The Research Of Lithium Metal Battery Based On Biomass Derived Carbon Materials

Lithium metal batteries have attracted great attention because of their high energy density.As for the anode material lithium metal,the uneven deposition of lithium will cause dendrites,resulting in poor cycling performance and safety problems.As for cathode materials,sulfur cathode can react without catalysis.It makes Li-S battery is the most promising lithium metal battery system which can be commercialized.However,there are some problems such as nonconductivity of sulfur and discharge products,volume change and shuttle effect of polysulfide.Aiming at the above problems,corresponding research works have been carried on this paper and the details are as follows:1.We utilizing the three-dimensional skeleton structure of the natural wood,firstly loading the silver nanoparticles on the channel of wood.Then we deposited enough lithium metal in it by means of electrochemical deposition and finally designed dendrite-free Li composite anode even after long cycle test.The composite anode uses the complete and well-arranged pore channels retained by natural wood materials as the skeleton,and there is enough space for lithium deposition,which can greatly reduce the volume change of lithium anode during the cycle.At the same time,silver nanoparticles are used as seeds to induce lithium deposition due to their lipophilicity,which can help lithium deposit uniformly in the pore channels of carbon skeleton,thus avoiding the formation of lithium dendrites.The half-cell test shows the composite anode can stably work over 450 h and 300 h at a current density of 1 mA cm^-2 and 3mA cm^-2 respectively.LFP full cell tests reveal that the Ag-WDC battery have a steady work time over 400 h.These results show that silver nanoparticles can effectively promote the deposition/stripping process of lithium and reduce the occurrence of side reactions.Moreover,this composite structure based on carbon wood can be an excellent host of lithium metal and realize the protection of lithium metal anode.2.To solve the problem of sulfur cathode,we designed a nitrogen doped sulfur cathode material?N-KF-S?,the kapok fiber,which have a hollow structure and can reach a high capacity of sulfur.This hollow structure can realize the high load of sulfur and avoid the cathode volume change during the cycle.Moreover,the attraction of nitrogen to the polysulfide can inhibit the shuttle effect.TG analysis showed that the amount of N-KF-S sulfur was 83.81%,while the amount of C-KF-S was 78.61%.Further electrochemical tests showed that the electrochemical performance of N-KF-S was better than that of undoped C-KF-S.