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1.
Small ; : e2406243, 2024 Oct 04.
Artigo em Inglês | MEDLINE | ID: mdl-39363796

RESUMO

Anode materials storing large-scale lithium ions gradually decrease electrochemical performance due to severe volume changes during cycling. Therefore, there is an urgent need to develop anode materials with high electrochemical capacity and durability, without deterioration arising due to the volume changes during the electrochemical processes. To date, mesoporous materials have received attention as anode materials due to their ability to mitigate volume expansion, offer a short pathway for Li+ transport, and exhibit anomalous high capacity. However, the nano-frameworks of transition metal oxide collapse during conversion reactions, demanding an improvement in nano-framework structure stability. In this study, ordered mesoporous nickel manganese oxide (m-NMO) is designed as an anode material with a highly durable nanostructure. Interestingly, m-NMO showed better cycle performance and higher electrochemical capacity than those of nickel oxide and manganese oxide. Operando small-angle X-ray scattering and ex situ transmission electron microscopic results confirmed that the binary m-NMO sustained a highly durable nanostructure upon cycling, unlike the single metal oxide electrodes where the mesostructures collapsed. Ex situ X-ray absorption spectroscopy proved that nickel and manganese showed different electrochemical reaction voltages, and thus undergoes sequential conversion reactions. As a result, both elements can act as complementary nano-propping buffers to maintain stable mesostructure.

2.
Small Methods ; : e2400843, 2024 Sep 11.
Artigo em Inglês | MEDLINE | ID: mdl-39258344

RESUMO

Metal selenides have received extensive research attention as anode materials for batteries due to their high theoretical capacity. However, their significant volume expansion and slow ion migration rate result in poor cycling stability and suboptimal rate performance. To address these issues, the present work utilized multivalent iron ions to construct fast pathways similar to superionic conductors (Fe-SSC) and introduced corresponding selenium vacancies to enhance its performance. Based on first-principles calculations and molecular dynamics simulations, it is demonstrated that the addition of iron ions and the presence of selenium vacancies reduced the material's work function and adsorption energy, lowered migration barriers, and enhances the migration rate of Li+ and Na+. In Li-ion half batteries, this composite material exhibites reversible capacity of 1048.3 mAh g-1 at 0.1 A g-1 after 100 cycles and 483.6 mAh g-1 at 5.0 A g-1 after 1000 cycles. In Na-ion half batteries, it is 687.7 mAh g-1 at 0.1 A g-1 after 200 cycles and 325.9 mAh g-1 at 5.0 A g-1 after 1000 cycles. It is proven that materials based on Fe-SSC and selenium vacancies have great applications in both Li-ion batteries and Na-ion batteries.

3.
ACS Appl Mater Interfaces ; 16(37): 49227-49235, 2024 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-39235950

RESUMO

High-nickel (Ni ≥ 90%) cathodes which have a high specific capacity hold great potential for next-generation lithium-ion batteries (LIBs). However, their practical application is restricted by their high interfacial reactivity because of the presence of residual lithium (Li) compounds on the surface. Herein, the LiNi0.9Co0.06Mn0.04O2 (NCM90) cathode is surface-modified with sulfur (S) via a simple and feasible dry mixing and low-temperature heat treatment, converting the residual lithium compound on the surface into inactive lithium sulfate (Li2SO4). This induces the formation of a stable inorganic enriched electrode-electrolyte interface on the cathode surface and inhibits the occurrence of side reactions, ultimately inhibiting lattice collapse and the dissolution of transition metal ions. After modifying, the capacity retention rates of NCM90/Li and NCM90/graphite cells are both greatly enhanced after long cycling. This work provides a new idea for the rational design of the electrode-electrolyte interface of high-nickel cathodes.

