High-performance Li-ion Batteries Research Articles

Extending Cycle Life of Li-Ion Batteries Via Gas-Phase Nanocoating of Cathode Active Materials

The further penetration of the electric vehicles is dependent on the development of high-performance Li-ion batteries in terms of cost, cycle life, energy density, safety as well as sustainability. It is expected, in the short term, EVs will rely more on Li-ion technologies using active materials such as Ni-rich NMC cathode and Si anode for developing high specific energy and lower cost batteries1.However, these active materials are facing multiple serious challenges which could hinder their targeted performance. Regarding this, Ni-rich NMC cathode active materials (CAM), in spite of their high energy density as a result of higher Ni content, tend to undergo dramatic capacity fade. Since most degradation mechanisms are related to the surface of active materials, immense research and development efforts have been dedicated to surface modification techniques, and especially coating strategies2,3.Examples of surface modification strategies include sol-gel, hydro/solvothermal deposition, and dry coating. A main drawback of these techniques is that they are not capable of precise control of the film thickness and uniformity. On the other hand, gas-phase coating techniques, such as atomic or molecular layer deposition, can address these shortcomings by offering a precise thickness control even in the range of angstroms and pinhole-free conformal coatings. As such, these coatings are better suited at mitigating interfacial degradation. Various nanocoating chemistries, such as oxides, fluorides, nitrides, phosphates and aluminates protect and stabilize the surface of Ni-rich cathode materials through the different pathways. In this talk, we explore the benefits of gas-phase nanocoatings, and will show how we can produce surface modified Ni-rich CAM (e.g. NMC-811) in a continuous process that is ready for mass production. References M. S. E. Houache, C. H. Yim, Z. Karkar, and Y. Abu-Lebdeh, Batteries, 8 (2022).D. Weber, Đ. Tripković, K. Kretschmer, M. Bianchini, and T. Brezesinski, Eur. J. Inorg. Chem., 2020, 3117–3130 (2020).M. Lee et al., Chem. Mater., 34, 3539–3587 (2022).Y. Zhao, K. Zheng, and X. Sun, Joule, 2, 2583–2604 (2018).

A Stable Fe3O4-Based Hybrid Anodes for High Performance Li-Ion Batteries

There is an increasing demand for high-performance Li-ion batteries especially due to environmental concerns. To meet the high-performance requirements of the Li-ion batteries, conversion-type anodes stand out with their capacities. The crystal structure of magnetite (Fe3O4) benefits from its empty interstitial sites which hinders volume changes during the insertion and extraction of lithium ions. Combined with its high theoretical lithium storage capacity and abundance, Fe3O4 has great potential as an alternative anode. Yet in its practical use, the material suffers from severe capacity degradation, mainly due to the formation of a passive metallic iron layer on the electrode [1]. Another suggested mechanism responsible for the deterioration of the performance is the formation of electrochemically inactive FeO-based side products upon delithiation process [2].In this study, we utilize reduced graphene oxide (rGO) as a substrate for the ultrafine Fe3O4 nanoparticles to form a two-dimensional hybrid material with improved characteristics. Under a mild hydrothermal condition, nanoparticles were deposited by a simple redox process in an interconnected porous network of graphene. Graphene aids in improving the Fe3O4 performance not only by reducing the charge transfer resistance, buffering the volume change induced stresses and facilitating the ion transport but also by forming an effective interface with the delocalized electrons of Fe3O4 to further result in the increase of battery capacitance by the interfacial conjugation mechanism, as confirmed by in-situ EIS measurements. The Fe3O4 particles have been effectively stabilized on the rGO surface, becoming less prone to agglomeration during cycling. Consequently, the deliverable specific capacity of the hybrid material was gradually improved upon extended cycling, reaching from 1500 mAh/g up to 2200 mAh/g at 0.5 A/g at the end of 100 cycles of operation. The increase of the specific capacity during the extended cycling was attributed to the chemical and structural changes of the electrode material evaluated by TEM and ex-situ EELS measurements. It was confirmed that the particle size is greatly reduced to 1-2 nm scale, improving the lithium-ion diffusion kinetics by the increased surface area and reversibility of the redox reaction upon graphene contribution. Moreover, the aged cells were observed to still deliver around 1100 mAh/g capacity upon more than 250 times cycling at 1 A/g, indicating the great potential of the ultrafine Fe3O4 decorated reduced graphene hybrids as superior performance Li-ion battery anode materials.

