Our Research
Our group focuses on beyond-lithium battery chemistries and materials. The PI has >10-year reserach experience in beyong-lithium batteries.
Intercalation chemistry of electrode materials
Beyond-Li batteries such as Na-ion, K-ion and Ca-ion batteries hold the advantages of cost-effectiveness and environmental sustainability, but they face challenges, particularly around the large ion sizes, in terms of developing electrochemical performance. This requires the introduction of new intercalation materials to accommodate large-sized ions and allow facile ion diffusion, as well as the understanding of ion intercalation chemistry. Our group is interested in discovering new intercalation materials for Na-ion, K-ion and Ca-ion batteries and probing the intercalation reactions and structure/phase change in these materials. In recent years we have developed special interest in mixed ion battery systems, where more than one ion species is present in the batteries and ion intercalation mechanism is strongly dependent on the interactions between the intercalation host structure and the two or more ion species in the battery.
Electrodeposition of metal anodes
Na and K metal anode batteries are another family of emerging beyond-Li batteries. The use of Na and K metals as the anode to replace graphite in a conventional Li-ion battery largely increases the capacity of the battery and at the same time, moves away from Li due to the concerns around the environmental impact and materials sustainability of Li and Co precursors. The key to successfully delivering Na and K metal anode batteries is to achieve stable Na and K electrodeposition and in another word, stable plating and stripping processes. The group is particularly interested in achieving this through functionalizing battery separator and modifying anode current collector. Our approaches make use of the interaction between Na-ion/K-ion, functional groups, and integrated compounds to regulate Na/K nucleation sites, redistribute Na-ion/K-ion flux, and supress Na/K dendrite growth. Also, our approaches do not involve handling Na and K metals and can be scalable.
Ion storage mechansim of conversion cathodes
Understanding the mechanism of storing ions in electrode materials lies at the heart of battery research. This is particularly crucial for investigating emerging beyond-Li batteries, as variations on ion size and charge density may trigger unexpected electrochemical processes during ion storage, i.e., new mechanisms. Studies have shown that beyond-Li systems are not Li analogues that need updating, but rather systems that are fundamentally different in many aspects. The group is interested in investigating the electrochemical process to store Na-ion/K-ion in conversion materials, particularly chalcogens (S and Se for Na/K-S/Se batteries) and metal chalcogenides (sulfides and selenides for Na-ion and K-ion batteries). We employ a range of ex-situ and in-situ characterization techniques to probe the structural and phase change of the conversion materials during ion insertion and corelate characterization results to electrochemical performance. This allows us to improve material and electrode designs as well as battery testing protocols.
Xu Research Group 