Cathode Morphology Research Articles

Nanofibers endow NASICON-type Na3.3La0.3Zr1.7Si2PO12 electrolyte/Na4MnCr(PO4)3 cathode excellent electrochemical properties

All-solid-state sodium-ion batteries (ASSSIBs) using composite polymer electrolytes (CPEs) are promising candidates for addressing the high cost, safety issues, and limited energy density of traditional lithium-ion batteries. The microstructure and morphology of active ceramic filler and cathode seriously affect the construction of ion/electron transport channels and electrochemical performance, while the contact tightness at the electrode/CPE interface determines the release of energy storage performance in ASSSIBs. Here, NASICON-type Na3.3La0.3Zr1.7Si2PO12 (NLZSP) ceramic nanofibers (NFs) and Na4MnCr(PO4)3@C (NMCP@C) NFs are prepared via electrospinning. NLZSP long NFs (L-NFs) can be uniformly dispersed in PVDF-HFP using ultrasonic treatment to create rapid ion transport pathways within the ceramic and polymer/ceramic interphases, enabling the CPE to achieve high ionic conductivity of 3.36 × 10−4 S·cm−1, wide electrochemical stability window (ESW) exceeding 5 V, low activation energy (Ea) of 0.28 eV and sodium-ion transference number (TNa+) of 0.65 at room temperature. Meanwhile, NMCP@C NFs can enhance electron conductivity and reduce the sodium ion migration path, and finally achieve a superhigh specific capacity (161 mAh·g−1) and energy density (534 Wh·kg−1) at 0.1C. Additionally, the integrated NMCP@C/CPE structure is incorporated into NMCP@C/CPE//Na solid state sodium metal batteries (SMBs), which exhibits excellent rate performance and high capacity retention of 78.8 % at 1C (1.4–4.3 V) and 70.5 % at 0.5C (1.4–4.6 V) after 200 cycles. This study offers valuable insights into constructing high-performance ASSSIBs.

A Thermal Tanks-in-Series Model for Simulating over-Discharge Cycling in Lithium-Ion Batteries

Energy storage will play a crucial role in the transition to clean and renewable sources of energy production to meet future consumption demands.1 Lithium-ion (Li-ion) batteries are widely adopted due to their high energy density, low self-discharge rate and fast charging capabilities for applications like electric vehicles and grid storage.2 Li-ion batteries for high voltage operations, where several cells are connected in series, can experience inadvertent over-discharge due to differences between cells3,4. These differences can arise due to many reasons including changes in internal resistance and deviation in electrochemical degradation that can cause divergence of cell open circuit potentials. Over-discharge is a condition when the manufacturer recommended lower voltage limit is crossed while discharging4, which results in various side effects such as electrolyte decomposition, capacity degradation, cathode morphology change and possible internal short circuit3,5. Increase in anode potential during over-discharge leads to copper dissolution from the anode current collector and subsequent plating within cell components. The Solid Electrolyte Interface (SEI) can decompose during excessive deintercalation and reform during charging, reducing the lithium inventory. Excessive heat generation during cycle life testing after occurrences of over-discharges has been found in some cases to lead to temperatures >150 °C6,7.Temperature plays a key role in the electrochemical performance of individual cells, affecting the diffusivities of ions, kinetics of reactions and rate of degradation of the battery. A physics-based modeling approach coupled with a thermal model can be employed to understand the effect of over-discharge on the electrochemical behavior of Li-ion batteries and provides insights into the interplay of various degradation mechanisms that cause capacity fade.The Thermal Tank-In-Series9,10(TTiS) model is a systematically volume-averaged form of the standard pseudo-2-dimensional (p2D)11 model with energy balance equations for the current collectors, cathode, separator and anode. This reduces the number of equations in the model and improves computational speed while maintaining accuracy, as it is sensitive to changes in the battery’s state of charge (SOC) and cell temperature, which helps predict the overpotential changes to the cell electrodes and thermodynamics.We use the TTiS model to identify the dominant fade mechanisms in 3 sets of experimental cycling and temperature data for the: i) normal operating window (2.5V – 4.2V), ii) 5 initial cycles of over-discharge (1.5V – 4.2V) followed by normal operation until 20% capacity fade and iii) 5 cycles of periodic over-discharge every 20 cycles, until 20% capacity fade. Analysis on the effect of C-rate, ambient temperature and voltage window of operation will facilitate understanding the temperature behavior and overpotentials in a cell sandwich. Key considerations required in extending a model to simulate over-discharge will also be examined. References S.P. S. Badwal, S. S. Giddey, C. Munnings, A. I. Bhatt, and A. F. Hollenkamp, Frontiers in Chemistry, 2, 28 (2014).G. Pistoia. Lithium-Ion Batteries: Advances and Applications. First ed. Elsevier, Amsterdam (2014).R. Guo, L. Lu., M. Ouyang, X. Feng. Sci Rep 6, 30248 (2016).G.Zhang, X. Wei, S. Chen, J. Zhu, G. Han, and H. Dai. J. Power Sources, 521, 230990. (2022).C. Fear, D. Juarez-Robles, J. A. Jeevarajan, and P. P. Mukherjee, J. Electrochem. Soc., 165, A1639–A1647 (2018).D. Juarez-Robles, Purdue Univ. Ph.D. Thesis (2019).H. Maleki and J. N. Howard, J. Power Sources, 160, 1395–1402 (2006).H. Liu, Z. Wei, W. He, and J. Zhao, Energy Convers. Manag., 150, 304–330 (2017).A. Subramaniam, S. Kolluri, S. Santhanagopalan, and V. R. Subramanian, J. Electrochem. Soc., 167, 113506 (2020).A. Subramaniam, S. Kolluri, C. D. Parke, M. Pathak, S. Santhanagopalan, and V. R. Subramanian, J. Electrochem. Soc., 167, 013534 (2020).M. Doyle, T. F. Fuller, and J. Newman, J. Electrochem. Soc., 140, 1526 (1993)

