Paper review
Lucas Hille ∗, Marc P. Noecker, Byeongwang Ko, Johannes Kriegler, Josef Keilhofer, Sandro Stock, Michael F. Zaeh
TUM School of Engineering and Design, Technical University of Munich, Germany
In this study, Despite the electrochemical benefits of laser electrode structuring, the process is not yet implemented in state- of-the-art industrial battery production due to a limited knowledge regarding its implementation into the manufacturing process chain. In this study, three process integration positions for laser structuring of graphite anodes, which are either after coating, after drying or after calendering, were experimentally evaluated. The obtained electrodes were analyzed regarding geometrical, mechanical and electrochemical characteristics. The results indicate that the material ablation process is governed by the evaporation of solvent and binder for wet and dry electrodes, respectively. As a consequence, electrodes structured in wet condition exhibited fewer particle residues on the electrode surfaces and a high coating adhesion strength. In contrast, laser structuring of dry electrodes significantly reduced the pull-off strengths of the electrode coatings. A tortuosity reduction and an increased discharge capacity at high C-rates by laser structuring were observed for all structured electrodes, but with higher performance improvements for electrodes structured in dry state. Although a partial clogging of the structures was observed in electrodes structured before calendering, laser structuring yielded a comparable electrochemical performance of electrodes which were structured in dry condition before and after calendering.
Takashi TSUDA ∗ a,Yuta ISHIHARA a, Tatsuya WATANABE a, Nobuo ANDO b, Takao GUNJI a, Naohiko SOMA c, Susumu NAKAMURA d, Narumi HAYASHI e, Takeo OHSAKA b, and Futoshi MATSUMOTO a
a Department of Materials and Life Chemistry, Kanagawa University, 3-27-1 Rokkakubashi, Kanagawa-ku, Yokohama, Kanagawa 221-8686, Japan
b Research Institute for Engineering, Kanagawa University, 3-27-1 Rokkakubashi, Kanagawa-ku, Yokohama, Kanagawa 221-8686, Japan
c Wired Co., Ltd., 1628 Hitotsuyashiki shinden, Sanjo, Niigata 959-1152, Japan
d Department of Electrical and Electronic Systems Engineering, National Institute of Technology, Nagaoka College, 888 Nishikatakai, Nagaoka, Niigata 940-8532, Japan
e Industrial Research Institute of Niigata Prefecture, 1-11-1 Abuminishi, Chuo-ku, Niigata 950-0915, Japan
In this study, The degradation of charging/discharging capacities in the rate-performance test of lithium iron phosphate (LFP) cathodes with different loading amounts of an active material on both sides of a current collector (i.e., “unbalanced”LFP/LFP cathodes) in a laminated cell (typically composed of anode/separator/unbalanced cathodes/separator/anode) was not observed actually at low C-rates (e.g., 0.1 C). However, the rate-performance data obtained at high C-rates (e.g., >5 C) indicated that the imbalance of the loading amounts of an active cathode material on both sides of an Al current collector causes a significant capacity degradation. We have found that it is possible to prevent the capacity degradation observed at high C-rates by holing the unbalanced LFP/LFP cathodes in a micrometer-sized grid-patterned way (the percentages of the holed area are typically several %) using a pico-second pulsed laser: The non-holed unbalanced LFP/LFP cathodes exhibited a considerable capacity degradation at C-rates which are, for example, larger than 5 C, while the holed ones showed no degradation in capacity even at high C-rates (e.g., 5– 20 C). Forming micrometer-sized grid-patterned holes in the LFP/LFP cathodes leads to an improved capacity and high-rate performance of their charging/discharging processes.
Lucas Hille ∗, Marc P. Noecker, Byeongwang Ko, Johannes Kriegler, Josef Keilhofer, Sandro Stock, Michael F. Zaeh
TUM School of Engineering and Design, Technical University of Munich, Germany
For this study, microscopic diffusion channels were introduced into graphite anodes and NMC622 cath- odes through short-pulsed laser radiation. The impact on the performance of coin cells comprising anodes and cathodes in pristine and structured conditions, respectively, was investigated in a discharge rate test. At high rates (1 C –3C), particularly cells with laser-structured anodes showed a significant increase in capacity retention of up to 10 % in comparison to cells with pristine anodes. Characteristic features in the incremental capacities indicated cell polarization and diffusion inhibition as the rate-limiting mechanisms at high discharge rates and revealed differences in the dominating deintercalation stages between the cell configurations. Fitting an equivalent circuit model to the impedance spectra of symmetric cells showed a reduction of the ionic resistances by approx. 45 % for the anodes and approx. 21 % for the cathodes through laser structuring. A similar behavior was observed for the MacMullin numbers and effective tor- tuosities of the electrodes. In conclusion, laser structuring offers a particular potential to overcome the diffusion-limiting characteristics of the graphite anodes. The insights into the proportionate impact of anode or cathode structuring are of high value for the design and manufacturing of future lithium-ion batteries.
