For effective use of renewable energy it must be coupled to energy storage devices with high efficiencies. One such technology is a battery, where the stored chemical energy can be converted into the electrical energy through the electrochemical reactions. We started the Li battery studies since 2002. Currently, our research covers the Li-ion batteries, Li-S batteries, Li-O₂ batteries, and all-solid-state batteries. Here, I will present some results relating to the electrode materials, electrolyte, and electrode achitectures in our group.

We reported the Li-ion battery based on LiFePO₄ cathode_, which exhibits a good cyclability of 5,000 cycles and a considerable capacity retation of 90 % at -40℃. This novel type battery has been industied and applied for electric vehicles in the low temperature region. The NMC ternary battery and high-voltage battery based on LiNi_0.5Mn_1.5O₂ are also introduced. Besides the cathode, some promising results relating to the anode part will be also introduced, including the graphene and VPO₄/rGO. For Li-S battery, we firstly present a novel cathode of Mo₂C nanorods-S composite, which exhibits a much lower capacity decay of 0.058 % per cycle at 2 C over 500 cycles. Additionally, the carbon-based separator decorated by red phsphorus nanoparticles for Li-S battery will be also introduced, which displays a good rate performance and a considerable cyclability of 500 cycles with 730 mAh/g. For Li-O₂ battery, we reported the yolk-shell Co₂CrO₄ nanospheres as highly active catalysts. Based on the experimental results and DFT calculations, a direct evidence of Co₂CrO₄ employment being linked to the Li₂O₂ morphology was firstly provided and a catalytic mechanism was proposed. In addition, a 3D foam-like composite composing of Mo₂C nanorods decorated by different amount of N-doped carbon was directly employed as the O₂ electrode without applications of any binder and current collector. The fundamental information about the key factors and steps involved in the Li₂O₂ formation and decomposition was revealed. We will also introduce a flexible, self-standing, and binder-free O₂ electrode by growing the flower-like MoS₂ microspheres with sulfur deficiencies onto the CTs (Def-MoS₂@CTs). Futhermore, I will introduce a novel electrolyte of a binary mixtures of highly concentrated tetraglyme electrolyte (HCG4) and 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether (TTE) for the Li-O₂ battery, which exhibits good wettability, enhanced ionic conductivity, considerable non-flammability, and high electrochemical stability. For all-solid-state battery, we will introduce a solid polyer electrolyte based on poly(ethylene oxide), which shows a superior electrochemical property with a decent lithium transference number of 0.35, a wide electrochemical stability window above 5 V vs. Li⁺/Li, and a low interfacial resistance. In addition, a triblock copolymer polystyrene-poly (ethylene glycol)-polystyrene (PS-PEG-PS) as the polymer electrolyte for all-solid-state battery will be also introduced, which displays a highly electrochemical stability and a considerable cyclability. Besides some fundermental results, I would like to introduce some industry-level developments in our pilot-line of batteries, because we cooperated with some enterprises of electric vehicles in China since 2009.

I would like to apply an oral presentation if possible. Thanks for your consideration.