Corrosion of Aluminum Current Collector in Cost Effective Rechargeable Lithium-Ion Batteries

Rechargeable lithium ion batteries (LIB) have been widely used as commercial energy storage systems for portable equipment, electronic devices and high power applications (e.g. electronic vehicles). One issue with the commercialized LIB is that expensive, highly toxic and flammable organic solvents are used in the electrolyte and the fabrication process of electrodes. The toxic organic based solvents increase the production cost and lead to significant safety concerns in the event of a battery overcharge or short circuit. The recent development of “green manufacturing” technology allows manufacturers to replace the organic solvents used in the cathode coating process by aqueous based slurries. In addition, the further transition from organic based LIB system to completely aqueous based lithium ion battery (ARLB) has attracted a lot of attention recently because of its potential to significantly reduce manufacturing cost and eliminate the risks and environmental issues associated with the commercialized, organic based lithium ion batteries. Such new aqueous-based technologies often use basic aqueous solutions with high pH value, which brings concerns on the possible occurrence of aluminum current collector corrosion. The corrosion of aluminum current collector in lithium ion batteries is one of the possible factors that affect the long-term performance and safety of lithium-ion batteries. In this work, the corrosion phenomenon of aluminum current collector in lithium ion batteries that use aqueous-based chemistries is explored experimentally and theoretically. Here, the corrosive aqueous media defined in lithium-ion battery systems includes the aqueous based slurry used in the fabrication of cathode coating, aqueous lithium nitrate electrolyte and aqueous lithium sulfate electrolyte. This research aims to reveal the corrosion behavior, corrosion mechanisms and corrosion kinetics of aluminum in exposure to aqueous environment during the fabrication and service life of aqueous-based lithium-ion battery systems, and shed light on the management of corrosion in the design of cost effective lithium ion batteries. Corrosion of aluminum can occur during the manufacturing of lithium ion batteries when aqueous-based cathode slurries is used during cathode coating process. The corrosion mechanism of AA1085 in exposure to aqueous based cathode slurry was investigated by surface characterization on aluminum after exposure tests and measuring electrochemical characteristics. In exposure tests, the alkaline pH value of aqueous-based cathode slurries and immersing time were revealed as the principle factors that control the corrosion of aluminum during the cathode manufacturing process. The nickel manganese cobalt oxide active material used in the slurry does not have a direct impact on corrosion of the aluminum current collector. The initiation and evolution of localized corrosion on aluminum are closely related to the formation of galvanic cells between aluminum matrix and intermetallic particles. X-ray photoelectron spectroscopy confirmed that the pH of cathode slurry was the only factor that influence the surface composition of aluminum. The oxide passive film gradually degraded into hydroxide with the elapsing exposure time. Electrochemical characterizations showed that aluminum electrodes gave remarkably different response to the different pH of test solutions. The time-pH-variant electrochemical response was ascribed to the change of passive film and electric double layer properties. The electrochemical stability of high-purity aluminum in 2 M Li2SO4 and 5 M LiNO3 ARLB electrolytes was evaluated over a range of pH conditions by cyclic voltammetry, linear sweep voltammetry and chronoamperometry. Aluminum presented high corrosion resistance at pH 5, pH 7 and pH 9 within the stability windows of both electrolytes. At the pH 11 condition, 2 M Li2SO4 is capable of inhibiting aluminum from pitting, although the inhibiting effect is not sustainable and crystallographic pitting occurs under a continuously applied anodic potential. Aluminum was well passivated against pitting in 5 M LiNO3 electrolyte at pH 11 due to the formation of a thick corrosion product barrier layer. Raman spectra showed the presence of sulfate and nitrate anions on aluminum surface after cyclic voltammetry at pH 11. The chemical adsorption mechanisms of sulfate and nitrate anions on aluminum were proposed to explain the dependency of electrochemical stability of aluminum on pH, anodic potential and type of anions. The applicability of aluminum as current collector in ARLB using the 2 M Li2SO4 and 5 M LiNO3 electrolytes was discussed. The corrosion kinetics of AA1085 in Li2SO4 and LiNO3 aqueous rechargeable lithium-ion battery electrolytes at pH 11 under the influence of various experimental variables was studied using chromoamperometry. AA1085 is susceptible to crystallographic pitting corrosion in Li2SO4 electrolytes. The rate of pit nucleation and the rate of pitting growth on AA1085 both decreased at higher Li2SO4 concentrations or at lower anodic potentials. In LiNO3 electrolytes, AA1085 was passivated against pitting corrosion due to the formation of a thick, uniform corrosion product layer. The repassivation rate was slightly enhanced by increasing the electrolyte concentration and anodic potentials. X-ray photon electron spectroscopy spectra showed the formation of a thin sulfate-incorporated passive film, which comprises Al2(SO)418H2O, Al(OH)SO4 and Al(OH)3 on electrode before the occurrence of pitting growth in 2 M Li2SO4 electrolyte. The thick corrosion product layer formed in 5 M LiNO3 electrolyte is composed of Al(OH)3 and AlOOH. Raman spectroscopy on deionized water, LiOH solution, Li2SO4 and LiNO3 depicted changes of solution structure with increasing electrolyte concentrations. The influence of extrinsic factors, including the alkaline solution and the anodic potential, and intrinsic factors, such as the surface chemical adsorption of anions, chemical state of passive films and dissolubility of electrolytes, on the corrosion kinetics of AA1085 in slightly alkaline Li2SO4 and LiNO3 electrolytes are revealed. The intermetallic particles containing Fe and Si in aluminum alloys have electrochemical potentials that differ from that of aluminum matrix, resulting in the formation of galvanic couples and detrimental pitting corrosion. The electrochemical characteristics of AA1100, surface treated AA1100 with “intermetallic-free” surface, home-synthesized Al2Fe and Al2FeSi0.67 alloy were measured by potentiodynamic polarization in alkaline solutions with the addition of Li2SO4 and LiNO3. In general, intermetallic alloys presented noble corrosion potentials compared to AA1100 specimens. The addition of sulfate anions in the solution does not suppress the selective dissolution of aluminum on intermetallic alloys in 0.001 M and 1 M LiOH solutions, which increases the cathodic efficiency of intermetallic alloys and promotes the galvanic corrosion. The corrosion potential difference is significantly reduced when 2 M LiNO3 is added into the alkaline solution. Meanwhile the anodic dissolution rate that corresponds to the preferable dissolution of Al also decreases. Raman spectra revealed that the inhibiting effect of LiNO3 on selective dissolution of aluminum is due to the formation of Fe3O4 passive film above the corrosion potential. the cathodic polarization curves showed that the intermetallic alloys sustain higher cathodic current than AA1100 and surface-treated Al. The magnitude of cathodic current density measured on the electrodes follows the following order: Al2Fe\u3eAl2FeSi0.67\u3eAA1100\u3esurface-treated AA1100. The change of composition and structure on the intermetallic surface during anodic polarization influences the selective dissolution process, the passivity status and in turn affects the cathodic efficiency of the intermetallic

