Quantitative Kinetic Analysis Research Articles

Oxygen/Fluorine Dual‐Doped Porous Carbon Nanopolyhedra Enabled Ultrafast and Highly Stable Potassium Storage

AbstractCarbon‐based materials are promising anodes for potassium‐ion batteries (PIBs). However, due to the significant volume expansion and structural instability, it is still a challenge to achieve a high capacity, high rate and long cycle life for carbonaceous anodes. Herein, oxygen/fluorine dual‐doped porous carbon nanopolyhedra (OFPCN) is reported for the first time as a novel anode for PIBs, which exhibits a high reversible capacity of 481 mA h g−1 at 0.05 A g−1 and excellent performance of 218 mA h g−1 after 2000 cycles at 1 A g−1 with 92% capacity retention. Even after 5000 robust cycles at 10 A g−1 with charging/discharging time of around 40 s, an unprecedented capacity of 111 mA h g−1 is still maintained. Such ultrafast potassium storage and unprecedented cycling stability have been seldom reported in PIBs. Quantitative kinetics analysis reveals that both diffusion and capacitance processes are involved in the potassium storage mechanism. Density functional theory calculations demonstrate that the O/F dual‐doped porous carbon promotes the K‐adsorption ability and can absorb multiple K atoms with slight structural distortion, which accounts for the high specific capacity, outstanding rate capability, and excellent cycling stability of the OFPCN anode.

Investigating the large potential window of NiCo2O4 supercapacitors in neutral aqueous electrolyte

The enhancement of potential window can be identified as one of the effective pathways to boost the energy density of supercapacitors to break the limitation of practical applications. NiCo2O4 nanosheet networks grown on carbon cloth are prepared via a facile cathodic electrodeposition process with a post-annealing procedure. A neutral electrolyte of mixing 2 M LiSO4 and 0.1 M CoSO4 is employed to enlarge the potential window of the as-prepared NiCo2O4/CC electrode to 0–1.2 V (vs SCE), while the corresponding potential window in alkaline electrolyte is merely 0–0.5 V. Moreover, the NiCo2O4/CC electrode shows an excellent cycling stability of maintaining 129.7% after 10,000 cycles in neutral electrolyte. The quantitative CV kinetic analysis is carried out to explore the charge storage mechanism, manifesting that capacitive contribution is estimated as high as 64.7–81.8% at the sweep rate of 3–10 mV s−1. Results demonstrate that this neutral electrolyte can greatly boost the electrochemical characteristics of the NiCo2O4 electrode and also provide the possibility of achieving better characteristics in the field of energy storage when applied in other battery-type materials.

Recent progress in dilatometry for quantitative analysis of precipitation kinetics

A high-stability non-contact dilatometer based on two-beam Michelson interferomtry was developed recently, enabling isothermal measurements of relative length changes in the sub-10−5 regime with minimized drift over times as long as 106 s. This advanced technique opens up novel potentials for quantitative studies of precipitation phenomena, which are associated with tiny relative length changes that have not been accessible before. Using a dilute Al-Mg- Si alloy as a case study, the amount of the metastable coherent β″- and of the semi-coherent β’-phase, as well as the amount of the stable β-phase could be determined quantitatively from isothermal length change measurements. This is accomplished by the distinct length change features that arise from the volume excess due to the precipitates, on the one hand, and the contraction of the matrix upon precipitation of solute atoms, on the other hand. Moreover, reaction-rate analyses of isothermal length change variations yield the kinetic parameters for the formation and transformation of the precipitates.

Fabrication of Porous Carbon with Controllable Nitrogen Doping as Anode for High‐Performance Potassium‐Ion Batteries

AbstractPotassium‐ion batteries (PIBs) are a potential alternative for lithium‐ion batteries (LIBs) due to the abundant reserves of potassium and the low redox potential of K+/K. Nonetheless, the practical application of PIBs is hampered by the fact that K+ has a large ion radium and cannot smoothly and reversibly insert/extract into the existing electrode materials. Herein, a series of nitrogen‐doped porous carbon materials with varied N content are synthesized and the effect of nitrogen content on the performance of PIBs is investigated. It is demonstrated that the N content is not in direct proportion to the K‐storage capacity of porous carbon considering the irregular change of specific surface area. Porous carbon with 12.44 at% N content (NPC‐2) exhibits the best performance among the synthesized samples on account of its large specific surface area associated with the superior porous structure as well as abundant defects. It delivers a high reversible capacity of 385 mAh g−1 at 0.05 A g−1, remarkable rate performance of 218 mAh g−1at 2 A g−1, and long‐term cycling stability maintaining 242 mAh g−1 after 800 cycles at 0.5 A g−1. The quantitative kinetics analysis verify that the K‐storage mechanism is mainly dominated by surface‐driven capacitive controlled process, which explains the superior rate capability. The theoretical simulation of different types of nitrogen adsorption and density of states (DOS) prove that pyridinic‐N and pyrrolic‐N exhibit higher affinity to K atoms and thus N‐doping is beneficial to the adsorption of K+ on the surface of electrode. This work provides a basic reference for the subsequent development of carbon anode materials for potassium‐ion batteries.

