Collector For Lithium-ion Batteries Research Articles

Passivation and corrosion of Al current collectors in lithium-ion batteries

State-of-the-art lithium-ion batteries inevitably suffer from electrode corrosion over long-term operation, such as corrosion of Al current collectors. However, the understanding of Al corrosion and its impacts on the battery performances have not been evaluated in detail. The passivation, its breakdown, and corrosion of the Al resulted in the deterioration of the solid/solid interface and electrode integrity. Additionally, localized diffusion of F−/Al3+ brought the irreversible current detrimental to the Coulomb efficiency (1.14% loss). Eventually, the behavior led to extensive capacity damage (>20%) to battery performance until lifespan. During the battery cycling, the passivation layer greater than 20 nm was generated near the median voltage. When the charging voltage rose, the passivation layer was squeezed and deformed by the newly generated Al-F-O particles, resulting in stress corrosion cracks. The passivation layer peeled off, and the nano-passivation layer material was re-generated as the voltage continued to rise. The above results were repeated, and the Al matrix was continuously consumed. The passivity breakdown with localized corrosion was derived from ethylene carbonate adsorption, which was highly correlated to the charge voltages, especially at 4.4 V and 4.8 V. The results will serve as a benchmark for electrode corrosion of other advanced energy storage materials, which is crucial for electrode engineering and performance modulation using interfacial design.

An electrochemically active textile current collector with a high areal capacity and a strong energy recovery effect using an interfacial interaction assembly

Conventional current collectors in lithium-ion batteries (LIBs) are generally nonactive components. However, enhancing their electroactive properties and increasing the electroactive surface area can significantly improve the areal energy performance of next-generation battery electrodes. Herein, we introduce an electrochemically active textile current collector that delivers high energy storage performance, achieved through interfacial interaction assembly-induced electroplating. We first prepared metal nanoparticle/multiwalled carbon nanotube multilayer-incorporated cotton textiles using complementary interaction-mediated layer-by-layer assembly, and subsequently electroplated them with Cu. The resulting textile exhibited a high areal capacity of ∼3.27 mA h cm−2 at 0.875 mA cm−2, excellent cycling stability, and a strong energy recovery effect, thanks to the synergistic contributions of the large active surface area of the fibril structure, the robust interfacial assembly, and the formation of a metal oxide NP/pseudocapacitive polymeric gel-like phase at the electrode/electrolyte interface. Moreover, when incorporating Li4Ti5O12 with a theoretical capacity of 175 mA h g − 1 into our textile current collector, the specific capacity and areal capacity of the LIB anode can be increased up to ∼573 mA h g − 1 and 8.60 mA h cm−2 (at 15 mg cm−2 LTO), respectively, outperforming those of previously reported LTO-based anodes.

Preparing ultra-thin copper foil as current collector for improving the LIBs performances with reduced carbon footprint

Adopting ultra-thin copper foil as the current collector is one of the most important strategies for improving the gravimetric energy density of lithium-ion batteries (LIBs), however, stumbled by the quality-control of physicochemical properties for ultra-thin foils. Herein, by utilizing combinative additives, the ≤ 4.5 µm ultra-thin electrolytic copper foil with appealing physicochemical properties is prepared, presenting very low Rz (surface roughness) of 1.74 µm and extraordinarily high tensile strength of 435.65 MPa. When being used as the current collector in LIBs, a high gravimetric energy density of 323.19 Wh/kg was achieved, outperforming both the commercial 9 µm candidate (205.81 Wh/kg) and the purchased 4.5 µm counterpart (310.48 Wh/kg). Also, decreasing the thickness of commercial copper foil (9 µm) to 4.5 µm demonstrates superiorities in both resources saving and environmental benignity, contributing to ∼32 million tons copper savings in 2030 and 40.6 % elimination in carbon footprint for copper foil preparation. The results herein can provide guidance for quality-controlled preparation of ultra-thin copper foil as well as new insights for resource savings and environmentally friendly manufacturing.

