Fast Capacity Research Articles

Rational Design of Prussian Blue Analogues for Ultralong and Wide-Temperature-Range Sodium-Ion Batteries.

Architecting Prussian blue analogue (PBA) cathodes with optimized synergistic bimetallic reaction centers is a paradigmatic strategy for devising high-energy sodium-ion batteries (SIBs); however, these cathodes usually suffer from fast capacity fading and sluggish reaction kinetics. To alleviate the above problems, herein, a series of early transition metal (ETM)-late transition metal (LTM)-based PBA (Fe-VO, Fe-TiO, Fe-ZrO, Co-VO, and Fe-Co-VO) cathode materials have been conveniently fabricated via an "acid-assisted synthesis" strategy. As a paradigm, the FeVO-PBA (FV) delivers a superb rate capability (148.9 and 56.1 mAh/g under 0.5 and 100 C, respectively), remarkable cycling stability over 30,000 cycles, high energy density (259.7 Wh/kg for the full cell), and a wide operation-temperature range (-60-80 °C). In situ/ex situ techniques and density functional theory calculations reveal the quasi-zero-strain and multielectron redox mechanisms of the FeVO-PBA cathode during cycling, supporting its higher specific capacity and stable cycling. It is considered that the d-d electron compensation effect between Fe and V enhanced the reversibility and kinetics of redox reactions and simultaneously improved the electronic conductivity and structural stability of the FeVO-PBA cathode. This work may pave a new way for the rational design of high-performance cathode materials with bimetallic reaction centers for SIBs.

Enhanced Electrochemical Performance of Dual-Ion Batteries with T-Nb2O5/Nitrogen-Doped Three-Dimensional Porous Carbon Composites

Niobium pentoxide (T-Nb2O5) is a promising anode material for dual-ion batteries due to its high lithium capacity and fast ion storage and release mechanism. However, T-Nb2O5 suffers from the disadvantages of poor electrical conductivity and fast cycling capacity decay. Herein, a nitrogen-doped three-dimensional porous carbon (RMF) was prepared for loading niobium pentoxide to construct a composite system with excellent electrochemical performance. The obtained T-Nb2O5/RMF composites have a well-developed pore structure and a high specific surface area of 1568.5 m2 g−1, which could effectively increase the contact area between the material and electrolyte, improving the electrode reaction and lithium-ion transfer diffusion. Nitrogen doping increased surface polarity, creating more active sites and accelerating the electrode reaction rate. The introduction of T-Nb2O5 imparted high power density and excellent cycling stability to the battery. The composites exhibited good electrochemical performance when used as dual-ion battery anode, with a stable cycle life of 207.2 mA h g−1 at 1 A g−1 current density after 650 cycles and great rate performance of 181.5 mA h g−1 at 5A g−1 was also obtained. This work provides the possibility for applying T-Nb2O5/RMF as an anode for a high-performance dual-ion battery.

Enhancing Stability and 6C Fast Charging in µSi||LiNi0.8Co0.1Mn0.1O2 Lithium-Ion Batteries Using Conductive Binders With Multiple Hydrogen Bonds.

Micro-sized silicon (µSi) anodes are an attractive alternative to graphite for high-energy lithium-ion batteries (LIBs) due to their low cost and high specific capacity. However, they suffer from severe volume expansion during lithiation, leading to fast capacity decay and poor rate capability. Herein, a new hybrid binder featuring a cross-linked conductive network and multiple hydrogen bonds for µSi anodes with high areal capacity is reported. This binder demonstrates multi-scale synergistic effects, including robust binder-derived solid electrolyte interphase, multiple networks to mitigate electrode pulverization and efficient ion/electron transfer pathways. As a result, the µSi anodes exhibit long-term cyclability and exceptional rate performance, achieving a high specific capacity of 1481.3 mAh g-1 at 12 A g-1 and maintaining 960.5 mAh g-1 at 20 A g-1. When paired with the LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode, the µSi||NCM811 full cell delivers an impressive capacity of 145.8 mAh g-1 under fast 6C charging conditions, along with high Coulombic efficiency during cycling. This research presents an effective strategy for enabling fast charging and stable cycling in high-energy µSi-based LIBs.

N, S-Rich SEI Derived From Continuously-Releasing Additive for Anode-Free Lithium-Metal Batteries in Commercial Carbonate Electrolyte.