Manipulation of interlayer spacing and surface charge of carbon nanosheets for robust lithium/sodium storage

The sluggish kinetics in anode materials severely prevents the practical use of lithium/sodium-ion batteries in many current and emerging applications. To overcome this bottleneck, we report a facile and scalable strategy to construct nitrogen and phosphorus co-doped carbon nanosheets with abundant electron-rich regions rendering a strong cation attraction and expanded interlayer spacing for fast lithium/sodium diffusion, which allows excellent rate capable anodes for lithium/sodium-ion batteries. Specifically, the as-prepared nanosheets afford outstanding pseudocapacitive behavior with superior rate capacities of 379 and 140 mA h g−1 at a high current density of 5.0 A g−1 for lithium and sodium storage, respectively, while the calendar life can be as long as thousands of cycles. The extraordinary rate capability is further demonstrated through combined use of quantitative kinetics analysis, galvanostatic intermittent titration technique measurements and theoretical simulation. Considering the extraordinary electrochemical performance and comprehensive analysis of pseudocapacitive lithium/sodium storage mechanism, this work holds great potential to serve as a fundamental reference for exploring robust pseudocapacitive electrode materials.

One-Pot Synthesis of Pd@PtnL Core-Shell Icosahedral Nanocrystals in High Throughput through a Quantitative Analysis of the Reduction Kinetics.

The rational design and implementation of a one-pot method is reported for the facile synthesis of Pd@PtnL (nL denotes the number of Pt atomic layers) core-shell icosahedral nanocrystals in a single step. The success of this method relies on the use of Na2 PdCl4 and Pt(acac)2 as the precursors to Pd and Pt atoms, respectively. Our quantitative analysis of the reduction kinetics indicates that the PdII and PtII precursors are sequentially reduced with a major gap between the two events. Specifically, the PdII precursor is reduced first, leading to the formation of Pd-based icosahedral seeds with a multiply-twinned structure. In contrast, the PtII precursor prefers to take a surface reduction pathway on the just-formed icosahedral seeds. As such, the otherwise extremely slow reduction of the PtII precursor can be dramatically accelerated through an autocatalytic process for the deposition of Pt atoms as a conformal shell on each Pd icosahedral core. Compared to the conventional approach of seed-mediated growth, the throughput for the one-pot synthesis of Pd@PtnL core-shell nanocrystals can be increased by more than 30-fold. When used as catalysts, the Pd@Pt4.5L core-shell icosahedral nanocrystals show specific and mass activities of 0.83 mA cm-2 and 0.39 A mgPt -1 , respectively, at 0.9 V toward oxygen reduction. The Pt-based nanocages derived from the core-shell nanocrystals also show enhanced specific (1.45 mA cm-2 ) and mass activities (0.75 A mgPt -1 ) at 0.9 V, which are 3.8 and 3.3 times greater than those of the commercial Pt/C, respectively.

Definitions of Pseudocapacitive Materials: A Brief Review

Pseudocapacitive materials generally offer both high capacitance and high rate capability, which has stimulated great efforts in developing the materials system and related energy storage devices. In recent years, however, with the extensive use of nanomaterials in batteries, fast redox kinetics comparable to pseudocapacitive have been achieved in many kinds of battery materials due to the much shortened ion diffusion lengths and highly exposed surface/interface as a result of nanosize effect. Consequently, the terms “pseudocapacitive materials” and “battery materials” are becoming more and more confusing. In this review, different opinions on the definition of pseudocapacitive materials and the evolution of the definitions as well as the resulting confusion will be firstly reviewed. Then, to accurately distinguish pseudocapacitive and battery materials, method with the consideration of both the electrochemical signatures (CVs and GCD) and quantitative kinetics analysis as a supplement is proposed. Finally, we end this review by discussing the possible device configurations of asymmetric supercapacitors and hybrid supercapacitors. The present review will help understanding the differences between pseudocapacitive materials and battery materials, and thus avoiding the definition confusion.

