| Metal-air batteries have attracted the attention due to their higher theoretical capacity and environment friendly compared to state-of-art Li-ion batteries.The Li-O2 battery has received the most attention because of its unique theoretical energy density compared to other rechargeable batteries.To date,the Li-O2 battery suffers from low practical specific capacity,poor cycling life and low energy efficiency,which severely limits its practical application.The electrochemical performance of Li-O2 battery is mainly dependent on the structure and catalytic activity of air cathode.Therefore,it is necessary to study the high performance cathodes for Li-O2 batteries,and further understanding the electrode structure and reaction mechanism of high-efficiency cathodes.Three-dimensional integrated wood-based cathode and kapok-based cathode with mesoporous structure for Li-O2 batteries were prepared.These two kinds of cathodes show excellent performance.The wood-based cathode has renewability,outstand cycling stability.And the kapok-based cathode possesses good flexibility.The major studies are summarized as followings:?1?A renewable wood-derived cathode with functionalized channels array for high-performance Li-O2 batteries is developed.The renewable cathode is obtained from natural wood after carbonization,activation and loading RuO2 nanoparticles.The specific area capacity of the assembled battery exceeds 8 mAh cm-2.And the energy efficiency is over 87.1%after100 cycles.Furthermore,the cathode can be fully regenerated.The structure of cathode and anchored catalyst after 300 cycles is almost unchanged compared with the initial according to the SEM images and TEM images.It indicate that a high stability and catalytic activity cathode can be reused.And we have explored the effect of cathode thickness,N doping and oxygen flow on the performance of Li-O2 batteries.The results show that the increase in cathode thickness does not decay the volume specific capacity,N doped and keep O2 flowing(only with a flow rate 20 m L min-1)can significantly improve performance of Li-O2 batteries.?2?An integrated ultra-high flexible electrode based on hollow kapok fibers is developed.The flexible electrode has the characteristics of low density,adjustable thickness,good mechanical strength and bendable folding of 180°.The intefrated flexible electrode is directly applied as a three-dimensional integrated flexible cathode to Li-O2 battery,and the specific capacity reached 5193 m Ah g-1 at a current density of 128 mA g-1?calculated by air electrode mass?.The kapok derived flexible electrode has three-dimensional integrated structure,hollow micron-sized channel,and abundant mesoporous structure on the channel wall,which achieve the rapid supply and effective use of reactants. |
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