara Rao Chinnam, Sumanth Chereddy, Dmitriy A. Dikin, Arun Venkatnathan, Stephanie L. Wunder & Michael J. Zdilla. A soft co-crystalline solid electrolyte for lithium-ion batteries. Nature Materials (2023).

- with inputs from Prof. Arun Venkatnathan