4.
ACS Nano ; 18(39): 26799-26806, 2024 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-39297802

RESUMO

The application of nanosized active particles in Li-ion batteries has been the subject of intense investigation, yielding mixed results in terms of overall benefits. While nanoparticles have shown promise in improving rate performance and reducing issues related to cracking, they have also faced criticism due to side reactions, low packing density, and consequent subpar volumetric battery performance. Interesting processes such as self-assembly have been proposed to increase packing density, but these tend to be incompatible with scalable processes such as roll-to-roll coating, which are essential to manufacture electrodes at scale. Addressing these challenges, this research demonstrates the long-range self-assembly of carbon-decorated V2O5 nanofiber cathodes as a model system. These nanorods are closely packed into thick electrode films, exhibiting a high volumetric capacity of 205 mA h cm-3at 0.2 C. This surpasses the volumetric capacity of unaligned V2O5 nanofiber electrodes (82 mA h cm-3) under the same cycling conditions. We also demonstrate that these energy-dense electrodes retain an excellent capacity of up to 190.4 mA h cm-3(<2% loss) over 500 cycles without needing binders. Finally, we demonstrate that the proposed self-assembly process is compatible with roll-to-roll coating. This work contributes to the development of energy-dense coatings for next-generation battery electrodes with high volumetric energy density.

5.
ACS Appl Mater Interfaces ; 16(40): 53621-53630, 2024 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-39317991

RESUMO

Long-term durability and safety are required to develop Li-ion batteries that can operate at high voltages. However, side reactions, including the release of O2 from the electrode and CO2 from the organic electrolyte, occur at the positive-electrode/electrolyte interface during charging at high voltages. In this study, universal neural network potential (UNNP)-driven molecular dynamics (MD) calculations are used to investigate the mechanism of the reaction between LixCoO2 (0 ≤ x ≤ 1) or LixNiO2 (0 ≤ x ≤ 1), as the positive-electrode material, and an ethylene-carbonate-based electrolyte, with a solid-liquid interface composed of ∼1700 atoms. Molecular CO2 and O2 evolve from the partially or fully Li-deintercalated LixNiO2, while no gas-evolution reactions are observed for LixCoO2. Hence, compared LixNiO2, the LiCoO2 electrode is more stable toward the decomposition of ethylene carbonate in the charged state. The decomposition reactions at the solid-liquid interface during charging are also analyzed using a NN force field. This study provides a robust approach involving MD simulations using UNNP to better understand the side reactions in electrochemical devices, which can guide manufacturers in selecting appropriate materials.

6.
Small ; : e2406173, 2024 Sep 03.
Artigo em Inglês | MEDLINE | ID: mdl-39225362

RESUMO

Covalent organic frameworks (COFs), featuring structural diversity, permanent porosity, and functional versatility, have emerged as promising electrode materials for rechargeable batteries. To date, amorphous polymer, COF, or their composites are mostly explored in lithium-ion batteries (LIBs), while their research in other alkali metal ion batteries is still in infancy. This can be due to the challenges that arise from large volume changes, slow diffusion kinetics, and inefficient active site utilization by the large Na+ or K+ ion. Herein, microwave-assisted imide-based 2D COF, TAPB-NDA covalently connected with amine-functionalized carbon nanotubes (TAPB-NDA@CNT) targeting the application in both Li-/Na-ion batteries, is synthesized. As-synthesized, TAPB-NDA@CNT50 displays the good performance as LIB cathode with a specific capacity of ≈138 mAh g-1 at 25 mA g-1, long cycling stability (81.2% retention after 2000 cycles at 300 mA g-1), with excellent reversible capacity retention of ≈79.6%. Similarly, TAPB-NDA@CNT50, when employed in sodium-ion battery (SIB), exhibited 136.7 mAh g-1 specific capacity at 25 mA g-1, retained ≈80% of the reversible capacity after 1000 cycles at 300 mA g-1 and showing excellent rate performance. The structural advantage of TAPB-NDA@CNT will encourage researchers to design COF-based cathodes for the alkali ion batteries.

