PhD Thesis Presentation
Li-ion batteries (LIBs) have been widely used since its first production by Sony in 1991 due to their high energy density. However, the ever-growing demand of energy market calls for higher requirements for batteries, such as low cost, high safety, and even higher energy density. Therefore, many post Li-ion technologies have been studied to replace LIBs with special purposes of reducing the cost, enhancing the safety, and improving the energy density.
Na-ion batteries (NIBs) are considered as cost-effective alternatives to LIBs, while the safety issue remains a problem for conventional NIBs due to the existence of organic liquid electrolytes. An effective solution to this safety issue is to replace hazardous liquid-state electrolytes with solid-state electrolytes (SSEs) that are non-flammable. However, major problems regarding SSEs, such as low ionic conductivity and poor interfaces, should be carefully addressed.
Metal-air battery is also regarded as a promising post Li-ion technology because of its higher energy density as compared to LIBs. However, the commercialization of metal-air battery is greatly hindered by the sluggish kinetics and poor reversibility of the oxygen reactions at the cathodes. Therefore, efficient and bifunctional oxygen catalysts are in urgent demand.
This thesis has two parts. In the first part, we focus on addressing the major problems of SSEs for NIBs. We fabricated composite-polymer-electrolytes (CPEs) with PVDF framework and NASICON-type ceramic fillers and investigated the physical properties and electrochemical performance of CPEs. We also modified the CPEs to achieve improved interfaces and better compatibility with electrodes. In the second part, we developed a series of efficient oxygen catalysts with manganese oxides with a rock-salt or perovskite structure. Special attention is given to enhance the activity as well as activate the bifunctionality of magnates towards both OER and ORR.
(Supervisor: Prof. Francesco Ciucci)