| WANG Jingbo,CAO Li,LI Songyuan,XIAO Rongshi,HUANG Ting.Texturing of Cu Foil Current Collector by Femtosecond Laser Deep Ablation and Its Effect on Performance of Lithium-ion Batteries[J],53(1):115-122 |
| Texturing of Cu Foil Current Collector by Femtosecond Laser Deep Ablation and Its Effect on Performance of Lithium-ion Batteries |
| Received:November 24, 2022 Revised:May 05, 2023 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2024.01.011 |
| KeyWord:green femtosecond laser laser ablation Cu foil current collector Si-based electrode cycling stability |
| Author | Institution |
| WANG Jingbo |
Faculty of Materials and Manufacturing, Beijing University of Technology, Beijing , China |
| CAO Li |
Faculty of Materials and Manufacturing, Beijing University of Technology, Beijing , China |
| LI Songyuan |
Faculty of Materials and Manufacturing, Beijing University of Technology, Beijing , China |
| XIAO Rongshi |
Faculty of Materials and Manufacturing, Beijing University of Technology, Beijing , China |
| HUANG Ting |
Faculty of Materials and Manufacturing, Beijing University of Technology, Beijing , China |
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| Abstract: |
| The significant volume expansion of Si-based electrodes is very likely to lead to electrode materials exfoliation at the interface of Cu foil current collectors, and the interfacial stability of the electrode is a critical issue to be addressed urgently. Femtosecond laser ablating is an advanced surface processing technology, which can produce micro-nano surface structures with regular patterns and significantly improve the adhesive strength. In this paper, a green femtosecond laser with a wavelength of 515 nm was employed to deeply ablate and texture the Cu foils (9 μm-thick), and the effects of laser energy density and effective pulse number on the surface morphology and micro-nano structure of Cu foil as well as the cycle stability of Si-based electrodes of Cu foil samples with different structures were investigated. A femtosecond laser (TruMicro 5280 Femto Edition, TRUMPF) equipped with a scanning galvanometer (Scanlab Hurry SCAN14) was employed to deeply ablate the groove structure on the Cu foil surface. The univariate method was adopted. Firstly, the effective pulse number was fixed at 5, and the laser energy density was 1.27, 1.91, 2.55, 3.18, 3.82, 6.37 J/cm2, respectively. Then the laser energy density was fixed at 3.18 J/cm2, and the effective pulse number was 5, 25, 50, 75, respectively. Based on the results, Cu foils with different groove densities and groove depths were designed. The surface morphology of Cu foil was observed with a scanning electron microscope (HITACHI S-3400N) and a super-depth-of-field microscope (KEYENCE VHX-950F). The elemental content of the Cu foil surface was characterized with an energy spectrometer. The active material layer was formulated and coated on the surface of the Cu foil current collector. The active material layer was composed of 70% of active material Si (100 nm in diameter), 20% of binder and 10% of conductive agent. The electrodes (active layers and current collectors) were dried for 8 h at 80 ℃ under vacuum before they were transferred into the glove box for cell assembly. The cells were tested by galvanostatic cycling at 1C rate. It was found that the ablation threshold of the green femtosecond laser of Cu foil was 0.52 J/cm2, and the width of the ablated area increased gradually with the laser energy density. But when the laser energy density was too high, the ablating effect appeared "saturation" phenomenon. The surface of the ablated groove was nanostructured and no significant oxidation occurred. The optimal laser energy density for deeply etching was 3.18 J/cm2, and the depth of the groove could be regulated by changing the effective pulses number. The cycle stability of the Si-based electrodes gradually increased with the increase of groove density and depth. It was worth noting that when the groove density was 75% and the groove depth was 6 μm, the capacity remained 911 mA.h/g after 300 cycles at 1C with a retention rate of 89%. Using femtosecond laser deep ablation method and optimizing the laser parameters can successfully prepare micron-groove structure on the surface of Cu foil. The nanostructure increases the adhesive strength between the electrode and the current collector, while the micro-groove structure protects the electrode and alleviates its volume expansion. The deeply ablated Cu foil significantly improves the exfoliation of the Si-based electrodes and achieves the enhancement of the electrochemical performance. |
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