7.
Gels ; 10(9)2024 Aug 29.
Artigo em Inglês | MEDLINE | ID: mdl-39330165

RESUMO

The rapid expansion of flexible and wearable electronics has necessitated a focus on ensuring their safety and operational reliability. Gel polymer electrolytes (GPEs) have become preferred alternatives to traditional liquid electrolytes, offering enhanced safety features and adaptability to the design requirements of flexible lithium-ion batteries. This review provides a comprehensive and critical overview of recent advancements in GPE technology, highlighting significant improvements in its physicochemical properties, which contribute to superior long-term cycling stability and high-rate capacity compared with traditional organic liquid electrolytes. Special attention is given to the development of smart GPEs endowed with advanced functionalities such as self-protection, thermotolerance, and self-healing properties, which further enhance battery safety and reliability. This review also critically examines the application of GPEs in high-energy cathode materials, including lithium nickel cobalt manganese (NCM), lithium nickel cobalt aluminum (NCA), and thermally stable lithium iron phosphate (LiFePO4). Despite the advancements, several challenges in GPE development remain unresolved, such as improving ionic conductivity at low temperatures and ensuring mechanical integrity and interfacial compatibility. This review concludes by outlining future research directions and the remaining technical hurdles, providing valuable insights to guide ongoing and future efforts in the field of GPEs for lithium-ion batteries, with a particular emphasis on applications in high-energy and thermally stable cathodes.

8.
Adv Mater ; : e2410277, 2024 Sep 09.
Artigo em Inglês | MEDLINE | ID: mdl-39246136

RESUMO

Lithium metal batteries paired with high-voltage LiNi0.5Mn1.5O4 (LNMO) cathodes are a promising energy storage source for achieving enhanced high energy density. Forming durable and robust solid-electrolyte interphase (SEI) and cathode-electrolyte interface (CEI) and the ability to withstand oxidation at high potentials are essential for long-lasting performance. Herein, advanced electrolytes are designed via trio-functional additives to carbonate-based electrolytes for 5 V Li||LNMO and graphite||LNMO cells achieving 88.3% capacity retention after 500 charge-discharge cycles. Theoretical calculations reveal that adding adiponitrile facilitates the presence of more hierarchical DFOB- and PF6 - dual anion structure in the solvation sheath, leading to a faster de-solvation of the Li cation. By combining both fluorine and nitrile additives, an efficient synergistic effect is obtained, generating robust thin inorganic SEI and CEI films, respectively. These films enhance microstructural stability; Li dendrite growth on the Li electrode is being suppressed at the anode side and transition-metals dissolution from the cathode is being mitigated, as evidenced by cryo-transmission electron microscopy and synchrotron studies.

9.
ACS Nano ; 18(34): 23380-23391, 2024 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-39157965

RESUMO

Rapid capacity fading, interfacial instability, and thermal runaway due to oxygen loss are critical obstacles hindering the practical application and commercialization of Ni-rich cathodes (LiNi0.8Co0.1Mn0.1O2, NCM811). Herein, a Sn4+/F- codoping and LiF-coated Ni-rich cathode, denoted as NCM811-SF, is structurally fabricated that demonstrates very high cyclic and thermal stabilities. The introduction of Sn4+ regulates the local electronic structure and facilitates the conversion of the layered structure into a spinel phase; F- captures lithium impurities to form LiF coatings and forms TM-F bonds to reduce Ni/Li disordering. The compositionally complex codoping strategy reduces the internal structure strain, inhibits the Li+/Ni2+ intermixing during cycling and degradation of the nanoscale structure, and further improves the thermal stability and the crystal structure. The cathodic electrode showed a little volume shift at 2.8-4.5 V, which significantly decreased lattice flaws and fractures generated by local strain, based on detailed analyses performed using COMSOL simulations, X-ray diffraction, and scanning transmission electron microscopy. Benefiting from this, after 300 cycles, our as-prepared NCM811-SF cathode maintains 85.4% of its initial capacity at 4.5 V and has an excellent reversible capacity equal to 169 mAh·g-1 at 1 C. In addition, the NCM811-SF/graphite cell in a pouch-type complete cell retained 94.8% of its starting capacity following 500 cycles. These findings underscore the effectiveness of introducing the Sn-O and TM-F bonds in improving the durability and electrochemical efficiency of the cathode material, which makes it a good choice for high-efficiency Li-ion batteries.

