Relationship between Pore Design on Current Collectors, the Reaction Temperature and the Rate of Li⁺ Ion Pre-doping Reaction to Laminated Graphite/Porous Current Collector Anodes

Abstract

The fabrication process of porous copper (Cu) current collectors having the pore diameter (3-50 µm) 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 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. It was found in this study that the conditions of hole diameter (5 µm) 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.

Relationship between Hole Design on Anode Electrode, the Reaction Temperature and the Rate of Li⁺ Ion Pre-doping Reaction to Porous Laminated Graphite Anodes

“…Graph 電極上の開口径とドープ速度との関係の 検討 反応温度 25°C，開口率 1% におけるドープ速度の開口 径依存性の検討結果をFig. 6(A) に示す．Figure 6(A) には 穴あき Graph 電極の結果と前報で報告した17 Cu 集電箔に 穴をあけた後，Graph 層を塗工した電極(Cu 集電箔上の Graph 層の密度は 0.50-0.52 g cm ¹3 ，両面塗工 Graph 電極に おける片面の Graph 層の厚さは，77 µm)を用いた結果を した． 例 えば，Fig. 6(B-D) の 場 合， 開 口 径 50 µm の場合，5 番目の電極まで，開口径 20，10 µm の場 合，それぞれ 7，9 番目の電極までドープが進んでいると…”

Study on Li Metal Deposition, SEI Formation on Anodes and Cathode Potential Change during the Pre-Lithiation Process in a Cell Prepared with Laminated Porous Anodes and Cathodes

“…We believe that their strategy is the best option for the mass production of LIBs as well as LICs; however, the performance needs improvement, and the application of this method to the LIB production process must be confirmed. In our previous studies [12,13], to improve the pre-lithiation performance in the perpendicular pre-doping method, micrometer-sized through-holes through which Li + ions can pass were formed directly on anode and cathode active material-coated electrodes to accelerate the pre-lithiation. The prelithiation rate of the anodes in the cell could thus be effectively increased.…”