Shapoing Wu ∗, Hongpeng Zheng, Xinyue Wang, Nan Zhang, Weizheng Cheng, Benwei Fu, Haochang Chen, Hezhou Liu, Huanan Duan
State Key Labortaory of Metal matrix Composites, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, PR Chine
For this study, A thick electrode with high areal capacity is a promising way to improve the energy density of batteries, but the development of a thick electrode is limited by poor mechanical stability and sluggish ion and electron transport. Here, we design a self-supporting cathode that consists of cellulose nanofibers, multi-walled carbon nanotubes, and lithium iron phosphate (LFP), and introduce a uniform microchannel structure to the cathode by laser drilling technology. The cellulose nanofibers and multi-walled carbon nanotubes construct a conductive network. The microchannel structure enables outstanding ion and electron transport and significantly improves the rate capability of the electrode. Meanwhile, the local heat by the laser produces an amorphous carbon layer on the inner surface of the microchannel, which helps form a stable cathode-electrolyte interface and enhances the capacity retention of the thick electrode. Notably, the drilled thick cathode with an LFP load of 40 mg cm−2 and an areal capacity of 5.33 mAh cm−2 exhibits substantially improved cycling stability at 0.5C than the undrilled samples. This work demonstrates a promising design concept for thick electrodes to high-performance energy storage devices.
5.Wettability in electrodes and its impact on the performance of lithium-ion batteries
Dong Hyup Jeon ∗
Department of mechanical System Enginnering, Dongguk University-Gyeongju, Gyeongju 38066, Republic of Korea
Wettability by the electrolyte is claimed to be one of the challenges in the development of high-performance lithium-ion batteries. Non-uniform wetting leads to inhomogeneous distribution of current density and unstable formation of solid electrolyte interface film. Incomplete wetting influences the cell performance and causes the formation of lithium plating in the anode, which leads to safety issue. Research has pointed out that insufficient wetting could be found in the electrode, and the wetting characteristics would be different in each electrode. Here we use lattice Boltzmann simulation to show the electrolyte distribution and understand the wetting characteristics in the cathode and anode. We develop a multiphase lattice Boltzmann model with the reconstruction of electrode microstructure using a stochastic generation method. We use a porous electrode model to identify the effect of wettability on the cell performance and to elucidate the dependence of capacity on the wettability. Our results would lead to more reliable lithium-ion battery designs, and establish a framework to inspect the wettability inside electrodes.
Nathan Dunlap a, Dana B. Sulas-Kern a, Peter J. Weddle a, Francois Usseglio-Viretta a, Patrick Walker a, Paul Todd a, David Boone b, Andrew M. Colclasure a, Kandler Smith a, Bertrand J. Tremolet de Villers a, Donal P. Finegan a
a National Renewable Energy Laboratory (NREL), 15013 Denver West Parkway, Golden, CO 80401, United States of America
b Clarios, 5757 North Green Bay Avenue, Florist Tower, Milwaukee, WI 53209, United States of America
Laser ablation is a scalable technique for decreasing the effective tortuosity of electrodes by selectively removing material with high precision. Applied to 110μm thick electrode coatings, this work focuses on understanding the impact of laser ablation on electrode material properties at the beginning of life and synergistic impacts of ablated channels on cell performance throughout their cycle life. Post laser ablation, local changes in chemistry, crystallography, and morphology of the laser-impacted electrode regions are investigated. It is shown that femtosecond pulsed laser ablation can achieve high-rate material removal with minor material damage locally at the interface of the impacted zones. The capacity achieved during a 6C (10 min) constant-current constant-voltage charge to 4.2 V improved from 1 mAh cm−2 for the non-ablated electrodes to almost 2 mAh cm−2 for the ablated electrodes. This benefit is attributed to a synergistic effect of enhanced wetting and decreased electrode tortuosity. The benefit was maintained for over 120 cycles, and upon disassembly decreased Li-plating on the graphite anode was observed. Finally, multi-physics modeling in conjunction with wetting analyses showed that laser ablating either one of the electrodes led to substantial improvements in wetting and rate capability, indicating that substantial performance benefits can be achieved by ablating only the graphite anode as apposed to both electrodes.
