Cycling Performance Research Articles

Transformative Effect of Li Salt for Proactively Mitigating Interfacial Side Reactions in Sodium-Ion Batteries.

The robust respective formations of a solid electrolyte interphase (SEI) and pillar at the surfaces of hard carbon and O3-type positive electrodes are the consequences of integrating LiPF6 salt into a sodium-ion battery electrolyte that considerably strengthens both interfaces of positive and negative electrodes. The improvement of cycle performances due to the formation of highly passivating SEI on the hard carbon electrode is induced by the alternated solvation structure following the addition of Li salt, which inhibits sodium-ion and electron leakage from further electrolyte decomposition. The SEI with incorporated Li is less soluble than Na-based SEI, and the passivation ability of the initially formed SEI can thus be well preserved. Conversely, the gas evolution caused by oxygen release is reduced considerably by the marginal surface intercalation of Li ions at the surface of the O3-positive electrode. Additionally, the LiF layer that forms on the O3 surface diminishes additional deterioration of the electrolyte after formation. Compared with the fluoroethylene carbonate additive that is typically applied, a simultaneously strengthened interface yields major improvements in capacity retention.

MOF-Derived Hollow Dodecahedral Carbon Structures with Abundant N Sites and Co Nanoparticle-Modified Cu Foil for Dendrite-Free Lithium Metal Battery

In this work, hollow dodecahedral carbon structures with abundant N-doping sites and metal nanoparticles (NC-Co-CNTs) based on MOF-derivative materials were designed and prepared as host materials for lithium metal to ensure uniform lithium deposition on a Cu current collector. NC-Co-CNTs have good electrical conductivity, which ensures fast electron transport and Li+ transfer. The carbon nanotubes catalytically derived by Co can promote the uniform distribution of Li+ along the hollow dodecahedral carbon surface and deposition inside the cavity, and the larger electronegativity of N-doped sites and lithophilic sites such as Co nanoparticles can effectively adsorb lithium, inducing the Li+ to be deposited in the form of spherical lithium in a dendrite-free state, inhibiting the growth of dendritic lithium and improving the electrochemical performance of the lithium metal battery. Based on the above advantages, the electrodes of NC-Co-CNT-based symmetric cells present superior cycling performance for more than 1100 h with low overpotential at 1 mAh cm−2/1 mAh·cm−2. Even cycling at high current density of 5 mA cm−2 and high deposition parameters of 5 mAh cm−2, it still cycles for up to 800 h at a relatively low overpotential.

Interfacial Electron Modulation of AgxCuy@ZIF-8 for Photothermally Catalyzing CO2 Organic Transformations.

Efficiently converting CO2 into valuable chemicals under mild conditions is extremely challenging due to its thermodynamic and kinetic stability. The carboxylation/cyclization of alkynes catalyzed by Cu or Ag nanoparticles (NP) is one of the green pathways for CO2 utilization. However, these reactions are often limited by harsh conditions, as well as the migration, aggregation, and leakage of metal NP during the reaction. Herein, the AgxCuy heterostructure alloy NP are surrounded by a porous metal-organic framework, forming core-shell AgxCuy@ZIF-8 catalysts. Thanks to the light-to-heat capability, these catalysts exhibited excellent catalytic activity in converting various alkynes and CO2 to alkynyl carboxylic acids and promoting the cyclization reactions of propargyl amines with CO2 under ambient conditions using blue LED irradiation. The remarkable catalytic activity of Ag1Cu1@ZIF-8 is attributed to the optimized electronic states of Ag and Cu NP, as well as the core-shell structure that enhances photothermal effects around the catalytic center. In addition, the ZIF-8 shell not only improves the substrate transport but also inhibits the aggregation, migration, and loss of alloy NP cores during the reaction, contributing to enhanced cycling performance compared to unencapsulated Ag1Cu1 NP. The catalytic reaction mechanisms were disclosed by a variety of spectral characterizations, control experiments, and DFT calculations.

Ester-Guided Dynamic Li+ Solvation Enables Plating-Less, Fast-Charging Li-Ion Batteries.

