Investigation on the parameter dependency of the perforation process of graphite based lithium-ion battery electrodes using ultrashort laser pulses

Abstract

Perforation of lithium-ion battery electrodes has recently become an increasing interest in science and industry. Perforated electrodes have shown improved electrochemical properties compared to conventional, nonperforated electrodes. It has been demonstrated that through perforation, the fast-charging capability and the lifetime of these batteries can be significantly improved. The electrodes for lithium-ion batteries consist of a copper foil onto which the electrode material is applied as a porous layer. This layer is mainly composed of active material particles, which are bound together by a binder phase. Here, synthetic graphite was used as an active material. Up to now, it has been shown that an advantageous and precise perforation geometry can be produced by ultrashort laser pulse ablation. Since the ablation volumes during perforation of the porous electrode material with ultrashort laser pulses are unusually high compared to solids, this work investigates the parameter dependency on the ablation mechanisms in detail. For this purpose, in particular, single-pulse ablation was investigated with respect to the ablation thresholds at different pulse durations. The pulse durations were varied over a large range from 400 fs to 20 ps. By varying the number of pulses per perforation up to 50 and the single-pulse energy up to 45 μJ, it could be shown that a homogeneous ablation down to the conductor foil through the 63 μm thick active material layer can be achieved.

Thickness and surface estimation of thin porous media based on 3D image data

“…The next thin, porous material to be analyzed is a laser-patterned graphite anode from a Li-ion battery manufactured by Kleefoot et al [8]. The anode was scanned with a Bruker SkyScan2211 using a resolution of 250 nm.…”

Investigation of process mechanisms in laser-based microstructure adaptation of lithium-ion electrodes by fast IR-emission measurement

“…This accumulation is mainly due to the pulse frequency of 1000 kHz. When processing graphite electrodes using ultrashort pulse lasers, previous studies 11 have already shown the influence of different parameters on the ablation depth and diameter. For example, a high frequency like the 1000 kHz we used in this study, produces a high ablation depth.…”

The Impact of Structural Pattern Types on the Electrochemical Performance of Ultra-Thick NMC 622 Electrodes for Lithium-Ion Batteries

“…In addition, an enhanced capacity retention at high discharge/charge rates and a reduced charge transfer resistance were observed in cells containing laser-patterned Li(Ni 0.5 Mn 0.3 Co 0.2 )O 2 (NMC 532) [21], Li(Ni 0.6 Mn 0.2 Co 0.2 )O 2 (NMC 622) [22][23][24], LiCoO 2 (LCO) [25], Li(Ni 0.8 Mn 0.1 Co 0.1 )O 2 (NMC 811) [26,27], LiFePO 4 (LFP) [28], graphite [23,25,29], and Si/graphite (see reference [30] and those cited therein) using line patterns with varying pitches. In addition, alternative patterns such as throughholes in LFP cathodes [31][32][33], blind holes in graphite [34][35][36][37][38][39], and grid patterns in Si/graphite anodes [40] have also been reported. In general, the discharge capacity is enhanced for cells with laser-structured electrodes in contrast to those with unstructured electrodes when they are discharged for less than 2 h. However, the electrode material, mass loading, and pattern type influence the capacity increase.…”