Structuring of the Surface of Thin Carbon Films During Activation by Microsecond Current Pulses

The influence of current activation by electric pulse breakdown on changes in surface morphology and emission characteristics of a field emission cathode made on the basis of carbon films obtained by deposition in a microwave gas discharge plasma was studied. Current activation of these films was carried out by applying voltage pulses of microsecond duration until an electrical breakdown occurred. It is shown that during activation, the morphology of the film surface in the breakdown region changes with the formation of a micro-sized emitting structure, which significantly improves the field emission characteristics of cathodes based on carbon films.

Stable and improved voltage plate of Li/SOCl2 battery using carbon electrodes with active carbon

Active carbon (AC) is synthesized using pitch coke as a precursor with a KOH activation approach followed. AC with different specific surface areas can be obtained by controlling the activation time of KOH. The activation time of AC1, AC2 and AC3 is 1 h, 1.5 h and 2 h, with the surface areas of 1233, 1484 and 1639 m2 g−1, respectively. The phase, surface chemical structure, morphology as well as the microstructure of the AC are investigated by XRD, Raman, IR, XPS, BET, SEM and TEM. The obtained ACs displayed a size around 300 μm with lots of nanoholes and functional group involving –OH, –COOH. When employed as the catalytic active materials in the carbon cathodes for Li/SOCl2 batteries, the discharged voltage was improved to around 0.15 V with an enhanced stable platform. Whereas the energy of the batteries containing the ACs is similar as that the conventional batteries, as well as the morphology of the carbon cathode with ACs exhibited a dense LiCl on the surface, suggesting that the ACs can enhance the reduction reaction of SOCl2, but could not act as the nucleation sites for the synthesis of nanoscale LiCl to form a loose film for a long discharge life.

Surface Evolution of Ni Electrode Under Cathodic Polarization in Acidic Solution

The surface morphology and structure of nickel cathode is closely related to its service performance and stability for water electrolysis applications. However, the surface evolution of nickel under cathodic polarization has not been systematically studied. In this work, we investigated the morphology evolution of the Ni electrode under cathodic polarization by altering the current density, temperature and composition of electrolyte. A corrosion rate of less than 0.0054 mm a−1 is observed under cathodic polarization at 0.2 mA cm−2. Uniform corrosion appears at low current density (0.2–2 mA cm−2) while serious pitting at high current density (20–200 mA cm−2). The corrosion preferentially takes place at the surface flaws, scratches and cavities. The cathodic corrosion is due to the uneven distribution of the surface potential between the plane and the depression part of the electrode. The mechanism is further confirmed by finite element simulation. The obtained result may provide reference for the design and application of various Ni-based cathodes.

