1. School of Energy Engineering, Ulsan National Institute of Science & Technology, Ulsan, Korea 689-798, Beamline Research Division, Pohang Accelerator Laboratory, Pohang, Korea 790-784, Department of Applied Chemistry, Hanyang University, Ansan, Korea 426-791, Battery R&D, LG Chem, Ltd. 104-1, Moonji-dong, Yuseong-gu, Daejeon, Korea 305-380, and Department of Materials Science and Engineering, Stanford University, Stanford, California 94305