1. Design and preparation of spinel oxide nanomaterials for energy storage application

Spinels with the formula of AB2O4 (where A and B are metal ions) and the properties of catalysis have taken significant roles in applications of energy storage/conversion. In our group, various spinels with controlled preparations and their applications in oxygen reduction/evolution reaction (ORR/OER) and batteries are realized. The physico-chemical characteristics of spinels such as their compositions, structures, morphologies, defects and substrates have been rationally regulated through various approaches. This regulation can yield spinels with improved ORR/OER catalytic activities, which can further accelerate the speed, prolong the life and narrow the polarization of fuel cells, metal–air batteries and water splitting devices. The future applications of spinels are considered to be closely related to environmental and energy issues, which will be aided by the development of new species with precise preparations and advanced characterizations.

2. Develop High Performance Lithium Battery Cathode Materials

Nickel-rich layered and Li-rich Mn-based transition metal oxides are attractive cathode materials for rechargeable lithium-ion batteries to build next-generation lithium-ion batteries with high energy density exceeding 400 W h kg−1. However, these two kinds of cathodes are suffer from inherent structural and thermal instabilities, besides, lack of in-depth understanding of oxygen redox chemistry that limit the deliverable capacity and cycling performance. Our group has explored various strategies including the synthesis method, doping and coating strategy to improve the cyclic stability and rate capability.

3. Develop High Performance Quinone Compounds Organic Electrode Cathode Materials

Organic materials have attracted much attention for their utility as lithium-battery electrodes because their tunable structures can be sustainably prepared from abundant precursors in an environmentally friendly manner. Nevertheless, the electronic conductivities of organic electrode materials are usually poor, which leads to inferior power density and the requirement of large amounts of conductive carbon additives. This poor conductivity also limits the active material mass loading one can use and lowers the energy density. The densities of reported organic electrode materials are typically low (1–2 g cm−3), which leads not only to low volumetric energy density but also to limited mass loading and a requirement for greater amounts of battery accessory materials. Our group hope to stimulate high-quality applied research that might see the future commercialization of organic electrode materials.

4. Designing and exploitation of solid-state electrolyte

Developing solid-state electrolyte (SSE) for batteries is an effective way to solve safety issues. However, how to develop high-performance SSE and compatible interface for constructing solid-state sodium batteries is still challenging. In our group, we mainly focus on developing advanced SSE and interface engineering for Li/Na-ion batteries. The structure-property correlations and design principles of different inorganic and organic SSE are discussed in depth. The comprehensive performance of SSE depends on the structural characteristics such as defects, crystallinity, and stability of bonds. The design principles mainly include increasing the density of mobile Li+ or Na+, reducing the energy barrier, immobilizing anions, adjusting the stability of bonds, adding specific buffer layers, and increasing interfacial contact area. We hope to provide fundamental insights and future perspectives to design advanced SSE and concomitant interface for next-generation rechargeable solid-state batteries.