Dual-gate design enables intrinsic safety of high-energy batteries

The safety issue hampers the application of high-energy lithium-ion batteries in electric vehicles, grid energy storage, electric ships and aircrafts. The chemical cross-talk, which refers to the migration of energetic intermediates between cathode and anode, initiates battery self-heating and accelerates the intensive heat release during battery thermal failure. However, blocking the chemical cross-talk is extremely hard. Previously, we may expect a thermally stable separator can guard the gate between battery cathode and anode, however, large amount of hot gas breaks the defense mechanically not thermally. Draining the cross-talk gas is of equal importance with blocking it. Herein, a dual-gate design notion is proposed, using separator as “block gate” and vent valve as “removal gate” to regulate the spatial distribution of energetic species to reduce the major heat release during battery thermal runaway. The design is validated by more than 50 battery chemistries. Typically, the maximum temperature of NMC811||Gr pouch cell decreases from >800 °C to <300 °C, the highest temperature rising rate decreases from 761.0 °C/s to 0.013 °C/s. The morphology and crystalline change of cathode verify that the chemical cross-talk is successfully suppressed. Moreover, such design has little side effect on the electrochemical performance of batteries. The dual-gate design breaks the bottleneck for the safety design of high energy batteries, providing insight into the safe utilization of electrochemical energy storage materials.

Clean and efficient preparation of metallic bismuth from methane-sulfonate electrolyte in the membrane electrolysis cell

As a prevailing hydrometallurgical extraction system for bismuth sulfide concentrate, the acidic chloride solution has superior applicability to raw materials and high recovery ratio of metallic bismuth. Nevertheless, it has disadvantages of being easily volatile and strongly corrosive, as well as large energy consumption and poor deposition morphology during chloride electrolysis. Methane-sulfonic acid (MSA) solution is widely considered as the next generation of green hydrometallurgical system, due to its excellent physicochemical properties such as high metal salts solubility, low volatility, and biodegradability. In this study, membrane electrolysis technique was adopted based on the acidic bismuth methane-sulfonate leaching solution, and the influence of electrolyte composition, cathode current density (CCD), and temperature parameters on the bismuth conversion ratio (BCR) and deposition rate (BDR), techno-economic indicators and cathodic bismuth morphology were studied. The results show that the CCD affects the deposits morphology significantly, and the bismuth metal is partially dark and composed of loose ellipsoidal particles at high current density. Under the optimal conditions (70 g/L Bi3+ ions, 5 g/L Fe2+ ions, 110 g/L MSA, 35 °C, 180 A/m2), high-purity metallic bismuth (Bi 99.97 %) with silver-white luster is obtained. The BCR and BDR are 9.43 % and 0.46 kg/(h·m2), respectively. The cathodic current efficiency (CCE) reaches over 98 %, and specific energy consumption (SEC) is less than 715 kWh/t Bi. Compared with the traditional chloride system, the MSA-based membrane electrolysis medium has advantages of environmental friendliness, low occupational risks, low carbon and energy consumption, and can thus provide a sustainable green solution for bismuth hydrometallurgy.

Comparative Analysis of LiCo0.6Sr0.4O2 Cathode Electrochemical Performance in Oxide- and Proton-Conducting Intermediate-Temperature Solid Fuel Oxide Cells

Solid fuel oxide cells (SOFCs) are made up of three main parts: anode, electrolyte, and cathode. The main challenge in SOFCs is their high operating temperature, which can reach 1000 °C and lead to cell degradation issues. To address this, the utilization of lithium-based materials is suggested for the cathode component, facilitating intermediate-temperature SOFC operation within the temperature range of 500 to 800 °C. Previous studies have demonstrated the potential of producing high-quality lithium-based cathode ink using a triple-roll mill (TRM). By employing the fabrication parameters recommended in these studies, the lithium-based cathode (LCSO) was tested in different working environments, specifically the oxide-conducting SOFC and proton-conducting SOFC. The LCSO inks were screen-printed on SDC for oxide-conducting SOFC and BCZY for proton-conducting SOFC electrolyte before the analysis. Electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM) are used to characterize the electrochemical performance and morphology of the LCSO cathode. Based on the results, the LCSO cathode is found to respond well in oxide-conducting SOFC environment with an area-specific resistance (ASR) value of 0.75 ohms-cm2 compared to proton-conducting SOFC which shows an ASR value higher by 11.45 ohms-cm2.

