Battery Electrodes Research Articles

Ultrathin (15 nm) Carbon Sheets with Surface Oxygen Functionalization for Efficient Pseudocapacitive Na‐ion Storage

AbstractDisordered carbon is the state of the art anode material for Na‐ion batteries due to their increased interlayer spacing and good electronic conductivity. However, its practical application is hindered by average specific capacity, poor rate performance, low coulombic efficiency and limited cycling stability. Herein, we report the superior pseudocapacitance enhanced Na‐ion storage of in situ surface functionalized carbon nanosheets. Anodes composed of ultrathin (~15 nm) carbon nanosheets demonstrated excellent reversible specific capacity (375 mAh/g at 25 mA/g), rate performance (150 mAh/g at 2 A/g), long‐term cycling performance (1000 cycles at 1 A/g) and coulombic efficiency (~100 %). Considerably higher pseudocapacitance (up to ~78 %) is also identified in this case compared to amorphous carbon particles. Spectroscopic and electrochemical studies proved Na‐ion intercalation in to the disordered carbon and pseudocapacitive storage driven by oxygen‐containing surface functional groups. Outstanding electrochemical performance is credited to the synergy between diffusion limited intercalation and pseudocapacitive surface Na‐ion storage. The demonstrated synthetic method of in situ functionalized carbon nanosheets is inexpensive and scalable. The strategy of functional group and morphology induced pseudocapacitive Na‐ion storage offer new prospects to design high‐performance Na‐ion battery electrodes.

Effect of PVdF Distribution on Properties and Performance of Dry Spray-Coated Graphite Electrodes for Lithium-Ion Batteries for Electric Vehicle Applications

We used electrostatic dry spray-coating to fabricate graphite/PVdF anodes. We compared the morphological, mechanical, electrical, and electrochemical properties of electrodes fabricated with three different mixing times of dry electrode components. Quantitative and novel relationships between the PVdF distribution and the electrode properties were obtained. Our investigations suggest that our fabrication methods are viable alternatives for producing electrodes with comparable properties to those fabricated using traditional wet solvent-based methods. Overall, our work provides insights into new and promising methods for fabricating high-quality dry-sprayed electrodes (DSEs) with high mass loadings for use in a variety of electrochemical applications such as electric vehicles.

A new strategy for semi quantitative analysis of pore structure for lithium-ion battery electrodes

The Lithium ions diffusion dynamic, electrons transfer and the growth of the solid electrolyte interfaces are in close relation to the pore structure of the anodes. The widely used mercury intrusion porosimetry suffers from serious severe reaction with the copper and aluminum substrate, and unable to provide the pore structure evolution in the cross-section direction of the electrode. And the X-ray computed tomography faces limitations in identifying the carbon gel phase and is associated with high costs. Therefore, it is of substantial interest to directly investigate the cross-sectional pore structure from SEM morphologies. In this study, the using of resin protected polishing method to expose the cross-sectional structure is proposed to analyze the porosity evolution of the cross-sectional structure for lithium-ion battery anode. This method can clearly expose the cross-sectional structure of the electrode preventing the disturbance of the height fluctuation of the active particles. The influence of the coating processes on the pore structure is studied with the help of image J software and the machine leaning plug-in. The porosity changes of the electrode along with the coating depth are clearly elucidated. This method provides a convenient and efficient solution on the structure characterization of the electrode in Lithium-ion batteries.

Graphene oxide synthesis from coconut fiber powder using triple superphosphate catalyst and its potency for secondary battery electrode

Coconut fiber, considered an organic waste, emerges as a promising alternative carbon source for graphene oxide production—a material characterized by its conductive nature due to oxidation and the introduction of functional groups. The synthesis process involves carbonization with varied holding times (10, 20, and 30 minutes) and the utilization of Triple Superphosphate (TSP) and Ferrocene catalysts at concentrations of 10 wt.% and 20 wt.%. Subsequently, the sonication method is employed to enhance the electrical conductivity of graphene oxide post-carbonization. Notably, the electrical conductivity tests, conducted using a sourcemeter, revealed the optimum performance at 20 minutes of carbonization duration and a 20 wt.% TSP catalyst concentration, yielding an impressive electrical conductivity of 11,489.86 S/m. These findings underscore the significance of tailored parameters in optimizing graphene oxide synthesis for applications such as high-conductivity battery anodes.