The extremely fast charging (XFC) of Li-ion cells is an urgent milestone in promoting the widespread adoption of electric vehicles. However, EV-targeted cell designs with thicker electrodes compromise the XFC capability when conventional electrolytes are used, leading to hazardous Li plating and a considerable loss in Li inventory. This study presents noncarbonate solvents for superionic conductive, low-viscosity high-concentration electrolytes (HCEs). A methyl acetate (MA)-based HCE with a solid-electrolyte interphase (SEI)-stabilizing additive (3MF) was comparatively examined using a dimethyl carbonate (DMC) solvent, which has an extra oxygen atom in the molecule, across all aspects, including solvation structures, interfacial kinetics, and bulk Li+ transport. The 3MF electrolyte demonstrated outstanding XFC performance in a pouch cell (1.2 Ah) format and outperformed DMC-based HCE, showcasing improved cycling performance at low temperatures (-20 °C), 10 C-rate (6-min charging), and with a thick electrode (6.0 mAh cm-2). By satisfying the energy barrier thresholds for Li+ desolvation and Li+ migration across the SEI, MA can guide smaller solvation clusters and serve as a molecular lubricant along the Li+ percolation pathway in the HCE framework, which is crucial for boosting XFC capabilities.

Charge-Induced Defective MOF-801 with Enhanced Sorption Heat for Efficient Hydrogen Storage.

Metal-organic frameworks (MOFs) are considered ideal candidates for H2 physisorption materials due to their high surface area and tunable pore structures/environments. However, their interaction with hydrogen is too weak to fully exploit their surface area advantages, necessitating the exploration of effective adsorption enhancement strategies. Here, a defective MOF-801 is reported as an H2 physisorption material and investigate the enhancement of hydrogen adsorption by charge-inducing. Based on the excellent stability of MOF-801, the material retains good porosity after acid vapor etching, compared to the initial MOF-801 (810 m2g-1), the surface area reaching up to 970 m2g-1. The mild etching method leads to excess charges around the zirconium (Zr) of MOF-801, forming specific defective sites with excellent adsorption heat, inducing hydrogen polarization, and enhancing hydrogen capacity. The total H2 uptake increases from 5.02 wt.% (MOF-801) to 8.58 wt.% (Cl@MOF-801) at 77 K and 80bar. Additionally, the material exhibits excellent cycling performance, stably cycling 10 times at 8MPa and maintaining a total capacity of 8.56 wt%. The results reveal that tuning H2 adsorption heat by charge induction is a promising strategy to exploit the potential of porous materials for efficient H2 storage.

Multifunctional Additive for Electrolyte Stabilization and Electrode/Electrolyte Interphase Regulation in High-Voltage Lithium Metal Batteries.

Lithium-metal batteries (LMBs) incorporating nickel-rich cathodes have the potential to achieve superior energy densities. However, challenges associated with the electrolyte-electrode interphases (EEIs) have impeded the successful transition of these advanced systems into practical applications. In this study, azidotrimethylsilane (ATMS) is introduced as a multifunctional additive for traditional carbonate-based electrolytes. The azido group in ATMS plays a dual role in electrochemical reactions, with multiple nitrogen (N) atoms engaging in both nucleophilic and electrophilic interactions. These N atoms tend to undergo preferential oxidation reactions at the cathode, forming a stable cathode electrolyte interphase, while also undergoing preferential reduction reactions at the anode to inhibit lithium dendrite growth. The Si-N bond in the ATMS structure has unique reactivity, effectively neutralizing HF produced from LiPF6 decomposition, thus preventing the recurrent formation of EEIs in the battery. As a result, the long-cycle performance of Li||NCM811 is significantly improved, with capacity retention increasing from 34.7% in baseline electrolyte to 82.6% after 600 cycles. Similarly, ATMS enhances the cycling performance of Li||Li symmetric cells, extending their lifespan to over 800 h, and improves the Coulombic efficiency of Li||Cu cells from 81.6 to 91.6%. The synergistic effect of ATMS on both anodes and cathodes further significantly enhances the high-voltage performance of the LMBs.

