Comprehensive Electrochemical Performance Research Articles

Dealloying-constructed hierarchical nanoporous bismuth-antimony anode for potassium ion batteries

Bi-Sb alloys are appealing anode materials for potassium ion batteries (PIBs) but challenged by their enormous volumetric variation during operation. Herein, a facile one-step dealloying protocol was devised and utilized to prepare the Bi-Sb alloys that manifest an exotic bicontinuous hierarchical nanoporous (np) microstructure ideal for volume-change mitigation and K+ transport percolation. The growth mechanism fostering the peculiar morphology of the np-(Bi,Sb) alloys was investigated and clarified via operando X-ray (XRD) and ex-situ scanning electron microscopy (SEM). In particular, the np-Bi6Sb2 electrode, optimized for comprehensive electrochemical performance, achieves decent reversible capacities and a superior lifespan, as benchmarked with the monometallic references and other Bi-Sb alloy electrodes. The (de)potassiation mechanism of the np-(Bi,Sb) alloys was studied by operando XRD and further rationalized by density functional theory (DFT) calculations, whereby a homogeneous (segregation-free) and robust two-step electrochemically-driven phase transformations’ catenation of (Bi,Sb) ↔ K(Bi,Sb)2 ↔ K3(Bi,Sb) was reliably established to substantiate the outstanding reversibility of the np-(Bi,Sb) anodes in PIBs.

Nitrogen-doped porous graphene/MnO2 composite as sulfur hosts for lithium-sulfur batteries

Lithium‑sulfur batteries have been considered as a promising chemical power source owing to the low costs, high energy densities, and nontoxicity. However, sulfur-based cathodes have several shortcomings, including poor electrochemical activity and fast capacity attenuation. In this work, manganese dioxide (MnO2) and nitrogen-doped porous graphene (pNGA) were introduced to the sulfur cathode to improve its electrochemical activity and prevent the rapid decay of capacity. The pNGA/MnO2 composite with a three-dimensional architecture was fabricated by steam etching of nitrogen-doped graphene aerogel and chemical deposition of MnO2 nanoparticles. In this structure, the nitrogen-doped porous graphene acts as a skeleton to form a conductive network. The MnO2 particles anchored on graphene sheets have a good interaction with polysulfides. The as-prepared pNGA/MnO2@S cathode shows an excellent comprehensive electrochemical performance. The calculated specific capacities are 1144, 1007, 920, 852, and 762 mA h g−1 at 0.1C, 0.2C, 0.5C, 1C, and 2C respectively. In addition, the pNGA/MnO2@S cathode displays a good cycling performance: the specific capacity maintains at 887 mA h g−1 at 0.5C over 100 cycles.

Effects of Comonomers on the Performance of Stable Phosphonate-Based Gel Terpolymer Electrolytes for Sodium-Ion Batteries with Ultralong Cycling Stability.

Gel polymer electrolyte (GPE) is one of the most promising alternatives to solve the bottlenecks of nonaqueous liquid electrolytes such as decomposition, safety hazards, and growth of dendrites. In this work, three novel methyl phosphonate-based crosslinking gel terpolymer electrolytes with different comonomers are designed and prepared by in situ radical polymerization. The gel polymer electrolytes have excellent thermal stability, wide electrochemical windows (≥4.9 V), and high ionic conductivities (±3 mS cm-1), and may be used as less-flammable electrolytes for sodium-ion batteries. 31P NMR spectra, Arrhenius plot, and density functional theory (DFT) calculations confirm that multifunctional phosphonate structural units promote the dissociation of NaClO4 and help to transport the sodium ions freely in the polymer framework. X-ray photoelectron spectroscopy (XPS) results show that the gel polymer electrolytes have the capability of inhibiting liquid electrolyte decomposition and the formation of the stable solid electrolyte interphase (SEI) film. The Na3V2(PO4)3/GPE/Na cells exhibit better ultralong cycling stability and enhanced temperature performance than those of liquid cells. Strikingly, GPE1 has the best comprehensive electrochemical performance, especially the rate performance and long-term cycling stability with a capacity retention ratio of 82.6% after 3500 cycles, which indicates that different comonomers have obvious effects on the performance. Therefore, the full cell of SnS2/GPE1/Na3V2(PO4)3 is evaluated and delivers good cycling stability of 500 cycles, holding a great prospect for the design and production of phosphorus-containing electrolytes for safer sodium-ion batteries.