Featured with the highest possible energy density, anode-free lithium-metal batteries (AFBs) are still challenged by the fast capacity decay, especially for the ones operated in commercial carbonate electrolytes, which can be ascribed to the poor stability and continual broken/formation of the solid-electrolyte interface (SEI) formed on the anode side. Here, sacrificial additives, which have low solubility in carbonate electrolytes and can be continuously released, are proposed for AFBs. The sacrificial and continuously-releasing feature gifts the additives the capability to form and heal the SEI during the long-term cycling process, thus minimizing the loss of active Li and enabling the AFLMBs with high loading LiNi0.8Co0.1Mn0.1O2 (21.7mg cm-2) cathode a high capacity-retention of 68.9% after 50 cycles in commercial carbonate electrolyte, in contrast to the control cell failed after 30 cycles. This work presents a simple and potential strategy for the practical applications of AFLMBs.

Suppressed P3-O3' Phase Transition and Enhanced Na+ Diffusion Kinetics of O3-Type Layered Oxide Cathode via Multivariate Doping.

O3-NaNi1/3Fe1/3Mn1/3O2 has attracted much attention as a cathode for sodium-ion batteries, because of its low cost and high sodium-ion storage capacity. However, its slow Na+ diffusion kinetics and harmful P3-O3' phase transition with severe bulk strain at high voltage leads to poor rate capability and fast capacity fading. Herein, we propose a multivariate doping strategy with Cu, Mg, and Ti ions to solve the above problems of the O3-NaNi1/3Fe1/3Mn1/3O2 cathode. The O3-Na(Ni1/3Fe1/3Mn1/3)0.9Cu0.03Mg0.02Ti0.05O2 (NFMCMT) cathode exhibits enlarged Na+ diffusion channels and a strengthened layered structure, which improves the Na+ diffusion kinetics, suppresses the harmful P3-O3' phase transition at high voltages, and inhibits the intragranular fatigue cracks, leading to enhanced rate capability and cycling performance. As a result, the NFMCMT exhibits outstanding performance in the 2-4.1 V voltage window, delivers a discharge capacity of 151.2 mAh g-1 with the 81.5% capacity retention for 100 cycles at 0.1 C, and 83.1% capacity retention for 300 cycles at 5 C. Especially in the rate performance, the NFMCMT delivers a 115.6 mAh g-1 and 100.1 mAh g-1 discharge capacity even at 5 and 10 C. This work provides an effective multivariate doping strategy for development of high-performance layered oxide cathodes for sodium-ion batteries.

Advancing lithium-ion battery performance with heteroatom-based anode architectures for fast charging and high capacity.

Electric vehicles (EVs) are on the brink of revolutionizing transportation, but the current lithium-ion batteries (LIBs) used in them have significant limitations in terms of fast-charging capabilities and energy density. This feature article begins by examining the key challenges of using graphite for fast charging and silicon for achieving high energy density in LIBs. Firstly, it explores various design strategies employed by researchers worldwide to improve the fast-charging performance of graphite, such as surface coatings, morphological modifications, and binder design. However, instead of modifying graphite, a more effective approach is to use materials with inherently beneficial properties-specifically, hard carbons. The article then reviews the design strategies for increasing capacity while maintaining structural stability in silicon-based anodes, including encapsulated structures and embedded matrices. Overall, this article provides a comprehensive overview of diverse approaches aimed at advancing both fast-charging capability and energy density in LIBs.

High efficiency removal of Cs+ by Fe-Co framework PBAs from radioactive wastewater

The widespread application of nuclear energy has increased the risk of contamination by radionuclide 137Cs. Prussian blue analogues are considered to be excellent materials for the removal of 137Cs from wastewater due to their unique structure. In this work, Cs+ adsorbent for PBAs with Fe-Co framework, potassium iron hexacyanocobaltate (PBAFe), was synthesized by room temperature precipitation method. Systematic structural characterization and performance results of PBAFe showed that it has a specific surface area of 452.8 m2/g and an average pore size of 8.6nm, providing more active sites for Cs+. The adsorption of Cs+ on PBAFe exhibited fast reaction kinetics (within 10min) and high adsorption capacity (82.90mg/g), and the removal rate of Cs+ reached 98.57%. The efficient removal of Cs+ by PBAFe in various real water environments showed its excellent selectivity and potential for practical application. In addition, adsorption mechanism studies showed that the adsorption of Cs+ was achieved by ion exchange with K+ in the PBAFe lattice. PBAFe has the advantages of simple synthesis and good selectivity, and has potential application in the harmless treatment of Cs+ in radioactive wastewater.