Solar fuels design: Porous cathodes modeling for electrochemical carbon dioxide reduction in aqueous electrolytes

The reduction of carbon dioxide emissions is crucial to reduce the atmospheric greenhouse effect, fighting climate change and global warming. Electrochemical CO2 reduction is one of the most promising carbon capture and utilization technologies, that can be powered by solar energy and used to make added-value chemicals and green fuels, providing grid-stability, energy security, and environmental benefits. A two-dimensional finite-elements model for porous electrodes was developed and validated against experimental data, allowing the design and performance improvement of a porous zinc cathode morphology and its operational conditions for an electrolyzer producing syngas via the co-electrolysis of CO2 and water. Porosity, pore length, fiber geometric shape, inlet pressure, system temperature, and catholyte flow rate were explored, and these parameters were thoroughly tuned by using the smart-search Nelder-Mead's multi-parameter optimization algorithm to achieve pronouncedly higher, industrial-relevant current density values than those previously reported, up to 263.6 mA/cm2 at an applied potential of −1.1 V vs. RHE.

What Affects More the NMC811 Cathode Powders: Lithium Excess, Washing or Aging?

Lithium Nickel Manganese Cobalt Oxides with R-3m space group have gained significant attention in recent years due to their high energy density, high power capability, and long cycle life. There are several synthesis methods to obtain NMC active powders, like solid-state or sol-gel, but co-precipitation synthesis is a widely used method for preparing NMC cathode materials for lithium-ion batteries, offering advantages in terms of control over particle size, morphology, and homogeneity (Xie et al., 2016).The main difficulty of synthesizing Ni-rich materials is the minimization of the degree of Li/Ni cation mixing, which refers to the interchange of the nickel and lithium ions in the 3a/3b sites of the crystal lattice. Perfect NMC materials have a hexagonal layered structure of α-NaFeO2-type, where Li and transition metal atoms form alternating layers between oxygen layers. To minimize phenomenon of cation mixing an excess of lithium source prior to sintering is required (Arai et al., 1995).However, unreacted lithium remain on the surface of NMC after the synthesis in the form of Li2O and it turns into LiOH and Li2CO3 as impurities if stored in ambient conditions. Those residual lithium compounds (RLC) on NMC811 surface can have significant impacts on the cathode's morphology, crystal structure, surface chemistry and, thus, electrochemical performance. Despite it was previously shown that Ni-rich materials have poor charge-discharge capacity retention, related to the electrolyte oxidization at the positive electrode surface (Jung et al., 2017) and/or structural changes of the material, such as large c-axis shrinkage, at high potentials (Teichert et al., 2020), many efforts are made to synthesize Ni-rich NMC for battery applications.Our research explores the impact of lithium excess on the physicochemical properties of NMC811. We compared self-made fresh samples with commercially available NMC811 in terms of structural parameters, morphology and electrochemical performance at high C-rates before and after lithium surplus was washed. Lithium removing procedure was applied to mitigate issues with RLC during battery operation, such as electrolyte degradation and gassing (Hartmann et al., 2022). However, over-washing can change physical properties of NMC811, including surface reconstruction as a consequence of the leaching of active transition metal ions and lithium from the cathode. Therefore, it is important to carefully optimize the washing procedures to balance the removal of RLC with the preservation of the cathode's electrochemical performance and stability.Here we want to point the effectiveness of washing procedure on NMC811 morphology, structural stability and electrochemistry. Additionally, our studies addressed the effects of calendar aging of active powders, i.e. prolonged shelf-storage in an ambient conditions for washed and unwashed samples, especially an influence of LiOH and Li2CO3 on structural parameters, electrodes preparation and electrochemical behavior. We want to open the discussion about preferable strategy on storage of Ni-rich NMCThe work was supported by the University of Warsaw through Action I.3.4. “The circular economy – energy storage”: "New electrode materials for next generation Li-ion batteries" (project no. PSP 501-D112-20-0001340) within the “Excellence Initiative – Research University (2020-2026)” programme of the Ministry of Science and Higher Education, Poland.ReferencesArai, H., Okada, S., Ohtsuka, H., Ichimura, M., Yamaki, J., 1995. Solid State Ion 80, 261–269.Hartmann, L., Ching, C.H., Kipfer, T., Koch, M., Gasteiger, H.A., 2022. J Electrochem Soc 169, 070516.Jung, R., Metzger, M., Maglia, F., Stinner, C., Gasteiger, H.A., 2017. J Phys Chem Lett 8, 4820–4825.Teichert, P., Eshetu, G.G., Jahnke, H., Figgemeier, E., 2020. Batteries 6, 8.Xie, H., Hu, G., Du, K., Peng, Z., Cao, Y., 2016. J Alloys Compd 666, 84–87.