Redefining closed pores in carbons by solvation structures for enhanced sodium storage

Closed pores are widely accepted as the critical structure for hard carbon negative electrodes in sodium-ion batteries. However, the lack of a clear definition and design principle of closed pores leads to the undesirable electrochemical performance of hard carbon negative electrodes. Herein, we reveal how the evolution of pore mouth sizes determines the solvation structure and thereby redefine the closed pores. The precise and uniform control of the pore mouth sizes is achieved by using carbon molecular sieves as a model material. We show when the pore mouth is inaccessible to N2 but accessible to CO2 molecular probes, only a portion of solvent shells is removed before entering the pores and contact ion pairs dominate inside pores. When the pore mouth is inaccessible to CO2 molecular probes, namely smaller than 0.35 nm, solvent shells are mostly sieved and dominated anion aggregates produce a thin and inorganic NaF-rich solid electrolyte interphase inside pores. Closed pores are accordingly redefined, and initial coulombic efficiency, cycling and low-temperature performance are largely improved. Furthermore, we show that intrinsic defects inside the redefined closed pores are effectively shielded from the interfacial passivation and contribute to the increased low-potential plateau capacity.

Construction of Ti3C2Tx MXene with Hopping Migration Mechanism via Deep Eutectic Supramolecular Polymers Anode for Sodium Ion Batteries

AbstractThe potential applications of high‐power sodium‐ion batteries are numerous, including use in distributed energy storage power plants and electric vehicles. In order to develop anode materials with fast sodium‐ion reaction kinetics and high reversibility, the use of deep eutectic supramolecular polymers to electrode materials is pioneered. The LA‐DESP is in situ polymerized on the Ti3C2Tx MXene surface, resulting in electrode materials that exhibit rapid reaction kinetics and high‐capacity retention. The supramolecular polymer network constructs channels for high‐speed transport of ions and electrons, and also provides more Na+ pseudocapacitance storage sites. In addition, the superior mechanical properties of the polymer network help protect MXene structure from damage during cycling, resulting in ultrastable Na+ storage. The hopping migration mechanism of Na+ through the polymer‐constructed ion transport channels is proposed. As the anode of SIBs half‐cells, it exhibits remarkable cycling performance of 114.4 mAh g−1 and a capacity loss of only 5.1% at 1000 mA g−1 after 1500 cycles. This study opens a new way to rationally design the structure of MXene polymers and promotes the application of deep eutectic supramolecular polymers in electrodes.

Effects of LATP Particle Size on the Residual Moisture of Separator Coating and the Performance of NCM811 Batteries.

Li1+xAlxTi2-x(PO4)3 (LATP) is a NASICON-type solid electrolyte that presents stability in aqueous media and high ion conductivity. With these advantages, it is expected to be used as a cathode and separator coating material for lithium-ion batteries to improve battery performance. However, it also displays a high level of residual moisture introduction due to its strong water absorption. Meanwhile, LATP particle size is a key influential factor for the residual moisture level and thereby produces an impact on the battery performance. In this research, we prepared three different particle sizes of LATP (100, 500, and 1000 nm) to investigate their effects as separator coatings on residual moisture and NCM811 battery performance. The results indicate that the water absorption of LATP is much higher than that of Al2O3 with the same particle size; the use of nanoscale LATP keeps the residual moisture of the LATP/PE separator rather high. When the particle size is in the range of 100-1000 nm, the battery's cycling performance gradually deteriorates with the decrease of the particle size, among which the degradation of rate performance is more noticeable. More importantly, the research finds that LATP particles coated with polydopamine (PDA) can effectively reduce the coating's residual moisture. After being coated with PDA, LATP particles with a particle size of 1000 nm result in the residual moisture content within the composite separator decreasing from 2136 to 408 ppm, thereby contributing to the optimal performance of NCM811||Li and NMC811||C batteries.

Fast Phase Transformation Enabled by Cu Single Atom Stabilized 1T‐Rich MoS2 for Efficient Magnesium Ion Storage

AbstractRechargeable magnesium batteries (RMBs) have drawn tremendous attention for large‐scale energy storage systems due to their low cost and high safety. However, the high charge density and the slow diffusion of Mg2+ in the cathode material limit the development of practical Mg cathode materials. Molybdenum disulfide (MoS2) is considered as an attractive electrode material for RMBs owing to its layered structure and high theoretical capacity. Unfortunately, its limited intercalation sites and slow phase transitions between 2H and 1T during cycling will lead to low capacity and poor rate capability. Herein, a Cu single atom doped MoS2 (SACu‐MoS2) is designed for the first time to address the above challenges. The Cu single atom in MoS2 strengthens the interaction between Mg2+ and MoS2 and promotes electron transfer, thereby achieving excellent rate capability. The enhancing effect of Cu single atom facilitates the reversible conversion between 2H and 1T. As a result, the obtained SACu‐MoS2 exhibits a high specific capacity (up to 375 mAh g−1 at 20 mA g−1), excellent rate capability (122 mAh g−1 at 1000 mA g−1) and outstanding cycling performance (up to 109 mAh g−1 after 500 cycles at 500 mA g−1). This work provides decisive guidance for a feasible technical solution and analyses the deep mechanisms on tuning of metal sulfide electrodes for advanced RMBs.

