Anode Current Collector Research Articles

Guiding lithium-ion flux to avoid cell's short circuit and extend cycle life for an anode-free lithium metal battery

The uncontrolled lithium dendrite growth during cycling causes safety issues that impede lithium metal batteries from practical applications. In anode-free lithium metal batteries (AFLMBs), the unregulated plating of lithium on bare copper enforces a more severe growth of lithium dendrite. Herein, we guide the direction of lithium (Li) depositions towards the backside of gold sputter perforated polyimide film (PI@Au), which serves as an anode current collector. Thus, Li can deposit on the surface of PI@Au, and subsequently, Li growth takes place in the direction away from the separator face (ASF). This backside deposition and growth tactic allow the battery to operate safely, even when lithium dendrite exists. Remarkably, the dendrite free separator facing (SF) of PI@Au anode demonstrates highly improve cycling stability. Hence, PI@Au//LFP cell is capable of maintaining capacity retention (CR) of 20% for 340 cycles with an average Coulombic efficiency (Av. CE) of 98.7% (0.5 mA/cm2). In contrast, the control cell (Cu//LFP) runs only for 165 cycles under the same value of CR. This work not only proposes an innovative approach in developing ultra-safe AFLMBs but also validates the feasibility of electrically nonconductive substrates as anode current collectors by modifying their lithiophilicity.

An integrated highly stable anode enabled by carbon nanotube-reinforced all-carbon binder for enhanced performance in lithium-ion battery

Conversion and alloy-type anode materials suffer from large volume expansion during lithiation process, which causes the destruction of intact electrode structure and loss of efficient electrical contact between current collector and particles of anode material, resulting in fast capacity decay and poor cycling stability. Herein, a combined slurry-casting and heat-treatment approach has been adopted to prepare highly stable integrated anode composed of anode materials particles and all-carbon binder consisting of commercial carbon nanotubes (CNTs) and polyvinylidene fluoride (PVDF) derived carbon. This all-carbon binder shows a strong cohesive ability to copper current collector compared with traditional PVDF binder, and could effectively bind anode material particles and current collector. Moreover, CNTs reinforced all-carbon binder provides a robust mechanical and high conductive network to ensure structural stability of integrated anode, in which volume expansion of anode materials could be effectively suppressed during lithiation process. The integrated electrode with tin dioxide and silicon as active materials exhibits remarkable long-term cycling stability, maintaining 861.4 mA h g−1 after 500 cycles and 902.4 mA h g−1 after 300 cycles at 0.5C, respectively. This simple yet effective strategy is compatible with the traditional anode manufacture process, demonstrating its great potential in the practical use.

Rolled electrodeposited copper foil with modified surface morphology as anode current collector for high corrosion resistance in lithium-ion battery electrolyte

A novel preparation method has been proposed that using electrodeposited copper foil as raw material and then performing asymmetrical rolling and surface morphology modification to improve the corrosion resistance of the copper foil current collector in lithium-ion battery electrolyte for long-term storage. The results of electrochemical experiments show that the corrosion current density of rolled electrodeposited (RE) copper foil is only 10% of that of electrodeposited (ED) copper foil. After RE copper foil is stored in the electrolyte for 100 days, its capacity retention rate is ~91.2%, which is much higher than 75.6% of ED copper foil and 80.8% of rolled copper foil. The fraction of low-Σ CSL boundaries of RE copper foil is 33.6%, which is much higher than 2.2% for rolled copper foil and 8.7% for ED copper foil. The large fraction of low-Σ CSL boundaries and disrupted RHABN in RE copper foil is an effective structure to inhibit corrosion; Asymmetrical rolling and surface morphology modification significantly increase the compressive residual stress and surface roughness of RE copper foil, which can effectively improve the corrosion performance of copper foil. The RE copper foil with modified surface morphology provides a new idea for the next generation of high-performance lithium-ion battery current collector materials.

