Fabrication of Porous Current Collectors for Li Ion Capacitor with Pico-Second Pulse Laser and Acceleration of Li+ Ion Pre-Doping Reaction to Laminated Graphite/Porous Current Collector Anodes

Tuesday, 30 May 2017
Grand Ballroom (Hilton New Orleans Riverside)
T. Tsuda, F. Ando, Y. Mochizuki, T. Gunji, T. Tanabe, S. Kaneko, T. Ohsaka (Kanagawa University), K. Itagaki, N. Soma (Wired Co., Ltd), and F. Matsumoto (Kanagawa University)
The fabrication process of porous copper (Cu) current collectors having the pore diameter (3-50 mm) and the rate of opening area (1-4 %) was developed with a system constructed with a pico-second pulse laser and a polygon mirror. The fabricated porous Cu current collectors (Fig. 1) were used to evaluate the porous design on the Cu current collector for exhibiting higher Li+ doping reaction rate with cells in which graphite electrodes were laminated with separators and the laminated graphite anode opposites to Li metal through a separator (Fig. 2). It was found in this study that the conditions of hole diameter (5 mm) and the rate of opening area (1%) is the best one to realize high Li+ doping rate and that the rate determining step of the pre-doping reaction is the diffusion of Li+ion in the pore of the Cu porous current collectors.

Fig. 1 Surface SEM images of prepared porous Cu current collectors. Magnified SEM image of a pore: (A) a view from the plane of incidence of a laser, (B) a view from the plane of emission of a laser. Opening rate of pore on the current collectors: (C) 1 and (D) 2.5 %. The pore size is a constant of 20 mm in all SEM images.

Fig. 2 Schematic description of a cell for pre-doping reaction with graphite layer/porous current collector anodes and a Li metal.