High-quality femtosecond laser cutting of battery electrodes with enhanced electrochemical performance by regulating the taper angle: Promoting green manufacturing and chemistry

Laser cutting electrode technology is an environmentally friendly and sustainable manufacturing method that offers many benefits, such as low energy consumption and greenhouse gases, no waste production, no tool wear, flexible manipulation, and multi-scale processing. However, achieving high cutting quality with adjustable notch shape and controllable dimension precision is still a cutting-edge challenge. In addition, the influence of laser cutting on the microscopic structure and electrochemical performance of battery electrodes has not been fully illustrated. Here, the Li₄Ti₅O₁₂ (LTO) electrode is cut using a femtosecond laser technology. The processing parameters are systematically optimized, and the influence of laser cutting taper structure on the structure and performance of LTO electrodes is comprehensively investigated. It is found that laser photoionization and the generated plasma could create oxygen vacancies and thus more Ti³⁺/Ti⁴⁺ defects in the LTO electrodes, resulting in increased electronic conductivity. Moreover, proper taper structure could help improve electrolyte infiltration as well as Li⁺ diffusion kinetics. As a result, the laser cutting LTO electrode with the optimized taper angle of T = 0.004 shows excellent electrochemical performance. The capacity retention is more than 99.2 % after 400 cycles at 1C, and the specific capacity reaches ∼60 mAh g⁻¹ at a high rate of 60C, which is about 1.7 times higher than that of mechanically cutting LTO electrodes. The outstanding electrochemical performance is also demonstrated by LiFePO₄||Li₄Ti₅O₁₂ full cells. This work could pave the way for the development and application of laser technology in cutting battery electrodes.