Researchers are developing fast-charging solid-state batteries

Researchers are developing fast-charging solid-state batteries
Test set-up for the solid-state battery: the battery of the size of a button cell is located in the middle of the acrylic glass casing, which ensures permanent contact with the battery. Credit: Forschungszentrum Jülich / Regine Panknin

Solid-state batteries are currently associated with great hopes. They contain no liquid parts that could leak or catch fire. For this reason, they are insensitive to heat and are considered much safer, more reliable and longer lasting than conventional lithium-ion batteries. Jülich scientists have now presented a new concept, which allows ten times greater currents during loading and unloading than previously described in the literature. The improvement they achieved by a “smart” choice of materials. The focus was on consistently good passability. All components were made from phosphate compounds that match chemically and mechanically very well.

The low current is considered one of the sticking points in the development of solid-state batteries. It causes the batteries to take a relatively long time to charge. It usually takes about 10 to 12 hours for a solid-state battery to be full again. By contrast, the new cell type that Jülich scientists have designed takes less than an hour to recharge.

“With the concepts described so far, only very small charge and discharge currents were possible, which can be traced back to problems at the internal solid-state interfaces. This is where our concept, which is based on a favorable combination of materials and which we have already patented, starts “explains Dr. Hermann Tempel, working group leader at the Jülich Institute for Energy and Climate Research (IEK-9).

In conventional lithium-ion batteries, a liquid electrolyte is used, which usually contacts the electrodes very well. With their textured surface, the electrodes absorb the fluid like a sponge, creating a large contact area. In principle, two solids cannot be joined together so completely. The contact resistance between the electrodes and the electrolyte is correspondingly higher.

“In order to allow the largest possible flow of current across the layer boundaries, we have built all the components from very similar materials: anode, cathode, and electrolyte were all made of different phosphate compounds, the charging rates of over 3C (with a capacity of about 50 mAh / g), which is ten times higher than the values otherwise found in specialist literature, “explains Hermann Tempel.

As a stable carrier material is a solid electrolyte to which the phosphate electrodes are applied on both sides by the screen printing process. The materials used are reasonably priced and relatively easy to process. Unlike conventional lithium-ion batteries, the new solid-state battery is also largely free of toxic or harmful substances.

“In initial tests, the new battery cell was fairly stable over 500 charge and discharge cycles and still had over 84 percent of its original capacity,” Dr. Shicheng Yu. Theoretically, even a loss of less than one percent should be feasible, “said Shicheng Yu, who used the battery as part of a funding program of the China Scholarship Council (CSC) at the Jülich Institute for Energy and Climate Research (IEK-9 ) has developed and tested.

Institute Director Prof. Rüdiger-A. Eichel is also convinced of the advantages of the new battery concept. “The energy density is currently very high at around 120 milliamp hours per gram (mAh / g), even though it is still slightly below that of today’s lithium-ion batteries,” explains Eichel. In addition to the development of electromobility, the spokesman for the Helmholtz Association’s “Batteriespeicher” topic also sees future application areas for solid-state batteries in other areas: “Solid-state batteries are currently being developed at high pressure as energy stores for second-generation electric vehicles, but we believe that solid-state batteries will do so In addition, in other fields of application will prevail, where it depends on long service life and safe operation,

Prof. Rüdiger Eichel, director of the IEK-9 at Forschungszentrum Jülich and spokesman for the Topics “Battery Storage” of the Helmholtz Association, with a model of the solid-state electrolyte.

Original publication: Shicheng Yu, Andreas Mertens, Hermann Tempel, Roland Schierholz, Hans Kungl, and Rüdiger-A. Acorn
Monolithic All-Phosphate Solid-State Lithium-Ion Battery with Improved Interfacial Compatibility
ACS Appl. Mater. Interfaces (published online June 12, 2018), DOI: 10.1021 / acsami.8b05902

Additional Information:
Institute of Energy and Climate Research, Foundations of Electrochemistry (IEK-9)

Contact Person:
Prof. Dr. Rüdiger-A. Eichel
Head of the Institute of Energy and Climate Research, Fundamentals of Electrochemistry (IEK-9)
Tel .: +49 2461 61-5124

Dr. Hermann Tempel
Institute for Energy and Climate Research, Fundamentals of Electrochemistry (IEK-9)
Tel .: +49 2461 61-96570

Dr. Shicheng Yu
Institute for Energy and Climate Research, Foundations of Electrochemistry (IEK-9)
Tel .: +49 2461 61-96894

Press contact:
Dr. Regine Panknin
Corporate Communications
Tel .: +49 2461 61-9054

Tobias Schlößer
Corporate Communications
Tel .: +49 2461 61-4771

Source: Researchers are developing fast-charging solid-state batteries

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