Eliminating the crystal water in hydrated iron fluoride towards fast and high Li-ion storage capacity with ultralong cycling stability

Fluorides as conversion electrodes show great promise for Li-ion batteries due to their high theoretical capacity. However, their use is limited by low electronic conductivity and slow reaction kinetics. Additionally, fluorides usually contain crystal water in their structure, and the impact of this water on their performance is not well understood. Herein, we created FeF3@CNF nanofibers using simple electrospinning and fluorination processes as a potential anode for Li-ion batteries. These nanofibers, with FeF3 nanoparticles (∼50 nm) embeded in carbon, provide efficient pathways for lithium ion transport. By comparing the performance of FeF3 with and without crystal water through theoretical calculations and kinetics analysis, we found that removing the crystal water improves reaction kinetics and reduces mechanical strain, resulting in a significantly higher specific capacity, faster kinetics, and excellent cycling stability. In/ex-situ analytical techniques demonstrate that the rapid Li+ storage in the FeF3@CNF anode is due to a reversible conversion mechanism and particle refinement during cycling. The FeF3@CNF anode shows a kinetic advantage that matches well with activated carbon cathode, leading to superior cycling stability. This work highlights the crucial role of removing crystal water in optimizing fluoride-based electrodes and offers new insights for developing high-performance fluoride-based anodes for lithium-ion capacitors.

Oxygen vacancy-assisted construction of phosphorus-doped layers to improve the lithium storage performance of T-Nb2O5

T-Nb2O5 is a promising anode material for high power density lithium-ion batteries (LIBs) due to its fast lithium storage capacity and safe lithiation potential. However, its practical application is hindered by its low electronic conductivity. In this work, we improved the electrochemical performance of T-Nb2O5 by surface P-doping and the N-doped carbon substrate. Surface P-doping guided by defects enhances the electronic conductivity of the material, which can synergize with N-doped carbon substrates to form a conductive network and accelerate the lithiation/delithiation process. More importantly, surface P-doping does not destroy the internal crystal structure of the material, ensuring the stability of the Nb2O5 during the charge/discharge process. When used as the anode for LIBs, the Nb2O5-P/N-C exhibits great cycling stability and high-current charge/discharge performance. The specific capacity of Nb2O5-P/N-C exceeds 116 mAh g−1 after 1000 cycles at 1000 mA g−1. This work presents a novel approach to improve the electrochemical performance of T-Nb2O5.

Exploring the Synergy of SnS2 and Graphite in Composite Anodes: Influence of Graphite Size and Morphology