High-energy LiNi0.90Co0.04Mn0.03Al0.03O2 cathode material with lithium-reactive Li0.34La0.56TiO3 coating and Li2NiO2 lithium supplying for enhanced performance lithium-ion batteries

In the work, we have focused on the surface variations of the LiNi0.90Co0.04Mn0.03Al0.03O2 induced by the lithium ion conductor Li0.34La0.56TiO3 and over-lithiated oxide Li2NiO2 double coverings. The influence of various covering materials on particles morphology, crystal structure and electrochemical properties have been explored. It is found that the Li0.34La0.56TiO3 firm layer could reduce the catalytic decomposition of electrolyte and further maintain the stable particles morphology and crystal structure of cathode after long-term cycling. In addition, the Li2NiO2 served as the lithium supplement additive could compensate the irreversible active lithium ions loss during cycling and then relieve the cyclic capacity attenuation. Comparatively, the cathodes after Li0.34La0.56TiO3 coating deliver the obvious enhanced rate capability, superior discharging capacity at low temperature and more stable cyclic performance than those of pristine LiNi0.90Co0.04Mn0.03Al0.03O2. Besides, the Li0.34La0.56TiO3 and Li2NiO2 co-coated sample demonstrates the superior safety performance and cyclic stability when applied in the pouch battery in comparison with the pristine cathode.

Enhanced cycle performance and synthesis of LiNi0.6Co0.2Mn0.2O2 single-crystal through the assist of Bi ion

LiNi0.6Co0.2Mn0.2O2 (NCM622) single-crystal material was successfully prepared by introducing Bi ions. The influence of Bi ions introduction on the morphology, structure, and performance of NCM622 single-crystal material was explored. Introducing Bi ions can promote the growth of the primary particles of the cathode, and the NCM622 single-crystal material can be synthesized at a lower temperature. The single-crystal synthesized with the help of Bi ions can improve the interfacial stability of the material surface. And at a rate of 1C and voltage range of 2.8–4.3 V, the sample with 4000 ppm Bi addition introduced has a cycle retention rate of 88.67 % after 150 cycles. Simultaneously, we used SEM, XRD, EDS, TEM, XPS, and EBSD to reveal how Bi ions promote the generation of single-crystal morphology of cathode.

Effect of low magnetic field during nickel electroplating on morphology, structure, and hardness

Nickel (Ni) layers are commonly utilized in various applications, such as automotive components. By using a magnetic field during the electroplating process, it is possible to achieve better properties. Ni electroplating was conducted in 0.5 M nickel sulphate in this research. Various low intensities of the magnetic field (0.08 T and 0.14 T) were applied during the electroplating process. In the past, it has been demonstrated that an increase in low magnetic field could result in a decrease in crystallite size and a rise in hardness. Samples were weighed with a digital scale to determine the deposition rate and current efficiencies. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and hardness tester were performed to investigate Ni layers properties. The magnetic field influences the deposition rate, cathodic current efficiency, surface morphology, structure, and hardness properties. The increase in the magnetic field caused a wider grain and smaller crystallite sizes. The crystallite sizes of the NiS - 0, NiS - 8, and NiS - 14 samples are 33.536 nm, 33.083 nm, and 28.540 nm, respectively. The hardness of the NiS - 0, NiS - 8, and NiS - 14 samples are 212.33 HV, 255.01 HV, and 267.214 HV, respectively. Higher hardness could be reached by reducing the size of crystallites. The influence of the magnetic field could enhance hardness during the electroplating process.

Simulation and Optimization of the Auxiliary Cathode for Inter-Electrode Discharge Electric Field in Microarc Oxidation.

