KJ Ceramics 31

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Detailed Program

Paper Number : CO-I01

Time Frame : 16;30~16:55

Presentation Date : Friday, 28, November

Session Name : Computational Ceramic Science and Engineering

Session Chair 1# : Seungwu Han

Session Chair 2# : Nakeshi Nishimatsu

Multi-scale computational design of active components for Li-ion batteries

Byungchan Han

DGIST

With advanced computing power and soft engineering first principles computation opened new areas for discovering new materials. If combined with rigorous statistical mechanics this approach becomes even more powerful tool, in particular, for screening promising candidates from wide range of sampling space. This presentation shows two such examples regarding energy materials: solid-state electrolyte and high energy density cathode for Li-ion battery application.

Fundamental diffusion mechanisms of Li-ion in the solid-state NASICON structures were studied using first principles density functional theory (DFT) calculations and validated with experimental measurements. For two materials without (Li1.0Ge2.0(PO4)3, LGP) and with (Li1.5Al0.5Ge1.5(PO4)3, LAGP) an Al3+-doped materials to (LGP), thermodynamically the most plausible diffusion path and the activation energy along the way were rigorously evaluated. Based on the calculated results we propose that aliovalent doping can significantly enhance Li-ion conductivity as high as 100 times depending on the doing level. More interestingly, we discovered that the doped Al3+ ions create new diffusion path that allows at least two Li-ions cooperatively interact to transport together at the same time with substantially reduced activation barriers compared with other paths. We validated the calculated Li-ion conductivities in the two solid-state materials by experimental measurements ending up with good agreement with the prediction.

As the second example, we studied the electrochemical and thermal stabilities of high-Ni compounds for cathode materials for Li-ion batteries. It was known that incorporating high Ni composition improves energy densities, however, only by scarifying structural integrity. Our studies unveil the underlying mechanisms of the degradation on atomic scale, and propose methodologies ensuring those two materials properties: high energy density and cyclability with a high voltage window.

This presentation sorts out key atomic descriptors in designing energy materials leading to high functionality for engineering-scale systems.

Figure 3. Diffusion paths of Li ions in solid-state LGP and LAGP electrolytes.

Acknowledgements :

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