Technique reveals internal structure of rechargeable batteries

Researchers from Lancaster University have developed a technique to observe the 3D internal structure of rechargeable batteries. The research, published in Nature Communications, was led by Professor Oleg Kolosov from Lancaster University in collaboration with University College London and NEXGENNA Faraday Institution Consortium.

The researchers used a novel 3D Nano-Rheology Microscopy (3DNRM)-based technique to visualise the 3D nanostructure inside rechargeable batteries, from the molecular-scale electrical double layer to the nanoscale-thick electrochemical surface layer on the graphite anode surface in a lithium-ion battery. This enabled the direct observation of the progression of the whole three-dimensional structure of the solid electric interface (SEI), a nanoscale passivation layer formed on the battery electrode–electrolyte interface that predetermines key battery properties.

The researchers were able to reveal key predictors of SEI layer formation in a complex interplay of molecular dimension electrical double-layer structures, surface properties of carbon layers and solvent–Li-ion interaction in the electrolyte. The nanoarchitecture of solid–liquid interfaces is critical for high-performance batteries, but it has been difficult to characterise reaction interfaces within batteries due to their inherent inaccessibility.

“So far, understanding the SEI formation mechanism is still a most challenging and least explored area due to the lack of an interfacial characterisation technique capable of both nanoscale resolution and operation in the working battery environment,” said Dr Yue Chen, lead author of the study.

The dynamics of interfacial reactions define energy flow and conversion and govern chemical species transfer in important physical, chemical and biological processes, from catalytic reactions, energy storage and release in batteries, to antigen–antibody interactions and information transmission across neural cells. This opens up a range of areas for the new technique, from energy storage and chemical engineering to biomedical applications.

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