Beyond slurry cast: Patterning of a monolithic active material sheet to form free-standing, solvent-free, and low-tortuosity battery electrodes

Beyond slurry cast: Patterning of a monolithic active material sheet to form free-standing, solvent-free, and low-tortuosity battery electrodes

Influence of Cathode Calendering Density on the Cycling Stability of Li-Ion Batteries Using NMC811 Single or Poly Crystalline Particles

Calendering of battery electrodes is a commonly used manufacturing process that enhances electrode packing density and therefore improves the volumetric energy density. While calendering is standard industrial practice, it is known to crack cathode particles, thereby increasing the electrode surface area. The latter is particularly problematic for new Ni-rich layered transition metal oxide cathodes, such as NMC811, which are known to have substantial surface-driven degradation processes. To establish appropriate calendering practices for these new cathode materials, we conducted a comparative analysis of uncalendered electrodes with electrodes that have a 35% porosity (industrial standard), and 25% porosity (highly calendered) for both single crystal (SC) and polycrystalline (PC) NMC811. PC cathodes show clear signs of cracking and decrease in rate capability when calendered to 25% porosity, whereas SC NMC811 cathodes, achieve better cycling stability and no penalty in rate performance at these high packing densities. These findings suggest that SC NMC811 cathodes should be calendered more densely, and we provide a comprehensive overview of both electrochemical and material characterisation methods that corroborate why PC and SC electrodes show such different degradation behaviour. Overall, this work is important because it shows how new single-crystal cathode materials can offer additional advantages both in terms of rate performance and cycling stability by calendaring them more densely.

Addressing Strain and Porosity Changes of Battery Electrodes Due to Reversible Expansion through DEM Simulations

In this work, discrete element method (DEM) simulations were used to probe changes in electrode porosity, electrode strain, and the resultant pressure changes for composite electrodes comprised of active material and binder particles. Through the results acquired by these simulations, three cases that are representative of two limiting cases for electrode operation, and one case for realistic electrode face pressure during operation were captured and the implications on design and performance are discussed. Predicting changes in the porosity is a unique insight that is difficult if not impossible to capture experimentally but is important for predicting changes in electrochemical performance during cycling, and should be addressed early on in the design phase for automotive and grid storage battery design and performance.

Investigating mass transport in Li-ion battery electrodes using SECM and SICM

Lithium-ion batteries (LIBs) are indispensable as global energy production transitions to sustainable production. Nevertheless, the use of LIBs in renewable energy storage applications is challenging due to their limited power densities. To comprehend the origin of this limitation, it is crucial to investigate the effect of electrode architecture on the Li+ ion transport within their pores (solution-phase). In this work, the solution phase transport in various porous Li4Ti5O12 (LTO) films was investigated using scanning ion conductance microscopy (SICM) and scanning electrochemical microscopy (SECM). When the porosity of LTO film increases, SECM and SICM approach curves show an increase in current. This is attributed to the ion transport through the film pores. The 2D topographical mapping using both techniques shows their ability to detect the LTO film's heterogeneity. Most importantly, this work gives insight into the complementary nature of the two scanning probe techniques as demonstrated by the comparable MacMullin numbers.

One-step synthesis of g-C3N4/TiVCTx MXene electrodes for lithium-ion batteries and supercapacitors

The wide-ranging application of lithium-ion batteries (LIBs) is currently restricted by their slow ion dynamics and low capacity, which hinders the development of innovative electrode materials. Herein, the graphitic carbon nitride (g-C3N4)/TiVCTx composite was fabricated through in situ pyrolysis of urea to generate g-C3N4 nanosheets on the surface of TiVCTx nanosheets. The as-prepared g-C3N4 protective layer can reduce the degree of oxidation of TiVCTx MXene, restrain the re-stacking of TiVCTx nanosheets and minimize the risk of undesirable side reactions. As expected, the g-C3N4/TiVCTx electrode exhibits remarkable specific capacity of 1025.3 mAh/g after 150 cycles at 0.1 A/g and 558.3 mAh/g after 1000 cycles at 1.0 A/g for LIBs and a high specific capacitance of 508.9F g−1 in 0.5 M Na2SO4 electrolyte at 1.0 A/g after 7000 cycles for supercapacitors (SCs). Furthermore, the assembled g-C3N4/TiVCTx-30//LiFePO4 full cell presents stable specific capacity of 505.5 mAh/g at 0.1 A/g after 100 cycles and 255.2 mAh/g at 0.1 A/g along with a Coulombic efficiency of 97.9 % after 50 cycles at − 20 °C, demonstrating excellent low temperature tolerance. Density functional theory (DFT) calculation results indicated that the g-C3N4/TiVCTx-30 exhibits strongest adsorption capacity for Li+ with an adsorption energy of −3.85 eV. The introduction of g-C3N4 improves the insertion and extraction kinetics of Li+, effectively reducing the diffusion barrier. Consequently, the g-C3N4/TiVCTx-30 electrode exhibits potential application prospects in high-performance electrochemical energy storage devices. Our work provides valuable insights and significant research implications for improving the specific capacity and stability of TiVCTx MXene in the field of energy storage.