3D Printed Lithium-Metal Full Batteries Based on a High-Performance Three-Dimensional Anode Current Collector

A three-dimensional (3D) printing method has been developed for preparing a lithium anode base on 3D-structured copper mesh current collectors. Through in situ observations and computer simulations, the deposition behavior and mechanism of lithium ions in the 3D copper mesh current collector are clarified. Benefiting from the characteristics that the large pores can transport electrolyte and provide space for dendrite growth, and the small holes guide the deposition of dendrites, the 3D Cu mesh anode exhibits excellent deposition and stripping capability (50 mAh cm-2), high-rate capability (50 mA cm-2), and a long-term stable cycle (1000 h). A full lithium battery with a LiFePO4 cathode based on this anode exhibits a good cycle life. Moreover, a 3D fully printed lithium-sulfur battery with a 3D printed high-load sulfur cathode can easily charge mobile phones and light up 51 LED indicators, which indicates the great potential for the practicability of lithium-metal batteries with the characteristic of high energy densities. Most importantly, this unique and simple strategy is also able to solve the dendrite problem of other secondary metal batteries. Furthermore, this method has great potential in the continuous mass production of electrodes.

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.

Analysis of current collection in micro-tubular solid oxide fuel cells: An empirical and mathematical modelling approach for minimised ohmic polarisation

Data from electrochemical impedance spectroscopy (EIS) of a 152 mm long, 6.8 mm outer diameter (OD) segmented-in-series micro-tubular solid oxide fuel cell (μT-SOFC) coupled with equivalent circuit modelling (ECM) support a circuit model and a continuum resistance path model to investigate the ohmic polarisation and current distribution for various current collector configurations on a micro-tube. Minimising the characteristically long axial current conduction pathways of μT-SOFCs is critical to maximise cell performance, particularly of cells more than a few centimetres long. Optimal positioning of a single current collector minimises the performance losses from the electrode. Multiple current collector terminals increase cell performance over a single terminal, but positioning must still be optimised. Sizing of the current collector terminal is critical to limit the loss of active area of the cathode. A trade-off between terminal sizing/spacing and loss of active area can lead to sub-optimal current collection. The models are generalised for all possible current collector configurations. We identify simple criteria to determine the maximum current collection efficiency of single and multiple anode current collectors for a range of cell geometries. The design tool allows early consideration to cell sizing as a function of anode current collection during cell and stack development.

Lithiophilic and Antioxidative Copper Current Collectors for Highly Stable Lithium Metal Batteries

AbstractDesigning copper (Cu) current collectors is a convenient way to stabilize lithium (Li) metal anodes. However, Cu current collectors and their derived Li/Cu anodes still face several obstacles, including lithiophobic and oxidizable Cu surface, cumbersome anode fabrication process, and low Li utilization. Here, a formate‐treatment strategy is presented to reconstruct Cu current collectors with a passivation layer covered Cu(110) surface. This method can easily be generalized to increase the lithiophilicity and oxidation resistibility of Cu current collectors. Using the formate‐treated Cu nanowire network as an anode current collector, the full cell consisting of a LiFePO4 cathode and Li/Cu anode with a low negative/positive capacity ratio delivers an excellent cycling performance with 74.8% capacity retention after 1000 cycles at 1 C. In addition, a concept of an upper current collector is introduced to simplify the manufacturing procedure of Li/Cu anodes. This work provides new insights into the design and construction of high‐performance Li/Cu anodes.

Rolled electrodeposited copper foil with modified surface morphology as anode current collector for high performance lithium-ion batteries

Abstract A novel method that taking electrodeposited copper foil as a raw material undergoes asynchronous rolling and surface morphology modification at room temperature was proposed, and the rolled electrodeposited (RE) copper foil with excellent mechanical properties and modified surface morphology was obtained to be used as the anode current collector of high-performance lithium-ion batteries. The surface roughness of RE copper foil (Ra = 1.8 μm) is significantly higher than that of the traditional electrodeposited copper foil (Ra = 0.22 μm) when the thickness is 6 μm. The hilly surface morphology of RE copper foil helps to enhance the interfacial adhesion between current collector and active material, which contributes to the reduction of charge transfer resistance and improvement of specific capacity and rate performance. The mechanical properties of RE copper foil are significantly improved after asynchronous rolling. The excellent mechanical properties of RE copper foil current collector can maintain good electrical contact integrity of electrode active material during lithiation-de-lithiation and significantly improve the cycle life. The discharge capacity of RE electrode is maintained at 329.6 mAh g−1 and exhibits 91.1% capacity retention for 200 cycles at 500 mAg−1, which is much higher than the electrodes with electrodeposited and rolled copper foils as the current collector.