Predictive Modeling Techniques for Adaptive Face Retouching

This publication describes predictive modeling techniques for adaptive face retouching according to a predictive model on a computing device. The adaptive face retouching enables preservation of important features that may depict diversity, persona, and uniqueness in images where retouching is applied by a computer. In the techniques, an algorithm may be implemented to balance image attributes from a variety of sources and categories. The algorithm may further reduce unnecessary, redundant processing on the computing device by storing computed attributes within a facial attribute database. As such, diverse facial features may be maintained while allowing adequate face retouching without requiring overuse of computing resources

Excitation of extraordinary modes inside the source of Saturn's kilometric radiation

The electron cyclotron maser instability (ECMI) of extraordinary mode waves was investigated with the parameters observed in Saturn's kilometric radiation (SKR) sources. Previous studies employed simplified dispersion relations, and did not consider the excitation of the relativistic (R) mode. This mode is introduced by considering the relativistic effect in plasmas consisting of both cold and hot electrons. Using particle-in-cell simulations, we investigated the excitation of R and X modes based on the measured data. Using the reported value of the density ratio of energetic to total electrons $n_e/n_0=24\%$, the most unstable mode is the R mode. The escaping X-mode emissions are amplified only if the energetic electrons are dominant with $n_e/n_0 \ge 90\%$. For these cases, only the X mode is excited and the R mode disappears due to its strong coupling. The results are well in line with the linear kinetic theory of ECMI. The properties of both the R and X modes are consistent with the observed SKR emissions. This raises questions about the nature of the measured electric field fluctuations within ``presumed'' SKR sources. The study provides new insights into the ECMI process relevant to SKR emission mechanisms