Fundamental benchmarking of the discharge properties of negative electrodes in lead acid batteries

The unprecedented scale of energy storage deployment needed to allow high penetration of intermittent renewable energy sources into the electrical grid places significant economic cost and performance targets on battery technologies. Lead batteries, owing to their highly abundant and inexpensive raw materials, can be considered an important solution to grid storage as long as they achieve high material utilization, fast recharge rates, and long cycle life. To address the limitations in material utilization, we need to revisit the electrochemical processes during the discharge step and answer the following question: what are the fundamental limits of the discharge reaction? In this work we discuss how well-defined lead metal surfaces with nanometer scale roughness allow us to resolve the accessible discharge capacity for both faradaic and non-faradaic processes as a function of electrolyte concentration and in the presence of traditional additives. The direct connection between PbSO4 layer morphology and discharge rates gives us important insights on the mechanism of discharge as related to the dissolution and passivation events. This work sets the stage for reimagining the design of lead batteries with implications to grid storage applications.

Colloidal hot injection synthesis of Cu2FeSnS4 nanoparticles towards an enhanced capacity anode material for Li-ion batteries

The increasing demand for portable energy storage devices has prompted a considerable exploration into advanced anode material with higher Li-ion battery capacities. Quaternary chalcopyrite semiconductors have generated significant attention as promising materials in applications such as optoelectronic devices, energy conversion, and energy storage devices. In this paper, Cu2FeSnS4 (CFTS) nanoparticles were prepared through a colloidal hot injection method (HIM). The structural analysis indicates that the CFTS nanoparticles exhibit a pure tetragonal structure characterized by high crystallinity. The morphological and elemental analysis shows the stoichiometric synthesis of CFTS nanoparticles with significant agglomeration of crystallites, accompanied by variation in size. The CFTS nanoparticles, employed as an anode material for Li-ion batteries, demonstrated significant performance characterized by high reversible capacity and stability at ambient temperature. The initial discharge capacity is achieved at 1181 mAhg−1 and retains 528 mAhg−1 during charge-discharge cycles within the voltage range of 0.005 to 3.0 V (versus Li/Li+) after 5 cycles. The CFTS nanoparticle performance findings indicate its promising implementation as an anode electrode in Li-ion batteries.

Development of V2O3 Nanostructures for Alkali Metal Ion Batteries: A Novel Approach through Mild Metal Vapor Reduction and Interface Engineering.

V2O3 has been extensively researched as a battery electrode material due to its ample reserves and high theoretical capacity. However, the synthesis of valence-sensitive V2O3 presents technical challenges as it requires a strict combination of high-temperature treatment and a narrow range of oxygen partial pressures. This study proposes a gentle Li vapor-assisted thermal reduction method to synthesize pure-phase V2O3 at a relatively low temperature of 480 °C without any hazardous gases. It has been discovered that reducing the temperature also improves the specific surface area of the nanoto-mesoscale hierarchical structures and enhances the reactive sites between their secondary grains. These advantages enable the V2O3 micronano particles to store higher levels of Li+, Na+, and K+, increase ionic transport, and tolerate volume expansion. It demonstrates a significant capacity of 767 mA h g-1 in lithium-ion batteries, 393 mA h g-1 in sodium-ion batteries, and 209 mA h g-1 in potassium-ion batteries. It has also been discovered that the crystal structure of V2O3 is easily adjustable by varying the synthesis temperature, which significantly affects the electrochemical storage mechanism. The V2O3 synthesized at 480 °C with low crystallinity exhibits a notable intercalation reaction, facilitating the electrochemical kinetics of reversible insertion/extraction of Li+, Na+, and K+. In contrast, the highly crystalline sample synthesized at 580 °C displays pseudocapacitance behavior instead of an intercalation reaction. The highly crystalline sample synthesized at 680 °C exhibits a thorough pseudocapacitance reaction possessing the capacitive functionality for the electrochemical storage of Na+ or K+ with larger ion radii. This study describes a new synthesis strategy and rational modification of vanadium-based electrodes for alkali metal ion batteries, leading to the development of reasonably priced rechargeable battery systems with applications extending beyond lithium-ion batteries.