Local Measurement of Anode Current Collector Potential in a PEM Water Electrolyzer

The current collector (CC) components (bipolar plate and porous transport layer) of a polymer electrolyte membrane water electrolyser (PEMWE) comprise one of the highest proportion of the cost of the stack [1]. It is widely accepted that the PEMWE CC material needs to withstand the relatively high potentials encountered at the anode electrode, with ex situ qualification testing typically carried out at an applied potential of at least 2 V vs the standard hydrogen electrode (SHE). As a result, platinum-coated titanium is the common material of choice. However, we offer a counter hypothesis that it is unlikely that the corrosion potential of the anode CC is equal to that of the anode electrode due to the very low ionic conductivity of the pure water phase separating the two components.In this work, an innovative in situ reference electrode consisting of a Nafion®/H2SO4 salt bridge connected to a reversible hydrogen electrode is used to measure the corrosion potential of the anode CC during PEMWE cell operation. Using this technique, we demonstrate for the first time that the corrosion potential of the anode current collector is effectively decoupled from that of the anode electrode [2]. Furthermore, we demonstrate that carbon paper can be applied as anode CC material without any noticeable corrosion taking place.The implications of this work are that significantly cheaper materials such as carbon or carbon-coated stainless steel can be used for CC components, which could reduce the cost of PEMWE technology substantially. The key advance is the use of a thin porous spacer layer between the anode and the CC. Factors that may influence the implementation of this new concept are discussed, including the influence of spacer layer tortuosity and water conductivity on the corrosion potential of the CC.

Depletion of Lithium Inventory and Devolution of Lithium-Electrolyte Interface in Lithium-Sulfur Batteries

The lithium-sulfur (Li-S) chemistry holds tremendous potential for realizing the next generation of rechargeable batteries with high energy density and low cost. Despite its promise, the practical development of Li-S batteries is hindered by its limited cyclability, which is mainly caused by the poor plating and stripping efficiency of the lithium-metal anode. In liquid electrolytes, lithium deposits adopt a mossy dendritic filamentous morphology with high surface area. Due to the reactive nature of lithium, the electrolyte irreversibly decomposes on the lithium surface, which consumes both the lithium and electrolyte supply in the cell. However, significant questions remain about the mechanisms that underlie lithium inventory loss and the role of the lithium-electrolyte interface. Further commercial adoption of Li-S batteries is conditional on developing an effective strategy for improving the reversibility of lithium deposition, which is in turn dependent on developing a clear mechanistic understanding of lithium degradation with cycling.In this study, we use the anode-free full cell configuration, which pairs a Li2S cathode with a bare nickel foil as the anode current collector. Since there is no excess lithium in the system (N/P ratio = 1), the cyclability of anode-free full cells depends on the electrochemically accessible lithium inventory in the system. By identifying the sulfur-limited and lithium-limited regimes in the cycling of anode-free full cells, the lithium inventory loss rate per cycle (LILR) can be quantitatively estimated. This parameter provides an effective, robust, and quantifiable description of lithium degradation with cycling in cells with a limited lithium inventory. Lithium degradation displays a strong dependence on the applied current density, with the LILR increasing from 0.6% per cycle to 1.8% per cycle when the current rate is increased from C/10 to C/5.Time-of-flight secondary ion mass spectrometry (ToF-SIMS) was applied to analyze the chemical composition of the deposited lithium in the anode-free full cells with different cycle numbers. The integrated intensity for Li2 -, which is indicative of metallic lithium, was found to show negligible variation with cycle number. In contrast, the electrochemically accessible lithium inventory is known to show a clear decrease with cycling. Thus, there is poor correlation between the lithium inventory available with cycle number and the amount of metallic lithium detected with ToF-SIMS. This indicates that lithium inventory depletion in Li-S batteries is not just due to the loss of lithium in parasitic side reactions with the electrolyte to form lithium SEI compounds (Li+), but largely due to the formation of electrochemically inaccessible “dead” metallic lithium. Further analysis with ToF-SIMS revealed the growth of a thick layer of electrolyte decomposition products on the surface of the deposited lithium. Since the decomposition products are expected to be ionically insulating, lithium-ion access to and from the metallic lithium underneath is blocked, which renders it electrochemically inaccessible or “dead”.The bulk of the deposited lithium is found to be composed of fully reduced decomposition products, such as Li2O, Li2S, LiH, and LiOH. In particular, the hydrogen-containing decomposition products such as LiH and LiOH are found to show a sharp decrease in concentration with cycling. This is attributed to the substantial gas evolution that occurs at the lithium anode during cell operation. These gases include H2, CH4, and C2H4, and their generation is correlated with the loss of lithium inventory with cycling. This could play an additional role in limiting electrochemical accessibility to the trapped metallic lithium by blocking off ionic and electronic conduction pathways, especially if the gases themselves are trapped in void spaces of the porous lithium deposit.This work illuminates the mechanisms that underlie the loss of lithium inventory in Li-S batteries by a careful application of the anode-free full cell configuration and analytical tools, such as ToF-SIMS. The role of the devolving lithium-electrolyte interface in engendering lithium degradation with cycling is clarified. The framework demonstrated in this work and the conclusions drawn are applicable not just to Li-S batteries, but to lithium-metal-based batteries in general. It is hoped that the insights generated in this work can motivate efforts towards enabling stable operation of lithium-metal anodes and long cycle life for energy-dense Li-S batteries. Figure 1