Investigation of porous multi-carbon layers constructed on submicron silicon flakes for high-performance Li-ion batteries anode

Low initial coulombic efficiency (ICE) of crystal silicon anode is fatal for lithium-ion batteries, leading to impossibility for commercial application. In this study, the submicron flaky silicon particles recycled from Si waste in photovoltaic industry clustered and formed into new structure through liquid-phase pyrolysis of amorphous carbon. After covered by amorphous carbon layer, the silicon flakes are surrounded by carbon skeleton of mesh-porous to be a Nitrogen-doped submicron silicon/multi-carbon material (SCN). The initial coulombic efficiency of SCN reaches 88.55 % at high discharge/charge capacities of 960.4/850.5 mAh g−1, which owe to the appropriate amorphous carbon on surface of Si for reducing the initial irreversible capacity loss due to solid electrolyte interface layer. The capacity retention of SCN keeps to a high stage up to 74.8 % after 100 cycles. It is realized that the Nitrogen-doped reticulated porous carbon not only improves the transport of particles, but also mitigates the volume expansion of silicon during charging and discharging and improves the cycling stability of the electrode. The stable performance of large-size silicon particles in the anode provides a good guarantee for the future development of lithium-ion batteries.

Optimizing Si-Dominant Anodes in High-Energy Li-Ion Batteries with a Binary Binder System: Exploring Impacts on Adhesion, Cohesion, and Electrochemical Performance

Silicon anode stands out as a promising game-changer for Li-ion batteries (LIBs) due to its remarkable gravimetric and volumetric capacities, boasting 4200 mAh/g1 and 2200 mAh/cm3, respectively. In addition, its operating voltage of 0.4 V vs Li/Li+, abundant availability, and environmental friendliness make Si a strong candidate to revolutionize energy densities in the next-generation high-performance LIBs. However, challenges arise during lithiation as silicon undergoes an expansion of ~300% of its initial volume, leading to a cascade of detrimental effects on the electrode.1 The micron-sized silicon particles tend to pulverize, and resulting in fragmented silicon particles that become electrically isolated. Such volume variations compromise the adhesion of the Si electrode to the current collector. Furthermore, the repetitive expansion and shrinkage cycles contribute to cohesive failure within the electrode. Collectively, these factors considerably diminish the electrochemical performance and lifespan of Si anodes. Consequently, these challenges have placed major constraints on the utilization of silicon, making it currently viable only at levels below 10 wt% in LIB anodes, thereby impacting the commercial feasibility of Si-dominant anodes in high-energy LIBs.Such challenges in Si anodes impose strict demands on the binder, requiring it to maintain intimate contact between electrode components and to the current collector and preserve the integrity of ion and electron transport channels during frequent volume changes upon cycling. Obviously, the traditional binders like PVDF or carboxymethylcellulose (CMC)/Styrene-butadiene rubber (SBR) are not suitable options for addressing these specific challenges.Many approaches have been explored to address such requirements including increased crosslinking, different binding functionalities, adhesion promoters, etc.2 In this study, we investigate a binder system comprising two key components: (i) an acrylic acid-based polymer enriched with a high concentration of carboxyl groups. This component not only forms effective bonds with the silicon surface but also fosters interactions with other polar species, facilitating the self-healing properties. (ii) Incorporating a styrene-butadiene-based polymer, renowned for its exceptional flexibility, improves adhesion and enhances the tensile properties of the electrode, particularly in response to volume expansion challenges. We evaluated the characteristics of the binders and electrode properties, including adhesion to the current collector, cohesion within the electrode, and binder distribution. These properties were subsequently correlated with the initial columbic efficiencies (IEC) and electrode cycle life in Si-dominant/NMC811 cells. We show that there is an optimal binder ratio that achieves the desired adhesion and significantly enhances cohesive strength, leading to improved cycling stability compared to a single binder system.