Currently, research on the edge effect issue in the micro-arc oxidation process primarily focuses on investigating process conditions and enhancing additives. However, some scholars have utilized finite element analysis software to simulate the edge effect during the simulation process, overlooking the investigation of the morphology of the auxiliary cathode. This study analyzes the growth characteristics of the oxide film on aluminum alloy 2A12 during micro-arc oxidation. Additionally, the inter-electrode discharge electric field is simulated using the finite element analysis method. The auxiliary cathode is optimized to mitigate the influence of the edge effect on the film layer. The findings indicate that employing a cylindrical shape as the auxiliary cathode instead of a rectangular groove leads to an increased thickness of the micro-arc oxidation film. However, it also results in an augmented length of the film layer affected by the edge effect at both ends of the workpiece. Decreasing the distance between the auxiliary cathode and the workpiece surface leads to a higher thickness of the obtained micro-arc oxidation film. Decreasing the length of the auxiliary cathode results in a reduction in both the thickness of the film layer on the workpiece surface and the area affected by the edge effect. Increasing the eccentric cone ratio of the auxiliary cathode enhances the uniformity of the micro-arc oxidation film layer. In this study, we present a novel auxiliary cathode model that incorporates a smaller cylindrical shell at the center and eccentric cone shells on each side. This model has the potential to enhance the optimization rate of the micro-arc oxidation film layer on cylindrical workpieces by 17.77%.

Facile synthesis of spherical Li3V2(PO4)3/C and 2LiVPO4F⋅Li3V2(PO4)3/C cathode materials by spray drying for lithium-ion battries

Monoclinic Li3V2(PO4)3 is a promising cathode material for lithium–ion batteries due to its safety performance and high theoretical capacity. However, the efficient and large-scale preparation of stable composite remains a challenge. Herein, spherical Li3V2(PO4)3/C and 2LiVPO4F⋅Li 3V2(PO4) 3/C cathode materials were prepared by an efficient spray drying method. The structure and morphology of the as-prepared cathode were studied via X-ray diffraction and scanning electron microscopy. Li3V2(PO4)3/C synthesized at 750°C for 8 h shows the best crystallinity and uniform ball diameter distribution. Based on the optimized conditions, 2LiVPO4F⋅Li3 V2(PO4)3/C was also successfully prepared in the same way. Electrochemical results indicate that Li3V2(PO4)3/C exhibits a superior initial discharge-specific capacity of 143.6 mAh⋅g[Formula: see text]at 0.1 C rate in the range of 3.0–4.5 V, corresponding to a capacity decay rate of 2.79% after 50 cycles. The multi-voltage platform of 2LiVPO 4F⋅Li3V2(PO4)3/C has the advantage of high energy density. The good electrochemical performance reveals that spray drying was a promising approach to prepare monoclinic Li3V2(PO4)3 series cathode materials.

High‐Voltage Stability of Small‐Size Single Crystal Ni‐Rich Layered Cathode for Sulfide‐Based All‐Solid‐State Lithium Battery at 4.5 V

AbstractMechanical damage of NCM811 (LiNi0.8Co0.1Mn0.1O2), severe interfacial side reactions, and physical contact failure of cathode and solid electrolyte (SE) are the main obstacles for it to achieve high‐voltage stability in all‐solid‐state batteries (ASSLBs). The cathode morphology effects on the structural integrity are directly related to the electrochemical performance of ASSLBs. In this work, small‐size single crystal NCM811 (S‐SC) is synthesized for sulfide‐based ASSLBs to solve mechanical damage and contact failure issues. In addition, the interfacial stability is improved by a Li2O pre‐lithiation strategy. Cross section polisher‐scanning electron microscopy (CP‐SEM) is applied to reveal the mechanical structure evolution behavior of NCM811 cathodes with different morphology. Electrochemical impedance spectroscopy (EIS), time of flight secondary ion mass spectrometry (TOF‐SIMS), and X‐ray photoelectron spectroscopy (XPS) technologies are applied to characterize the interfacial stability among cycling. As a result, with a high mass loading of 35.67 mg cm−2 and high current density of 7.13 mA cm−2, the Li2O pre‐lithiated S‐SC (S‐SC‐PL) cathode delivers extraordinarily high‐voltage stability of 100% after 500 cycles at 2.72–4.4 V and 100% after 200 cycles at 2.72–4.5 V in ASSLBs. This work provides an effective cathode morphological design strategy to improve high‐voltage stability of Ni‐rich layered cathodes for sulfide‐based ASSLBs.

