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Nanoparticles in lithium-sulphur batteries detected with neutron experiment

Date:
September 6, 2019
Source:
Helmholtz-Zentrum Berlin für Materialien und Energie
Summary:
A team has for the first time precisely analyed how nanoparticles of lithium sulphide and sulphur precipitate onto battery electrodes during the course of the charging cycle. The results can help increase the service life of lithium-sulphur batteries.
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Lithium-sulphur batteries are regarded as one of the most promising candidates for the next generation of energy storage devices. They have a theoretical gravimetric energy density that is five times higher than that of the best lithium-ion batteries currently available. And they even work at sub-zero temperatures of down to -50 °C. In addition, sulphur is inexpensive and environmentally friendly.

However, their capacity so far has fallen sharply with every charge-discharge cycle, so that such batteries are not yet long-lasting. The loss of capacity is caused by complicated reaction processes at the electrodes inside the battery cell. It is therefore particularly important to understand exactly how the charge (sulphur) and discharge (lithium sulphide) products precipitate and dissolve. While sulphur precipitates macroscopically and therefore lends itself to examination by imaging techniques or X-ray diffraction during cycling, lithium sulphide is difficult to detect due to its sub-10-nm particle size.

Insight into this has now been provided for the first time by investigations with the BER II neutron source at the HZB. Dr. Sebastian Risse used a measuring cell he developed to illuminate lithium-sulphur batteries with neutrons during charging and discharging cycles (operando) and simultaneously performed additional measurements with impedance spectroscopy.

This enabled him and his team to analyse the dissolution and precipitation of lithium sulphide with extreme precision during ten discharge/charging cycles. Since neutrons interact strongly with deuterium (heavy hydrogen), the researchers used a deuterated electrolyte in the battery cell to make both the solid products (sulphur and lithium sulphide) visible.

Their conclusion: "We observed that the lithium sulphide and sulphur precipitation does not take place inside the microporous carbon electrodes, but instead on the outer surface of the carbon fibres," says Risse. These results provide a valuable guide for the development of better battery electrodes.


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Materials provided by Helmholtz-Zentrum Berlin für Materialien und Energie. Note: Content may be edited for style and length.


Journal Reference:

  1. Sebastian Risse, Eneli Härk, Ben Kent, Matthias Ballauff. Operando Analysis of a Lithium/Sulfur Battery by Small-Angle Neutron Scattering. ACS Nano, 2019; DOI: 10.1021/acsnano.9b03453

Cite This Page:

Helmholtz-Zentrum Berlin für Materialien und Energie. "Nanoparticles in lithium-sulphur batteries detected with neutron experiment." ScienceDaily. ScienceDaily, 6 September 2019. <www.sciencedaily.com/releases/2019/09/190906092806.htm>.
Helmholtz-Zentrum Berlin für Materialien und Energie. (2019, September 6). Nanoparticles in lithium-sulphur batteries detected with neutron experiment. ScienceDaily. Retrieved October 31, 2024 from www.sciencedaily.com/releases/2019/09/190906092806.htm
Helmholtz-Zentrum Berlin für Materialien und Energie. "Nanoparticles in lithium-sulphur batteries detected with neutron experiment." ScienceDaily. www.sciencedaily.com/releases/2019/09/190906092806.htm (accessed October 31, 2024).

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