Surface modification of silicon nanowires via drop-casting for high-performance Li-ion battery electrodes: SiNWs decorated with molybdenum oxide nanoparticles

The functionalization of molybdenum oxide (MoO3) nanoparticles is presented as a method to significantly enhance the cycling stability of lithium-ion battery (LIB) anodes based on silicon nanowire (SiNW) arrays. Transition-metal oxides have emerged as promising candidates for advanced anode materials in modern Li-ion batteries. In this study, we explore a novel approach involving the deposition of MoO3 nanoparticles via unique drop-casting technique onto pre-fabricated SiNW arrays, fabricated using a straightforward one-step metal-assisted chemical etching (MACE) process. The primary objective is to assess their potential suitability as anode materials for Li-ion batteries. Our methodology entails the top-down synthesis of binder-free hybrid electrodes, achieved by depositing Mo oxides nanostructures onto SiNW arrays through a combination of drop-casting and thermal annealing processes. The resulting MoO3@SiNWs hybrid structure exhibits distinctive and specialized attributes, including exceptional structural resilience, diminutive particle dimensions, and a porous configuration. These features effectively enhance electron and ion accessibility at the electrode-electrolyte interface.Electrochemical assessments reveal that the MoO3@SiNWs hybrids exhibit superior lithium storage performance compared to bare SiNW electrodes. Particularly under high current densities, MoO3 nanoparticles deposited via drop-casting technique demonstrate improved cycling stability and increased capacity. The enhanced electrochemical characteristics are primarily ascribed to the synergistic effects between the MoO3 nanoparticles and SiNW arrays. The findings of this study strongly suggest that the MoO3@SiNWs hybrid structure holds substantial promise as anode materials for high-performance energy storage devices.

Porous carbon with the synergistic effect of cellulose fibers and MOFs as the anode for high-performance Li-ion batteries

The commercial graphene for Li ion batteries (LIBs) has high cost and low capacity. Therefore, it is necessary to develop a novel carbon anode. The cellulose nanowires (CNWs), which has advantages of low cost, high carbon content, is thought as a good carbon precursor. However, direct carbonization of CNWs leads to low surface area and less mesopores due to its easy aggregation. Herein, the metal-organic frameworks (MOFs) have been explored as templates to prepare porous carbon due to their 3D open pore structures. The porous carbon was developed with the coordination effect of CNWs and MOFs. The precursor of MOFs coordinates with the −OH and − COOH groups in the CNWs to provide stable structure. And the MOFs was grown in situ on CNWs to reduce aggregation and provide higher porosity. The results show that the porous carbon has high specific capacity and fast Li+/electronic conductivity. As anode for LIBs, it displays 698 mAh g−1 and the capacity retention is 85 % after 200 cycles. When using in the full-battery system, it exhibits energy density of 480 Wh kg−1, suggesting good application value. This work provides a low-cost method to synthesize porous carbon with fast Li+/electronic conductivity for high-performance LIBs.

Cobalt Oxide 2D Nanosheets Formed at a Polarized Liquid|Liquid Interface toward High-Performance Li-Ion and Na-Ion Battery Anodes.

Cobalt oxide (Co3O4)-based nanostructures have the potential as low-cost materials for lithium-ion (Li-ion) and sodium-ion (Na-ion) battery anodes with a theoretical capacity of 890 mAh/g. Here, we demonstrate a novel method for the production of Co3O4 nanoplatelets. This involves the growth of flower-like cobalt oxyhydroxide (CoOOH) nanostructures at a polarized liquid|liquid interface, followed by conversion to flower-like Co3O4 via calcination. Finally, sonication is used to break up the flower-like Co3O4 nanostructures into two-dimensional (2D) nanoplatelets with lateral sizes of 20-100 nm. Nanoplatelets of Co3O4 can be easily mixed with carbon nanotubes to create nanocomposite anodes, which can be used for Li-ion and Na-ion battery anodes without any additional binder or conductive additive. The resultant electrodes display impressive low-rate capacities (at 125 mA/g) of 1108 and 1083 mAh/g, for Li-ion and Na-ion anodes, respectively, and stable cycling ability over >200 cycles. Detailed quantitative rate analysis clearly shows that Li-ion-storing anodes charge roughly five times faster than Na-ion-storing anodes.

Chemical Bonding and Activity of Atomically Dispersed Silicon in Two- and Three-Dimensional Materials.

