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Electrode Concept Formulation Diagram
and Image of Electron Microscope

The electrode structure of a conventional all-solid-state secondary cell consists of a solid electrolyte responsible for ionic conduction, a conductive additive that provides the means for electron conduction; active material responsible for storing energy; and a binder that holds these constituent parts physically and chemically.

ETRI researchers discovered through systematic experiments, however, that ions are transported even between graphite active material particles. And they proposed a new type of electrode structure for all-solid-state secondary cell consisting of only the active material and the binder. The researchers confirmed the possibility that even without a solid electrolyte additive within the electrodes, the performance of an all-solid-state secondary cell could be superior.

The theoretical feasibility of the novel structure proposed by ETRI was verified at DGIST through electrochemical testing (using a supercomputer) of a virtual model. ETRI researchers succeeded in demonstrating this structure in an actual experiment. ETRI named this technology 'diffusion-dependent all-solid-state electrode' and submitted a paper to an international journal.

If ETRI’s technology is adopted, solid conduction additive material will become unnecessary in the electrode; instead, the more active material can be squeezed into the same volume. In other words, the amount of active material in the electrode can be increased by up to 98wt% and as a result, the energy density can be made 1.5 times greater than the conventional graphite composite electrode.

The technology offers advantages in manufacturing process aspects as well. Sulfide-type solid electrolytes, which have high ion conductivity and moderate plasticity, are regarded as an excellent candidate for the fabrication of all-solid-state batteries. But due to its high chemical reactivity, the sulfide-type solid electrolytes leave battery developers with very few options when it comes to solvents and binders. In contrast, with the new ETRI electrode, developers can freely select the type of solvent and binder to use in the battery because the electrode contains no solid electrolytes that are highly reactive. This also permits researchers to pursue new approaches for improving the performance of all-solid-state secondary cells.

Dr. Young-Gi Lee, who was involved in this research, said, “We have revealed for the first time that ions can be diffused just with active materials. We are no longer bound to the structure used in existing all-solid-state secondary cells. We plan to develop secondary cells with even high energy densities, using this technology. We will also secure our rights to the core technology and work on a version that could be commercialized.”

Although ETRI conducted its research using graphite cathode active material, it intends to continue its research based on the same concept, using various other electrode materials. It is also planning to enhance the technology in order to increase efficiency. This can be accomplished by eliminating the interfacial issues among electrodes and thinning the volume of electrodes.

This research was carried jointly with Prof. Yong Min Lee and his team from DGIST under the auspices of ETRI. The first authors of the paper are Dr. Ju Young Kim of ETRI and Dr. Joonam Park of DGIST. The corresponding authors of the paper are Dr. Ju Young Kim of ETRI and Prof. Yong Min Lee of DGIST, and the research was funded by the Ministry of Science and ICT as part of the Climate Change Response Technology Development Project (National Research Foundation of Korea).

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Examining ion diffusion-based solid
electrodes, an ETRI invention.

03

Examining (dis)charge systemic ion
diffusion-based solid electrodes,
an ETRI invention.

The AI chip of ETRI can be used for performance power, remote healthcare, finance and banking, and face/behavior recognition as well as AI speakers and autonomous vehicles. It will also be of great help in localizing product components with deep learning and creating additional values.

ETRI aims to develop a chip capable of simultaneous learning and inference. The current AI uses simple inferences to answer a plain question such as “What will today’s weather be like?” Nonetheless, ETRI plans to advance the inference capability to the level of relating the climate change issue to the current weather and making the relevant arguments.