Appropriate properties of carbon nanotubes for the three-dimensional current collector in lithium-ion batteries

Appropriate properties of carbon nanotubes for the three-dimensional current collector in lithium-ion batteries

Spontaneous local redox reaction to passivate CNTs as lightweight current collector for high energy density lithium ion batteries

Extensive usage of highly conductive carbon materials with large specific surface area (e.g., carbon nanotubes, CNTs) in lithium ion batteries (LIBs), especially as current collector of anodes, suffers from low initial coulombic efficiency (ICE), large interfacial resistance, and severe embrittlement, as the large specific surface area often results in severe interfacial decomposition of the electrolyte and the formation of thick and fluffy solid electrolyte interphase (SEI) during cycling of LIBs. Herein, we demonstrate that when the CNT-based current collector and Na foil (which are being stacked intimately upon each other) are being placed in Na+-based organic electrolyte, local redox reaction between the Na foil and the electrolyte would occur spontaneously, generating a thin and homogeneous NaF-based passivating layer on the CNTs. More importantly, we found that owing to the weak solvation behaviors of Na+ in the organic electrolyte, the resulting passivation layer, which is rich in NaF, is thin and dense; when used as the anode current collector in LIBs, the pre-existing passivating layer can function effectively in isolating the anode from the solvated Li+, thus suppressing the formation of bulky SEI and the destructive intercalation of solvated Li+. The relevant half-cell (graphite as anode) exhibits a high ICE of 92.1%; the relevant pouch cell with thus passivated CNT film as current collectors for both electrodes (LiCoO2 as cathode, graphite as anode) displays a high energy density of 255 Wh kg−1, spelling an increase of 50% compared with that using the conventional metal current collectors.

Corrosion and protection of aluminum current collector in lithium-ion batteries

<p>Aluminum (Al) current collector, an important component of lithium-ion batteries (LIBs), plays a crucial role in affecting electrochemical performance of LIBs. In both working and calendar aging of LIBs, Al suffers from severe corrosion issue, resulting in the decay of electrochemical performance. However, few efforts are devoted to the research of Al compared to anode and cathode materials, electrolyte, and even separators in LIBs. Here, the recent research advance in Al corrosion and protection is reviewed. We first briefly overview Al corrosion mechanism and its affecting factors. Then, the advanced technologies used to evaluate the electrochemical, morphology and chemical properties of Al are summarized in order to uncover the Al corrosion mechanism in LIBs. Next, we review the Al protection strategies in Al, electrolyte, and inhibitors with function mechanism, materials selection and their structural design. Finally, we outlook the future research direction in Al corrosion and protection. This review provides experimental and theoretical supports in understanding Al corrosion and development of Al anticorrosion, which will be beneficial to the research communities including corrosions, advanced materials, and energy storage devices.</p>

Morphology evolution of the aluminum surface in a fluorine-containing environment.

The interaction between aluminum (Al) and F and O atoms is essential to understand the etching process of Al and alumina (Al2O3) by fluorine-containing gases. In addition, it also has an influence on the corrosion behavior of Al devices, e.g., the Al collector in lithium-ion batteries operates in fluorine-containing electrolytes. However, the understanding of the structural evolution of the Al surface by fluorination at the atomistic level still remains elusive. Here, the thermodynamic and kinetic behaviors of F adatoms as well as co-adsorbed F and O adatoms on typical Al surfaces have been systematically investigated by combining density functional theory (DFT) calculations, canonical Monte Carlo (CMC) simulations and reactive molecular dynamics (RMD) simulations. The results of DFT calculations indicate that there is a repulsion (about 0.07 eV on Al(111) and Al(110), and 0.7 eV on Al(100)) between the first nearest neighboring (1NN) F adatoms, while an attraction of 0.14 eV on Al(111) exists within a 1NN F-O pair. CMC simulations reveal that the configurations of co-adsorbed F and O adatoms on the Al(111) surface at medium to low temperature (<600 K) and low total coverage (<0.2 monolayer, ML) have F adatoms dispersed in the hexagonal islands of O adatoms due to the attraction within the O-O and F-O pairs and the repulsion between F adatoms. As the coverage increases, the surface undergoes serious deformation. The average 1NN coordination numbers (1st CN) of O-to-O, F-to-O and F-to-F are six, three and zero, respectively. As the temperature increases, the interactions among adsorbates begin to be disrupted: the 1st CNs of O-to-O and F-to-O decrease, while that of F-to-F increases. The O-F hexagonal pattern remains until above the Al melting temperature (>1200 K). For F adatoms, both their migration on the surface and the penetration into the subsurface are easier than those of O adatoms, confirmed by both the DFT and RMD simulations. Our study on the co-adsorbates with opposite lateral interactions is instructive for understanding the thermal etching of Al and Al2O3 by fluorine-containing compounds.