Modeling of Magnesium Intercalation into Chevrel Phase Mo6S8: Report on Improved Cell Design

AbstractA good understanding of the limiting processes in rechargeable magnesium batteries is key to develop novel high‐capacity/high‐voltage cathode materials. Thereby, the performance of magnesium‐ion batteries can strongly depend on the morphology of the intercalation cathode. Moreover, high mass loadings are essential for commercialization. In this work the influence of different mass loadings are studied in addition to the impact of the particle size distribution of the active material. Therefore, a detailed continuum model is developed, which is able to describe the complex intercalation of magnesium into a Chevrel phase (CP) cathode. The model considers the thermodynamics, kinetics and interplay of the two energetically different intercalation sites of Mo6S8, which results from its unique crystal structure, as well as the impact of the desolvation on the electrochemical reactions and possible ion agglomeration. Ideal combinations of mass loading and electrolyte concentration as well as the desired CP particle size are determined for the state‐of‐the‐art magnesium tetrakis(hexafluoroisopropyloxy)borate Mg[B(hfip)4]2 electrolyte.

Biomass-Derived Carbon Materials for the Electrode of Metal–Air Batteries

Facing the challenges of energy crisis and global warming, the development of renewable energy has received more and more attention. To offset the discontinuity of renewable energy, such as wind and solar energy, it is urgent to search for an excellent performance energy storage system to match them. Metal-air batteries (typical representative: Li-air battery and Zn-air battery) have broad prospects in the field of energy storage due to their high specific capacity and environmental friendliness. The drawbacks preventing the massive application of metal-air batteries are the poor reaction kinetics and high overpotential during the charging-discharging process, which can be alleviated by the application of an electrochemical catalyst and porous cathode. Biomass, also, as a renewable resource, plays a critical role in the preparation of carbon-based catalysts and porous cathode with excellent performance for metal-air batteries due to the inherent rich heteroatom and pore structure of biomass. In this paper, we have reviewed the latest progress in the creative preparation of porous cathode for the Li-air battery and Zn-air battery from biomass and summarized the effects of various biomass sources precursors on the composition, morphology and structure-activity relationship of cathode. This review will help us understand the relevant applications of biomass carbon in the field of metal-air batteries.

Meso-scale simulation of Li–O2 battery discharge process by an improved lattice Boltzmann method

The discharge process of lithium–oxygen battery (LOB) is a highly complicated multi-physics coupling phenomenon. Moreover, the cathode morphology presents a complex multi-scale structure with pore size ranging from nanometers to micronmeters, and plays a crucial role in determining the discharge performance. In this work, the cathodes consisting of carbon paper, electrode material, and electrolyte are first numerically reconstructed using a two-step reconstruction method considering the multi-scale morphology. A lattice Boltzmann model with an improved partial bounce-back scheme is proposed for modeling the discharge process given that the electrode porosity changes with the progress of discharge. The effects of micron-scale electrode spatial distribution on the O2 diffusion and LOB discharge performance are investigated. Results show that the increment of the electrode dispersion degree increases the O2 diffusion resistance due to the increase of electrolyte-electrode specific interface area. A large local electrode load near O2 inlet leads to a high O2 diffusion resistance and low O2 concentration owing to the large specific interface area and electrode volume. Cathodes with the minimum electrode load and maximum electrode dispersion degree present the optimal specific capacity of LOB. However, the specific capacity first increases significantly and then slightly decreases with the increase of local electrode load.

Stability evaluation and quantitative analysis of filmy cathode in solid oxide fuel cells under operating conditions

For interface-modified cathodes via the infiltration method, the quantitative analysis of degradation mechanism in solid oxide fuel cells (SOFCs) is the key to optimizing cell stability. Here, we prepare the anode-supported SOFC with a multifunction layer (MFL) cathode-infiltrated filmy La0.6Sr0.4CoO3-δ (LSC), which provides a peak power density as high as 1.1 W cm−2 at 750 °C, and outstanding durability with slight voltage loss under 0.5 A cm−2 and 750 °C for over 1000 h. According to collected data from electrochemical impedance spectroscopy (EIS) at different operating times, the distribution of relaxation time (DRT) and equivalent circuit model (ECM) methods are applied to quantify the contribution of different electrode processes to the whole voltage degradation during the cell operation. The result shows that oxygen ionic transport and charge transfer at the MFL/electrolyte interface dominate almost all voltage degradation (95.31%), while the oxygen surface exchange and oxygen ionic bulk diffusion in the cathode just contributes 1.82%. Microtopographic characterization provides that the filmy morphology of LSC cathode remains intact, but the Sr element enriches at the MFL/electrolyte interface. Therefore, the exacerbation of oxygen ionic transport and charge transfer at the MFL/electrolyte interface due to Sr enrichment is identified as the predominant degradation mechanism during long-term galvanostatic operation.