13 research outputs found
Laser Cutting Characteristics on Uncompressed Anode for Lithium-Ion Batteries
Lithium-ion batteries are actively used for many applications due to many advantages. Although electrodes are important during laser cutting, most laser cutting studies use commercially available electrodes. Thus, effects of electrodes characteristics on laser cutting have not been effectively studied. Since the electrodesâ characteristics can be manipulated in the laboratory, this study uses an uncompressed anode on laser cutting for the first time. Using the lab-made anode, this study identifies laser cutting characteristics of the uncompressed anode. First, the absorption coefficients of graphite and copper in the ultraviolet, visible, and infrared range are measured. The measured absorptivity of the graphite and copper at the wavelength of 1070 nm is 88.25% and 1.92%, respectively. In addition, cutting phenomena can be categorized in five regions: excessive cutting, proper cutting, defective cutting, excessive ablation, and proper ablation. The five regions are composed of a combination of multi-physical phenomena, such as ablation of graphite, melting of copper, evaporation of copper, and explosive boiling of copper. In addition, the top width varies in the order of 10 Îźm and 1 Îźm when applying high and low volume energy, respectively. The logarithmic relationship between the melting width and the volume laser energy was found
The Effect of Compactness on Laser Cutting of Cathode for Lithium-Ion Batteries Using Continuous Fiber Laser
Lithium-Ion Batteries (LIB) are growing in popularity for many applications. Much research has been focusing on battery performance improvement. However, few studies have overcome the disadvantages of the conventional LIB manufacturing processes. Laser cutting of electrodes has been applied. However, the effect of electrodesâ chemical, physical, and geometrical characteristics on the laser cutting has not been considered. This study proposes the effect of compression of cathode on laser cutting for lithium-ion batteries. The kerf width and top width of the specimens with laser irradiation are measured and the material removal energy is obtained. Observations of SEM photographs and absorptivity measurements are conducted. Increasing volume energies causes logarithmic increases in the kerf and top width. It is observed that the compressed cathode forms a wider kerf width than the uncompressed cathode under the same laser parameters. The top width of the uncompressed cathode is wider than the uncompressed cathode. The compression has a favorable effect on uniform cutting and selective removal of an active electrode
Electrical modification of a composite electrode for room temperature operable polyethylene oxide-based lithium polymer batteries
Lithium polymer batteries (LPBs) are considered to be the most promising alternatives to current lithium-ion batteries (LIBs), which have been known to exhibit certain safety issues. However, the relatively poor electrochemical performances of LPBs hinder their practical usage, particularly at high C-rates, moderate temperatures, and/or with high loading densities. Therefore, this study analyzes the use of a novel composite electrode for manufacturing room-temperature operable LPBs with high loading densities. Rapid decay in the rate capabilities of LPBs at high C-rates is found to be attributable to the increased electrical resistance in an electrode. To account for this, this study modified the composite electrode with various conducting fillers. Subsequently, the effect of the type and content of the conducting fillers on the performance of LPBs was systematically investigated using the composite electrode. The incorporation of the conducting fillers in the lithium iron phosphate (LFP) composite electrode was found to effectively reduce the electrical resistance and consequently improve the electrochemical performance of LPBs. Furthermore, LFP composite electrodes with a mixture of structurally different graphene (G) and carbon nanotube (CNT) (1 wt%) were observed to demonstrate synergistic effects on improving the electrochemical performance of LPBs. The results obtained in this study elucidate that the facilitated electrical conduction within a composite electrode is critically important for the performance of LPBs and the expedited diffusion of Li ^+
Improved cycle efficiency of lithium metal electrodes in Li-O-2 batteries by a two-dimensionally ordered nanoporous separator
We demonstrate a facile but very effective approach to improve the cycling efficiency of metallic lithium electrodes by controlling the pore morphology of separators. We employed anodized porous alumina as the model nanoporous separator and demonstrated the improvement of cycle efficiency of lithium electrodes in lithium-oxygen cellsclose3
Room-Temperature, Ambient-Pressure Chemical Synthesis of Amine-Functionalized Hierarchical CarbonâSulfur Composites for LithiumâSulfur Battery Cathodes
Recently, the achievement of newly
designed carbonâsulfur
composite materials has attracted a tremendous amount of attention
as high-performance cathode materials for lithiumâsulfur batteries.
To date, sulfur materials have been generally synthesized by a sublimation
technique in sealed containers. This is a well-developed technique
for the synthesizing of well-ordered sulfur materials, but it is limited
when used to scale up synthetic procedures for practical applications.
In this study, we suggest an easily scalable, room-temperature/ambient-pressure
chemical pathway for the synthesis of highly functioning cathode materials
using electrostatically assembled, amine-terminated carbon materials.
It is demonstrated that stable cycling performance outcomes are achievable
with a capacity of 730 mAhg<sup>â1</sup> at a current density
of 1 C with good cycling stability by a virtue of the characteristic
chemical/physical properties (a high conductivity for efficient charge
conduction and the presence of a number of amine groups that can interact
with sulfur atoms during electrochemical reactions) of composite materials.
The critical roles of conductive carbon moieties and amine functional
groups inside composite materials are clarified with combinatorial
analyses by X-ray photoelectron spectroscopy, cyclic voltammetry,
and electrochemical impedance spectroscopy