原文信息：
High-quality femtosecond laser cutting of battery electrodes with enhanced electrochemical performance by regulating the taper angle: Promoting green manufacturing and chemistry
原文链接：
https://www.sciencedirect.com/science/article/pii/S030626192401835X
Highlights
• 首次利用飞秒激光加工技术设计和制造了具有不同锥度结构的钛酸锂电极
• 激光辐照诱导电极中部分Ti4+被还原为Ti3+并产生了氧空位，有助于提升电极导电能力
• 激光精细可控加工的锥度结构能够显著改善电解液渗透和加快锂离子扩散动力学过程
• 半电池和全电池测试表明，当锥度角为0.04时，钛酸锂电极展示出最佳的电化学性能
Abstract
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 1 C, and the specific capacity reaches ~60 mAh g−1 at a high rate of 60 C, 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.
Keywords
Femtosecond laser
Cutting electrode
Lithium battery
Full cell
Electrochemical performance
Graphics
图1 激光切割加工系统示意图(a)及不同波长下铜箔和LTO电极的反射率比较(b)
图2 激光单脉冲能量(a)和激光功率(b)对LTO电极切割的影响；不同离焦量和重复扫描次数对LTO电极锥度角的影响(c)；单脉冲能量(d)、激光功率(e)和扫描次数(f)对电极切割时材料利用率的影响
图3 （a）切割锥度角T = 0.004的切割电极的SEM图像；（b）T = 0.004的切割电极的激光共聚焦显微CLSM图像；（c）不同样品的XRD图；（d）不同样品的XRD(111)衍射峰放大图；（e）不同样品的拉曼光谱；（f-i）不同样品的拉曼光谱（900 – 2000 cm−1）；（j）不同激光切割位置的拉曼光谱
图4 不同样品的XPS谱图
图5 不同锥度角和机械切割MC电极的电化学性能：（a）循环性能；（b）倍率性能；（c-e）恒流充放电曲线；（f）电化学阻抗谱EIS曲线；（g）循环伏安CV曲线；（h）电化学滴定GITT曲线与Li+扩散系数；（i-j）与其他已报道LTO电极的性能对比
图6 （a）电解液吸收测试设备；（b）电解液爬升高度及（c）不同电极样品电解液的吸收情况；（d-g）不同电极的润湿性测试；（h）激光切割电极的kirigami图案及其可拉伸性；（j）拉伸次数与电极内阻的变化规律
图7 LFP||LTO全电池的电化学性能：（a）全电池的组成及工作原理示意图；（b-c）不同全电池在不同倍率下的恒流充放电曲线；（d）不同全电池在1C倍率下的容量保持率；（e）不同全电池的循环性能
团队介绍
本研究由西安交通大学机械工程学院、西安交通大学精密微纳制造技术全国重点实验室、陕西省智能机器人重点实验室的研究人员共同完成。
通信作者简介：
孙孝飞，西安交通大学教授、博士生导师。长期从事先进储能材料与器件及其智能制造研究。在Advanced Functional Materials、Journal of Energy Chemistry、Energy & Environmental Materials等国际期刊发表SCI论文70余篇，编写教材和专著3部，获中国授权发明专利30余项、计算机软件著作权6项。
梅雪松，西安交通大学教授、博士生导师，长江学者特聘教授，教育部创新团队负责人。长期从事激光精密加工、数控技术、智能工厂和工业机器人等方面的研究。在Advanced Materials、International Journal of Extreme Manufacturing、IEEE Transactions on Industrial Informatics等期刊发表论文500余篇，主编教材和专著5部，获国内外发明专利200余项、计算机软件著作权50项。
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