Designing biochemistry project with local materials to increased student’s creativity

Creativity of students has become one of the demands that must be achieved in practicum courses. This study aims to look at the effect of Biochemistry lab-based project using local materials for the creativity of students. Implementation of research using a mixed method with embedded design. The effectiveness of the program is measured by pre-post test design. Topics implementation were done on a quantitative analysis of proteins, carbohydrates qualitative analysis, quantitative analysis of carbohydrates and enzyme kinetics. The research instrument is a matter of pre-tests and post-tests that use creative thinking skills tests in the form of a description, a section of creative products as well as the student questionnaire. Quantitative data analysis performed using SPSS 22.0 to see the significance of normality, the value of N-Gain, correlation to the correlation test the skills of creative thinking with creative products and the percentage of student responses to the lab performed. Qualitative data analysis is done through a questionnaire scale attitude. Biochemistry lab results showed the project-based local materials effective in enhancing the creativity of the students both in terms of creative thinking skills as well as creative products. Students are given the opportunity to design the lab in accordance with local materials used.

Attachment and Detachment of Particles from a Surface under Shear Flow

In a recent paper, we described a quantitative analysis of the detachment kinetics of beads adsorbed in a microfluidic system under laminar shear flow. In this paper, we extend this formalism to th...

High-precision isothermal dilatometry as tool for quantitative analysis of precipitation kinetics: case study of dilute Al alloy

An in-depth case study of precipitation kinetics for alloys is presented utilizing recent progress in high-precision isothermal dilatometry by measuring relative length changes down to the range of 10^{-5} and covering large timescales exceeding 10^5 s. Using a dilute Al–Mg–Si alloy as model system, the different phases that form during isothermal heat treatment could quantitatively be analyzed both with respect to the absolute amount of precipitates and with respect to the underlying kinetics. Owing to the distinct length change features upon multi-step precipitation processes, the formation of the metastable beta ''- and beta '-phases can unambigously be detected and furthermore can specifically be distinguished and resolved. From the reaction rate analysis of the precipitation-induced relative length change, that was isothermally measured for temperatures between 170 ^circ hbox {C} and 260 ^circ hbox {C}, the evolution with time of the atomic fraction of both the beta ''- and the beta '-phase was determined. The results were also used to construct the isothermal time–temperature–precipitation diagrams which are important for technologically relevant processes.

Reduction in internal friction in silica glass with high OH content

AbstractThe aim of this article was to investigate processes occurring during annealing of silica glass classified as being of type III (J Non Cryst Solids. 1970;5(2):123‐75). This is an inexpensive silica glass produced by many manufacturers across the globe. However, it can be successfully used for fabrication of high‐Q mechanical resonators. The relationship between residual internal stress and internal friction is elucidated. Quantitative analysis of the structural relaxation kinetics is presented. The influence of the cooling process for structural transformation is also discussed. On the basis of our results, we suggest optimal annealing conditions for minimizing internal friction type III silica glass. The results will be useful for further improvement of the Q‐factor of mechanical resonators, including the test masses of the next generation of gravitational wave detectors. Our approach might, in addition, be used for studying the modification of atomic structure in multicomponent glasses.

Bacterial-Derived, Compressible, and Hierarchical Porous Carbon for High-Performance Potassium-Ion Batteries

Hierarchical-structured electrodeshavingmerits of superior cycling stability and high rate performance are highly desired for next-generationenergy storage. For the first time, we reported a compressible and hierarchical porous carbon nanofiber foam (CNFF) derived from a sustainable and abundant biomaterial resource, bacterial cellulose, for boosting the electrochemical performance of potassium-ion batteries. The CNFF free-standing electrode with a hierarchical porous three-dimensional structure demonstrated excellent rate performance and outstanding cyclic stability in the extended cycling test. Specifically, in the long-term cycling-stability test, the CNFF electrode maintained a stable capacity of 158 mA h g-1 after 2000 cycles at a high current density of 1000 mA g-1, which has an average capacity decay of 0.006% per cycle. After that, the CNFF electrode maintained a capacity of 141 mA h g-1 at a current density of 2000 mA g-1 for another 1500 cycles, and a capacity of 122 mA h g-1 at a current density of 5000 mA g-1 for an additional 1000 cycles. The mechanism for the outstanding performance is that the hierarchical porous and stable CNFF with high surface area and high electronic conductivity provides sufficient sites for potassium-ion storage. Furthermore, quantitative kinetics analysis has validated the capacitive- and diffusion-controlled charge-storage contributions in the carbon-foam electrode. This work will inspire the search for cost-effective and sustainable materials for potassium electrochemical energy storage.