Regulating the interfacial behavior of carbon nanotubes for fast lithium storage

Carbon nanotubes (CNTs) have been recognized as a versatile platform to integrating with various electroactive materials for boosting the comprehensive electrochemical performance. However, CNTs with distinct interfacial characters may play different roles in the subsequent lithiation/delithiation process. Accordingly, systematically engineering the interface of CNTs on the lithium storage behavior is of fundamental significance but remains rare. Herein, the lithium storage performance of boron-doped carbon nanotubes (B-CNT), acid activated carbon nanotubes (aCNT) and commercial carbon nanotubes (CNT) have been systematically studied. We demonstrate that the B-CNT features as a prominent fast charging anode in terms of excellent rate performance and long cycling stability at large current density (an average Coulombic efficiency of 99.8% can be achieved at a high current density of 10 A g−1). The electrochemical kinetic analyses indicate pseudo-capacitance dominated mechanism of B-CNT leads to faster electron/ion transport kinetics. In-depth theoretical simulation suggests that moderate lithium adsorption energy of B-CNT is important to balance the adsorption and release of Li ions, thus resulting fast lithium storage capacity. As a verification, the composite electrode with B-CNT as additive and silicon as anode material also shows outstanding rate performance. Therefore, these basic researches can provide valuable guidance for reasonable design of CNTs-based composite electrode materials toward high-rate batteries.

Robust pseudocapacitive charge storage behavior in Li3VO4 induced by N doped MXene

High theoretical capacity and safety performance endow Li3VO4 with great promising as anode material for Li-ion batteries. However, approaches and inner mechanisms to advance the performance of Li3VO4 are limited. Herein, we demonstrate for the first time, continuously-high pseudocapacitive charge storage triggered by N doped MXene in a Li3VO4-based electrode, resulting in excellent comprehensive electrochemical performance. The hybrid electrode delivers high discharge capacity of 515.2 mAh g−1 after 500 cycles at 0.1 A g−1. After periodic rate performance test from 0.1 to 2.0 A g−1 for 410 cycles, the capacity of the hybrid electrode can be fully recovered. Followed by additional 1000 cycles at 0.5 A g−1, the hybrid electrode still delivers high discharge capacity of 457.6 mAh g−1. The robust capacitive charge storage induced by N doped MXene and the remarkable comprehensive electrochemical performance are referential for the design of high performance Li3VO4-based anode material, and the facile approach is beneficial for mass production toward practical application.Graphical abstract [Display omitted] N doped MXene induced robust pseudocapacitive charge storage in a Li3VO4 electrode is firstly demonstrated responsible for the excellent comprehensive electrochemical performance.

Study on Layered Double Hydroxide and Its Electrochemical Performance

The layered double metal hydroxide can be used as a battery cathode material with the advantages of good stability, easy synthesis and low price. This article mainly studies the electrochemical performance of Ruthenium-containing Fe-Ni layered double metal hydroxide as the cathode material of the battery. The experiment mainly adopts the hydrothermal method to prepare FeNiRu-LDHs, and further calcines them in an argon atmosphere at different temperatures to obtain FeNiRu-LDOs with different Ru concentrations at different temperatures. Through cyclic voltammetry curve and impedance analysis, temperature is used as a variable to determine the electrochemical performance of the material has been tested in groups, and it is found that the 20FeNi-LDO calcined at 450°C showes excellent electrochemical performance. XRD, RAMAN and SEM are further used to study the characterization properties of the sample, and it is found that the shape of Ru20FeNi-LDHs at 450°C is better. Meanwhile, the comprehensive electrochemical performance of Ru20FeNi-LDHs material is best.