Lithium-ion batteries (LIBs) are key components in today’s electric vehicles and energy storage systems and play a fundamental role in enabling various aspects of modern life. At the same time, the continuous demand of LIBs with higher energy density and prolonged cycle life has driven the research into exploring advanced anode materials.SnS2 has emerged in the past few years as a promising anode material for LIBs for several reasons. It exhibits a high theoretical capacity of 1209 mAh/g, as 4.4 Li ions can be stored per formula unit of SnS2, which can lead to high energy density cells. It also has high electrical conductivity, facilitating electron transport within the anode material.Additionally, SnS2 is stable in water, enabling water-based processing, which is a necessary step to increase the environmental friendliness of electrode fabrication. However, SnS2 suffers from low first-cycle coulombic efficiency and considerable volume expansion (~300%) during cycling, which causes mechanical stress, loss of electrical contact, continuous SEI cracking and re-formation leading to relatively fast capacity fading.Graphite, the state-of-the-art anode material, possesses excellent electrical conductivity, and exceptional cycling stability, allowing the anode to maintain its structural integrity over multiple charge-discharge cycles. It also experiences minimal volume expansion (~10%) and contraction during lithiation and de-lithiation, which helps maintain the anode’s structural stability. However, graphite shows a rather low theoretical capacity of only 372 mAh/g.By combining SnS2 and graphite, the strengths of both materials can be exploited, creating synergies that enhance the overall electrochemical performance. The symbiotic relationship between SnS2 and graphite opens possibilities for overcoming the limitations of the individual components, boosting the development of high-performance anodes.In this work, we aim to investigate the synergistic effects of SnS2 and graphite in composite anodes by carrying out a systematic study to assess the influence of the following parameters on the electrochemical performance: i) SnS2/graphite mass ratio, namely 50/50 and 90/10, ii) graphite morphology, i.e. flakes and spherical-shaped particles, iii) graphite particle size, i.e. particles with D90= 24µm and D90=6µm. In addition, to also evaluate the impact of preparation methods on electrochemical performance, two distinct approaches are employed: 1) high energy planetary ball-milling to create SnS2/graphite composite powders which are further processed into slurries and coated and 2) manual blending/mechanical mixing, i.e. mixing of SnS2 and graphite directly during slurry preparation for the creation of so-called "blends". Electrode processing was done in water using carboxymethylcellulose (CMC) and styrene-butadiene rubber (SBR) as water-soluble binders. This approach allows the effects of graphite structures, particle sizes, composite ratios, and preparation methods on the electrochemical performance of lithium-ion battery anodes to be quantified. Pre- and post-mortem analysis techniques (Raman spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM)) were employed to study the structural evolution and chemical changes within the electrodes, providing crucial insights into the performance differences observed.Preliminary results indicate that the preparation method does not affect the initial capacity but only the cycling stability. Indeed, both composites and blends with 90/10 and 50/50 ratios show initial capacities of around 520 and 460 mAh/g respectively. However, the composites exhibit better cycling stability compared to their counterparts processed with low-energy mixing. In blends with larger, spherical graphite particles, an 80% state-of-health (SOH) is achieved after 122 cycles, whereas composites made using the same graphite reach 80% SOH after 250 cycles. This pattern persists when comparing blends to composites incorporating smaller graphite particles with a flake-like structure. The composite achieves an 80% SOH at 202 cycles, while the blend only achieves 117 cycles. The SnS2/ graphite ratio also affects the cycling stability with a 50/50 ratio showing higher capacity retention in comparison to the 90/10 ratio for both composites and blends. As a final step, the best performing composite and blend were tested in full-cells versus NMC811 to determine the practical applicability of the developed materials. Figure 1

Novel, Economically Scalable Approaches for the Development of High Energy Density, Long Cycle Life, and Safe Lithium-Sulfur Batteries

Lithium-sulfur (Li-S) batteries are identified as one of the most promising next-generation battery technologies owing to their high theoretical specific energy, material abundance, and low cost advantages. However, commercialization of Li-S batteries has not been widespread due to severe technical challenges1-3 including the lithium polysulfide (PS) dissolution/shuttling effect, a major cause of fast capacity degradation over cycling in Li-S batteries. In our recent work,4 a thin film of nanolayer-polymer-coated-carbons (NPC) was deposited on sulfur electrodes (NPC-S), which enabled the resultant Li-S battery cells to deliver a high specific capacity of ~1,600 mAh/g, approaching the theoretical specific capacity limit of sulfur, without adding any appreciable dead weight or volume to the batteries. Our electrochemical, analytical, and computational results suggested that the realization of the near-theoretical specific capacity from our practical Li-S battery cells was a result of the effective PS-trapping power and the increased redox reaction kinetics for sulfur « PS’s conversions during battery charge and discharge.In this talk, we will present our continued efforts to further develop the advanced Li-S battery technology where a novel, cycle-stabilizing and safety-enhancing approach is implemented, for the first time, in the Li-S batteries, in concert with the NPC-S approach. Using this synergistic strategy, the resultant Li-S battery cells demonstrated not only the near-theoretical specific capacity of sulfur (Figure 1a), but also a significantly improved cycle stability, retaining ~80% of the initial capacity after 300 charge-discharge cycles (Figure 1b). Various characterization techniques are being employed to help understand reaction mechanisms of the outstanding Li-S battery performance. In addition to the performance benefits, we will show that these approaches are simple, economically scalable, and, therefore, offer a promising potential for the development of high energy density, long cycle life, and safe Li-S batteries for practical applications. References Wang, S.; Wang, Z.; Chen, F.; Peng, B.; Xu, J.; Li, J.; Lv, Y.; Kang, Q.; Xia, A.; Ma, L. "Electrocatalysts in lithium-sulfur batteries". Nano Research 2023, 1-30.Zhao, F. L.; Xue, J. H.; Shao, W.; Yu, H.; Huang, W.; Xiao, J. "Toward high-sulfur-content, high-performance lithium-sulfur batteries: Review of materials and technologies". J Energy Chem 2023, 80, 625-657. DOI: 10.1016/j.jechem.2023.02.009.Hu, X.; Huang, T.; Zhang, G.; Lin, S.; Chen, R.; Chung, L.-H.; He, J. "Metal-organic framework-based catalysts for lithium-sulfur batteries.". Coordination Chemistry Reviews 2023, 475, 214879.Hasan, M. W.; Huynh, K.; Lama, B.; Razzaq, A. A.; Smdani, M. G.; Akter, F. N.; Maddipudi, B.; Shende, R.; Paudel, T. R.; Xing, W. "A Highly Effective Polysulfide-Trapping Approach for the Development of High Energy Density, Scalable Lithium-Sulfur Batteries". J Electrochem Soc 2024. DOI: 10.1149/1945-7111/ad3ebf. Acknowledgment This work was supported by the Linda and Larry Pearson Endowed Chair at the Department of Mechanical Engineering, South Dakota School of Mines & Technology, and the South Dakota Governor Research Center for Electrochemical Energy Storage at South Dakota School of Mines & Technology. Figure 1