High-sensitivity graphene MEMS force and acceleration sensor based on graphene-induced non-radiative transition

The micro-electromechanical-system (MEMS) force and acceleration sensor utilizing the graphene-induced non-radiative transition was investigated. The graphene-induced non-radiative transition is very sensitive to the distance, and the deflection of the graphene ribbon is highly susceptive to applied force or acceleration. Thus, a high-sensitivity MEMS sensor can be achieved with detecting the graphene ribbon's deflection of 1 nm, the force of 0.1 pN, and the acceleration of 0.1 mg. The MEMS sensor, with a size of only tens of microns, can be charged by light irradiation without connecting power sources. In addition, it allows long-distance detection, i.e., wireless transmitter circuit can be omitted. Therefore, it will have significant application prospects in the fields of micro-smart devices, wearable devices, biomedical systems, and so on.Comment: 21 pages, 4 figure

Design and Parameter Study of a Self-Compensating Hydrostatic Rotary Bearing

The influence of design parameters on the static performance of a newly designed self-compensating hydrostatic rotary bearing was investigated. The bearing was designed by incorporating the main attributes of angled-surface self-compensating bearing and opposed-pad self-compensating bearing. A governing model based on flow conservation was built to theoretically study the static performance, and the methodology was validated by experiments. It is pointed out that the influence factors on the bearing static performance are the designed resistance ratio of the restricting land to the bearing land, the inner resistance ratio of the land between pockets to that between the pocket and the drain groove, the initial clearance ratio of the restricting gap to the bearing gap, and the semiconical angle. Their effects on the load carrying capacity and stiffness were investigated by simulation. Results show that the optimum designed resistance ratio is 1; the initial clearance ratio should be small, and the inner resistance ratio should be large

Self-assembly of copper and cobalt complexes with hierarchical size and catalytic properties for hydroxylation of phenol

A feasible and effective self-assembly method to synthesize different scale coordination polymers in highly dilute solution (from nanocrystals to microcrystals and to bulk crystals) without any blocking agent has been described. The growth of crystalline particles was controlled by removing the particles at different reaction times to interrupt the growth at the desired size. The nano and microscale particles show better catalytic conversions and selectivities in the hydroxylation of phenols than the bulk crystals

BRAD, the genetics and genomics database for Brassica plants

<p>Abstract</p> <p>Background</p> <p>Brassica species include both vegetable and oilseed crops, which are very important to the daily life of common human beings. Meanwhile, the Brassica species represent an excellent system for studying numerous aspects of plant biology, specifically for the analysis of genome evolution following polyploidy, so it is also very important for scientific research. Now, the genome of <it>Brassica rapa </it>has already been assembled, it is the time to do deep mining of the genome data.</p> <p>Description</p> <p>BRAD, the Brassica database, is a web-based resource focusing on genome scale genetic and genomic data for important Brassica crops. BRAD was built based on the first whole genome sequence and on further data analysis of the Brassica A genome species, <it>Brassica rapa </it>(Chiifu-401-42). It provides datasets, such as the complete genome sequence of <it>B. rapa</it>, which was <it>de novo </it>assembled from Illumina GA II short reads and from BAC clone sequences, predicted genes and associated annotations, non coding RNAs, transposable elements (TE), <it>B. rapa </it>genes' orthologous to those in <it>A. thaliana</it>, as well as genetic markers and linkage maps. BRAD offers useful searching and data mining tools, including search across annotation datasets, search for syntenic or non-syntenic orthologs, and to search the flanking regions of a certain target, as well as the tools of BLAST and Gbrowse. BRAD allows users to enter almost any kind of information, such as a <it>B. rapa </it>or <it>A. thaliana </it>gene ID, physical position or genetic marker.</p> <p>Conclusion</p> <p>BRAD, a new database which focuses on the genetics and genomics of the Brassica plants has been developed, it aims at helping scientists and breeders to fully and efficiently use the information of genome data of Brassica plants. BRAD will be continuously updated and can be accessed through <url>http://brassicadb.org</url>.</p

GeoGauss: Strongly Consistent and Light-Coordinated OLTP for Geo-Replicated SQL Database