A top-down cutting method for construction of high-performance fiber-shaped quasi-solid-state asymmetric supercapacitors

Fiber-shaped asymmetric supercapacitors (FSASCs) have great potential as a future wearable energy storage system because of good weavability, a wide operating voltage window, and high energy density. Conventional bottom-up construction methods for fiber supercapacitors are time-consuming or highly costly. This work proposes a novel facile top-down cutting method to construct FSASCs. FSASCs with desired sizes can be rapidly constructed and easily scaled up by cutting a thin-film supercapacitor into fiber-shaped devices. Serial and parallel FSASCs free of external wire connection were assembled by cutting stacked film supercapacitors and multiplying the cutting width, respectively. Besides, the as-prepared FSASCs exhibit superior comprehensive electrochemical performance, including a high volumetric capacitance of 14.7 F/cm3, a high energy density of 93.5 μWh/cm2, and excellent flexibility. The cutting method with advantages of high simplicity, low cost, and high efficiency may be a general construction method for fiber-shaped energy storage devices.

Pseudocapacitive Anode Materials toward High‐Power Sodium‐Ion Capacitors

AbstractSodium‐ion storage technology holds great promise for large‐scale, sustainable, and low‐cost green energy storage systems. Overcoming the main limitations of sluggish Na+ diffusion kinetics and achieving high‐power sodium‐ion storage devices is critical but full of challenges. Recently, emerging pseudocapacitive sodium‐ion storage materials are attracting attention due to their superior rate capability and other comprehensive electrochemical performance. Herein, this review covers the charge storage mechanism, features, and performance of pseudocapacitive sodium‐ion storage anode materials and the assembled sodium‐ion capacitors. The research processes of state‐of‐the‐art pseudocapacitive sodium‐ion storage anode materials, which display remarkable rate performance, high specific capacity and cycling stability, are introduced and discussed. Using the pseudocapacitive anode materials, advanced sodium‐ion capacitors deliver high energy density at high power density. In the end, the outlooks of pseudocapacitive sodium‐ion storage materials toward future high‐power sodium‐ion capacitors are briefly proposed.

Influence of Sm doping on thermodynamics and electrochemical performance of AB5+z alloys in low-temperature and high-power Ni-metal hydride batteries

AB5-type negative electrode materials have been extensively used for Ni-metal hydride batteries. However, their rate capabilities have hindered them from being more extensively applied, especially in hybrid electric vehicles at low temperatures. Here, a hyper-stoichiometric AB5.09 alloy is designed and Sm is doped to achieve high-power performance. The influence of the microstructural characteristics, thermodynamic stabilities and comprehensive electrochemical performance resulting from the substitution of Sm for La and Ce is investigated. This work demonstrates that the addition of Sm results in a decrease in the maximum capacity and hydride stability. Furthermore, with the stress concentration relieving effect from the increase of anisotropy of the c/a ratio, the cycling stability increases significantly. Due to the formation of the Ni2MnAl catalytic phase, all alloys possess a high density of phase boundaries and exhibit good high-rate discharge performance. The high-rate dischargeability and specific power are further improved after Sm doping, with the high-rate discharge capacity retention rate reaching 81.4% at 3000 mA g−1. Although Sm adversely affects the surface catalytic properties of the electrodes, the high Sm content alloy exhibits higher specific power and discharge capacity at −40 °C due to the decrease in hydride stability.

CuS nanoblocks embedded in the three-dimensional porous carbon as composite anode materials for high-performance lithium-ion battery

CuS-based anode materials have high theoretical capacity and good electrical conductivity and have a wide range of sources, safety, and low pollution. Therefore, how to improve the comprehensive electrochemical performance of CuS-based anode materials is of great significance. Herein, CuS and porous carbon were modified by a simple one-pot method, and finally the CuS@PC composite material was obtained, and then, the samples were subjected to XRD, TEM (HTEM), and SEM characterization and electrochemical performance testing. The results show that the CuS@PC composite material shows a better performance than pure CuS. After 55 cycles at the current density of 0.1 A g−1, the discharge capacity remained at 336.4 mAh g−1 (the discharge capacity of the pure phase CuS material was only 56.4 mAh g−1). Moreover, through the multiplication test, it was found that the invertibility of the CuS@PC material was better.