Tellurium-Polysulfide Chemistry Enables Stable Operation of Lithium-Sulfur Batteries with Limited Lithium Inventory and Electrolyte Supply

The practical realization of lithium-sulfur (Li-S) batteries with high energy density is currently limited by the poor cyclability of the lithium-metal anode. Lithium plating and stripping in the liquid ether-based electrolyte is irreversible over long-term cycling and this leads to rapid capacity fade. Due to the reducing nature of lithium, parasitic side reactions with the electrolyte also occur with considerable severity during cell operation. This eliminates a significant portion of the available lithium inventory and electrolyte supply, and the cell fails prematurely. These problems can be sidestepped by employing surplus lithium and electrolyte in the cell, but this compromises the stack-level energy density. Stabilizing lithium deposition and reducing electrolyte decomposition is of critical importance to enabling commercially viable Li-S batteries with high energy density and long cycle life.The chemistry of Li-S batteries is unique due to the generation of polysulfide intermediates at the cathode that are soluble in the electrolyte. The polysulfides migrate to the anode side, which fundamentally alters its interfacial chemistry by forming reduced sulfide species (Li2S/Li2S2) on the lithium surface. These species are known to have an intrinsically stabilizing effect on lithium deposition, although it is not sufficient to enable stable operation of Li-S batteries at reasonable current densities. Nevertheless, the modification of electrolyte-soluble polysulfide species offers a unique opportunity for tuning the interfacial chemistry of the lithium-metal anode towards stabilizing lithium deposition and reducing electrolyte decomposition.Tellurium, which sits two position below sulfur in Group 16 of the periodic table, is an excellent candidate element for modifying the composition of polysulfide intermediates in Li-S batteries and forming potentially favorable components in the lithium SEI layer. It was found that elemental tellurium (Te0) could be facilely assimilated into polysulfide species to form soluble mixed polytellurosulfide species when left in an ethereal solution of Li2S6. This was confirmed by the characteristic isotopic signature of tellurium using mass spectrometry. The polytellurosulfide species were found to reduce on the surface of lithium metal to form red-colored lithium thiotellurate (Li2TeS3), which was confirmed by X-ray techniques. In contrast to Li2S, Li2TeS3 is expected to be a significantly better ionic conductor due to the reduced electron density around the sulfur atoms. This would help engender a uniform lithium-ion flux on the lithium surface, enabling homogenous lithium deposition.Based on the results above, elemental tellurium was simply added in a 1 : 10 molar ratio to the sulfur/Li2S cathode to modify the chemistry of Li-S batteries. During cell operation, the generated polysulfides (Li2Sn) reacted with the Te0 additive in the cathode to form polytellurosulfide (Li2TexSy) species in-situ. The crossover of these tellurium-containing species to the anode side was confirmed by the detection of a significant amount of Li2TeS3 on the lithium surface. The favorable properties of Li2TeS3 as a lithium SEI component enabled the formation of dense and uniform lithium deposits and significantly improved lithium cycling efficiency. In the anode-free full cell configuration, which pairs a Li2S cathode with a bare anode current collector and contains zero excess lithium (N/P ratio = 1), the addition of tellurium improved cycle life by a factor of 7. The loss of the limited lithium inventory in the anode-free cell was reduced from 2% per cycle to 0.25% per cycle.Time-of-flight secondary ion mass spectrometry (ToF-SIMS) revealed the drastically reduced electrolyte decomposition on lithium surface due to tellurium-stabilized lithium deposition. The reduced electrolyte decomposition could allow a limited electrolyte supply to be retained for a longer number of cycles, thus enabling extended cyclability under lean-electrolyte conditions. This was confirmed using large-area pouch cells employing a high-loading sulfur cathode (5.2 mg cm-2), a lithium-foil anode, and a low electrolyte/sulfur (E/S) ratio of 4.5 µl mg-1. Under such stringent cell design conditions, the pouch cells could be cycled stably for nearly 100 cycles with the addition of tellurium. In contrast, the control cell failed within 25 cycles.This work demonstrates a novel, effective, and robust strategy of adding tellurium to the sulfur/Li2S cathode for stabilizing lithium deposition and reducing electrolyte decomposition in Li-S batteries. This improves cycle life in energy-dense cell configurations operating with a limited lithium inventory or electrolyte supply. Importantly, this approach is scalable as no expensive or complicated pre-treatments or coatings of the lithium-metal anode are necessary. The unique chemistry of tellurium in the polysulfide-rich environment of Li-S batteries opens a new frontier in research in Li-S batteries, bringing them one step closer to reality. Figure 1