10.
Angew Chem Int Ed Engl ; : e202410396, 2024 Aug 08.
Artigo em Inglês | MEDLINE | ID: mdl-39115462

RESUMO

The pursuit of carbon-neutral energy has intensified the interest in green hydrogen production from direct seawater electrolysis, given the scarcity of freshwater resources. While Ni-based catalysts are known for their robust activity in alkaline water oxidation, their catalytic sites are prone to rapid degradation in the chlorine-rich environments of seawater, leading to limited operation time. Herein, we report a Ni(OH)2 catalyst interfaced with laser-ablated LiFePO4 (Ni(OH)2/L-LFP), derived from spent Li-ion batteries (LIBs), as an effective and stable electrocatalyst for direct seawater oxidation. Our comprehensive analyses reveal that the PO4 3- species, formed around L-LFP, effectively repels Cl- ions during seawater oxidation, mitigating corrosion. Simultaneously, the interface between in situ generated NiOOH and Fe3(PO4)2 enhances OH- adsorption and electron transfer during the oxygen evolution reaction. This synergistic effect leads to a low overpotential of 237 mV to attain a current density of 10 mA cm-2 and remarkable durability, with only a 3.3 % activity loss after 600 h at 100 mA cm-2 in alkaline seawater. Our findings present a viable strategy for repurposing spent LIBs into high-performance catalysts for sustainable seawater electrolysis, contributing to the advancement of green hydrogen production technologies.

11.
Int J Mol Sci ; 25(15)2024 Aug 04.
Artigo em Inglês | MEDLINE | ID: mdl-39126084

RESUMO

Nowadays, owing to the new technological and industrial requirements for equipment, such as flexibility or multifunctionally, the development of all-solid-state supercapacitors and Li-ion batteries has become a goal for researchers. For these purposes, the composite material approach has been widely proposed due to the promising features of woven carbon fiber as a substrate material for this type of material. Carbon fiber displays excellent mechanical properties, flexibility, and high electrical conductivity, allowing it to act as a substrate and a collector at the same time. However, carbon fiber's energy-storage capability is limited. Several coatings have been proposed for this, with nanostructured transition metal oxides being one of the most popular due to their high theoretical capacity and surface area. In this overview, the main techniques used to achieve these coatings-such as solvothermal synthesis, MOF-derived obtention, and electrochemical deposition-are summarized, as well as the main strategies for alleviating the low electrical conductivity of transition metal oxides, which is the main drawback of these materials.


Assuntos
Fibra de Carbono , Capacitância Elétrica , Fontes de Energia Elétrica , Eletrodos , Lítio , Nanoestruturas , Óxidos , Lítio/química , Fibra de Carbono/química , Óxidos/química , Nanoestruturas/química , Elementos de Transição/química , Condutividade Elétrica , Metais/química
12.
Chemistry ; 30(50): e202400189, 2024 Sep 05.
Artigo em Inglês | MEDLINE | ID: mdl-38958147