On the basis of the especially tunable electronic property of Si, several kinds of nanomaterials with atomically dispersed Si were constructed and characterized by extensive first-principles calculations and ab initio molecular dynamics (AIMD) simulations. The new-type Si(X≡Y)n wide-bandgap semiconductors featuring through-space d-π* hyperconjugation exhibit unique properties in photoelectric conversion, photoconductivity, structural mechanics, etc. The SiC8 siligraphene with the planar tetracoordinate Si (ptSi) has a high lithium-storage capacity and comparably facile surface migration behaviors of both Li and Li+, making it a promising anode material for high-performance Li-ion batteries. The atomically dispersed Si sites of 2D monolayer materials, such as ptSi and three- and four-coordinated Si atoms, generally exhibit remarkable catalytic activity toward CO2 activation with different electron mechanisms, resulting in different scaling relations between the activity and the p-band center. The computational findings enrich the understanding of structural and chemical properties of silicon and open up avenues for developing Si-based functional materials.

Breaking Mass Transport Limitations by Iodized Polyacrylonitrile Anodes for Extremely Fast-Charging Lithium-Ion Batteries.

The fast-charging capability of rechargeable batteries is greatly limited by the sluggish ion transport kinetics in anode materials. Here we develop an iodized polyacrylonitrile (I-PAN) anode that can boost the bulk/interphase lithium (Li)-ion diffusion kinetics and accelerate Li-ion desolvation process to realize high-performance fast-charging Li-ion batteries. The iodine immobilized in I-PAN framework expands ion transport channels, compresses the electric double layer, and changes the inner Helmholtz plane to form LiF/LiI-rich solid electrolyte interphase layer. The dissolved iodine ions in the electrolyte self-induced by the interfacial nucleophilic substitution of PF6 - not only promote the Li-ion desolvation process, but also reuse the plated/dead Li formed on the anode under fast-charging conditions. Consequently, the I-PAN anode exhibits a high capacity of 228.5 mAh g-1 (39 % of capacity at 0.5 A g-1 delivered in 18 seconds) and negligible capacity decay for 10000 cycles at 20 A g-1 . The I-PAN||LiNi0.8 Co0.1 Mn0.1 O2 full cell shows excellent fast-charging performance with attractive capacities and negligible capacity decay for 1000 cycles at extremely high rates of 5 C and 10 C (1 C=180 mA g-1 ). We also demonstrate high-performance fast-charging sodium-ion batteries using I-PAN anodes.

Design of a Bioinspired Robust Three-Dimensional Cross-Linked Polymer Binder for High-Performance Li-Ion Battery Applications.

Si has the highest theoretical capacity (4200 mA h g-1) among conventional anode materials, such as graphite (372 mA h g-1), but its large volume expansion leads to deterioration of the battery performance. To overcome this problem (issue), we investigated the use of polysaccharide-based 3D cross-linked network binders for Si anodes, in which the polysaccharide formed an effective 3D cross-linked network around Si particles via cross-linking of polysaccharide with citric acid (CA). Sodium alginate (SA), a natural polysaccharide extracted from brown algae, is a suitable binder material for Si anodes because its abundant hydroxyl (-OH) and carboxyl (-COOH) groups form hydrogen and covalent bonds with the -OH groups present on the Si surface. We found that CA-cross-linked (CA-SA) could effectively prevent the volume expansion of Si anodes through the formation of 3D cross-linked network structures. In addition, the CA-SA binders provide enhanced adhesion strength, enabling the fabrication of more robust electrodes than those prepared using binders with linear structures ("linear binders"). In particular, the fabricated Si-based electrode (high mass loading of 1.5 mg cm-2) with CA-SA binder exhibited outstanding areal capacity (∼2.7 mA h cm-2) and excellent cycle retention (∼100% after 100 cycles).