Theoretical Model to Evaluate the Impact of Consumer Behaviour on Business Performance

This paper focuses on the problematic of how the different factors that tend to influence consumer behaviour: sociocultural; economic; personal; psychological, can positively affect the innovation cycle and, consequently, the business performance, in both quantitative and qualitative terms. Based on the existing literature, a theoretical model was conceptualized. This model, supported by nine operational propositions, was called “Model for the Evaluation of the Impact of Consumer Behaviour on Business Performance,” because of the role that the factors system assumes on its execution and its consequent relation with the innovation cycle and business performance dimension. Following an empirical-formal methodology, the investigation process involved the collection of data through a questionnaire, applied to a representative set of SME’s from the Portuguese economic fabric - resorting to a sampling universe associated companies of the Portuguese Entrepreneurial Association (AEP). It ́s our objective and conviction, after the estimation process, through the application of a modelling process based on structural equations, to confirm the existence of positive and statistically relevant effects among the three dimensions that make up the developed model.

Vibration-Induced Stabilization of Lithium Anodes: Synergistic Effects of Morphological and SEI Evolution.

Lithium metal is a highly attractive anode material for next-generation energy storage systems due to its extremely high energy density and low redox potential. Despite the growing interest in lithium metal batteries for electric vehicles (EVs), the effect of mechanical vibrations-a common condition in automotive environments-on lithium metal anodes has rarely received attention. In this study, the impact of linear shear vibration on Li metal anodes is investigated and the resulting electrochemical behavior is analyzed. Cells exposed to horizontal vibration exhibited a thinner Li electrodeposition layer compared to non-vibrated cells (7.18µm vs 11.3µm). This vibration-induced effect also delayed the increase in overpotential in Li||Li symmetric cells, extending their cycling life by up to 30%. Moreover, full cell comprising Li metal and LiFePO4 demonstrated enhanced stability under horizontal vibration. Physicochemical and electrochemical analyses revealed that the Li2O-rich solid electrolyte interphase (SEI) formed on the electrode surface, leading to densely packed Li deposits and improved cycling performance. These findings present a novel strategy to enhance the electrochemical performance of Li electrodes through the application of linear vibration, offering valuable insights for designing EV batteries.

Exquisite hybridized electrocatalyst with moderate selenium element integration for reliable lithium-sulfur batteries.

Exquisite hybridized electrocatalyst with moderate selenium element integration for reliable lithium-sulfur batteries.

A biomimetic host from a poultry bone structure enables dendrite‐free lithium deposition

AbstractLithium metal anode is one of the ideal anode materials for the next generation of high‐energy‐density battery systems. Unfortunately, the uneven nucleation of Li leads to dendrite growth and volume changes during cycling, resulting in poor electrochemical performance and potential safety hazards, which hinder its practical application. In this work, a low‐cost chicken‐bone‐derived carbon material (CBC) with a biomimetic structure was designed and synthesized using a simple one‐step carbonization method. Combining theoretical calculations and experimental results, the self‐doped N and S heteroatoms in CBC are demonstrated to effectively reduce the binding energy with Li atoms and lower the nucleation overpotential. After uniform nucleation, the Li metal grows in a spherical shape without dendrites, which is related to the reduction of the local current density inside the biomimetic crosslinking structure of CBC. Benefiting from this favorable Li growth behavior, the Li@CBC electrode achieves ultra‐low nucleation overpotential (15.5 mV at 0.1 mA cm−2) and superdense lithium deposition (zero volume expansion rate at a capacity of 2 mAh cm−2) without introducing additional lithiophilic sites. The CBC retains a high Coulombic efficiency of over 98% in 479 cycles (1 mA cm−2 and 1 mAh cm−2) when applied in a half‐cell with Li, and shows an excellent rate and cycling performance when applied in a full cell with LiFePO4 as the cathode.