Facile Fabrication of Nitrogen‐Doped Porous Carbon as Superior Anode Material for Potassium‐Ion Batteries

AbstractPotassium‐ion batteries (PIBs), using carbon materials as the anode, are regarded as a promising alternative to lithium‐ion batteries owing to the feasible formation of stage‐1 potassium intercalation compounds (KC8). However, due to the large radius of the potassium ion, graphite‐based electrodes still suffer poor rate capability and insufficient cycling life. In this work, a hierarchically nitrogen‐doped porous carbon (NPC) is reported for the first time. The NPC electrode delivers a high reversible capacity of 384.2 mAh g−1 after 500 cycles at a current density of 0.1 A g−1 and an outstanding rate capability of 185 mAh g−1 at 10.0 A g−1, which surpasses most of the reported carbonaceous electrodes in PIBs. The excellent performance can be ascribed to the surface‐driven behavior dominated K‐storage mechanism, which is verified by quantitative kinetics analysis. Theoretical simulation results further illuminate the enhanced K affinity in N‐doped active sites, which accounts for the superior rate performance of the NPC electrode. In addition, galvanostatic intermittent titration technique measurements further quantify the diffusion coefficient of K ions. Considering the superior electrochemical performance of the electrode and comprehensive investigation of the K storage mechanism, this work can provide fundamental references for the subsequent research of potassium‐ion batteries.

Rapid characterization of the activities of lignin-modifying enzymes based on nanostructure-initiator mass spectrometry (NIMS)

BackgroundProducing valuable fuels and chemicals from lignin is a key factor for making lignocellulosic biomass economically feasible; however, significant roadblocks exist due to our lack of detailed understanding of how lignin is enzymatically depolymerized and of the range of possible lignin fragments that can be produced. Development of suitable enzymatic assays for characterization of putative lignin active enzymes is an important step towards improving our understanding of the catalytic activities of relevant enzymes. Previously, we have successfully built an assay platform based on glycan substrates containing a charged perfluorinated tag and nanostructure-initiator mass spectrometry to study carbohydrate active enzymes, especially various glycosyl hydrolyses. Here, we extend this approach to develop a reliable and rapid assay to study lignin-modifying enzymes.ResultsTwo β-aryl ether bond containing model lignin dimer substrates, designed to be suitable for studying the activities of lignin-modifying enzymes (LMEs) by nanostructure-initiator mass spectrometry (NIMS), were successful synthesized. Small-angle neutron scattering experiments showed that these substrates form micelles in solution. Two LMEs, laccase from the polypore mushroom Trametes versicolor, and manganese peroxidase (MnP) from white rot fungus Nematoloma frowardii, were tested for catalytic activity against the two model substrates. We show that the reaction of laccase and MnP with phenolic substrate yields products that arise from the cleavage of the carbon–carbon single bond between the α-carbon and the adjacent aryl carbon, consistent with the mechanism for producing phenoxy radical as reaction intermediates. Reactions of the nonphenolic substrate with laccase, on the other hand, adopt a different pathway by producing an α-oxidation product; as well as the cleavage of the β-aryl ether bond. No cleavage of the carbon–carbon bond between the α-carbon and the aryl carbon was observed. To facilitate understanding of reaction kinetics, the reaction time course for laccase activity on the phenolic substrate (I) was generated by the simultaneous measurement of all products at different time points of the reaction. Withdrawal of only a small sample aliquot (0.2 μL at each time point) ensured minimum perturbation of the reaction. The time course can help us to understand the enzyme kinetics.ConclusionsA new assay procedure has been developed for studying lignin-modifying enzymes by nanostructure-initiator mass spectrometry. Enzyme assays of a laccase and a MnP on phenolic and nonphenolic β-aryl ether substrates revealed different primary reaction pathways due to the availability of the phenoxy radical intermediates. Our assay provides a wealth of information on bond cleavage events not available using conventional colorimetric assays and can easily be carried out in microliter volumes and the quantitative analysis of product formation and kinetics is rapidly achieved by NIMS. This is the first time that NIMS technology was applied to study the activities of lignin-modifying enzymes. Unlike other previous works, our use of amphiphilic guaiacylglycerol β-O-4 substrate (I) enables the formation of micelles. This approach helps avoid the re-polymerization of the resulting monomeric product. As a result, our assay can clearly demonstrate the degradation pathways of phenolic guaiacylglycerol β-O-4 type of molecules with laccase and MnP.

