Plenary talk — Development of innovative electrochemical energy and conversion devices

Abstract

Summary form only given. The development of long-length, high current density Bi2Sr2CaCu2Ox wires and (RE)Ba2Cu3Oy coated conductors has now advanced New environmental regulations and oil crisis have induced the urgent adoption of electric vehicles and renewable energies. This will bring immense social and environmental benefits to the society, including reduced CO2 emissions, increased energy independence and energy security, and improved efficiency of transport. In this talk, I will report our research on electrode materials for lithium ion batteries, lithium-air batteries, lithium sulfur batteries and sodium ion batteries.A highly ordered mesoporous LiFePO4/C nanocomposite has been developed, in which LiFePO4 nanoparticles are embedded in conductive and interconnected carbon networks. This mesoporous nanoarchitecture ensures not only intimate contact between liquid electrolyte and active LiFePO4 nanoparticles, but also high electronic conductivity for both facile mass transfer and facile charge transfer. At the low current rate, mesoporous LiFePO4/C nanocomposite cathodes delivered a near theoretical capacity with ultrahigh coulombic efficiency and capacity retention. At high current rate, the cell also exhibited a satisfactory specific capacity with an excellent cyclability. Through material architecture design, LiFePO4 cathode material can meet the stringent requirements for high power applications such as electric vehicles and energy storage for smart grids. [1] Facet crystals with exposed highly reactive planes have attracted intensive investigations for applications such as hydrogen production, enhanced catalytic activity, and electrochemical energy storage and conversion. Herein, we report the synthesis of mesoporous NiO crystals with dominantly exposed {110} reactive facets by the thermal conversion of hexagonal Ni(OH)2 nanoplatelets. When applied as anode materials in lithium-ion batteries, mesoporous facet NiO crystals exhibit a high reversible lithium storage capacity of 700 mAh g-1 at 1 C rate in 100 cycles and an excellent cyclability. In particular, the dominantly exposed {110} reactive facets of NiO crystals lead to ultrafast lithium storage, which mimics the high power delivery of supercapacitors. [2] The synthesis of an effective cathode catalyst of ruthenium nanocrystals has been achieved by a surfactant assisting method. The as-prepared ruthenium nanocrystals exhibited an excellent catalytic activity as cathodes in Li-O2 batteries with a high reversible capacity of about 9,800 mAh g-1, a low charge-discharge over-potential (about 0.37 V), and an outstanding cycle performance up to 150 cycles (with a curtailing capacity of 1,000 mAh g-1). The electrochemical testing shows that ruthenium nanocrystals can significantly reduce the charge potential comparing to carbon black catalysts, which demonstrated that ruthenium based nanomaterials could be effective cathode catalysts for high performance lithium-O2 batteries.