Comparative effects of electrospinning ways for fabricating green, sustainable, flexible, porous, nanofibrous cellulose/chitosan carbon mats as anode materials for lithium-ion batteries

To develop a clean and sustainable carbon anode material derived from biomass with desirable properties for lithium-ion batteries (LIBs), bio-nitrogen (N)-doped composite carbon nanofibrous mats (CNFMs) were made using natural cellulose (CE) and chitosan (CS) by means of two different electrospinning ways (single-nozzle and coaxial-nozzle) coupled with pyrolysis. The conventional CNFMs that had a CE/CS ratio of 5:5 showed the best electrochemical performance, corresponding to a high specific capacity of 327 mAh g−1 at 100 mA g−1, good rate performance with specific capacity of 399 mAh g−1 at 30 mA g−1 and 210 mA g−1 at 1000 mA g−1, as well as excellent cycling stability after 300 cycles. The core–shell CNFMs with a thick outer layer of CS and large average fiber diameter (316 nm) at the same CE/CS ratio had higher pyridinic-N and pyrrolic-N contents but a lower degree of graphitization and BET surface area compared to the conventional CNFMs. It was concluded that the bio-N in CS was more uniformly doped into the CNFMs by the single-nozzle electrospinning way than by the coaxial one, and thus more effectively promoted a comprehensive electrochemical performance.

Polyquinoneimides as Organic Cathodes for Advanced Potassium-Ion Batteries

Due to abundant raw materials, low cost and high theoretical energy density, organic potassium ion batteries (OPIBs) have attracted more and more attention from researchers as next promising battery system. However, some challenges still need to be solved. For example, most small-molecule organic electrode materials faced serious dissolution problem in liquid electrolytes, resulting in poor cycle stability. In particular, there are relatively few reports on the current cathodes with really excellent comprehensive performance (such as: high specific capacity, high working voltage, long life-span and excellent rate performance) for OPIBs. In this article, two polyanthraquinoneimide polymers were successfully synthesized and used as organic cathode materials for potassium ion batteries. Attributed to the large molecular structure of the polymer, PPAQ and PNAQ both were successful to be insoluble in the electrolyte (1 mol/L KPF₆ in DME). After comparison, it was found that PNAQ exhibited better comprehensive electrochemical performance than PPAQ. At a current density of 100 mA/g, PNAQ achieved a stable discharge capacity of 138 mAh/g for 200 cycles and the retention rate was as high as 92%. At the same time, after 750 cycles at a high current density of 800 mA/g, the specific capacity of PNAQ still remained at 71 mAh/g with an average attenuation of only 0.03 mAh/g per cycle. Through an appropriate design process for the molecular structure, we proved that organic polymers could become excellent cathodes for potassium ion batteries.

In Situ Polymerized Conjugated Poly(pyrene‐4,5,9,10‐tetraone)/Carbon Nanotubes Composites for High‐Performance Cathode of Sodium Batteries

AbstractSodium batteries have attracted much attention in recent years because of their comprehensive electrochemical performance, high abundance, and low cost of sodium resources. However, the unsatisying energy density and poor cycling stability of current sodium batteries restrict their large‐scale applications. Here an in situ polymerization method to construct π‐conjugated poly(pyrene‐4,5,9,10‐tetraone)/carbon nanotubes (PPTO–CNTs) composites as cathode materials for sodium batteries is used. It is found that the π–π interaction between PPTO and CNTs in PPTO–CNTs composites overcomes the repulsion between each PPTO unit, leading to a flat configuration of PPTO and enhancing the electronic conductivity and active sites accessibility of PPTO–CNTs composites. Thus, PPTO–CNTs electrodes display a high discharge capacity of 360.2 mAh g−1, long cycling stability (a capacity retention of 95.1% after 1300 cycles), and high rate capability (194.5 mAh g−1 at 10.0 A g−1). Moreover, a pouch‐type Na//PPTO–CNTs cell with an energy density of ≈204.0 Wh kg−1PPTO+Na is fabricated, exhibiting a capacity retention of 91.2% after 100 cycles. In addition, the combination of experiments and theoretical calculations demonstrates the four‐sodium‐ion redox chemistry mechanism of each PPTO molecule unit. This work should promote the practical application of conjugated polymers in high‐performance sodium batteries.