Degradation of Al Current Collector in Lithium-Ion Batteries Using Liquid Phase Electron Microscopy

Degradation of Al Current Collector in Lithium-Ion Batteries Using Liquid Phase Electron Microscopy

Petal-shaped Copper(I) bromide Modified Copper/Graphite as Current Collector for Lithium ion Batteries

Petal-shaped Copper(I) bromide Modified Copper/Graphite as Current Collector for Lithium ion Batteries

Structural, Electrical, and Mechanical Properties Investigation of Open-Cell Aluminum Foams Obtained by Spark Plasma Sintering and Replication on Polyurethane Template.

The present paper illustrates a comparison of open-cell aluminum foams. The foams were fabricated by two different methods: spark plasma sintering and replication on a polyurethane template. The influence of pressure, temperature, and diameter of space holding material on foam obtained by the spark plasma sintering method was investigated. Additionally, the aluminum powder content in slurry and atmosphere during thermal processing of foam prepared by the replication technique were studied. The morphology and structure of obtained samples were analyzed by scanning electron microscopy and X-ray diffraction analysis. Supplementarily, mechanical properties and electrical conductivity were studied. The porosity of obtained samples was 83% for the SPS sample and 85% for the replication sample. The results of the studies carried out gave us an understanding that the SPS method is more promising for using the obtained foams as cathode current collectors in lithium-ion batteries due to excessive aluminum oxidation during sintering in the furnace.

EGaIn coated 3D-Cu foam as a self-healing current collector for lithium ion batteries

Traditional lithium-ion batteries are prone to cracks and perforations in extreme environments, which could cause electrochemical performance degradation or even safety problems. Here, based on the alloying reaction of liquid metal, through the adjustment of alloying temperature and reaction time, a uniform and stable dispersion of eutectic gallium indium liquid metal (EGaIn) on the surface and internal structure of the micro-etched 3D-Cu current collector (EGaIn@3D-Cu) is obtained. Furthermore, the graphite anode prepared with the EGaIn@3D-Cu current collector (the self-healing graphite anode) shows an excellent self-healing performance. Namely, the specific capacities of the self-healing graphite anode before and after scratch damage are 327.4 mA h g−1 and 309.6 mA h g−1, respectively, which is significantly better than that of the graphite anode assembled with 2D-Cu foil current collector. Therefore, the EGaIn@3D-Cu current collector prepared by a simple manufacturing process could effectively realizes the self-healing function, prevent the capacity degradation and improve the stability of the battery.

Corrosion of aluminium current collector in lithium-ion batteries: A review

Calendar and cycle ageing affects the performance of the lithium-ion batteries from the moment they are manufactured. An important process that occurs as a part of the ageing is corrosion of the current collectors, especially prominent in the case of the aluminium substrate for the positive electrode. Generally, aluminium resists corrosion due to the formation of a non-permeable film of native aluminium oxide. Nevertheless, at certain electrochemical conditions corrosion affects the interface of the current collector. As a consequence of corrosion, the cathode materials lose electrical and mechanical contact with the current collector, leading to capacity and power fading. Therefore, a deeper understanding of this process and effective corrosion inhibition are necessary to prevent the deterioration of the battery performance. This review provides an updated critical overview of the mechanisms of aluminium corrosion, methodologies for analysing this phenomenon, and approaches for its effective mitigation. As the influence of multiple factors on the corrosion process has a central impact, the review discusses how they specifically affect the undergoing processes. Therefore, appropriate examples of important factors like electrolyte composition, thermal conditions and electrochemical parameters are presented to explain the specific mechanism of aluminium corrosion. Since corrosion inhibition is an important technological issue with a tremendous economic impact the review summarises how to achieve this by adjusting the electrochemical system and enhancing the knowledge on the safe operation of the positive electrode.