RESUMO

Because of its high specific capacity and superior rate performance, porous carbon is regarded as a potential anode material for lithium-ion batteries (LIBs). However, porous carbon materials with wide pore diameter distributions suffer from low structural stability and low electrical conductivity during the application process. During this study, the calcium carbonate nanoparticle template method is used to prepare coal tar pitch-derived porous carbon (CTP-X). The coal tar pitch-derived porous carbon has a well-developed macroporous-mesoporous-microporous hierarchical porous network structure, which provides abundant active sites for Li+ storage, significantly reduces polarization and charge transfer resistance, shortens the diffusion path and promotes the rapid transport of Li+. More specifically, the CTP-2 anode shows high charge capacity (496.9 mAh g-1 at 50 mA g-1), excellent rate performance (413.6 mAh g-1 even at 500 mA g-1), and high cycling stability (capacity retention rate of about 100 % after 1,000 cycles at 2 A g-1). The clean and eco-friendly large-scale utilization of coal tar pitch will facilitate the development of high-performance anodes in the field of LIBs.

13.
ChemSusChem ; : e202400449, 2024 Jul 23.
Artigo em Inglês | MEDLINE | ID: mdl-39041945

RESUMO

Here, we have developed lithium-ion capacitors (LICs) with all the components, except the electrolyte solution, effectively recycled from the spent Lithium-ion batteries (LIBs). Hybrid capacitors, such as LICs, are potential breakthroughs in electrochemical energy storage devices, where most research is focused. These devices can simultaneously guarantee high energy and power by hybridizing battery-type and capacitive-type electrodes with two different reaction mechanisms. We have successfully upcycled the graphite, current collector, separator, etc., from the spent LIBs to fabricate a high-performance LIC. Our LIC consists of recovered graphite (RG) coated over recovered copper foil as an anode, recycled polypropylene as the separator, and reduced graphene oxide (rGO) synthesized from RG as the cathode. The RG half-cell exhibited an excellent specific capacity of 302 mAh g-1 even after 75 charge-discharge cycles with a coulombic efficiency of >99 %. The Li/rGO displayed remarkable cycling performance for over 1000 cycles with high stability and reversibility. Subsequently, the pre-lithiated RG (p-RG) electrode is paired with the rGO electrode under the balanced loading conditions to construct LIC, rGO/p-RG, delivering a maximum energy density of 185 Wh kg-1 with ultra-long durability of more than 10,000 cycles. The possibility of LIC under different climatic conditions is also explored, and its remarkable performance under various temperature conditions is worth mentioning.

14.
Angew Chem Int Ed Engl ; 63(42): e202410326, 2024 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-39054680

RESUMO

High-voltage ultrahigh-Ni cathodes (LiNixCoyMn1-x-yO2, x≥0.9) can significantly enhance the energy density and cost-effectiveness of Li-ion batteries beyond current levels. However, severe Li-Ni antisite defects and their undetermined dynamic evolutions during high-voltage cycling limit the further development of these ultrahigh-Ni cathodes. In this study, we quantify the dynamic evolutions of the Li-Ni antisite defect using operando neutron diffraction and reveal its coupling relationship with anionic redox, another critical challenge restricting ultrahigh-Ni cathodes. We detect a clear Ni migration coupled with an unstable oxygen lattice, which accompanies the oxidation of oxygen anions at high voltages. Based on these findings, we propose that minimized Li-Ni antisite defects and controlled Ni migrations are essential for achieving stable high-voltage cycling structures in ultrahigh-Ni cathodes. This is further demonstrated by the optimized ultrahigh-Ni cathode, where reduced dynamic evolutions of the Li-Ni antisite defect effectively inhibit the anionic redox, enhancing the 4.5 V cycling stability.

15.
Polymers (Basel) ; 16(13)2024 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-39000618

RESUMO

Realizing rechargeable cells with practical energy and power density requires electrodes with high active material loading, a remaining challenge for solid-state batteries. Here, we present a new strategy based on ionogel-derived solid-state electrolytes (SSEs) to form composite electrodes that enable high active material loading (>10 mg/cm2, ~9 mA/cm2 at 1C) in a scalable approach for fabricating Li-ion cells. By tuning the precursor and active materials composition incorporated into the composite lithium titanate electrodes, we achieve near-theoretical capacity utilization at C/5 rates and cells capable of stable cycling at 5.85 mA/cm2 (11.70 A/g) with over 99% average Coulombic efficiency at room temperature. Finally, we demonstrate a complete polymeric solid-state cell with a composite anode and a composite lithium iron phosphate cathode with ionogel SSEs, which is capable of stable cycling at a 1C rate.