SnP2O7 Covered Carbon Nanosheets as a Long‐Life and High‐Rate Anode Material for Sodium‐Ion Batteries

AbstractSnP2O7 attached to reduced graphene oxide (rGO) is synthesized by a solvothermal reaction, followed by a mild annealing in Ar/H2. As an anode material for sodium‐ion batteries, this composite is associated with the conversion reaction between Sn and SnP2O7 and the alloy reaction between Sn and NaxSn, as evidenced by ex situ techniques, such as high‐resolution transmission electron microscope images, selected area electron diffraction patterns, and X‐ray diffraction patterns. The close contact between SnP2O7 and rGO facilitates the charge transfer upon cycling and benefits the preservation of SnP2O7 on rGO even after pulverization. Therefore, this composite exhibits an extraordinary cycling stability. 99% of the initial capacity is remained after 200 cycles at 0.2 A g−1 and also 99% is kept after 1000 cycles at 1.0 A g−1. The similar results are also observed in full cells. Quantitative kinetic analysis confirms that sodium storage in this composite is governed by pseudocapacitance, especially at high rates. These results indicate the promising potential of metal pyrophosphates in sodium‐ion batteries.

Real-Time Visualization and Quantification of Human Cytomegalovirus Replication in Living Cells Using the ANCHOR DNA Labeling Technology.

Human cytomegalovirus (HCMV) induces latent lifelong infections in all human populations. Between 30% and nearly 100% of individuals are affected depending on the geographic area and socioeconomic conditions. The biology of the virus is difficult to explore due to its extreme sophistication and the lack of a pertinent animal model. Here, we present the first application of the ANCHOR DNA labeling system to a herpesvirus, enabling real-time imaging and direct monitoring of HCMV infection and replication in living human cells. The ANCHOR system is composed of a protein (OR) that specifically binds to a short, nonrepetitive DNA target sequence (ANCH) and spreads onto neighboring sequences by protein oligomerization. When the OR protein is fused to green fluorescent protein (GFP), its accumulation results in a site-specific fluorescent focus. We created a recombinant ANCHOR-HCMV harboring an ANCH target sequence and the gene encoding the cognate OR-GFP fusion protein. Infection of permissive cells with ANCHOR-HCMV enables visualization of nearly the complete viral cycle until cell fragmentation and death. Quantitative analysis of infection kinetics and of viral DNA replication revealed cell-type-specific HCMV behavior and sensitivity to inhibitors. Our results show that the ANCHOR technology provides an efficient tool for the study of complex DNA viruses and a new, highly promising system for the development of innovative biotechnology applications.IMPORTANCE The ANCHOR technology is currently the most powerful tool to follow and quantify the replication of HCMV in living cells and to gain new insights into its biology. The technology is applicable to virtually any DNA virus or viruses presenting a double-stranded DNA (dsDNA) phase, paving the way to imaging infection in various cell lines, or even in animal models, and opening fascinating fundamental and applied prospects. Associated with high-content automated microscopy, the technology permitted rapid, robust, and precise determination of ganciclovir 50% and 90% inhibitory concentrations (IC50 and IC90) on HCMV replication, with minimal hands-on time investment. To search for new antiviral activities, the experiment is easy to upgrade toward efficient and cost-effective screening of large chemical libraries. Simple infection of permissive cells with ANCHOR viruses in the presence of a compound of interest even provides a first estimation of the stage of the viral cycle the molecule is acting upon.

Exposing {010} Active Facets by Multiple-Layer Oriented Stacking Nanosheets for High-Performance Capacitive Sodium-Ion Oxide Cathode.

