Synthesis Of Carbon/Tin Based Composite Materials For Lithium-Ion Battery Anode

Human's development more and more replies on energy.With overconsumption of limited fossil resources,different new energy,such as wind,solar,tidal,geothermal,hydro-thermal and nuclear energy are gradually stepping into our daily life with overconsumption of limited fossil resources.However,the use of those energy styles is not as convenient as fossil combustion,so finding a way to converse them into storable energy becomes a super crucial topic.After tens of years' exploration,lithium ion battery,up to now,has been considered as the most effective solution to overcome that issue.Most of other energy types could be transformed to chemistry energy and stored in lithium ion battery.Now,many practical cathode materials have been developed for commercial application,such as LiCoO2,LiMnO2,LiFePO4 et al,while the anode mainly focuses on carbon material,like graphite.Rapid development of new technology has more strict requirements on energy density,fast-charging ability for lithium ion battery,but the current graphite has a very low specific capacity,which is hard to meet the expectation of human for future battery.Therefore,it is a key issue for researchers to look for a substitute anode material with high capacity for practical use.Plenty of researches have been reported to demonstrate that tin-based material is supposed to be a potential anode to substitute graphite because tin-based material possesses a high capacity for lithium storage and could release a great deal of electricity in theory,which makes.While more attempts are still needed to prepare a good tin based anode for commercial applications due to the drawbacks of tin in electrochemistry properties.In our work,we tried to improve the performances of Sn based anode materials through appropriate design of structures.In recent years,Sn-based materials have been explored as potential anodes for high-energy lithium-ion batteries.However,their severe volume expansion in lithiation procedure could lead to poor cycling property and inferior rate capability,which limit the applications of Sn-based materials in lithium-ion batteries.In this study,we have designed and prepared uniform Mn2SnO4/Sn/carbon composite cubic particles with a porous structure as anode material through facile hydrothermal method and subsequent annealing process.The results demonstrate that the well-crystallized three-dimensional(3D)cubes with rounded corners consist of nanoparticles uniformly arranged in carbon matrix.The as-made Mn2SnO4/Sn/C anode exhibits excellent electrochemical performance and delivers 908 mA h g-1 of discharge capacity up to the 100th cycle at a current density of 500 mA g-1,with a coulombic efficiency above 97%.The remarkable performance can be attributed to the formation of unique conductive frameworks and the porous structure.Besides,we reported a simple method to prepare nitrogen-doped graphene,with which nitrogen-doped graphene/SnO2 composite was successfully fabricated and served as a lithium battery anode.The results from electrically testing indicate that the as-prepared nitrogen-doped graphene/SnO2 electrode possesses a high revisable capacity and outstanding fast charging-discharging performance,which is possible to meet the requirements for portable electronic devices in the future.The super electrochemical properties could benefit from the synergistic effect of SnO2 nanoparticles that contributes a high capacity and nitrogen-doped graphene that owns enhanced electroconductivity.Besides,graphene nanosheet proved a large specific surface area for SnO2 nanoparticles to anchor on,which could efficiently overcome the structure destruction of SnO2 based electrodes during continuous charging and discharging tests.This concept can offer a general approach toward designing anode materials with better performance.Morever,we prepared a porous Sn/C composite material through a facile method that largely enhanced the performance of pure Sn electrode.A SnO2/C nano-sphere structured precursor was firstly synthesized by a simple hydro-thermal solution,which was subsequently treated under high temperature at an inert gas atmosphere to obtain the final porous Sn/C nano spheres.We studied its crystal phase,morphology,constitution and structures by applying XRD,SEM,TGA,BET and other measurements.The test results shown that the prepared Sn/C composite material possesses a big BET surface area and a low impedance.The electrical tests demonstrated that this Sn/C could exhibit excellent rate capability and release super reverse capacity after 50 cycles of charging/discharging process under a current density of 100 mA g-1.The result indicated that this composite anode with carbon and metal Sn has an improved life span and fast charging capability.Combining the merits of Sn of high theoretical capacity and carbon of good electricity conductivity,our synthesized Sn/C nanospheres prove to be a high-performance anode material.