In Situ Detecting Lithium-Ion Batteries Thermal Runaway with Resistance Temperature Detector

Advanced next-generation lithium-ion batteries (LIBs) can only be realized when the thermal safety-related incidents, which have been the roadblocks for development, are mitigated. A variety of advanced works have been proposed for safety enhancement viz., isolating shutdown separators, protective electrode coatings, electrolyte additives. However, they have been stalled from further developments on account of their narrow range in working voltage window, stability, performance, and response time. Also, to date in situ safety devices are known to drastically affect LIBs’ performance. Novel temperature measurement schemes have been developed to help battery management systems (BMS) for improved prediction such as Thermocouples, Thermistors, Fiber Bragg-grating (FBG) sensors, etc. but each has its limitation. Hence, this points towards developing an effective temperature management system that is capable of quick detections, compact, cost-effective, and light-weighted. Here, we are reporting in operando thermal runaway detection for LIBs, from beneath the anode current collector, using an internal resistance temperature detector (RTD). Sensing temperature fluctuations from the anode is more critical compared to the cathode is that it has a solid electrolyte interface (SEI) layer, which is comprised of reduced electrolytic compounds like ROCO2Li, (CH2OCO2Li)2 and ROLi and has lithium stored in graphitic interlayers. During thermal runaway events, decomposition of these compounds and reactions of the charged anode with electrolyte leads to the generation of an enormous amount of heat, which can induce fire, smoke, or explosion. Hence, sensing the anode becomes critical and gives direct access to this heat.Here, we studied three such thermal runway events, viz, external short circuit (ESC), overcharging, and overheat using multiple module calorimetry (MMC) to elucidate the thermal detection capabilities and presence of RTD inside the LIB. During ESC and overcharge tests, temperatures of around 36°C and 48°C were recorded using internal RTDs, respectively. These temperatures were about 9°C and 20°C more than the external RTDs. An interesting statistic about the internal RTD was its detection ability, which for 90% temperature rise was about 14 times faster than compared to the external RTD. RTD embedded mesocarbon microbeads (MCMB) anode half-cell was cycled at 0.25C rate giving a stable average capacity of 238 mAh g-1 over 200 cycles with voltage profile congruent to those reported in the literature. Modeling simulated tests elucidated the prevalence of different regions during thermal runaway events initialed by ESC and overcharge. Additionally, Multimode Calorimetry (MMC) for LIB with embedded internal RTD produced more endothermic peaks beyond 150°C and overall heat generated was 1.75 kJ g-1, which is significantly lower than conventional LIB. RTD assembly has another role of being a passive safety device while placed inside the LIB. Using thermal signatures from internal RTD, future BMS can provide a conducive environment for the LIBs, which would deliver power for high energy density applications such as in the grid-storage and EVs industries.