16.
Int J Biol Macromol ; 276(Pt 1): 133893, 2024 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-39019370

RESUMO

The idea of replacing liquid electrolytes with polymer electrolytes has been successful and the development of these electrolytes has provided acceptable results. With the start of using natural polymers in the polymer industry, as well as starch, these materials can be one of the most important candidates for the polymer matrix in electrolytes. In this study, starch has been investigated as a polymer electrolyte, poly[poly(ethylene glycol) methacrylate] (PEGMA) is grafted to the starch by radical polymerization, and synthesized copolymers are used as solid polymer electrolytes (SPEs). Furthermore, by adding N,N'-methylenebisacrylamide (MBA) as a cross-linking agent, gel polymer electrolytes (GPEs) are produced after swelling in the liquid electrolyte. After characterization, the synthesized polymer electrolytes are investigated in terms of electrochemical properties. The best ionic conductivity of 3.8 × 10-5 S cm-1 is obtained for SPEs whereas it is obtained 4.3 × 10-3 S cm-1 for GPEs at room temperature. The ion transfer number in the range of 0.47-0.91 confirms the compatibility between the electrolytes and electrode. Also, the prepared polymer electrolytes present excellent electrochemical properties, including, a wide electrochemical stability window above 4.7 V, good specific capacities in the range of 170-200 mAh g-1 with a storage capacity of more than 92 %, and Coulombic efficiency of about 98 % after 100 cycles at 0.2 C.


Assuntos
Fontes de Energia Elétrica , Eletrólitos , Géis , Metacrilatos , Polietilenoglicóis , Amido , Eletrólitos/química , Amido/química , Polietilenoglicóis/química , Géis/química , Metacrilatos/química , Lítio/química , Íons/química , Condutividade Elétrica , Polímeros/química
17.
ACS Appl Mater Interfaces ; 16(30): 39277-39286, 2024 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-39024540

RESUMO

An unstable solid electrolyte interphase (SEI) has been recognized as one of the biggest challenges to commercializing silicon (Si) anodes for high-energy-density batteries. This work thoroughly investigates a binary cation matrix of Mg2++Li+ electrolyte and its role in SEI development, suppression, and evolution of a Si anode. Findings demonstrate that introducing Mg ions dramatically reduces the SEI growth before lithiation occurs, primarily due to the suppression of solvent reduction, particularly ethylene carbonate (EC) reduction. The Mg2+ alters the Li+ cation solvation environment as EC preferably participates in the oxophyllic Mg2+ solvation sheath, thereby altering the solvent reduction process, resulting in a distinct SEI formation mechanism. The initial SEI formation before lithiation is reduced by 70% in the electrolyte with the presence of Mg2+ cations. While the SEI continues to develop in the postlithiation, the inclusion of Mg ions results in an approximately 80% reduction in the postlithiation SEI growth. Continuous electrochemical cycling reveals that Mg2+ plays a crucial role in stabilizing the deep-lithiated Si phases, which effectively mitigates side reactions, resulting in controlled SEI growth and stable interphase while eliminating complex LixSiy formation. Mg ions promote the development of a notably more rigid and homogeneous SEI, characterized by a reduced dissipation (ΔD) in the Mg2++Li+ ion matrix compared to the solely Li+ system. This report reveals how the Mg2++Li+ ion matrix affects the SEI evolution, viscoelastic properties, and electrochemical behavior at the Si interface in real time, laying the groundwork for devising strategies to enhance the performance and longevity of Si-based next-generation battery systems.

