Materials for Sustainability

  Thin-film batteries(TFBs) are not only highly safe, but their properties, including low self discharge, long cycle life, and flexibility, makes them suitable for a variety of applications, such as in flexible electronics, wearable devices, internet of things, and other small devices. Aside from ensuring the low cost and suitability for large-area solution processing of TFBs, the reduction of their processing temperature has remained as a significant challenge for their application in next generation flexible electronic applications on thermally labile substrates. Also, we are investigating oxide-based solid-state electrolyte, such as LIPON, LATP, and LLZO by using novel sol-gel synthesis. After the ionic conductivity and pure phase of the oxide thin film are confirmed, a coating layer can be applied to cathode materials such as LNMO, LCO, and NCM811 for improvement of cycle stability and discharge capacity of the Li-ion rechargeable batteries. 

1. Magnetocaloric Materials

Currently, refrigeration/freezing and air-conditioning account for approximately 20% of global electricity consumption, and it is predicted that these systems could triple their current electricity consumption by 2050 if the energy efficiency of these systems is not improved or new technologies are not introduced. And, a major problem of the vapor compression technology currently applied to these systems is that the gaseous refrigerant used accounts for approximately 10% of global greenhouse gas emissions and is therefore environmentally unfriendly. Therefore, as an ultimate alternative to the vapor compression technology, a caloric refrigeration/heat pumping technology using an environmentally friendly solid refrigerant has been in the limelight. These solid-state cooling technologies utilize magnetocaloric, electrocaloric, mechanocaloric, and multicaloric effects that combine these effects. Therefore, in order to develop low-cost and environmentally friendly transition metal-based magnetocaloric materials, we will find (or optimize) magnetic cooling materials based on machine learning and first-principles calculation, and we would like to synthesize the materials proposed by the theoretical prediction and characterize their physical properties.

2. Thermomagnetic Materials

Waste heat generated from various industrial and chemical processes accounts for approximately 72% of all electrical energy produced as of 2016, and their thermal energy is near room temperature, but it is difficult to convert this room temperature thermal energy into electrical energy. The available technologies are extremely limited. Thus, a technology for generating power from waste heat is increasingly attracting attention as a way to replace fossil fuels, so there is a strong need for energy materials and devices that convert low-grade waste heat into electricity. Magnetic materials are promising in this category of energy materials, especially magnetocaloric materials, which are applicable for applications that convert magnetic energy into thermal energy, and extensive research on these materials enables energy-efficient cooling. Considerable advances in these magnetocaloric materials offer the possibility of thermomagnetic generation (TMG), a reverse process that converts thermal energy into electrical energy. Therefore, in our group, a high-performance low-cost room temperature thermomagnetic material (TMM) for a high-efficiency thermomagnetic generator (TMG) for low-grade waste heat energy harvesting will be theoretically designed, synthesized, and characterized.