Multivariate Distribution Structured Anisotropic Inorganic Polymer Composite Electrolyte for Long-Cycle and High-Energy All-Solid-State Lithium Metal Batteries.

Solid polymer electrolytes are promising candidates for solid-state Li metal batteries owing to their favorable rheological properties and interfacial compatibility with cathodes and Li anodes. However, their limited ionic conductivity and low modulus lead to inferior electrochemical performance and dendrite growth. Herein, we developed a composite solid-state electrolyte comprising vermiculite sheets and a poly(vinylidene fluoride) (PVDF) matrix with multivariate distribution and an anisotropic structure. Within this assembly, some vermiculite sheets were suspended in the PVDF matrix to facilitate Li salt dissociation and Li+ transport, while others were tiled on the electrolyte surface, generating a dense, high-modulus Li2SiO3-rich solid electrolyte interphase via in-situ electrochemical reduction, which further improved interfacial kinetics and suppresses dendrite growth. As a result, a high conductivity of 1.38 mS cm-1 was achieved at room temperature, and the solid-state Li||Li cells displayed robust stability over 3000 h. The all solid-state LiNi0.6Co0.2Mn0.2O2||Li full cells delivered a specific capacity of 172 mAh g-1 at 0.2 C and 86% capacity retention after 500 cycles at 0.5 C. Additionally, practical cycle performance at a high loading (4.4 mAh cm-2) was achieved in pouch cells. Overall, multivariate distribution and anisotropic structuring offers a novel perspective for the preparation of high-performance solid-state electrolytes.

Customized Design of Biobased Elastomeric Antioxidative Interphase for High-Voltage Ni-Rich Cathodes.

High-voltage (≥4.5V) Ni-rich cathodes can help advance the development of the next generation of high-energy lithium-ion batteries. However, the high voltage used in Ni-rich cathodes deteriorates the cycling performance due to the structural disintegration of polycrystalline particles and electrolyte decomposition. Herein, a robust protective layer with high-voltage tolerance is applied to the surface of Ni-rich cathodes to address these challenges. The protective layer consists of a crosslinked bio-based elastomer (CBE) whose main chain is connected by saturated bonds, which confers high-voltage tolerance. CBE is an elastic material with viscoelastic properties, allowing it to serve as an energy dissipation layer that mitigates strain accumulation and preserves the structural integrity of the coated Ni-rich cathode. CBE also shows high polarity and rapid lithium-ion transport capabilities due to the presence of oxygen-containing components, which ensures tight wrapping of Ni-rich cathodes and improves their interfacial reaction kinetics. As anticipated, the 4.5V Li||LiNi0.6Co0.2Mn0.2O2 batteries exhibit an initial capacity of 176.7mA h g-1 and a capacity retention rate of 79.5% after 400 cycles. This study underscores the critical role of a customized protective layer in stabilizing Ni-rich cathodes at high voltages.

Performance Degradation Mechanism of High-Nickel Cathode Depending on Discharge Rates and Charge Voltages during Long-Term Cycling.

This study investigates the degradation mechanisms of high-nickel (Ni) layered oxide (LiNi0.83Co0.11Mn0.06O2) under varying discharge C-rates at a high cut-off voltage (4.3 V) during long-term cycling. Contradictory to conventional knowledge, a low discharge rate (0.1C) results in worse cycle performance than a high discharge rate (1C) at a high cut-off voltage. In-depth transmission electron microscopy analysis reveals that at a high C-rate discharge condition, more Ni ions are reduced from +3 to +2, yet the layered structure is maintained. In contrast, at a low C-rate, more Ni ions retain their +3 valence but the phase transition to the periodically ordered spinel occurs at some portion. The prolonged dwell time at high voltage forces Ni ions in Li layers to be locally ordered, and this phase transition more critically affects the cycling. Therefore, this study underscores that setting a proper cut-off voltage can be more significant to the cycle performance than the discharge C-rate.

General Oxygen Vacancy Engineering by Molten Zinc to Regulate Anode Redox for Durable Aqueous Zinc-Iodine Batteries.