Electrochemical deposition of leaf stalk-shaped polyaniline doped with sodium dodecyl sulfate on aluminum and its use as a novel type of current collector in lithium ion batteries

A cyclic voltammetry (CV) method employing a solution containing H2SO4, aniline and sodium dodecyl sulfate (SDS) as the electrolyte solution was utilized to prepare a SDS-doped polyaniline (PANI) film onto the surface of the commercial aluminum (Al) foil at room temperature generating a novel current collector of SDS-PANI coated Al (denoted as SP/Al). The SDS-doped PANI films prepared in the presence of 2 mM, 5 mM and 10 mM SDS were, respectively, nominated as film SP-2, SP-5 and SP-10. As shown by the SEM images, many irregular particles covered with numerous protuberances were prepared in the absence of SDS, and very interestingly, in the presence of SDS, leaf stalk-shaped particles were fabricated on the surface of the commercial Al foil. As indicated by XRD and FTIR results, the main component of the leaf stalk-shaped particles was PANI. Most important of all, the initial discharge capacities of the commercial LiFePO4 (abbreviated as LFP) on the novel current collectors of SP/Al at 0.2 C were all remarkably higher than that of LFP on the commercial Al foil. Particularly, even at 5 C after 10 cycles, the average discharge capacity of LFP on SP-5/Al (65 mA h g−1) was still about 30% larger than that on the traditional Al foil (50 mA h g−1). Presenting the fact, that using the SDS-doped PANI film coated Al foil to replace the conventional Al foil was a feasible way to promote the electrochemical performance of LFP, is the main dedication of this preliminary work.

Highly Reduced Graphene Assembly Film as Current Collector for Lithium Ion Batteries

Highly Reduced Graphene Assembly Film as Current Collector for Lithium Ion Batteries

Effect of deposition temperature on mechanical properties of nanotwinned Cu fabricated by rotary electroplating

A rotary electroplating system was used to fabricate high-strength nanotwinned copper (nt-Cu) foils with slanted columnar grain structures, which may serve as the anode current collector in lithium ion batteries (LIBs). By controlling the temperature of electrolyte bath and current density during electroplating, it is possible to tune the nanotwinned microstructure to optimize mechanical properties of the electroplated nt-Cu foils. The ultimate tensile strength (UTS) of nt-Cu foils has been enhanced by 60% of the ordinary nt-Cu from 403 MPa to 637 MPa. We found that UTS of the electroplated nt-Cu foils increases with decreasing temperature of electrolyte bath. The tensile strength of the nt-Cu foils increases approximately by 10 MPa for 1 °C decrease in the electrolyte temperature. The highest UTS of 637 MPa was obtained in rotary-electroplated at 6 °C and a current density of 11 ASD.

Significant enhancement of corrosion resistance of stainless steel with nanostructured carbon coatings by substrate-catalytic CVD

The bipolar plate is the major component of proton-exchange membrane fuel cells and also a critical contributor to the fuel cell performance. Metallic bipolar plate (MBP) has high impact resistance but its poor chemical stability limits the service lifetime and stack stability. One of the feasible methods to enhance the corrosion resistance of MBPs is the formation of conductive protective coatings on the MBP surface. In this work, nanostructured carbon coatings were deposited on stainless steel by chemical vapor deposition using the substrate itself as catalysts. Under the optimized conditions, the corrosion potential of carbon coatings with dense spherical structure on stainless steel (2.1 VRHE) is much higher than that of uncoated one (1.2 VRHE), and even greater than that of commercial graphite bipolar plates (1.7 VRHE), showing 75% and 23.5% improvement in corrosion resistance, respectively. Moreover, the corrosion current density of stainless steel with dense sphere-assembled coatings decreases to 0.2 mA/cm2, which is two orders of magnitude lower than that of graphite bipolar plates (27.4 mA/cm2) at the same applied potential (2.2 VRHE). The coated stainless steel with excellent anticorrosion properties has potential applications for MBPs in proton-exchange membrane fuel cells, electrochemical treatment of waste water, and current collectors in lithium-ion batteries.