Insights into Lithium Inventory Quantification of LiNi0.5Mn1.5O4-Graphite Full Cells

High voltage spinel cathode LiNi0.5Mn1.5O4 (LNMO) offers higher energy density and competitive cost compared to traditional cathodes in lithium-ion batteries, making it a promising option for high-performance battery applications. However, the fast capacity decay in the full cell hindered further commercialization. Therefore, it is crucial to evaluate lithium inventory across the entire battery system. The Li inventory evolution upon cycling in the LNMO-Graphite pouch cell is systematically studied by developing Lithium quantification methods on cathode, anode, and electrolyte. All the active and inactive Li in the system after cycling were quantified. The findings reveal that active Li loss is a primary factor contributing to capacity decay, stemming from unstable anode interphase caused by crosstalk. This crosstalk primarily originates from electrolyte degradation on the cathode under high-voltage operation, leading to increased moisture and acidity, subsequently corroding the anode interphase. In response, two approaches, including an Aluminum Oxide (Al2O3) surface coating layer on the cathode and Lithium difluoro(oxalato)borate (LiDFOB) electrolyte additives, are evaluated systematically, resulting in cycling stability enhancement. This study offers a quantitative approach to understanding the Li inventory loss in the LNMO-Gr system, providing unique insights and guidance into identifying critical bottlenecks for developing high voltage (>4.4V) lithium battery technology.

Localized High-Concentration Electrolytes for High-Voltage Disordered Rocksalt Cathode Materials

With the pursuit of high energy-density battery systems, cathode materials with high specific capacity and high working voltage are of high interest. Among the transition metal oxide cathode materials, lithium (Li)-rich cation disordered rock salt (DRX) cathode materials are promising candidates for next-generation high-energy-density Li batteries because they offer high specific capacities and cost benefits. Particularly, the manganese (Mn)-based DRXs show more promise due to the utilization of earth abundant material and good thermal stability of Mn. However, these cathodes often face big challenges when cycled in the state-of-the-art LiPF6/carbonate-based electrolytes at voltages up to 4.8 V. These include severe side reactions between the cathode and the electrolyte, transition metal dissolution and structural instability of the cathode particles, all of which result in fast capacity fading. In this work, we developed advanced localized high-concentration electrolytes (LHCEs) to mitigate these problems and enable stable cycling of a DRX cathode material, Li1.2Mn0.6Ti0.2O2 (LMTO). The LHCEs demonstrate high voltage stability of 4.9 V vs. Li/Li+ and capability of forming an ultrathin and stable cathode-electrolyte interphase. Consequently, Li||LMTO half cells with the optimal LHCE exhibit increased capacity, enhanced cycling stability and superior rate capability when compared to the cells with the conventional electrolyte. This work sheds the light of electrolyte development to enable practical DRX cathode-based high-energy Li batteries.

