The Preparation And Application Of Novel Carbon Nanomaterial For Lithium-ion And Lithium-sulfur Battery

Lithium-ion battery and lithium-sulfur battery(Li-S)are two kinds of typical representative of rechargeable lithium battery.Lithium ion battery has been extensively utilized in portable equipment for its high capacity,portability and environmental friendly.With high specific capacity/energy density,low cost and environment benign,the lithium sulfur battery has been regarded as one of the most promising rechargeable batteries.While most of commercialized lithium ion battery with low specific capacity cannot satisfy demand.And the poor cyclability and rate performance restrict the practical application of Li-S battery.Therefore,it is of great importance to improve the specific capacity of lithium anode and cycle stability of Li-S battery.In this paper,we apply graphene into the preparation of the lithium-ion anode and lithium-sulfur cathode to improve the discharge capacity.In addition,combined with the advantages of carbon materials,we have designed unique nano-architicture material and modified the surface of sulfur electrode with N element in order to study the effete of N-doping.The related work was mainly in the following studies:1.We rationally design a series of SnO2@rGO-Carbon particle framework nanoarchitectures by miro-wave co-precipitation method using an intermediate of KJ600(34 nm)or BP2000(15 nm),aiming at optimizing the lithium storage performance.Under the same loading of SnO2(-23%),the initial discharge capacity of SnO2@rGO-BP2000 anode is 1284.4 mAh·g-1.The reversible discharge capacity retention of 76%is remained after 60 cycles.Compared with other anode composite materials,SnO2@rGO-BP2000 displays much higher capacity and better cycling stability.2.We presented the rational synthesis of a nano-sandwich-type porous carbon/sulfur cathode by graphene oxide,glucose and ammonia.The initial discharge capacity of cathode is 1316.9 mAh·g-1 and 593.9 mAh·g-1 is remained after 100 cycles at 0.1 C.It suggested that such sandwich-type cathode demonstrates good electrochemical performance.To optimize the structure of cathode by coating PANI,an initial discharge capacity of cathode is 1335.2 mAh·g-1 and 62.4%is remained after 100 cycles.The result indicated that the well-designed nano-sandwich-type porous carbon/sulphur cathode and an elastic PANI coating help to retard the diffusion of polysulfides and to alleviate the volumetric expansion of sulfur.3.N-doped hollow carbon shell composite is synthesized by sodium oleate,NaSO4,FeCl3 and urea.Sulfur has been impregnated into the hollow shell by melting method to achieve good discharge specific capacity.An initial discharge of 1526.8 mAh·g-1 and reversible discharge capacity retention of 90%after 100 cycles is obtained at 0.5 C.It suggested that nitrogen doping could suppress the solution of polysulfides and improve the cycle stability of cathode.