Collectors For Li-ion Batteries Research Articles

Carbon nanotube tissue as anode current collector for flexible Li-ion batteries—Understanding the controlling parameters influencing the electrochemical performance

In an attempt to upgrade the performance of lithium (Li)-ion batteries, carbon nanotubes (CNTs) have been suggested as a high-energy anode material. However, CNTs induce high irreversible capacity loss during the first cycle of the battery, which still poses a scientific challenge. This study explores CNT tissue as a flexible light-weight alternative to the copper (Cu) foil as an anode current collector in Li-ion batteries, employing graphite active material. The study demonstrates the impact of the graphite mass loaded on the anode performance and suggests that with the increase in the graphite mass, the irreversible capacity loss is considerably decreased. At sufficiently high graphite loadings, the performance during the first cycle becomes comparable to that of an anode utilizing the Cu current collector. This research also presents several distinct chemical pretreatments to the tissue, aiming to further decrease the irreversible capacity loss. It is suggested that this goal may be accomplished by washing the CNT with sulfuric acid prior to anode preparation, prompting better performance.

Crater-like architectural aluminum current collectors with superior electrochemical performance for Li-ion batteries

Crater-like architectural aluminum current collectors is prepared by a simple chemical etching method with NaOH-based solutions, and investigate the effect of aluminum surface morphology on its electrochemical performance as cathode current collector in Li-ion batteries. Characterization data reveal an acceptable tensile strength and surface hydrophilicity in the etched aluminum current collector, together with the creation of a rough surface with many reticular crater-like pits. In Li-ion cells using LiCoO2 as the active material, the crater-like architectural aluminum foil is electrochemically stable as the current collector, when in contact with other cell components during the charge–discharge processes. The improved electrochemical performance is attributed to the good electrical contact between cathode material particles and the current collector, and the resulting efficient electron transfer.

Better cycle stability and rate capability of high-voltage LiNi0.5Mn1.5O4 cathode using water soluble binder

5V LiNi0.5Mn1.5O4 (LNMO) cathodes are prepared using carboxymethyl chitosan (CCTS) as a water soluble binder and carbon coated aluminum foils (CAl) as current collector in Li-ion batteries (LIBs). CCTS exhibits an electrochemical oxidation potential as high as 5.0V. The electrochemical performance of LNMO cathode with CCTS binder is investigated and compared with the commercial non-aqueous polyvinylidene difluoride (PVDF). CCTS-CAl-LNMO electrode shows higher capacity retention (95.8%) than that of PVDF-CAl-LNMO (92.9%) and PVDF-Al-LNMO (88.52%) after 100 cycles. And, CCTS-CAl-LNMO electrode exhibits better rate capability than PVDF-CAl-LNMO, and PVDF-Al-LNMO, retaining specific capacity of 95.8mAhg−1 at 10C rate, only 87.6mAhg−1 and 1mAhg−1 for PVDF-CAl-LNMO, and PVDF-Al-LNMO, respectively. This approach can also be extended its use to other cathode materials such as LiNi1/3Co1/3Mn1/3O2 (NCM).

Reduced Graphene Oxide Films with Ultrahigh Conductivity as Li-Ion Battery Current Collectors.

Solution processed, highly conductive films are extremely attractive for a range of electronic devices, especially for printed macroelectronics. For example, replacing heavy, metal-based current collectors with thin, light, flexible, and highly conductive films will further improve the energy density of such devices. Films with two-dimensional building blocks, such as graphene or reduced graphene oxide (RGO) nanosheets, are particularly promising due to their low percolation threshold with a high aspect ratio, excellent flexibility, and low cost. However, the electrical conductivity of these films is low, typically less than 1000 S/cm. In this work, we for the first time report a RGO film with an electrical conductivity of up to 3112 S/cm. We achieve high conductivity in RGO films through an electrical current-induced annealing process at high temperature of up to 2750 K in less than 1 min of anneal time. We studied in detail the unique Joule heating process at ultrahigh temperature. Through a combination of experimental and computational studies, we investigated the fundamental mechanism behind the formation of a highly conductive three-dimensional structure composed of well-connected RGO layers. The highly conductive RGO film with high direct current conductivity, low thickness (∼4 μm) and low sheet resistance (0.8 Ω/sq.) was used as a lightweight current collector in Li-ion batteries.

Bundled and densified carbon nanotubes (CNT) fabrics as flexible ultra-light weight Li-ion battery anode current collectors

Carbon nanotubes (CNT) fabrics were studied and evaluated as anode current collectors, replacing the traditional copper foil current collector in Li-ion batteries. Glavanostatic measurements reveal high values of irreversible capacities (as high as 28%), resulted mainly from the formation of the solid electrolyte interphase (SEI) layer at the CNT fabric surface. Various pre-treatments to the CNT fabric prior to active anode material loading have shown that the lowest irreversible capacity is achieved by immersing and washing the CNT fabric with iso-propanol (IPA), which dramatically modified the fabric surface. Additionally, the use of very thin CNT fabrics (5 μm) results in a substantial irreversible capacity minimization. A combination of IPA rinse action and utilization of the thinnest CNT fabric provides the lowest irreversible capacity of 13%. The paper describes innovative and rather simple techniques towards a complete implementation of CNT fabric as an anode current collector in Li-ion batteries, instead of the relatively heavy and expensive copper foil, enabling an improvement in the gravimetric and volumetric energy densities of such advanced batteries.