Evaluations of Reaction Heterogeneities in Battery Electrodes upon Fast Charging Using Operando Synchrotron Techniques

Recently, thick electrodes in lithium-ion batteries have drawn extensive attention as they effectively promote cell-level energy density by reducing the fraction of inactive components such as separators and current collectors. However, due to the sluggish electrolyte transport, the spatially non-uniform reaction can easily arise within a thick electrode design. Understanding the heterogeneous reaction and preventing it from happening is therefore critical as it may result in inferior rate performance, fast capacity degradation, and even safety hazards. This study aims to experimentally evaluate the reaction heterogeneities in thick electrodes by employing operando focused beam X-ray diffraction, and diffraction combined with X-ray absorption spectroscopy. We will compare the traditional graphite anode with different electrode designs in coin cell or pouch cell full cells upon 6C fast charging, therefore, quantitatively assessing the degree of reaction along the depth direction in electrodes under operational conditions. A detailed comparison between the experiments and simulations will help us better understand the origin of reaction heterogeneities in electrodes and guide the design of battery materials and structures in the future.

Ultrastable Cathodes Enabled by Controlled Ordered to Disordered Structure

Cathodes for next generation batteries are pressed for higher voltage operation (≥4.5V) to achieve high capacity with long cyclability and thermal tolerance. However, no existing cathode simultaneously fulfills all these requirements because high voltages lead to excessive Li extraction which places the materials under structural and electrochemical strains far beyond their thermodynamic stability limits. As a result, Li-deficient frameworks at high voltages are inherently fragile and susceptible to structural degradation, which leads to fast capacity fading, an issue that has yet to be resolved. Here, we show a new cathode option with a controlled structurally coherent architecture ranging from ordered to disordered framework that can fundamentally solve these challenges and break the voltage ceilings long imposed by existing cathodes. The novel cathode merges the advantages of ordered and disordered structures to simultaneously blend high-capacity and high-voltage operation at 4.5V without any capacity fading and even up to 4.7 V with negligible capacity decay, which the current known cathodes cannot achieve, even with cutting-edged modifications. Leveraging multiscale diffraction and imaging techniques, we reveal that the designed disordered structure surface is electrochemically and structurally indestructible even at harsh operating voltages due to densely packed framework and controllable Ni oxidation activities. This effectively alleviates surface parasitic reactions and irreversible phase transitions. In addition, structural coherence from ordering to disordering limits lattice parameter changes and mitigates lattice strain, resulting in enhanced morphological integrity with no particle cracking. Thermal stability was also significantly improved with this unique design. We expect that this innovative structural design will inspire a new wave of efforts to develop high performance cathodes for next generation battery materials.

Nanocatalysts for High-Energy-Density Lithium-Sulfur Batteries

Lithium-sulfur (Li-S) batteries hold promise to be the next-generation Li energy-storage systems due to the high theoretical energy density (2600 W h ), and the abundance and environmental friendless of sulfur. Nevertheless, challenges arising from the fundamental Li-S chemistry hamper the practical viability of Li-S batteries. Specifically, the dissolution of Li polysulfides and their slow conversion kinetics collectively cause irreversible loss of the active material and short cycle life. Efforts have been intensively dedicated in physical confinement or chemical trapping of Li polysulfides, yet such passive blocking strategy is unable to fundamentally and sufficiently suppress the accumulation of sulfide products in the electrolyte, especially for high sulfur loading and long cycling. Here, we report a Li cation-doped tungsten oxide electrocatalyst that allows accelerated conversion kinetics to counteract the polysulfide dissolution and migration. In addition, the significant lithium sulfide (Li2S) oxidation barrier necessitates activation with a high overpotential, which results in low sulfur utilization and fast capacity decay. Accordingly, we also report a heterostructured WOx/W2C nanocatalyst synthesized via ultrafast Joule heating, and the resulting heterointerfaces contribute to enhance electrocatalytic activity for Li2S oxidation, as well as controlled Li2S deposition. We studied the fundamental relationships between the improved electrocatalytic activity and the optimized structures of the electrocatalysts, demonstrated the electrocatalytic effect on battery performance and highlighted the future design of catalytic materials for the advancement of practical Li-S batteries.