A multi-analytical methodology for the characterization of industrial samples of spent Ni-MH battery powders

A multi-analytical methodology is implemented to characterize several sieving fractions of industrial samples of Black Mass (BM) powders originating from the thermo-mechanical treatment of cylindrical and prismatic-type spent nickel metal-hydride (Ni-MH) batteries. Elemental analyses of 17 elements (including C and O) indicate that the elemental composition of the powders (greater than93 %wt) does not depend on the battery type nor on the sieving fraction. XRD analyses evidence several phases (including Ni, NiO, CeO2 and C) but their quantification is not possible. Beyond these standard characterisations, magnetic susceptibility measurements demonstrate that the amount of metallic nickel versus nickel oxide increases with the sieving fraction, and that powders from prismatic-type batteries contain twice as much metallic nickel than cylindrical ones. Thanks to statistical analysis (based on clustering algorithms) of an electron probe µ-analysis (EPMA) compositional map, the complete methodology allows us to propose a full phase distribution for the BM particles. Three types of particles are identified and quantified. They originate from the partial oxidation of the battery components (anode active mass, anode current collector, cathode active mass and cathode current collector). The whole picture highlights the joint importance of battery ageing mechanisms, thermal deactivation and BM sieving steps on powder composition.

Molten Lithium-Brass/Zinc Chloride System as High-Performance and Low-Cost Battery

Summary Batteries with high safety, low cost, and reasonable energy density are essential for grid-scale energy storage and still remain elusive. Here, we report a solid electrolyte-based liquid lithium-brass/zinc chloride (SELL-brass/ZnCl2) battery using garnet-type lithium-ion solid electrolyte, lithium anode, and brass/ZnCl2 cathode. The chemistry of the cell reaction and the ability of being assembled in discharged state ensures a high safety. The use of low-cost ZnCl2 cathode can realize a low cell material cost of $16 kWh−1. The adoption of lithium anode guarantees a high theoretical energy density of 750 Wh kg−1 and 2,250 Wh L−1. Moreover, by using brass powder as a Zn source in the cathode, the Zn particle growth issue is successfully solved, and a good cycling stability of the battery can be obtained. As full cell performance and scalability are also verified, our SELL-brass/ZnCl2 battery shows a high potential for practical use in grid energy storage.

Comparison of High-Temperature Corrosion Behavior of a FeCrAl Anode Current Collector in Liquid Ag and O2 for the Solid Oxide Membrane Electrolysis Process

The high-temperature corrosion behavior of anode current collectors in liquid Ag under an oxidizing atmosphere was investigated. The weight gain in oxygen was higher than that of liquid Ag because of the effective barrier formed by Ag-rich layer coated on the corrosion layer. The thickness of the corrosion layer under oxygen was approximately twice that of the layer developed under liquid Ag because of the effective barrier originating from the Ag-rich layer. The corrosion products on the surface of the specimens in both oxygen and liquid Ag were Al2O3 and FeAl2O4 from 24 to 168 h. The surface morphology that was developed on the scale of the corroded layer represented a buckle structure in liquid Ag and a convoluted structure in oxygen, which resulted from the lateral growth of the oxide. This study proved the improved stability and cost-effectiveness of using FeCrAl alloy as a current collector in a solid oxide membrane system.

A green and facile approach for regeneration of graphite from spent lithium ion battery

Low-cost regeneration of graphite from spent lithium ion batteries (LIBs) enjoys great significance in solving the problems of utilization and pollution of spent graphite. In this study, a facile approach for recycling graphite from spent LIBs has been developed. Firstly, anode current collector is smelted under nitrogen atmosphere at 1673 K for 4 h. Then, copper and graphite are further separated from each other by simple ultrasonic vibration and sieving. The results show that more than 80% copper above the 200-mesh (0.075 mm) and 77.53% graphite under the 300-mesh (0.048 mm) can be recovered, and the purity of the recovered graphite is higher than 99.5%. The recycled graphite shows high capacity and good cycle performance (specific capacity can be high up to 360.8 mA h g−1 after 100 cycles at 1C and the retention rate is almost 100%).