Demonstrating the Feasibility of Al as Anode Current Collector in Li-Ion Batteries via In Situ Neutron Depth Profiling

The viability of using aluminum (Al) foil as the anode current collector in Li-ion batteries was demonstrated using in situ neutron depth profiling (NDP). A 500 nm thin Sn film, physical vapor deposited onto an Al foil, was monitored using NDP during lithiation and subsequent delithiation. Results indicate exclusive lithiation of the Sn electrode throughout the 0.05 to 1.00 V vs Li/Li+ range, leaving the Al foil current collector unlithiated even at the low potentials sufficient to lithiate Al. Additionally, 60–80 nm Sn nanoparticles suspended in a polyvinylidine fluoride (PVDF) matrix were cast onto an Al foil current collector and lithiated under constant current (C/6 rate). Results indicate the preferential lithiation of Sn nanoparticles. At lithiation potentials >0.3 V, Al lithiation is avoided even when the current collector is in direct contact with the electrolyte solution.

Aluminium Rods As Current Collectors and Electrodes for 3D Li-Ion Micro-Batteries

The microelectronics industry has advanced at a rapid pace in the last decade. Further advancements are hampered by the lack of suitable on-board power devices. Although Li-ion batteries are the primary choice for energy storage, they cannot store enough energy per foot-print area without compromising power capability. Three-dimensional Li-ion batteries could offer the solution by using all three dimensions for efficient energy storage on a relatively small foot-print area. Aluminium rods were obtained by template assisted galvanostatic deposition of aluminium into the pores of a commercial membrane. By the subsequent chemical dissolution of the membrane, free standing arrays of aluminium rods deposited on an aluminium substrate were obtained. It was shown that the use of a nucleation pulse prior to deposition led to a homogeneous deposition of aluminium rods, while the use of pulsed current rather than constant current resulted in a narrower distribution of the rods heights [1]. Aluminium is used as a current collector in Li-ion batteries. The deposition of TiO2 onto the aluminium rods was done by means of electrophoresis and a sol-gel derived impregnation method. While the electrophoretic deposition resulted in non-conformal coated rods, the impregnation method gave a thin amorphous deposit which could be cycled against lithium [2]. Finally, aluminium can be used as a negative active material, as it alloys with lithium. A study of the alloying and dealloying of lithium and aluminium was done on the 3D aluminium rods and a model for the lithiation and delithiation of aluminium has been proposed [3]. The aluminium rods were used as a negative electrode in a Li-ion battery against LiFePO4 coated on carbon foam positive electrode in a 3D cell with different geometries of the two electrodes [4].

Integration of Si in a metal foam current collector for stable electrochemical cycling in Li-ion batteries

We improve the electrochemical performance of Li-ion batteries by trapping micron-sized silicon particles inside a metal foam current collector in Li-ion batteries.

Genetically Programming Interfaces between Active Materials, Conductive Pathway and Current Collector in Li-Ion Batteries

In this work we genetically programmed the M13 virus, so that the new clone expressed multifunctional coat protein sequences that selectively bind to designated surfaces and species. Using these new clones, composite network consisting of ironphosphate nanowire (a-FePO4) and single wall carbon nanotubes were self-assembled onto aluminum surfaces. Spectroscopic and electrochemical characterizations confirmed the 3D-structure as well as the electrochemical activity of such composite nanowires.

Genetically Programming the Interfaces between Bio-Templated Cathode Nano-Particles and Current Collector in Li-Ion Batteries

not Available.

Fabrication of free-standing Cu nanorod arrays on Cu disc by template-assistedelectrodeposition

Free-standing Cu nanorod arrays on Cu foil have been fabricated by a template-assistedmethod. Cu nanorods were potentiostatically deposited on mechanically polished Cu foilusing anodized aluminum oxide templates as the deposition mask. Three electrolytesystems were compared, including two acid copper sulfate based solutions andone alkaline solution. The most uniform nanorods were achieved in the alkalineelectrolyte. The weight gain per unit area after electrodeposition has been used as adirect measure of average length of deposited Cu nanorods. It was found that ourcontrol over the uniformity in nanorod length across the array is important inreaching the maximized aspect ratio without aggregation. Through controlling theweight change it was possible to control the aspect ratio of nanorods and to avoidaggregation of nanorods. Our capability to fabricate free-standing Cu nanorodarrays of uniform height with maximized aspect ratio on Cu foil is especiallyimportant in applying this nanostructured Cu as a current collector in Li ionbatteries.