Retention Of Initial Capacitance Research Articles

Modified nano-CaCO3 hard template method for hierarchical porous carbon powder with enhanced electrochemical performance in lithium-sulfur battery

Lithium-sulfur (Li-S) battery was the most promising energy storage devices with ultrahigh energy density (2600 Wh kg−1). But it was impeded by poor electronic conductivity, serious shuttle effect, and enormous volume expansion. Herein, hierarchical porous carbons were simply prepared by a modified nano-CaCO3 hard-template method from glucose. The template-removal step was modified from HCl washing to HCl soaking. This allowed the microstructure of carbon product significantly involved. Furthermore, the mass ratio of CaCO3 nanoparticles and glucose played an important role in booming of hierarchical porous and specific surface area. When integrated with S, functioned as cathode in Li-S battery, improved electrochemical performances were exhibited, such as high initial discharge capacity and good capacity retention. This modified hard-template method suggested a promising way to fabricate hierarchical porous carbon matrix available to apply in advanced Li-S battery.

New Insights into the Mechanism of LiDFBOP for Improving the Low-Temperature Performance via the Rational Design of an Interphase on a Graphite Anode.

The high impedance of the solid electrolyte interphase (SEI) is one of the important factors that deteriorate the charge behavior of lithium-ion batteries (LIBs) at low temperatures, which hinders their practical application in portable electronic products and electric vehicles under extreme conditions. Based on this consideration, a LiF-rich SEI film with low impedance, using lithium difluorobis(oxalato)phosphate (LiDFBOP) as an electrolyte additive and a blank electrolyte without commercial additives, is constructed on a graphite surface. The decomposition mechanism of LiDFBOP is further deduced by density functional theory calculations. This additive inhibits the decomposition of the electrolyte and then forms a thin SEI film with more LiF. LiF, possessing high Young's modulus, makes the SEI film dense and stable. At the same time, more LiF/Li2CO3 interfaces are formed to increase the ionic conductivity. Benefiting from the components and the structure of the SEI, the graphite/Li cells exhibit excellent cycling stability (ca. 85.5% initial capacity retention for 200 cycles at 1 C) and an impressive low-temperature performance (ca. 200% capacity for electrolytes without LiDFBOP at -20 °C). This work presents an effective strategy for developing a functional electrolyte to meet the requirement of LIBs with enhanced low-temperature performance.

Rationally designed Mn2O3/CuxO core–shell heterostructure generated on copper foam as binder-free electrode for flexible asymmetric supercapacitor

Inherent poor conductivity and agglomeration of CuxO phase limit its further development in supercapacitors. High theoretical capacitance of Mn2O3 and the construction of core–shell heterostructure may provide a new strategy to solve these problems. Herein, the unique core–shell heterostructure of Mn2O3 nanosheets attached to CuxO nanowires is formed on copper foam (CF). This electrode material is prepared via an in-situ oxidation reaction followed by the combination of calcination and hydrothermal method. The areal capacitance of the as-obtained Mn2O3/CuxO/CF electrode at hydrothermal time of 9 h is 1403.5 mF cm−2 (779.7F g−1) at current density of 2 mA cm−2 (1 A g−1), which is much greater than that of other electrodes. It also exhibits a good stability with 92.8% retention of initial capacitance after 10,000 cycles. Besides, the flexible asymmetric supercapacitor (FASC) device is assembled by Mn2O3/CuxO/CF-9 and activated carbon (AC) coated on nickel foam (NF) as respective positive and negative electrodes. It can deliver specific capacitance of 512.7 mF cm−2 at 2 mA cm−2, and reaches 120.2 μWh cm−2 at a power density of 1.3 mW cm−2. The outstanding electrochemical characteristics may be ascribed to the unique core–shell heterostructure, making it potential application in the field of flexible supercapacitors.

