Towards the improvement of the state-of-art lithium-ion battery with liquid electrolyte, all-solid-state battery (ASSB) has become one of the most promising systems in the near future, due to the enhancement in the aspect of safety and volumetric energy efficiency. Even though thin film ASSBs have shown excellent performance, it is not suitable for large-scale applications due to its limited size. Therefore, development of bulk ASSB has gained great attentions in recent years. Different inorganic solid electrolytes (SE) have been intensively synthesized and investigated. The electric conductivity was thought to be the limiting factor. But it is no longer a big issue with the constant improvement of conductivity up to 1.2 * 10^-2 S/cm.^[1] On the other hand, the cell performance is limited to the high interfacial resistance generated between active material and solid electrolyte. A highly resistive layer at the interface between LiCoO₂ and sulfide SE was reported.^[2] This was considered to be the formation of space-charge layer or the mutual diffusion of elements between oxide cathode material and sulfide SE. ^[2,3] One of the solutions is the interposition of a buffer layer, which suppressed the increase of interfacial resistance and enabled the high-rate cycle of the ASSB.^[4]

However, a detailed study of the ASSB system was not yet reported. In this poster, an ASSB composed of oxide cathode and sulfur based SE will be introduced. The schematic diagram of the cell is shown in Figure 1. The design and the structure of the cell, characterizations of cell components with XRD, SEM and electrochemical impedance will be shown. The relationship between the design of composite cathode and the long cycle stability and rate performance of assembled cells will also be revealed. The influence of interfacial resistance between oxides and sulfide based SE on the cell performance will be discussed. The reasons for the capacity fading observed during cycling will be analyzed and possible solutions will be proposed.

[1]            N. Kamaya, K. Homma, Y. Yamakawa, M. Hirayama, R. Kanno, M. Yonemura, T. Kamiyama, Y. Kato, S. Hama, K. Kawamoto, A. Mitsui, Nat. Mater. 2011, 10, 682.

[2]          N. Ohta, K. Takada, L. Zhang, R. Ma, M. Osada, T. Sasaki, Adv. Mater. 2006, 18, 2226.

[3]          A. Sakuda, A. Hayashi, M. Tatsumisago, Chem. Mater. 2010, 22, 949.

[4]          N. Ohta, K. Takada, I. Sakaguchi, L. Zhang, R. Ma, K. Fukuda, M. Osada, T. Sasaki, Electrochem. commun. 2007, 9, 1486.