Development of a roll-to-roll high-speed laser micro processing machine for preparing through-holed anodes and cathodes of lithium-ion batteries

Aiming to improve the battery performance of lithium-ion batteries (LIBs), modification of the cathodes and anodes of LIBs using laser beams to prepare through-holes, non-through-holes or ditches arranged in grid and line patterns has been proposed by many researchers and engineers. In this study, a laser processing system attached to rollers, which realizes this modification without large changes in the present mass-production system, was developed. The laser system apparatus comprises roll-to-roll equipment and laser equipment. The roll-to-roll equipment mainly consists of a hollow cylinder with openings on its circumferential surface. Cathode and anode electrodes for LIBs are wound around the cylinder in the longitudinal direction of the electrodes. A pulsed beam reflected from the central axis of the cylinder can continuously open a large number of through-holes in the thin electrodes. Through-holes were formed at a rate of 100 000 holes per second on lithium iron phosphate cathodes and graphite anodes with this system. The through-holed cathodes and anodes prepared with this system exhibited higher C-rate performance than nontreated cathodes and anodes

Review of the structure and performance of through-holed anodes and cathodes prepared with a picosecond pulsed laser for lithium-ion batteries

To move the performance of lithium-ion batteries into the next stage, the modification of the structure of cells is the only choice except for the development of materials exhibiting higher performance. In this review paper, the employment of through-holing structures of anodes and cathodes prepared with a picosecond pulsed laser has been proposed. The laser system and the structure for improving the battery performance were introduced. The performance of laminated cells constructed with through-holed anodes and cathodes was reviewed from the viewpoints of the improvement of high-rate performance and energy density, removal of unbalanced capacities on both sides of the current collector, even greater high-rate performance by hybridizing cathode materials and removal of irreversible capacity. In conclusion, the points that should be examined and the problem for the through-holed structure to be in practical use are summarized

Improvement in Rate Capabilities of Hybrid Cathodes with Through‐Holed Layers of Cathode Material and Activated Carbon on Each Side of a Current Collector in Lithium‐Ion Batteries.

Abstract This study was conducted to improve the rate capability and cyclability of cathodes for lithium‐ion batteries (LIBs) with a hybrid cathode structure. The through‐holed LIB cathode material and activated carbon layers formed on each side of a current collector were drilled with a picosecond pulsed laser beam to prepare the cathode structure. The hybrid cathodes exhibited excellent rate capabilities of 93 % capacity retention at 100 C. The results were dependent on the weight percentage of the activated carbon relative to the total weight of the active materials and on the difference in discharge/charge voltages between the LIB cathode and activated carbon materials. The cathode had cycle stability at 50 C during 100 cycles. The performance characteristics of the hybrid cathode, the through‐holed and nontreated LIB cathodes, and the nontreated activated carbon cathodes were compared. In the Ragone plot, the hybrid cathode was located in the region where conventional through‐holed and nontreated cathodes would not be located