18.
Nanomaterials (Basel) ; 14(13)2024 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-38998743

RESUMO

Phosphorus (P) and TiO2 have been extensively studied as anode materials for lithium-ion batteries (LIBs) due to their high specific capacities. However, P is limited by low electrical conductivity and significant volume changes during charge and discharge cycles, while TiO2 is hindered by low electrical conductivity and slow Li-ion diffusion. To address these issues, we synthesized organic-inorganic hybrid anode materials of P-polypyrrole (PPy) and TiO2-PPy, through in situ polymerization of pyrrole monomer in the presence of the nanoscale inorganic materials. These hybrid anode materials showed higher cycling stability and capacity compared to pure P and TiO2. The enhancements are attributed to the electrical conductivity and flexibility of PPy polymers, which improve the conductivity of the anode materials and effectively buffer volume changes to sustain structural integrity during the charge and discharge processes. Additionally, PPy can undergo polymerization to form multi-component composites for anode materials. In this study, we successfully synthesized a ternary composite anode material, P-TiO2-PPy, achieving a capacity of up to 1763 mAh/g over 1000 cycles.

19.
Front Chem ; 12: 1427536, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38947957

RESUMO

Interfacial charge transfer reactions involving cations and electrons are fundamental to (photo/electro) catalysis, energy storage, and beyond. Lithium-coupled electron transfer (LCET) at the electrode-electrolyte interfaces of lithium-ion batteries (LIBs) is a preeminent example to highlight the importance of charge transfer in modern-day society. The thermodynamics of LCET reactions define the minimal energy for charge/discharge of LIBs, and yet, these parameters are rarely available in the literature. Here, we demonstrate the successful incorporation of tungsten oxides (WOx) within a chemically stable Zr-based metal-organic framework (MOF), MOF-808. Cyclic voltammograms (CVs) of the composite, WOx@MOF-808, in Li+-containing acetonitrile (MeCN)-based electrolytes showed an irreversible, cathodic Faradaic feature that shifted in a Nernstian fashion with respect to the Li+ concentration, i.e., ∼59 mV/log [(Li+)]. The Nernstian dependence established 1:1 stoichiometry of Li+ and e-. Using the standard redox potential of Li+/0, the apparent free energy of lithiation of WOx@MOF-808 (ΔGapp,Li) was calculated to be -36 ± 1 kcal mol-1. ΔGapp,Li is an intrinsic parameter of WOx@MOF-808, and thus by deriving the similar reaction free energies of other metal oxides, their direct comparisons can be achieved. Implications of the reported measurements will be further contrasted to proton-coupled electron transfer (PCET) reactions on metal oxides.

20.
Micromachines (Basel) ; 15(7)2024 Jun 27.
Artigo em Inglês | MEDLINE | ID: mdl-39064338

RESUMO

Graphite is a versatile material used in various fields, particularly in the power source manufacturing industry. Nowadays, graphite holds a unique position in materials for anode electrodes in lithium-ion batteries. With a carbon content of over 99% being a requirement for graphite to serve as an electrode material, the graphite refinement process plays a pivotal role in the research and development of anode materials for lithium-ion batteries. This study used three different processes to purify spherical graphite through wet chemical methods. The spherical graphite after the purification processes was analysed for carbon content by using energy-dispersive X-ray (EDX) spectroscopy and was evaluated for structural and morphological characteristics through X-ray diffraction (XRD), scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) analyses. The analyses results indicate that the three-step process via H2SO4-NaOH-HCl cleaning can elevate the carbon content from 90% to above 99.9% while still maintaining the graphite structure and spherical morphology, thus enhancing the surface area of the material for anode application. Furthermore, the spherical graphite was studied for electrochemical properties when used as an anode for Li-ion batteries using cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) measurements. The results demonstrated that the purification process significantly improves the material's capacity with a specific capacity of 350 mAh/g compared to the 280 mAh/g capacity of the anode made of spherical graphite without purification.

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