Effect of precursor particle size and morphology on lithiation of Ni0.6Mn0.2Co0.2(OH)2

In this paper, Ni0.6Mn0.2Co0.2(OH)2 precursors with several different morphologies and particle sizes are mixed with Li2CO3 and heat treated for 5, 7.5 and 10 h. The effects of the precursor properties on the degree of lithiation, electrochemical properties and volumetric capacities of lithiated product are compared. Based on the characterization results, a small (3 μm), narrow span precursor can be lithiated in a short period of time (5 h) and has good initial discharge capacity (185 mA h g− 1) and capacity retention (93% for 55 cycles). In contrast, a large wide-span precursor requires over 10 h for full lithiation. A highly porous precursor can be lithiated faster than traditional large wide-span materials, and has low cation mixing and good crystallinity. However, the volumetric energy density of porous material is low after lithiation compared to the other tested materials. Capacity retention after washing correlated with crystallographic properties of the sample.Graphic abstract

Neoteric hollow tubular MnS/Co3S4 hybrids as high-performance electrode materials for supercapacitors

Transitional metal chalcogenides with remarkable electrochemical performance are recently attracted growing interest as a novel type of material in the field of energy storage. Herein, neoteric hollow nanoscale tubular x-MnS/Co3S4 (x = 25, 50, 100, 200, 400) hybrids are achieved by two steps of ion exchange methods applying self-made cobalt chloride carbonate hydroxide (Co(CO3)0.35Cl0.20(OH)1.10) as precursor, sodium sulfide nonahydrate as a sulfur resource for anion exchange, and anhydrous manganese chloride as a manganese resource for cation exchange. When used in supercapacitors for the first time, the 200-MnS/Co3S4 sample manifests excellent electrochemical performance with high specific capacitance (627 Fg−1 at 1 A g − 1), exceptional rate capability (73.5% capacity retention from 1 to 50 A g − 1), and brilliant cycling stability (93.1% of initial capacity retention for 2000 cycles at 10 A g − 1). These results above indicate the great potential of hollow MnS/Co3S4 nano-tubes in the development of high-performance electrode materials for supercapacitors.

Bidirectionally Compatible Buffering Layer Enables Highly Stable and Conductive Interface for 4.5 V Sulfide‐Based All‐Solid‐State Lithium Batteries

AbstractHigh‐voltage all‐solid‐state lithium batteries (HVASSLBs) are considered attractive systems for portable electronics and electric vehicles, due to their theoretically high energy density and safety. However, realization of HVASSLBs with sulfide solid electrolytes (SEs) is hindered by their limited electrochemical stability, resulting in sluggish interphase dynamics. Here, a bidirectionally compatible buffering layer design scheme is proposed to overcome the interfacial challenges of sulfide‐based HVASSLBs. As a proof of concept, it is found that NASICON‐type LixZr2(PO4)3 surprisingly exhibit great compatibility with both 4.5 V LiCoO2 and Li6PS5Cl, based on the results of first‐principles calculations and various in situ/ex situ characterizations. This compatibility significantly restrains the interface reactivity and boosts interfacial Li‐ion transport. Therefore, 4.5 V sulfide‐based HVASSLBs can exhibit remarkably enhanced initial discharge capacity (143.3 vs 125.9 mAh·g−1 at 0.2C), capacity retention (95.53% vs 74.74% after 100 cycles), and rate performance (97 vs 45 mAh·g−1 at 2C). This work sheds light on the great prospects of sulfide‐based HVASSLBs with high‐rate characteristics, and constitutes a crucial step toward the rational design of interface and interphase chemistry for high‐performance sulfide‐based HVASSLBs.

Exploration of Metal/Ti3C2 MXene-derived composites as anode for high-performance zinc-ion supercapacitor

Following graphene, another two-dimensional transition metal carbide (Ti3C2Tx MXene) with unique properties has been widely used in the field of electrochemical energy storage. However, the inevitable interlayer stacking and agglomeration can easily lead to the limitation of its application. Herein, a three-dimensional metal/Ti3C2 MXene derivative composite material with nanobelt structure was prepared through simple alkalization and metal ion pre-intercalation strategies, which effectively avoids the re-stacking of flakes, while also optimizing the capacitance contribution and energy storage efficiency. In addition, the alkalized MXene-Zn composite (AMX-Zn) can replace traditional zinc foil to optimize the anode of zinc ion capacitors (ZIS). Finally, the ZIS assembled based on AMX-Zn anode and porous carbon (PC) cathode exhibit excellent specific capacity of 75.2 mAh g−1 and energy density of 60.2 Wh kg−1, as well as outstanding initial capacitance retention of 92.5% after 10000 charge-discharge cycles. This work provides an effective strategy for the design of the next-generation high-performance energy storage system and the optimization of the anode electrode of the aqueous zinc ion energy storage device.