Fe-N-C decorated fibrous network-wrapped biomass SiOx/C with gradient conductive structure for high performance Li-ion battery anodes

Fabrication of high performance silicon-based materials derived from natural biowastes plays a significant role in the green recycling of biomass resources. However, low utilization of organic component and poor lifespan hinders the its large scale applications. Herein, biomass derived SiOx/C-3 composite was encapsulated into Fe-N-C decorated carbon nanofibers network (Fe-N-C/SiOx/C-3) by a facile magnesiothermic reduction combined with electrostatic spinning strategy. The ingenious designed indirect contact biomass carbon/SiO2 interface effectively utilizes the organic components of rice husk and prevents the formation of SiC during reduction process. HAADF-STEM and XPS characterization confirmed the presence of Fe single atoms and the formation of Fe-N coordination bonds. Benefiting from the unique carbonaceous network and catalytic effect of Fe-N-C, the Fe-N-C/SiOx/C-3 exhibit excellent lithium storage properties (832.6 mAh g−1 after 250 cycles at 0.1 A g−1). Even at high current density (1 A g−1), the electrode can still remain a capacity of 602 mAh g−1 after 1000 cycles with capacity retention of 79.4%. The ex-situ SEM and XPS characterizations demonstrated that the gradient structure consisting of inner biomass-derived carbon and flexible carbonaceous networks enhanced the overall conductivity and structural integrity of the composite. Furthermore, the catalytic effect of Fe-N-C facilitates the rapidly formation of stable LiF-rich solid electrolyte interphase (SEI) films during charge/discharge process. The assembled LiFePO4‖Fe-N-C/SiOx/C-3 full cell shows excellent electrochemical performance (106.5 mAh g−1 after 100 cycles at 0.1A g−1), which provides insights into the fabrication of high performance biomass derived silicon based anodes.

Advancements in anode and cathode nanomaterials for high-performance Li-ion batteries

Commercially, lithium-ion batteries are the most popular batteries for electric devices, while energy density and stability have become more important for electric vehicles. Therefore, there is an increased interest in producing advanced lithium-ion batteries with a greater range of electric storage capability and improved electron transfer efficiency. Over the past few years, nanotechnology has been widely applied to enhance the physical properties of materials through the application of surface treatments or the modification of nanostructures. The significant development potential of nanotechnic applications for lithium-ion batteries is the reason for this discussion. There have been several advancements in graphene, carbon nanotubes, silicon-based and other metal-based anodes, lithium cobalt oxide, lithium iron phosphate, and nickel-based cathodes, their fabrication processes and understanding of mechanisms, as well as trends for further improvement of those previously discovered. These advancements have led to the development of batteries with greater capacity and greater performance, better stability, quicker charging times, and a longer cycle life.

Layered GeSe/thermally-reduced graphene oxide composites as efficient anodes for high-performance Li-ion batteries

Due to their layered structure and greater electrical conductivity compared to traditional metal oxides, layered metal selenides have been extensively explored as promising electrode materials for Li-ion batteries. The greatest obstacles to their continued growth, however, are the substantial volume change and particle agglomeration during cycling. In this work, layered GeSe/ thermally-reduced graphene oxide (TRG) composites were successfully synthesized by using a facile shear-force exfoliation approach. When a highly conductive TRG matrix was incorporated with GeSe particles, the resultant GeSe/TRG composite electrode achieved an impressive reversible capacity (>840.1 mAh g−1 at 0.1C), improved rate capability as well as excellent cycling stability. The remarkable improvement in electrochemical performance of the GeSe/TRG composite electrode corresponds to the TRG matrix, which potentially constructs an efficient conductive channel and serves as a flexible mechanical buffer for the restriction of volume expansion and particle aggregation.

Fundamental understanding on cyclability behaviors of ammonium vanadate nanoarchitectures as cathode materials for Li-ion batteries: A comparative insight of dual modification of precursor and morphology

Development of high-performance Li-ion battery electrodes has emerged as an important issue for satisfying good rate capability and long cycle life during electrochemical lithium (de) intercalation. As cathode materials, vanadium-based compounds are very appealing for energy-storage applications owing to their multiple valence states and coordination geometries. However, they still face bottlenecks such as less stable layered structure and intrinsically low ionic/electronic conductivity. This investigation records on two main parts of new strategic design and electrochemical lithium storage for NH4V4O10 (NHV) cathode nanostructures. NHV structures with diverse motifs (i.e. mat-like sheet, square-sheet microflowers, belt-based microflowers, and nano-belt) were systematically fabricated by tailoring the combined reducing agents (H2C2O4 + KSCN and K2C2O4 + HCl), and its concentrations under controlled hydrothermal protocol. Benefiting from H2C2O4 + KSCN as a mixed precursor in different molar ratios (2,1, 1,1, and 1:2), the electrode materials with various shapes such as mat-like sheet, square-sheet microflowers, belt-based microflowers achieved high specific capacities of 132.02, 162.54 and 172.02 mAh g−1, respectively. From results, the nanobelt-like NHV synthesized by the reducing environment of K2C2O4 + HCl with molar ratio of 1:2 at 180 °C for 24 h delivered an extraordinary discharge capacity of 196.76 mAh g−1 at a current density of 30 mA g−1 in a potential region of 1.8–4.0 V, which reach 87.28 % capacity retention over 50 cycles. However, in the process of using K2C2O4 + HCl, the change in hydrothermal conditions led to a decrease in the storage capacity and cyclability behavior. Such results will potentially help in engineering a novel strategy toward developing electrochemically appropriate constructions, which offer efficient vanadate-based nanostructures via modifying the structure and morphology with improved pathway for rapid electron transfer.