As one of the most promising cathodes for rechargeable sodium-ion batteries (SIBs), O3-type layered transition metal oxides commonly suffer from inevitably complicated phase transitions and sluggish kinetics. Here, a Na[Li0.05 Ni0.3 Mn0.5 Cu0.1 Mg0.05 ]O2 cathode material with the exposed {010} active facets by multiple-layer oriented stacking nanosheets is presented. Owing to reasonable geometrical structure design and chemical substitution, the electrode delivers outstanding rate performance (71.8 mAh g-1 and 16.9 kW kg-1 at 50C), remarkable cycling stability (91.9% capacity retention after 600 cycles at 5C), and excellent compatibility with hard carbon anode. Based on the combined analyses of cyclic voltammograms, ex situ X-ray absorption spectroscopy, and operando X-ray diffraction, the reaction mechanisms behind the superior electrochemical performance are clearly articulated. Surprisingly, Ni2+ /Ni3+ and Cu2+ /Cu3+ redox couples are simultaneously involved in the charge compensation with a highly reversible O3-P3 phase transition during charge/discharge process and the Na+ storage is governed by a capacitive mechanism via quantitative kinetics analysis. This optimal bifunctional regulation strategy may offer new insights into the rational design of high-performance cathode materials for SIBs.

High-performance sodium-ion hybrid capacitors based on an interlayer-expanded MoS2/rGO composite: surpassing the performance of lithium-ion capacitors in a uniform system

Hybrid supercapacitors (HSCs) are novel, promising devices having features of both batteries and supercapacitors. Herein, we report HSCs (Li-HSC and Na-HSC in a uniform system) based on an interlayer-expanded MoS2/rGO composite that show ultrahigh energy density and power density as well as superior cycle stability. The 3D network-structured interlayer-expanded MoS2/rGO nanocomposite (3D-IEMoS2@G) was synthesized and employed as the anode. Because the 3D architecture of the graphene skeleton frame delivered sufficient charges and the highly interlayer-expanded MoS2 achieved fast ion diffusion, the as-prepared composite exhibited excellent performance as the anode material for both LIBs and SIBs (1600 mAh g−1 at 100 mA g−1 for the LIB; 580 mAh g−1 at 100 mAh g−1 and 320 mAh g−1 at a high current density of 10 A g−1). When paired with nitrogen-doped hierarchically porous 3D graphene (N-3DG), the obtained Na-HSC surpassed Li-HSC in a uniform system, showing an excellent performance of 140 Wh kg−1 at 630 W kg−1, 43 Wh kg−1 at an ultrahigh power density of 103 kW kg−1 (charge finished within 1.5 s) and no distinct capacity attenuation after over 10000 cycles. Thus, a quantitative kinetic analysis was performed to understand the synergistic effect of the two electrodes and the resulting effect of ions in the hybrid supercapacitors and to further pave a general path for fabricating high-performance HSCs.

Quantitative analysis of the reduction kinetics of a Pt(II) precursor in the context of Pt nanocrystal synthesis

In this letter, we report a quantitative analysis of how a Pt(II) precursor is reduced to atoms at different temperatures for the formation of Pt nanocrystals with different morphologies and sizes. Our results suggest that in the early stage of a synthesis, the Pt(II) precursor is reduced to atoms exclusively in the solution phase, followed by homogeneous nucleation to generate nuclei and then seeds. At a relatively low reaction temperature such as 22°C, the growth of the seeds is dominated by autocatalytic surface reduction that involves the adsorption and then reduction of the Pt(II) precursor on the surface of the just-formed seeds. This particular growth pathway results in relatively large assemblies of Pt nanocrystals. When the reaction temperature is increased to 100°C, the dominant reduction pathway will be switched from surface to solution phase, producing much smaller assemblies of Pt nanocrystals. Our results also demonstrate that a similar trend applies to the seed-mediated growth of Pt nanocrystals in the presence of Pd nanocubes.

Coralloidal carbon-encapsulated CoP nanoparticles generated on biomass carbon as a high-rate and stable electrode material for lithium-ion batteries

Architecture of electrode materials plays an important role in achieving favorable electrochemical performance via providing fast electronic transport pathway and shorten lithium ion diffusion distance. Herein, ultrafine CoP nanoparticles were successfully embedded in carbon nanorod, which were grown on the biomass-derived carbon (BC). When applied as anode materials for lithium-ion batteries, these CoP@C/BC displayed capable specific capacity, remarkable rate ability and outstanding long-term cycling performance. The capacity was governed by combination of diffusion-controlled and capacitive processes, according to quantitative kinetic analysis. The good electrochemical performance is attributed to hierarchical construction of nanosized CoP embedded in carbon nanorod and BC with high conductivity composite, which relieve the volume changing of CoP and provide large electrode/electrolyte interface. The present design of hierarchical architecture can be extended to other transition metal-based oxides, sulfide and phosphide electrode materials for high performance alkali metal ion batteries.