Nayna Khosla a, Jagdish Narayan a, Roger Narayan a b, Xiao-Guang Sun c, Mariappan Parans Paranthaman c
a Department of Materials Science and Engineering, Centennial Campus, North Carolina State University, Raleigh, NC, 27695-7907, United States
b Joint Department of Biomedical Engineering, Centennial Campus, North Carolina State University and UNC Chapel Hill, Raleigh, NC, 27695, United States
c Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831-6100, United States
Nanosecond pulsed laser annealing significantly improves cyclability and current carrying capacity of lithium-ion batteries (LIBs). This improvement is achieved by engineering of microstructure and defect contents present in graphite in a controlled way by using pulsed laser annealing (PLA) to increase the number density of Li+ ion trapping sites. The PLA treatment causes the following changes: (1) creates surface steps and grooves between the grains to improve Li+ ion charging and intercalation rates; (2) removes inactive polyvinylidene difluoride (PVDF) binder from the top of graphite grains and between the grains which otherwise tends to block the Li+ migration; and (3) produces carbon vacancies in (0001) planes which can provide Li+ charging sites. From X-ray diffraction data, we find upshift in diffraction peak or reduction in planar spacing, from which vacancy concentration was estimated to be about 1.0%, which is higher than the thermodynamic equilibrium concentration of vacancies. The laser treatment creates single and multiple C vacancies which provide sites for Li+ ions, and it also produces steps and grooves for Li+ ions to enter the intercalating sites. It is envisaged that the formation of these sites enhances Li+ ion absorption during charge and discharge cycles. The current capacity increases from an average 360 mAh/g to 430 mAh/g, and C–V shows significant reduction in SEI layer formation after the laser treatment. If the vacancy concentration is too high and charge-discharge cycles are long, then trapping of electrons by Li+ may occur, which can lead to Li0 formation and Li plating causing reduction in current capacity.
Quansheng Li a b, Xuesong Mei a b c, Xiaofei Sun a b c, Yanbin Han a b, Bin Liu a b c, Zikang Wang a b, Anastase Ndahimana a b, Jianlei Cui a b c, Wenjun Wang a b c
a State key laboratory for manufacturing system engineering, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, China
b School of Mechanical Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, China
c Shaanxi Key Laboratory of Intelligent Robots, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, China
Owing to their excellent structural superiorities of large storage space, high specific surface area and reduced volume expansion during battery charge and discharge cycles, 3D porous current collectors have received much concern in the anode of lithium-ion batteries. However, reasonable designing and efficient manufacturing of 3D porous copper foils as current collectors (PCFCCs) remain a great challenge due to the small thickness, soft texture, and variability of copper foils. These material characteristics make it hard to manufacture 3D micro-structure on copper foils and impede the practical application of lithium-ion batteries in more fields. Herein, an efficient and effective strategy is reported to enhance the electrochemical performance of Li4Ti5O12 (LTO) electrodes via rationally designing and manufacturing 3D porous copper foils as current collectors. As a result, the 3D PCFCCs based LTO electrode displays low electrode polarization, excellent-cycle performance and ultra-high rate capacity. Moreover, the structures of various 3D PCFCCs are systematically studied for the first time, the design of 3D PCFCCs is optimized, and the mechanism of improving battery performance is explored. In addition, the proper micro-nano-pore-structures can facilitate electrolyte penetration and the solvated Li+ transport, and the excellent Li+ transmission ability of 3D PCFCCs is verified by simulation.
9.Electro-plating and stripping behavior on lithium metal electrode with ordered three-dimensional structure (2018)
Quan Li a b, Baogang Quan a, Wenjun Li a, Jiaze Lu a b, Jieyun Zheng a, Xiqian Yu a, Junjie Li a, Hong Li a
a Institute of Physics, Chinese Academy of Science, Beijing 100190, China
bUniversity of Chinese Academy of Sciences, Beijing 100049, China
The growth of lithium dendrite is one of the major problems that need to be solved before the application of metallic lithium anode to commercial rechargeable lithium batteries. The three-dimensional host framework with well-defined architecture acting as current collector has been proved to be able to regulate the lithium plating/stripping behavior and thus to suppress the dendrite growth. In this work, a surface-patterned lithium electrode (spLi) with hexagonal arrays of micro-sized holes has been successfully fabricated by micro-fabrication methods. By employing scanning electron microscope (SEM) and optical microscope, the lithium plating/stripping behavior on spLi was directly visualized. The electrochemical performances of the spLi electrode were evaluated in Li symmetric cell and Li|LiCoO2 half-cell using carbonate ester and ether based electrolyte. It is found that the geometry of the hole has a strong influence on the lithium plating/stripping behavior, and the deposited lithium perfers to fill in the micro-sized holes due to the favorable kinetics. The hole structure preserves throughout battery cycling with no obvious dendrite growth and surface roughness after multiple plating/stripping cycles. These phenomena can well explain the excellent electrochemical performances of the surface-patterned lithium electrode (spLi) compared with bare lithium electrode. This research also demonstrates that lithium metal can serve as stable framework to host lithium plating/stripping, nevertheless, efforts are still needed to further optimize the architecture to achieve more evenly lithium plating/stripping.