Large ligand metal-organic framework derived CoSe2 to improve sodium storage performance

Cobalt selenide has been regarded as a promising anode for sodium-ion battery owing to its high capacity. However, the issues of stacked problem and volume expansion during cycling significantly affects its performance. Herein, we used large-size ligands to successfully prepared a new cobalt metal–organic frameworks (MOFs), and used as a precursor to prepare CoSe2/MOFc by high-temperature selenization. Morphology characterizations revealed that due to the blocking effect of large-sized ligands, CoSe2 nanoparticles were evenly distributed on the carbon material. As an anode, CoSe2 /MOFc shows a good cyclic stability and high capacity (291 mAhg−1 after 1000 cycles at 1 Ag−1) due to the well dispersion of CoSe2 nanoparticles and the effective coating of carbon matrix. These results indicated that utilizingMOFs precursor with large ligands facilitates the distribution of nanoparticles on conductive carbon, allowing for the synthesis of sodium-ion battery electrodes with superior properties.

Biomass-Derived Materials for Advanced Rechargeable Batteries.

Biomass-derived materials generally exhibit uniform and highly-stable hierarchical porous structures that can hardly be achieved by conventional chemical synthesis and artificial design. When used as electrodes for rechargeable batteries, these structural and compositional advantages often endow the batteries with superior electrochemical performances. This review systematically introduces the innate merits of biomass-derived materials and their applications as the electrode for advanced rechargeable batteries, including lithium-ion batteries, sodium-ion batteries, potassium-ion batteries, and metal-sulfur batteries. In addition, biomass-derived materials as catalyst supports for metal-air batteries, fuel cells, and redox-flow batteries are also included. The major challenges for specific batteries and the strategies for utilizing biomass-derived materials are detailly introduced. Finally, the future development of biomass-derived materials for advanced rechargeable batteries is prospected. This review aims to promote the development of biomass-derived materials in the field of energy storage and provides effective suggestions for building advanced rechargeable batteries.

Simple Framework for Simultaneous Analysis of Both Electrodes in Stoichiometric Lithium-Sulfur Batteries.

A battery is composed of two electrodes that depend on and interact with each other. However, galvanostatic charging-discharging measurement, the most widely used method for battery evaluation, cannot simultaneously reflect performance metrics [capacity, Coulombic efficiency (CE), and cycling stability] of both electrodes because the result is generally governed by the lower-capacity electrode of the cell, namely the limiting reagent of the battery reaction. In studying stoichiometric Li-S cells operating under application-relevant high-mass-loading and lean-electrolyte conditions, we take advantage of the two-stage discharging behavior of sulfur to construct a simple framework that allows us to analyze both electrodes simultaneously. The cell capacity and its decay are anode performance descriptors, whereas the first plateau capacity and cell CE are cathode performance descriptors. Our analysis within this frame identifies Li stripping/plating and polysulfide shuttling to be the limiting factors for the cycling performance of the stoichiometric Li-S cell. Using our newly developed framework, we examine various previously reported strategies to mitigate these bottleneck problems and find modifying the separator with a reduced graphene oxide layer to be an effective means, which improves the capacity retention rate of the cell to 99.7% per cycle.

Mechanically Exfoliated Graphite for Highly Reversible Na-Storage with Carbon Coated Na3V2(PO4)3 Cathode with Low-Temperature Conditions.

Tremendous efforts are put forward to develop novel high-performance electrodes for Na-ion batteries (SIBs) in order to replace commercial Li-ion batteries (LIBs). Graphite, the most versatile anode for LIBs, fails to accommodate Na+ions owing to the poor thermodynamic stability of the binary graphite intercalation compound. This study aims to exfoliate the layers of graphite through a simple mechanical process at different time intervals (1, 5, 10, 20, 40, and 80h) and examine the potential candidate for Na-storage in the presence of carbonate-based electrolytes. This study reports that ball milling plays a vital role in the performance of the graphite in Na-storage. The graphite exfoliated for 80h (EG-80h) rendered an excellent reversible capacity of 209mAhg-1 with coulombic efficiency of >99% after 100 cycles in EC-based electrolyte. In situ impedance analysis is performed to validate the charge storage mechanism and Na-ion kinetics. The performance of EG-80h in a full-cell assembly is evaluated with a carbon-coated Na3V2(PO4)3 cathode, which exhibited an initial capacity of ≈75mAhg-1 andenergy density of 201Whkg-1. In addition, the adaptability of the NVPC/EG-80h cell at different temperatures is examined from -10 to 50°C, displaying excellent performance in both high and low-temperature conditions.