Influence of fuels in the sol-gel combustion synthesis of Li2MnO3 positive electrode material for Li-ion battery

The capacities of Li2MnO3 depend on the method of synthesis and synthesis conditions. The influence of the nature of fuel and fuel compositions on the sol-gel combustion synthesis (SCS) of Li2MnO3 and the concomitant effect on their electrochemical performance are reported. The use of glycine, citric acid fuels and their mixtures in the fuel stoichiometric compositions resulted in a violent reaction leading to loss of powders. Therefore, the fuel-rich (FR) composition that allows for better complexation of the metals in solution and doesn't result in any violent reaction is recommended in the SCS of Li2MnO3 and other ceramic oxides. The glycine FR composition produced Li2MnO3 with the poorest electrochemical performance that was ascribed to its rough morphology. The citric acid FR Li2MnO3 sample (C-FR) delivered the most comprehensive electrochemical performance considering its increasing discharge capacities with an increase in the current density, its suppression of the charge transfer resistance after the rate capability test, and good rate performance. The improved electrochemical performances of C-FR were attributed mainly to its large particle size and well-developed crystallites. The results show that the SCS of C-FR Li2MnO3 sample could be further optimized to exploit better electrochemical properties of this material.

Insight into the performance of the mesoporous structure SiOx nanoparticles anchored on carbon fibers as anode material of lithium-ion batteries

SiO x has aroused great attractions as a promising substitute for the anode materials of high-performance lithium-ion batteries (LIBs) because of the high specific capacity and the longer cycle life as well as relatively low volume expansion compared to Si. However, the unstable structure and poor conductivity of the SiO x lead to unideal electrochemical properties in LIBs, and thus hindering the widespread application of the SiO x anode. Herein, a facile approach has been put forward to prepare the high-performance mesoporous structure SiO x /carbon (m-SiO x /C) composites by electrospinning technique and sintering processes. The spherical SiO x nanoparticles are well anchored on the carbon fibers, and the reserved space can accommodate large volume expansion of the SiO x materials. Besides, the fibrous carbon materials can significantly enhance the conductivity for the SiO x anodes. Therefore, the resultant m-SiO x /C composites exhibit high discharge specific capacity of 1434 mAh g −1 at 500 mA g −1 with 67.5% capacity retention after 500 cycles and the good rate properties of 410 mAh g −1 at 2000 mA g −1 . In consequence, the reasonable structural design and innovative fabrication technique can facilitate the practical application for the m-SiO x /C composites and further promote the comprehensive electrochemical performance of LIBs.

Rapid in-situ fabrication of Fe3O4/Fe7S8@C composite as anode materials for lithium-ion batteries

Fe3O4 is currently one of the research hotspot of anode materials used in lithium-ion batteries because of its high theoretical lithium storage capacity, abundant in nature, low cost and environmental-friendly. However, problems such as poor electron conductivity and large volume change during lithium transfer often lead to deterioration of electrochemical performance which limits their practical application. Here, with a designed composite of Fe3O4/Fe7S8 supported by carbon skeleton, we used a facile and rapid rheological phase method to realize the in-situ construction of the Fe3O4/Fe7S8@C composites. The as-prepared composite shows three-dimensional (3D) interlaced lamellar structure self-assembled by nanoparticles with size of dozens of nanometers. Electrochemical measurements results inferred that the electrode displays better comprehensive electrochemical performance than conventional Fe3O4@C sample. For example, it delivers a reversible discharge capacity of 819 mAh g-1 at 1 A g-1 after 300 cycles and a capacity retention rate up to 83.6%. This is mainly due to the unique 3D interlaced lamellar structure and the support of carbon skeleton, which inhibits the volume change during lithium storage process. In addition, the presence of sulfide provides additional capacity and promotes the reaction kinetics. In view of the cost-effective feedstock and the convenience of preparation, this study provides an extensible strategy for advanced Fe3O4 anode materials of lithium-ion batteries.

