## 2 Materials and Methods  
### Electrode Preparation  
The commercially available battery cathode material NMC 622 (Targray, Canada) with an average particle size of 10 \(\upmu\)m, was used as active material, while polyvinylidene fluoride (PVDF, MTI Corporation, USA) and TIMCAL Super C65 (MTI Corporation, USA) were chosen as binder and conductive agent, respectively. PVDF powder was dissolved in N-methyl-2-pyrrolidone solvent (NMP, BASF, Germany) in advance, with a weight proportion of 1:10 in a vacuum mixer (MSK-SFM-7, MTI Corporation, USA) for 30 min.  
The cathode slurry was pre-mixed with 5 wt.% PVDF binder (dissolved in NMP), 5 wt.% Super C65 carbon black, and 90 wt.% NMC 622 for 1 h using SpeedMixer DAC 150 SP (Hauschild and Co. KG, Germany). Extra NMP solution was then added into the mixture, in order to control the viscosity of the slurry. The subsequent mixing procedure was carried out at 3000-3500 rpm for 1h. Finally, the slurry was tape casted onto a 20 \(\upmu\)m thick aluminum foil with a doctor blade (ZUA 2000.150, Zehntner GmbH, Switzerland) on a film coater (MSK-AFA-III, MTI Corporation, USA). The thickness of the coated cathode film was controlled by varying the gap of the doctor blade. The cathode sheet was dried afterwards for 4 h with the built-in heater at around 120 \({}^{\circ}\)C and subsequently cooled down to room temperature for 16 h. Afterwards, the cathode film was calendered using a hot rolling calender (Precision 4\" Hot Rolling Press/Calender, MTI Corporation, USA) at around 75 \({}^{\circ}\)C with a constant calendaring speed of 9 mm/s. The purpose of calendering procedure is to achieve an overall homogenous film thickness and to improve the particle-to-particle contact inside the electrode. For cathodes with different thicknesses, the porosity was adjusted to values of about 35% after calendaring.  
An ultrafast fiber laser (Tangerine, Amplitude Systemes, France), built in the flexible laser micromachining system PS450-TO (Optec s.a., Belgium), was used to realize a type of cold laser ablation. The ultrafast fiber laser system has a maximal average power of 35 W and a maximum pulse energy of 175 \(\upmu\)J at a wavelength of 1030 nm (M\({}^{2}\) \(<\) 1.2). By using a pulse picker, a modulator, and compressor, it was possible to adjust the laser repetition rate from single pulse up to 2 MHz. The pulse duration ranged from 380 fs up to 10 ps. For the laser ablation process, a line pattern was chosen with pitch distances ranging from 200 \(\upmu\)m to 600 \(\upmu\)m (Figure 1). The repetition rate was kept constant at 200 kHz. Laser scanning velocity was set to 500 mm/s, and laser power was 3 W. The laser pulse duration was 380 fs. An external exhaust was placed next to the sample during the structuring and cutting processes in order to remove the ablated materials. The laser process was performed in ambient air. For electrodes with different thicknesses, the repetition of the laser structuring process was adjusted to achieve line structure from the electrode surface down to the current collector without damaging the current collector. Cross-section analyses of the electrode using different repetitions were made in order to find appropriate parameters. Owing to the subsequent scale requirement of cell assembling, cathodes were cut to 12 mm in diameter for coin cell design using the ultrafast laser system (wavelength: 1030 nm, frequency: 200 kHz, laser scanning velocity: 200 mm/s, repetition: 10 times), and were subsequently kept in a vacuum oven (VT 6025, Thermo SCIENTIFIC, Germany) at 130 \({}^{\circ}\)C for 16 h.