Machine-Learning Assisted Analysis of Battery Electrode by PFIB-SEM Tomography

Machine-Learning Assisted Analysis of Battery Electrode by PFIB-SEM Tomography

Stabilization of P2 layered oxide electrodes in sodium-ion batteries through sodium evaporation

Sodium-ion batteries are well positioned to become, in the near future, the energy storage system for stationary applications and light electromobility. However, two main drawbacks feed their underperformance, namely the irreversible sodium consumption during solid electrolyte interphase formation and the low sodiation degree of one of the most promising cathode materials: the P2-type layered oxides. Here, we show a scalable and low-cost sodiation process based on sodium thermal evaporation. This method tackles the poor sodiation degree of P2-type sodium layered oxides, thus overcoming the first irreversible capacity as demonstrated by manufacturing and testing all solid-state Na doped-Na~1Mn0.8Fe0.1Ti0.1O2 ǀǀ PEO-based polymer electrolyte ǀǀ Na full cells. The proposed sodium physical vapor deposition method opens the door for an easily scalable and low-cost strategy to incorporate any metal deficiency in the battery materials, further pushing the battery development.

Highly Performing Sodium Metal Batteries Reinforced by a Self-Regulated Dual-Layered Solid Electrolyte Interphase via a Metal-Organic Framework.

Sodium-metal batteries, heralded for high energy density and cost-effectiveness, are compromised by an unstable solid electrolyte interphase (SEI) and dendrite formation, which hinder practical applications. Herein, a zirconium-based metal-organic framework nanostructure coating (ZMOF-NSC) was constructed in a low-loss, flexible manner. Comprehensive studies show that ZMOF-NSC, with its periodically ordered nanochannels and organized pore structures, enhances ion transport and decreases the Na+ migration energy barrier, thus ensuring uniform ion flux and achieving uniform spherical deposition. Additionally, ZMOF-NSC facilitates partial desolvation, catalyzing the formation of an inorganic-rich, dual-layered SEI that effectively protects the anode and suppresses dendrite formation. Consequently, the ZMOF-NSC@Na symmetric battery exhibits an impressive lifespan of over 2500 h, demonstrating extended operational longevity. The Na3V2(PO4)3∥ZMOF-NSC@Na batteries demonstrate exceptional cycling stability with 81% capacity retention after 2000 cycles at 10 C, maintaining stability over 3000 cycles at 20 C. Moreover, the NVP∥ZMOF-NSC@Na battery achieves an energy density of 370 Wh kg-1 and a power density of 10,484 W kg-1, indicating superior durability and performance. This significant finding highlights the significant potential of structured MOFs to induce a dual-layered SEI, advancing the commercialization of durable, dendrite-free sodium metal batteries. The precise design of self-assembled pore structures and surface active sites in MOFs demonstrates significant potential in advancing the commercialization of durable, dendrite-free electrodes of metal-based rechargeable batteries.

Current‐Adaptive Li‐Ion Storage Mechanism in High‐Rate Conversion‐Alloying Metal Chalcogenides

AbstractBeyond the high theoretical capacity, conversion‐alloying metal chalcogenides (CAMCs) exhibit exceptional high‐rate performance as Li‐ion battery electrodes. However, the inherent origin of the high‐rate performance remains elusive, especially given the lower intrinsic conductivity of CAMCs. Here, the correlation between phase evolution and charge transport dynamics in fully activated CAMCs is systematically investigated, elucidating a current‐adaptive Li‐ion storage mechanism to explain the anomalous high‐rate performance. Briefly, the deconversion reaction manipulated by ion diffusion acts as a “regulator” to adaptively modulate the transition from metal (high electronic conductivity) and lithium chalcogenides (high ionic conductivity) to CAMCs, thus removing the charge transport bottleneck without affecting the formation of the metal feedstock required for the alloying reaction. On this basis, the high capacity can be maintained at high rates through a “fading‐free” alloying reaction. This study offers a novel perspective for the design of high‐rate electrode materials.