Metal oxide- and metal-loaded mesoporous carbon for practical high-performance Li-ion battery anodes

The rapidly expanding Li-ion battery market needs new materials that can satisfy the increasing energy storage demand. Metal oxides and some metals such as tin are viable alternatives to graphite as Li-ion battery anodes, but their low conductivity and large volume change during cycling impose severe challenges that need to be overcome. Confinement of metal oxide and metal nanomaterials within mesoporous carbon (MC) is an effective strategy in this regard, but complex synthesis and nanoparticle aggregation have hindered its application. Herein, we report a facile, scalable and generalized methodology for the room-temperature synthesis of metal oxide and metal nanoparticles within a MC host. The approach has been successfully applied to achieve uniform distribution and prevent aggregation of a large variety of metal oxide and metal nanomaterials in MC support. These nanocomposites were screened as Li-ion battery anodes, and the optimal candidates were shown to be superior to previously reported systems. Our synthesis method was scaled up using commercial MC. The nanocomposites were validated in a high-loading electrode (4 mg/cm2) with a practical voltage range (< 2 V vs. Li+/Li), showing impressive initial Coulombic efficiency (> 100%), and excellent stability (∼ 500 mAh/g after 250 cycles at 0.2 A/g), which was 1.5–2x better than commercial graphite at the same testing conditions. The facile nature, universality and versatility of our approach make it possible to load various metal oxide and metal nanomaterials within different types of MC. These nanocomposites would be of significant interest to different fields, such as energy storage and conversion, sensing, and catalysis.

High-Rate One-Dimensional α-MnO2 Anode for Lithium-Ion Batteries: Impact of Polymorphic and Crystallographic Features on Lithium Storage.

Manganese dioxide (MnO2) exists in a variety of polymorphs and crystallographic structures. The electrochemical performance of Li storage can vary depending on the polymorph and the morphology. In this study, we present a new approach to fabricate polymorph- and aspect-ratio-controlled α-MnO2 nanorods. First, δ-MnO2 nanoparticles were synthesized using a solution plasma process assisted by three types of sugars (sucrose, glucose, and fructose) as reducing promoters; this revealed different morphologies depending on the nucleation rate and reaction time from the molecular structure of the sugars. Based on the morphology of δ-MnO2, the polymorphic-transformed three types of α-MnO2 nanorods showed different aspect ratios (c/a), which highly affected the transport of Li ions. Among them, a relatively small aspect ratio (c/a = 5.1) and wide width of α-MnO2-S nanorods (sucrose-assisted) induced facile Li-ion transport in the interior of the particles through an increased Li-ion pathway. Consequently, α-MnO2-S exhibited superior battery performance with a high-rate capability of 673 mAh g-1 at 2 A g-1, and it delivered a high reversible capacity of 1169 mAh g-1 at 0.5 A g-1 after 200 cycles. Our findings demonstrated that polymorphs and crystallographic properties are crucial factors in the electrode design of high-performance Li-ion batteries.

