Preparation And Properties Investigation Of Biomass Derived Carbon Materials As Cathode Of Li-O₂ Batteries

New energy is one of the focuses of the current world.Affected by the terrible environment and other factors,all countries in the world urgently need a new type of clean energy to replace the fossil fuels.The content of lithium in our country is rich,the country advocates lithium battery related research and development of new energy batteries.The widely used lithium-ion battery,for its lower theoretical energy density,can not meet people's needs.Lithium-air batteries have a very high theoretical energy density?11400wh/kg?,which close to the energy density of gasoline?13200wh/kg?,is expected to become a new generation of energy which replace lithium-ion battery.At present,the research on lithium-air battery is still at a relatively early stage,and the diffusion of O₂ at the air electrode?cathode?is slow.At the same time,many reactions which are not wanted occur during charging and discharging of the batteries.Some problems?such as excessive charge-discharge over-voltage and so on?all make the battery far from being able to reach the theoretical energy density,at the same time cycle performance can not meet the practical needs either.In this paper,a simple method was descripted,which is using silkworm cocoon?SCC?as raw material,to obtain a three-dimensional self-supporting cathode material through a simple carbonization process.We then applied this material to assemble a lithium-air battery and our material makes it a higher specific capacity with an excellent cycle performance.And then through the N element doping,we successfully improved the catalytic activity of our material on the ORR/OER,with reducing the over-voltage of charging-discharging,and improving the cycle performance.Finally,a further supported metal oxide was used as a catalyst which was grown on our material to make the Li-O₂ battery and then the battery performance was also tested.The specific research contents are as follows:?1?Porous cathode electrode material?SCC?with 3D self-supporting structure was obtained by carbonization treatment using silkworm cocoons as raw material after washing,flattening and shearing.?2?The SCC is treated at high temperature in Ar gas,and the N element is doped by heating in Ammonia atmospheres.At the same time,the SCC has a higher specific surface area and a higher catalytic activity.The material is marked as SCC-N.We made batteries with SCC-N,and then tested the battery performance.?3?Metal oxides?cobalt and nickel elemental oxides?were loaded on the SCC and N respectively.Hydrothermal method was used to grow them directly onto the support?SCC and SCC-N?.The biomass-derived carbon material with the metal oxide catalyst which were grew on was used as a battery cathode material,a battery was fabricated and the related properties were tested.After nickel,cobalt ratio adjustment,and hydrothermal precursor solution concentration adjustment,the final determination of the best effect of Ni Co O_x.