10.Processing of lithium metal for the production of post-lithium-ion batteries using a pulsed nanosecond fiber laser (2022)
Johannes Kriegler, Tran Manh Duy Nguyen, Lazar Tomcic, Lucas Hille, Sophie Grabmann, Elena Irene Jaimez-Farnham, Michael F. Zaeh
Technical University of Munich (TUM); TUM School of Engineering and Design; Department of Mechanical Engineering, Institute for Machine Tools and Industrial Management (iwb); Boltzmannstrasse 15, 85748 Garching, Germany
Lithium metal is a favored anode material in various post-lithium-ion battery types. Developing processing routines for lithium anodes is necessary to pave the way for large-format lithium metal batteries. Laser cutting is a feasible production process to create the required electrode contours. In the scope of this work, model calculations were used to derive implications of the cell design on the relevant range of lithium layer thicknesses. Furthermore, nanosecond-pulsed laser cutting was evaluated for separating 50 μm-thick lithium foils. Cause-effect relationships between process parameters and quality criteria were analyzed through empirical investigations. The ablation thresholds for various pulse durations were determined experimentally. Different process regimes were identified using scanning electron microscopy with explosive boiling at high fluences as the most efficient ablation mechanism enabling cutting speeds of up to 6.6 m s−1. The influence of the peak pulse fluence, the pulse frequency, the pulse duration, and the pulse overlap on the formation of melt superelevations at the cut edge was studied using laser scanning microscopy. The presented results contribute to a better understanding of the nanosecond-pulsed laser process and provide a basis for developing tailored process strategies for laser cutting of lithium metal within industrial-scale battery production.
11.Nanosecond laser lithography enbles concave-convex zinc metal battey anodes with ultrahigh areal capacity (2022)
Zechuan Huang a, Haoyang Li b, Zhen Yang b, Haozhi Wang a, Jingnan Ding a, Luyao Xu c, Yanling Tian d, David Mitlin e, Jia Ding a, Wenbin Hu a
a Key Laboratory of Advanced Ceramics and Machining Technology (Ministry of Education), School of Materials Science and Engineering, Tianjin University, Tianjin 300072, China
bSchool of Mechanical Engineering, Tianjin University, Tianjin 300072, China
cShenzhen Zhongwu Technology Co., Ltd., Shenzhen 518052, China
dSchool of Engineering, University of Warwick, Coventry CV4 7AL, UK
eMaterials Science Program & Texas Materials Institute, The University of Texas at Austin, Austin, TX 78712-1591, USA
Laser processing is employed to fabricated zinc-ion battery (ZIB) anodes with state-of-the-art electrochemical performance from commercial zinc foils. Lasers are widely utilized for industrial surface finishing but have received minimal attention for zinc surface modification. Laser lithography patterned zinc foils “LLP@ZF” are hydrophilic, with an electrolyte contact angle of 0°. This is due to the concave-convex surface geometry that enhances wetting (periodic crests, ridges and valleys, roughness 16.5 times planar). During electrodeposition LLP@ZF's surface geometry generates a periodic electric field and associated current density distribution that suppresses tip growth (per continuum simulations). Per Density Functional Theory (DFT) its surface oxide is zincophilic, resulting in low nucleation barriers during plating (e.g. 3.8 mV at 1 mA cm−2). A combination of these attributes leads to stable dendrite-free plating/stripping behavior and low overpotentials at fast charge (e.g. 48.2 mV at 8 mA cm−2 in symmetric cell). Cycling is possible at an unprecedented areal capacity of 50 mA h cm−2, with 400 h stability at 1 mA cm−2. Moreover, exceptional aqueous zinc battery (AZB) performance is achieved, with MnO2-based cathode loading 10 mg cm−2 and corresponding anode capacity 7.6 mA h cm−2. A broad comparison with literature indicates that LLP@ZF symmetric cell and full battery performance are among most favorable.
