Chemicals | Lovis 2000 M/ME: Low Temperature Viscosity Measurements for Battery Electrolytes

Perform viscosity measurements down to -20 °C with Lovis 2000 M/ME with cooling option. Test even highly corrosive solvents for ion salts by using unbreakable PCTFE capillaries with small filling volumes (110 μL or 450 μL). Handling of the sample inside a glove box filled with inert gas and a hermetically closed system prevent contamination or evaporation of the sample.

Since the introduction of the lithium-ion batteries in 1990, the interest in this technology has emerged steadily, not only for portable devices but also for the automotive industry. Their high energy density as well as outstanding cycle stability are the main reasons for commercial success, but several problems arise with the usage of the most common non-aqueous electrolytes, which contain lithiumhexafluoro-phosphate (LiPF6) as conductive salt and a mixture of cyclic and non-cyclic organic carbonates.

In addition to the high purity required of all used solvents (e.g. traces of protic impurities such as water can cause severe deterioration of the cell performance after a short life / cycle time) the cell performance has to be stable over a broad temperature range from arctic to tropical conditions without any significant degradation. Therefore, an exact characterization of newly developed electrolytes at different temperatures is an essential part in the lithium-ion cell research today.

These challenges have to be considered for all other upcoming battery systems like magnesium ion cells or sulfur cells, too.
Therefore, research companies use different standard electrochemical measurements for monitoring batteries. In this connection viscosity, conductivity and – if required – density measurements of the electrolytes support those investigations. The performance of the charge and discharge rate of a rechargeable battery, that is the ion transport, is characterized by the ion conductivity, which depends on the viscosity and the dielectric constant.

This application report shows how the Lovis can be used for electrolyte measurements even at temperatures below zero. The Lovis, equipped with cooling option and in combination with the capillary made of PCTFE, enables measurement of highly corrosive substances over a wide temperature range.

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