Impact of Carbonate Additive on Cycle Life of Layered Metal Oxide Cathode in Localized High Concentration Electrolyte

Layered metal oxides are the leading cathode materials for high energy Sodium-ion batteries (SIBs). However, some drawbacks include fast capacity fade due to side reactions with the electrolyte, especially with high voltage (>4V vs Na+/Na). Localized high-concentration electrolytes (LHCE) have been shown to mitigate side reactions with the positive electrode due to their unique local structure, which favors the formation of a robust inorganic cathode electrolyte interphase (CEI). This study investigates the role of carbonate additives in LHCE on further extending the cycle life of layered oxide cathodes, specifically O3- NaNi0.6Mn0.2Co0.2O2. Systematic characterization, including galvanostatic cycling, electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy, gives insights into the mechanism for extended cycle life.

Salt-Concentrated Electrolyte Constructing High Elasticity Modulus Interphase for Li-Rich Layered Oxide Cathode.

Stable electrolytes are urgently required for lithium-ion batteries based on lithium-rich layered oxides (LLOs), which generally suffer from fast capacity and voltage decay at high voltages up to 4.8 V. Herein, we report a salt-concentrated electrolyte consisting of 4 M lithium hexafluorophosphate (LiPF6) salt in ester solvents of fluoroethylene carbonate (FEC) and dimethyl carbonate (DMC) to alleviate the above challenges. The solvent structure in the 4 M electrolyte shows more volatile DMC integrated with Li+ and more free antioxidative FEC compared with a 1 M electrolyte, broadening the operation voltage. Simultaneously, this electrolyte endows a thin yet high elasticity modulus LiF-rich interphase on the LLOs surface, which can effectively prevent diverse side reactions and transition metal migration, consequently improving the electrochemical performance with a voltage decay of only 0.46 mV/cycle and capacity retention of 80.3% after 500 cycles. This simple and effective approach boosts the development of high-energy-density batteries using LLOs.

End-Group Dye-Labeled Poly(hemiacetal ester) Block Copolymers: Enhancing Hydrolytic Stability and Loading Capacity for Micellar (Immuno-)Drug Delivery.

Polymers with hemiacetal esters integrated in their backbone provide beneficial degradation profiles for (immuno-) drug delivery. However, their fast hydrolysis and low drug loading capacity have limited their applications so far. Therefore, this study focuses on the stability and loading capacity of hemiacetal ester polymers. The hydrophobicity of the micellar core has a tremendous effect on the hemiacetal ester stability. For that purpose, we introduce a new monomer with a phenyl moiety for stabilizing the micellar core and improving drug loading. The carrier functionality can further be expanded by post-polymerization modifications via activated ester groups at the polymer chain end. This allows for covalent dye labeling, which provides substantial insights into the polymers' in vitro performance. Flow cytometric analyses on RAW dual macrophages revealed intact micelles exhibiting significantly higher cellular uptake compared to degraded species, thus, highlighting the potential of end group functionalized poly(hemiacetal ester)s for (immuno)drug delivery purposes.

The MoS2/rGO embed in macro-porous PAN gel as a novel DGT binding phase for the rapid and accurate detection of trace Hg(II)

The development of binding gels with a fast uptake rate, high capacity, and good selectivity could be beneficial for trace Hg(II) detection based on the DGT technology. In this study, a novel PAN@MoS2/rGO-DGT was assembled by using the nanocomposite embedded in polyacrylonitrile membrane (PAN@MoS2/rGO) as the binding phase. The interior regular finger-like macropore of the gel provided a convenient channel for the rapid mass diffusion of Hg(II), and the abundant sulfur offered the paramount driving force for trapping Hg(II). These endowed the PAN@MoS2/rGO with an impressive reaction rate, capacity, and selectivity toward Hg(II) and featured the PAN@MoS2/rGO-DGT with excellent diffusion rate (D) and adaptability in the complex matrixes across a wide range of pH, ion strength, common cations. However, the uptake of Hg(II) was influenced by the high content of chloride, thus a calibrated model was established based on the chloride concentration to correct the accumulated mass and D. After that, the high accuracy of this method was confirmed through the good consistency between Hg(II) concentration assessed by DGT and in bulk solution when the DGT was deployed to the river water, seawater, and domestic wastewater at the static and dynamic Hg(II) concentration. Field trials in the prawn farming seawater and lake water also showed a negligible deviation of Hg(II) content from the DGT and the conventional method, acquiring the actual Hg(II) level as 1.07–3.69 ng/L. The findings highlighted the application potential of macropore PAN gel hybrid with nanocomposite as a promising binding phase for trace Hg(II) or other pollutant detection.