Optimization of a passive direct methanol fuel cell with different current collector materials

Towards the introduction of passive direct methanol fuel cells in the market, it is mandatory to achieve an optimum balance between its cost, efficiency and durability. To achieve that and knowing that the current collectors are responsible for about 80% of these systems weight, different current collector materials were tested in the anode and cathode sides of a passive direct methanol fuel cell, towards a cost and weight reduction. The best configuration was used to assess the lifetime of the developed passive direct methanol fuel cell. The cell performance and lifetime was evaluated through polarization measurements and these results were explained under the light of the electrochemical impedance spectroscopy data. A major novelty of this study is the use of an innovative equivalent electric circuit that accurately describes a passive direct methanol fuel cell, which allowed the identification and quantification of the different performance losses that negatively affect these systems efficiency.The maximum power density of 5.23 mW/cm2 was achieved using Titanium as anode current collector and Stainless Steel as cathode current collector and a methanol concentration of 7 M. The durability tests showed a lifetime of 200 h and a loss of efficiency of 41%.

A review on structuralized current collectors for high-performance lithium-ion battery anodes

As environmentally friendly and high-energy density rechargeable energy storage devices, lithium-ion batteries (LIBs) have thriving prospects in the field of energy. The current collector, which serves as an important component of LIBs, significantly influences the electrochemical performance of the battery. Numerous efforts have been spent on the design and fabrication of high-performance negative current collectors in the field of LIBs to achieve excellent battery performances. These high-performance current collectors are mostly structuralized to achieve special functions. Hence, different types of structuralized current collectors used for LIB anodes are comprehensively discussed and summarized in this paper. The structuralized current collectors used in LIB anodes are classified into planar-plate-based special-surface current collectors and the 3D framework-based porous current collectors. Both types of the structuralized current collectors are further divided into the single-component and multicomponent current collectors. More subsections are provided and focus on providing description of the developing strategies, fabrication methods, electrochemical behaviors, in-depth reasons for high performances, and advantages and challenges for real applications of the structuralized current collectors in detail. Subsequently, the challenges and future research directions of structuralized anode current collectors are reasonably clarified. Based on an objective summary of the high-performance negative current collectors, this review provides an enlightening guide for the future development of current collectors and LIBs. The fundamental conclusions can also be extended to other energy storage devices.

Polyaniline/Copper Composite Anode Current Collectors Prepared through Electrochemical Polymerization for Lithium‐Ion Batteries

AbstractHerein, a new type of composite anode with a Cu foil current collector modified with polyaniline (PANI) was prepared (PANI/Cu). SEM manifests that the PANI layer is 1.8 μm thick and composed of PANI particles with a diameter of 50 nm nanometers, which provides a large contact surface area to enhance the strength of adhesion to the electrode material. FTIR and UV/Vis analysis confirmed that the PANI layer existed in the emeraldine (conductive) form. Half‐cells were assembled by using PANI/Cu and bare/Cu (both coated with Li4Ti5O12 electrode material) as the working electrode, and Li wafers as the counter electrode. Cycling performance tests demonstrated that, after cycling for 500 cycles at 1 C, the discharge capacity was 155.0 mAh g−1 and 137.6 mAh g−1 for PANI/Cu battery and bare/Cu battery, respectively. Electrochemical impedance revealed the impedance of the PANI/Cu battery is decreased effectively by the PANI layer.

Advanced Current Collectors for Alkali Metal Anodes

High-energy-density batteries are in urgent need to solve the ever-increasing energy storage demand for portable electronic devices, electric vehicles, and renewable solar and wind energy systems. Alkali metals, typically lithium(Li), sodium(Na) and potassium(K), are considered as the promising anode materials owing to their low electrochemical potential, low density, and high theoretical gravimetric capacities. However, the problem of dendrite growth of alkali metals during their plating/stripping process will lead to low Coulombic efficiencies, a short lifespan and huge volume expansion, eventually hindering their practical commercialization. To resolve this issue, a very effective approach is engineering the anodes on structured current collectors. This review summarizes the development of the alkali metal batteries and discusses the recent advances in rational design of anode current collectors. First, the challenges and strategies of suppressing alkali-metal dendrite growth are presented. Then the special attention is paid to the novel current collector design for dendrite-free alkali metal anodes. Finally, we give conclusions and perspective on the current challenges and future research directions toward advanced anode current collectors for alkali metal batteries.