| 학회 | 한국공업화학회 |
| 학술대회 | 2010년 봄 (05/13 ~ 05/14, BEXCO(부산)) |
| 권호 | 14권 1호 |
| 발표분야 | Energy Storage and Conversion |
| 제목 | Composites of Silicon Nanoparticles for Li Ion Battery Anodes |
| 초록 | Silicon possesses the highest theoretical energy density among common elements, and is cheap and easy to handle.Therefore, it is an attractive candidate to replace graphite for charge storage in the anode of lithium ion batteries.Various forms of Si electrode materials have been tested, including Si particles mixed with a binder and conducting carbon, nano-wires, thin films, and 3-D porous particles. However, they are still not satisfactory for commercial applications, either because of poor cycling stability, cost of manufacturing, and/or insufficient capacity improvement.Furthermore, many of these engineered structures, such as nanowires and thin films, need to be used with a metallic current collector as support, the weight of which significantly lowers the overall storage capacity of the electrode assembly. One approach to low-cost, high energy density anode material based on silicon nanoparticles is to disperse these nanoparticles in electrically conducting carbon-based materials, such as conducting carbon layers and graphene papers.Encapsulating the Si nanoparticles in a thin layer of graphitic carbon derived from carbonization of resorcinol-formal dehyde gel greatly enhance the cycling stability.Composites of Si nanoparticles and graphene papers are even more effective.These Si nanoparticle-graphene papers can be prepared readily from an aqueous suspension of exfoliated graphene oxide sheets and Si nanoparticles by filtration.After reducing the graphene oxide to graphene in the composite by heating in hydrogen at elevated temperatures, XRD of the resulting free-standing sheets showed the formation of both well crystallized and poorly crystallized regions of graphite and retention of Si nanoparticle size and metallic Si crystal structures.Simultaneously, the electrical conductivity increased significantly.SEM images of the composite, in both the reduced or unreduced form, show oriented sheets of graphene sandwiching Si nanoparticles, consistent with the TEM images.The electrochemical cycling tests show that the storage capacities of Si-graphene composite electrodes were high initially, achieving ＞2500 mAh/g of composite for some preparations, and maintained capacities ＞1500 mAh/g after 300 cycles.Our data suggest that composites of Si nanoparticles highly dispersed between graphene sheets, and supported by a 3-D network of graphite formed by reconstituting regions of graphene stacks, form anode materials of high Li ion storage capacities and cycling stability. |
| 저자 | Harold H. Kung |
| 소속 | Northwestern Univ. |
| 키워드 | lithium-ion batteries; silicon; anode; nanoparticles |