Oxygen vacancy engineering plays a crucial role in regulating surface chemistry for managing redox behaviors. However, controllable implantation of oxygen vacancy and safe and cost-effective production remain challenging. Herein, we report a general molten zinc reduction technology to prepare oxygen-deficient oxides with tunable vacancy content, synthetic universality, and industrial compatibility under mildly elevated temperature. Taking TiO2 as an example, theoretical study demonstrates thermodynamically favorable zinc affinity on TiO2 with increasing surface coverage supporting molten Zn supply. Featuring favorable electronic structures and inferior hydrogen evolution activity, TiO2-x nanoparticles were used to decorate aqueous Zn anodes, which demonstrate much improved cycling stability, verified by theoretical and in situ and ex situ investigations. Eventually, zinc-iodine batteries were assembled using modified Zn anodes, which achieved favorable cycling performance due to the regulated anode redox and alleviated self-discharge behaviors. This work provides a general oxygen vacancy engineering technology with an in-depth understanding for durable aqueous zinc batteries and related systems.

Impact of Parameters on Gas Turbine Performance Using Energy Analysis

Gas turbine power plant performance was investigated using parametric analysis. Thermodynamic relationships were used to develop models that simulated the gas turbine performance under varying operating conditions. The gas turbine located at the Transcorp Power, Ughelli, Nigeria, was used for simulation employing MATLAB R2017b codes. The model demonstrated that the gas turbine performance is significantly influenced by operational parameters, for example, relative humidity (RH), compression ratio (CR), ambient temperature (AT) and turbine inlet temperature. The results showed that for every 0.7% increase in AT, compressor power consumption increased by 2.5%, and for every 25% increase in RH, compressor power requirement and heat supply increased by 55%. The efficiency analysis reveals that as RH increases from 40% to 50%, cycle efficiency decreases by 0.022%. Net power output increases as RH increases. Specific fuel consumption (SFC) increased as AT and compression ratio increased; a 2.25% increase in AT resulted in a 0.25% increase in SFC. A 1.85% increase in AT resulted in a 0.23% decrease in net power and a 0.68% decrease in net power output. According to the findings, increasing the CR and the temperature of the turbine inlet improves overall efficiency while decreasing AT. The thermal efficiency decreased with an increase in AT, whereas it increased as turbine inlet temperature increased. The CR, AT, and turbine inlet temperature are all major factors in the overall performance of a gas turbine. As a result, controlling the thermodynamic parameters is economically feasible for cycle performance and advantageous for gas turbine operations.

Ti-Doped, Mn-Based Polyanionic Compounds of Na4Fe1.2Mn1.8(PO4)2P2O7 for Sodium-Ion Battery Cathode

Na4Fe3(PO4)2P2O7 (NFPP) is recognized as a prospective electrode for sodium-ion batteries (SIBs) because of its structure stability, economic viability and environmental friendliness. Nevertheless, its commercialization is constrained by low operating voltage and limited theoretical capacity, which result in a power density significantly inferior to that of LiFePO4. To address these limitations, in this work, we first designed and synthesized a series of Mn-doped NFPP to enhance its operating voltage, inspired by the successful design of LiFe1-xMnxPO4 cathodes. This approach was implemented to enhance the operating voltage of the material. Subsequently, the optimized Na4Fe1.2Mn1.8(PO4)2P2O7 (1.8Mn-NFMPP) sample was selected for further Ti-doped modification to enhance its cycle durability and rate performance. The final Mn/Ti co-doped Na4Fe1.2Mn1.7Ti0.1(PO4)2P2O7 (0.1Ti-NFMTPP) material exhibited a high operating voltage of ~3.6 V (vs. Na+/Na) in a half cell, with an outstanding reversible capacity of 122.9 mAh g−1 at 0.1 C and remained at 90.6% capacity retention after 100 cycles at 0.5 C. When assembled into a coin-type full cell employing a commercial hard carbon anode, the optimized cathode material exhibited an initial capacity of 101.7 mAh g−1, retaining 86.9% capacity retention over 50 cycles at 0.1 C. These results illustrated that optimal Mn/Ti co-doping is an effective methodology to boost the electrochemical behavior of NFPP materials, achieving mitigation of the Jahn–Teller effect on the Mn3+ and Mn dissolution problem, thereby significantly improving structural stability and cycling performance.