Multinational enterprises conduct global business that has a demand for geo-distributed transactional databases. Existing state-of-the-art databases adopt a sharded master-follower replication architecture. However, the single-master serving mode incurs massive cross-region writes from clients, and the sharded architecture requires multiple round-trip acknowledgments (e.g., 2PC) to ensure atomicity for cross-shard transactions. These limitations drive us to seek yet another design choice. In this paper, we propose a strongly consistent OLTP database GeoGauss with full replica multi-master architecture. To efficiently merge the updates from different master nodes, we propose a multi-master OCC that unifies data replication and concurrent transaction processing. By leveraging an epoch-based delta state merge rule and the optimistic asynchronous execution, GeoGauss ensures strong consistency with light-coordinated protocol and allows more concurrency with weak isolation, which are sufficient to meet our needs. Our geo-distributed experimental results show that GeoGauss achieves 7.06X higher throughput and 17.41X lower latency than the state-of-the-art geo-distributed database CockroachDB on the TPC-C benchmark

TRACE ELEMENTS MAY BE RESPONSIBLE FOR MEDICINAL EFFECTS OF SAUSSUREA LANICEPS, SAUSSUREA INVOLUCRATE, LYCIUM BARBARUM AND LYCIUM RUTHENICUM

Background: The pharmacodynamics of Saussurea laniceps, Saussurea involucrata, Lycium barbarum and Lycium ruthenicum have been researched, and trace elements have been considered as the essential elements, but little attention has been paid to the trace elements of the herbal medicine. We would like to report on the content of copper (Cu), manganese (Mn), iron (Fe), zinc (Zn) and selenium (Se) levels in the four herbal medicines. Materials and Methods: A total of 20 whole plant materials were collected of each species in China. The content of Cu, Mn, Fe and Zn in the dried aerial parts was estimated by the standard atomic absorption spectrophotometry. The level of Se was detected using hydride generation atomic fluorescence spectrometry. Results: The mean concentrations of Cu, Mn, Fe, Zn and Se in S. laniceps were 7.758±0.924μg/g, 201.3±16.24μg/g, 222.7±35.10μg/g, 18.48±2.913μg/g and 1.42±0.16μg/g, respectively; S. involucrata were 19.56±2.20μg/g, 88.75±8.53μg/g, 812.7±126.9μg/g, 34.85±3.81μg/g and 1.04±0.05μg/g, respectively; L. barbarum were 10.83±0.26μg/g, 9.598±0.32μg/g, 55.65±3.83μg/g, 11.92±0.27μg/g and 11.84±0.59μg/kg, respectively; L. ruthenicum were 12.67±0.39μg/g, 13.78±1.13μg/g, 98.04±5.03μg/g, 14.46±1.27μg/g and 35.12±2.34μg/kg, respectively. Conclusion: This study provided the trace elements content of Cu, Mn, Fe, Zn and Se in the four herbal medicines. The trace elements are maybe other functional compounds for medicinal effects. Deep relationship between pharmacological and trace elements contents, especially its mechanism of action should be future research

Obeticholic acid and ferrostatin-1 differentially ameliorate non-alcoholic steatohepatitis in AMLN diet-fed ob/ob mice

Introduction: Non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH) are common chronic liver diseases with limited treatment options.Methods: Ob/ob mice (6 weeks old) were fed with the Control diet or amylin liver NASH (AMLN) diet for 24 weeks to establish the NASH, the AMLN diet-fed mice were treated with obeticholic acid (OCA), ferrostatin-1 (Fer-1) or their combination for 7 weeks. Finally, various clinical profiles were assessed.Results: Our results indicate that Fer-1 exerts better effects on improving body weight, blood glucose levels, transaminase levels and insulin resistance than OCA. OCA has a profound effect on ameliorating lipid accumulation. OCA and Fer-1 differentially inhibit the activation of hepatic Kupffer cells and HSCs. The combination of OCA and Fer-1 significantly reduces inflammation and protects mice against liver oxidative stress. OCA and Fer-1 differentially reshape the intestinal microbiota and affect the hepatic lipidome.Discussion: Our study compares the effects of OCA, Fer-1 and their combination on various clinical profiles in NASH. These data demonstrate that different drug combinations results in different improvements, and these discoveries provide a reference for the use of the OCA, Fer-1 and their combination in the clinical treatment of NAFLD/NASH