With a promising combination of cathode and electrolyte, researchers at HIU want to make very high energy density possible.

Battery Research New lithium metal battery: extremely high energy density with remarkably good stability

Editor: Alexander Stark

The researchers used a promising combination of a cathode and an electrolyte to increase the energy density and stability of lithium-metal batteries. The resulting battery achieves standard values.

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With a promising combination of cathode and electrolyte, researchers at HIU want to make very high energy density possible.

(Photo: Amadeus Bramsiepe, KIT)

Karlsruhe – Lithium-ion batteries are currently the most popular mobile power supply solution, but the technology is reaching its limits with some requirements. This is especially true of electric mobility, where light and compact vehicles with long distances are in demand. Lithium-metal batteries are an alternative: they have a high energy density, which means they store a lot of energy per mass or volume. But their stability is a challenge—because the electrode materials interact with common electrolyte systems.

Researchers at the Karlsruhe Institute of Technology (KIT) and the Helmholtz-Institut Ulm – Electrochemical Energy Storage (HIU) have now found a solution. While you’re reporting in Joule magazine, you’re using a new and promising set of material. They use a low-cobalt-rich nickel-rich layer cathode (NCM88). This provides a high energy density. With the commonly used commercially available organic electrolyte (LP30), the stability leaves much to be desired.

With the liquid ionic electrolyte ILE (right), the structural changes in the NCM88 nickel-rich cathode can be largely avoided;  88% of the battery capacity is retained for more than 1,000 charge cycles.
With the liquid ionic electrolyte ILE (right), the structural changes in the NCM88 nickel-rich cathode can be largely avoided; 88% of the battery capacity is retained for more than 1,000 charge cycles.

(Photo: Fanglin Wu and Dr. Matthias Konzel, KIT/HIU)

Storage capacity decreases as the number of charge cycles increases. Professor Stefano Passerini, HIU Director and Head of the Battery Electrochemistry Research Group, explains why: “In the LP30 electrolyte, particulate cracks occur on the cathode. The electrolyte reacts within these cracks and destroys the structure. In addition, a thick, alga-like lithium-containing layer forms on the cathode”. So the researchers used a non-volatile, non-flammable liquid ionic with anionic (ILE) instead. Dr. says. Guk-Tae Kim of HIU’s Battery Electrochemistry Research Group.

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88% of capacity is retained for more than 1000 charge cycles

Results: Using the NCM88 cathode and the ILE electrolyte, the lithium-metal battery achieves an energy density of 560 Watt-hours per kilogram (Wh/kg). Its storage capacity is initially 214 mA per gram (mA/g); 88 percent of capacity is retained over 1,000 charge cycles. The Coulomb efficiency, which refers to the ratio between the drawn capacity and the supplied capacity, is on average 99.94%. Since the displayed battery also has a high level of safety, researchers from Karlsruhe and Ulm have taken an important step on the path to carbon-neutral mobility.

Original publication: Fanglin Wu, Shan Fang, Matthias Kuenzel, Angelo Mullaliu, Jae-Kwang Kim, Xinpei Gao, Thomas Diemant, Guk-Tae Kim, Stefano Passerini: The double anion liquid electrolyte enables nickel-rich cathodes in lithium-metal batteries. Joules. Cell Press, 2021. DOI: 10.1016 / j.joule.2021.06.014

(ID: 47576438)

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