Back cover: Investigating the oxidation state of Fe from LiFePO4‐based lithium ion battery cathodes via capillary electrophoresis (elps.202000097) and Accessing copper oxidation states of dissolved negative electrode current collectors in lithium ion batteries (elps.202000155)

Back cover: Investigating the oxidation state of Fe from LiFePO₄‐based lithium ion battery cathodes via capillary electrophoresis (elps.202000097) and Accessing copper oxidation states of dissolved negative electrode current collectors in lithium ion batteries (elps.202000155)

Novel Cathode Electrode with Superior Rate Capability Using Perforated Aluminum Current Collector for Lithium-Ion Batteries

Electrodes were fabricated using a perforated aluminum current collector and a standard aluminum foil, and the relationship between the electrochemical performance of the battery and the current collector was investigated. The perforated aluminum foil improved the contact characteristics between the cathode materials particles and the current collector. Also, electrochemical performance indicators such discharge capacity and rate characteristics were improved due to the increased adhesion of the electrode using the perforated current collector.

Taguchi method in experimental procedures focused on corrosion process of positive current collector in lithium-ion batteries

Planning the design and discussing the results are routine tasks carried out daily by researchers all over the world. This study is focused on making these stages of research time- and cost-efficient without affecting the reliability of the data. Following the principles of the Taguchi method brings such a result. This approach ensures the quality of research by optimisation of the experimental procedure. In the presented work, the Taguchi method solves an exemplary research problem of the corrosion process of aluminium current collector in lithium-ion batteries. Operating factors selected for the optimisation include temperature (25, 35, 45 °C), the volume ratio of ethylene carbonate to diethyl carbonate in the solvent (1:1, 1:2, 1:4), and type of lithium salt (LiPF6, LiTFSI, LiBOB). Using three operating factors with three levels of variability requires data assembly in an orthogonal array L9 with nine experimental runs in total. In this study, the Taguchi approach is validated by performing a full-factorial procedure of twenty-seven individual experiments. The response of tested systems is analysed by cyclic voltammetry and electrochemical impedance spectroscopy, which enables the evaluation of corrosion parameters in each experimental run. The assessed parameters indicate the intensity of the aluminium corrosion depending on the operating conditions. These conditions cause unwanted variance, which accelerates corrosion and lowers the life expectancy of lithium-ion batteries. The Taguchi signal-to-noise-ratio analysis reveals that the most significant variation is caused by the lithium salt in the electrolyte (S/N LiBOB ≥ LiPF6 > LiTFSI). Temperature and alkyl carbonates play a secondary role. The Taguchi prediction method is also consistent with the full-factorial approach, which warrants reliability.

Accessing copper oxidation states of dissolved negative electrode current collectors in lithium ion batteries.

A novel capillary electrophoresis (CE) method with ultraviolet-visible spectroscopy (UV-Vis) detection for the investigation of dissolved Cu+ and Cu2+ in lithium ion battery (LIB) electrolytes was developed. This method is of relevance, as the current collector at the anode of LIBs may dissolve under certain operation conditions. In order to preserve the actual oxidation states of dissolved copper in the electrolytes and to prevent any precipitation during sample preparation and CE measurements, neocuproine (NC) and ethylenediamine tetraacetic (EDTA) were effectively applied as complexing agents for both ionic copper species. However, precipitation and loss of the Cu+ -NC-complex for quantification occurred in presence of the commonly applied conducting salt lithium hexafluorophosphate (LiPF6 ). Therefore, acetonitrile (ACN) was added to the sample in order to suppress this precipitation. Dissolution experiments with copper-based negative electrode current collectors in a LIB electrolyte were conducted at 60°C under non-oxidizing atmosphere. First findings regarding the copper species via CE revealed dissolved Cu+ and mainly Cu2+ . However, primarily Cu+ dissolved from the passivating oxide layer (Cu2 O and CuO) of the current collector due to the formation of acidic electrolyte decomposition products. Due to the instability of Cu+ in the electrolyte a further disproportionation reaction to Cu0 and Cu2+ occurred. The results show the high potential of this CE method for prospective investigations regarding the current collector stability in new battery electrode formulations and correlations of dissolution events with dissolution mechanisms and battery cell operation conditions.