Non-carbonized porous lignin-free wood as an effective scaffold to fabricate lignin-free Wood@Polyaniline supercapacitor material for renewable energy storage application

As a green and sustainable porous material, wood has attracted more and more attention of researchers, especially in the field of energy storage. However, the poor conductivity of wood limits its application. Herein, a kind of non-carbonized lignin-free wood (LFW)@PANI supercapacitor material is fabricated for renewable energy storage application. The resultant hybrid used as electrode material of supercapacitor shows a good comprehensive electrochemical performance: 1) A high cycle stability of ~96% after experiencing 5000 cycles. 2) A high specific capacitance of ~800 F g−1 and 192 F cm−3 3) Good rate performance. 4) A high energy efficiency of more than 80%. 5) High energy densities of 41 Wh kg−1 (57 Wh L−1), meanwhile maintaining high power densities of 43 kW L−1 (68 kW kg−1). Compared with the way of carbonization, non-carbonized treatment not only save energy but also be greener. This work is expected to provide more insights and possibilities for application of renewable wood-based materials.

Anchoring nitrogen-doped carbon particles on lithium titanate to enhance its lithium storage performance

Lithium titanate is a promising anode material for lithium-ion batteries, but its specific capacity and rate performance are low, which restricts its further development. In this paper, by modifying with anchoring carbon particles on the surface, the electrochemical energy storage performance of lithium titanate has been improved at a deeper voltage (0.01–3 V vs. Li+/ Li). The experimental results show that the modified lithium titanate has significant improvement in specific capacity, rate and cycle stability (305.7 mAh g−1 at 0.1 A g−1, 157 mAh g−1 at 5 A g−1, and 245.3 mAh g−1 at 0.1 A g−1 after 800 cycles). Further research found that the improvement of lithium titanate performance is mainly related to a multi-step restore of Ti4+ below 0.6 V, but not to the electrochemical redox of Ti4+/Ti3+ at 1.55 V. This work provided an effective way to promote the comprehensive electrochemical performance of LTO-based materials.

Biotemplate Synthesis of Fe3O4/Polyaniline for Supercapacitor

Abstract The controllable synthesis of Fe3O4/PANI (polyaniline) based on natural three-dimensional (3D) porous DE (diatomite) is clarified. The successful transition from DE/FeOOH to DE/Fe3O4 was realized by hydrothermal method and subsequent carbon reduction reaction. The fabricated PANI coating on DE/Fe3O4 was performed by a common chemical oxidation method. The successful synthesis of DE/Fe3O4/PANI is proved by XRD, XPS, FTIR and Raman test. DE/Fe3O4/PANI (denoted as DFP-50) hybrid composite exhibits a higher specific capacitance due to the good synergistic effects between DE/Fe3O4 and PANI. Moreover, to further explore the influences of PANI on electrochemical properties, DFP-25 and DFP-100 have been synthesized by adjusting the experimental parameter of PANI. Electrochemical tests of DFP-25 display that DFP-25 composite shows the best comprehensive electrochemical performance that can achieve a balance between increasing specific capacitance and maintaining cycle stability. The results shows DE/Fe3O4/PANI hybrid composite holds great potential for economical supercapacitor.

How does the active site in the MoSe2 surface affect its electrochemical performance as anode material for metal-ion batteries?

In this work, we implement density functional theory (DFT) simulations to study how active sites in the MoSe2 surface affect its electrochemical performance as anode material for metal-ion batteries (metal ions including Li, Na, K, Mg, and Al ions). Se vacancy MoSe2 (0 0 1) and MoSe2 (1 1 0) are considered to provide active sites for metal ions. The adsorption energies, diffusion energy barriers, electronic conductivity and open circuit voltage profile (OCV) are evaluated. According to our calculations, MoSe2 (0 0 1) with Se vacancy occupied by Mg ion shows similar diffusion energy barriers and comparable OCV to the pristine MoSe2 (0 0 1). Moreover, Mg ion shows much lower diffusion barriers than the other ions. Besides that, MoSe2 (1 1 0) shows much higher adsorption energies than the (0 0 1) section, indicating its high capacity for metal-ion batteries. However, MoSe2 (1 1 0) also exhibits much higher diffusion energy barriers, which would inhibit its rate capability. Comparatively, MoSe2 (0 0 1) with Se vacancies can improve the conductivity of MoSe2, and the conductivity increases with the number of Se vacancies increases. Consequently, MoSe2 (0 0 1) with single Se vacancy has comprehensive electrochemical performance for Mg-ion battery anode, including low Mg-ion diffusion energy, comparable OCV, and high electronic conductance.