Synthesis of 1D/2D VO2 (B) nanowire/g-C3N4 hybrid architectures as cathode materials for high-performance Li-ion batteries

Owing to energy density, powder density, and eco-friendliness, Li-ion batteries (LIBs) are increasingly used in transportable electronic devices and electric vehicles. Monoclinic VO2 (B) has been broadly used as a cathode owing to its abundance, affordability, high capacity, and multiple oxidation states, but it's low repeatability and slow kinetics have restricted its practical applications. To mitigate these shortcomings, novel 1D/2D VO2 (B) nanowire/g-C3N4 hybrid architecture cathode materials were synthesized via hydrothermal method, and its electrochemical activity (i.e., repeatability constancy and rate capability) for LIBs was investigated. X-ray diffraction experiments confirmed that VO2 (B) exhibited a monoclinic crystal phase. SEM images revealed that the g-C3N4 and VO2 (B) presented sheet-like morphologies and comprised nanowires of uniform thickness, respectively. Electrochemical experiments revealed that the hybrid architectures showed a capacity of 779 mAh/g, and VO2 (601.4 mAh/g) and g-C3N4 (340.6 mAh/g) at 0.1 C current density. The remarkable electrochemical activity of the materials was attributed to their distinctive structures, excellent electronic conductivity associated with g-C3N4 sheets, small transport distances for Li+ ions, and fast charge transmission owing to the presence of VO2 (B) nanowires attached to g-C3N4 sheets. Consequently, distinct VO2 (B) nanowire/g-C3N4 hybrid architectures delivered suitable electrode performance to facilitate the design of high-power LIBs and these hybrid composites can serve as suitable cathode materials for rechargeable LIBs.

In-situ growth of LiFePO4 on graphene through controlling phase transition for high-performance Li-ion battery

The incorporation of graphene (G) has been widely employed to ameliorate the inferior intrinsic electronic and ionic conductivities for phosphate-based cathode materials. Herein, we report on the successful synthesis of an in-situ growth of LiFePO4 on graphene, accomplished through a novel multi-step Precipitation-Hydrothermal-Solid state process. The process involves in-situ precipitation on graphene sheets to yield G/FePO4, followed by a wet chemical lithiation process for synthesizing G/LiFePO4OH. Subsequently, the G/LiFePO4 cathode material, featuring a carbon-coated layer, is produced from LiFePO4OH through a tavorite-olivine phase transition process conducted at 600 °C. As compared to the simple mixing technique, in-situ growth has been proven to be highly efficient for achieving thorough integration of LiFePO4 with graphene. The utilization of LiFePO4OH, a newly developed precursor, has demonstrated effective lithiation method and superior phase purity. Utilizing graphene as a two-dimensional carbon network for embedding LFP nanoparticles results in a composite material that exhibits remarkably high-rate performance with 140.0 mAh g−1 at 20C (~92 % of the capacity at 0.2C) and exceptional cycling behavior with a retention rate of ~98 % even after 1000 cycles at 1C. These remarkable findings emphasize the potential of the in-situ growth of LiFePO4 on graphene process for phosphate-based cathode.

Candle soot-metal-organic framework-based hierarchical electrode as high-performance anode for Li-ion batteries

Recently, cobalt oxide-based materials have been considered high-performance anode materials. However, cobalt oxide materials display drawbacks such as capacity fade, poor cycle life, and substantial structural strain. In this work, we report a facile synthesis of carbon-cobalt oxide composite to improve the electrode's storage capabilities and cycle life. First, metal–organic framework-based cobalt oxide nano leaves are synthesized by simple coprecipitation followed by calcination. After that, candle soot-derived carbon nanoparticles are uniformly deposited on the cobalt oxide nano leaves by a simple flame synthesis method to form a composite electrode. The fractal-like interconnected carbon nanoparticles improve the electron conducting pathways. In contrast, metal–organic framework-derived porous cobalt oxide nano leaves enhance energy storage abilities through reversible conversion reactions. The superior performance of the composite electrode is established from the galvanostatic charge–discharge experiments. Also, the composite electrode has delivered outstanding specific capacities of 811 and 503 mAh g−1 at 50 and 1000 mA g−1 current densities, respectively. Furthermore, the composite electrode exhibited good cyclic stability at 1000 mA g−1 current density by delivering an excellent specific charge capacity of 490 mAh g−1 even after 400 cycles. Therefore, these superior electrochemical properties confirm the potential applicability in high-performance and stable Li-ion batteries.

Facile and controllable synthesis of nitrogen self-doped chitosan-derived carbon for high-performance Li-ion batteries

Facile and controllable synthesis of nitrogen self-doped chitosan-derived carbon for high-performance Li-ion batteries