Investigating the Solid Electrolyte Interface (SEI) of Sodium Ion Batteries

Lead Research Organisation: University of Cambridge
Department Name: Chemistry

Abstract

Lithium ion batteries are of fundamental importance to the modern world because of their use in many devices, such as portable electronics. Looking to the future, storing energy is set to become increasingly important for other large-scale applications including electric vehicles and grid storage of energy generated by renewable energy sources, such as wind and solar. However, lithium reserves are limited to only a few countries, and the increased demand for lithium causes a commensurate increase in expense. Therefore, the development of cheap alternatives to lithium ion batteries is highly desirable. As sodium has a similar chemistry to lithium and is readily available (sodium is approximately 1200 times more abundant than lithium and is more evenly distributed in the earth's landmass), there has been an increased interest in developing sodium-ion batteries.

Within sodium ion batteries, sodium ions are transferred from a cathode to an anode through an electrolyte during charging and then from the anode to the cathode during discharging. As the battery is cycled, a solid layer builds up at the interface between the electrolyte and the electrodes. This layer is called the solid electrolyte interphase (SEI) and it is formed mainly from decomposition products of the electrolyte. The SEI is of crucial importance to the battery as it protects the anode by inhibiting the transfer of electrons from the anode to the electrolyte, whilst also allowing sodium ions to transfer from the electrolyte to the anode. The ideal SEI is therefore both an ionic conductor and an electrical insulator.

To improve battery technologies, we must provide a better understanding of the SEI. This project sets out to characterise chemical composition and morphology of the SEI formed in sodium ion batteries by using a variety of techniques including solid-state NMR, X-ray photoelectron spectroscopy, and Raman spectroscopy.

Publications

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Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/R512461/1 01/10/2017 30/09/2021
1944642 Studentship EP/R512461/1 01/10/2017 30/09/2021 Thomas Henry Smith