2005 Fiscal Year Final Research Report Summary
First-principles electronic structure investigation to design a functional molecular-electrode
| Project/Area Number |
16550002
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Physical chemistry
|
|---|
| Research Institution | Faculity of Engineering, Iwate University |
|---|
Principal Investigator |
NISHIDATE Kazume Iwate University, Faculty of Engineering, Associate Professor, 工学研究科, 助教授 (90250638)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
HASEGAWA Masayuki Iwate University, Faculty of Engineering, Full Professor, 工学部, 教授 (00052845)
|
|---|
| Project Period (FY) |
2004 – 2005
|
| Keywords | Carbon nanotube / Li ion / defect / First-principles / electronic structure / secondary battery / adsorption energy |
|---|
| Research Abstract |
It has been experimentally suggested that carbon nanotube is one of the most promising candidates as a negative electrode of Li-ion secondary battery. We apply the density functional theory to study the energetics of interlayer binding in graphite and also the energetics of lithium ion adsorption on single-wall carbon nanotubes (SWNTs) to elucidate theoretically the microscopic nature of the intercalation dynamics. We use both the local density approximation (LDA) and the generalized gradient approximation (GGA) for the exchange-correlation energy functional. Two types of SWNTs, metallic (5,5) armchair SWNT and semiconducting (8,0) zigzag SWNT, were chosen as samples in our calculations since the diameters of these SWNTs are nearly the same. While no significant difference is found between the relaxed structures calculated in the LDA and GGA, different results are obtained for the lithium adsorption energies. Next, dynamics of the lithium diffusion through the defective SWNT is studied by using the first-principles molecular dynamics simulation method, in which all the atoms are allowed to move following the Newtonian equation of motion while the electronic states are solved exactly at each time step. Initially the lithium atom is placed outside the SWNT, right above the center of the ring and no external force is applied. Extensive molecular dynamics calculations showed that the lithium can not diffuse through the defect free hexagonal ring and the n=7 and n=8 membered defective rings of the (5,5) SWNT but can diffuse into the (5,5) SWNT through the n=9 membered defective ring.
|