Co‐Co3O4 Embedded in Carbon Nanotube Derived from a Zeolitic‐Imidazolate Framework as Anode Material for Lithium‐Ion Batteries

Co and carbon nanotube (CNT) were prepared as anode materials to be used in lithium rechargeable batteries from the zeolitic‐imidazolate framework‐67 (ZIF‐67) using the solvothermal method. By annealing ZIF‐67 at different temperatures between 400 and 700 °C, the carbon framework was changed to CNTs, and Co or Co3O4 nanoparticles were embedded in the CNTs (Co or Co3O4/CNT). The Co/CNT was converted to Co‐Co3O4/CNT by further treatment at 160 °C in air. The Co3O4/CNT showed high initial capacities (1582 mAh/g) but poor capacity retention during cycling. However, the air treatment of the Co/CNT at 160 °C enhanced its discharge capacity (935 mAh/g) and capacity retention during cycling.

Carbon nanotubes interpenetrating MOFs-derived Co-Ni-S composite spheres with interconnected architecture for high performance hybrid supercapacitor

Recently, carbon nanotubes (CNT)-based interconnected architectures exhibit promising prospects in supercapacitors due to their flexibility and high electrical conductivity. Herein, a three-dimensional (3D) interconnected network structure combined with conductive carbon nanotubes interpenetrating MOFs-derived Co-Ni-S composite spheres (Co-Ni-S/CNTs) was synthesized. Such 3D interconnected architecture significantly leads to a favorable electronic structure, fast charge-transfer capacity, and more pseudocapacitive. The Co-Ni-S/CNTs-based hybrid electrode exhibits an extraordinary specific capacitance of 540.6C g−1 at 1 A g−1 and competitive rate performance (capacity retention rate of 69.9% when the current density increases to 10 times). Subsequently, a hybrid supercapacitor is assembled using Co-Ni-S/CNTs as the positive electrode and commercial activated carbon as negative electrode. The device delivers a high energy density of 63.5 W h kg−1 at 800 W kg−1 and keeps 83.0% initial capacitance retention after 10,000 cycles. The encouraging performances demonstrate the significant contribution of the 3D interconnected architecture for the future energy storage.

“Carbon quantum dots-glue” enabled high-capacitance and highly stable nickel sulphide nanosheet electrode for supercapacitors

A facile “carbon quantum dots glue” strategy for the fabrication of honeycomb-like carbon quantum dots/nickel sulphide network arrays on Ni foam surface is successfully demonstrated. This design realizes the immobilization of nanosheet arrays and maintains a strong adhesion to the collector, forming a three-dimensional (3D) honeycomb-like architecture. Thanks to the unique structural advantages, the resulting bind-free electrode with high active mass loading of 6.16 mg cm−2 still exhibits a superior specific capacitance of 1130F g−1 at 2 A g−1, and maintains 80% of the initial capacitance even at 10 A g−1 after 3000 cycles. Furthermore, the assembled asymmetrical supercapacitor delivers an energy density of 18.8 Wh kg−1 at a power density of 134 W kg−1, and outstanding cycling stability (100% of initial capacitance retention after 5000 cycles at 5 mA cm−2). These impressive results indicate a new perspective to design various binder-free electrodes for electrochemical energy storage devices.

ZnF2 doped porous carbon nanofibers as separator coating for stable lithium-metal batteries

In this work, the ZnF2 doped three-dimensional (3D) porous carbon nanofibers (ZnF2-PCNFs) were prepared via the electro-blow spinning (EBS) and carbonization strategy. And its applications as promising interlayer to hybridize with metal Li as composite anode for lithium metal batteries (LMBs) were systematically investigated and researched. The 3D interconnected porous skeleton with a high electrical conductivity and large surface area could reduce the local current density and endow the significantly enhanced interfacial compatibility between the interlayer and lithium electrode including a high lithium-loading capacity. Moreover, the lithiophilic ZnF2 nanoparticles formed in-situ during carbonization process could provide more active sites to trigger an analogous alloying reaction with Li to guide the Li plating/stripping more homogeneous. For the assembled Li||LiFePO4 (LFP) batteries with ZnF2-PCNFs, the optimal initial discharge capacity and capacity retention after 500 cycles at 1C were 142.70 mAh g−1 and 96.42%, respectively. The symmetric Li||Li batteries further showed that the ZnF2-PCNFs coating interlayer could hinder Li dendrite growth and improve the cycling stability. In addition, the obtained Li||S battery with ZnF2-PCNFs also delivered the outstanding cycle performance among the various samples based on the convenient transport channels of Li ions and the strong adsorption or captured ability of ZnF2-PCNFs to species. These facts demonstrated that the prepared ZnF2-PCNFs coating acting as interlayer between separator and anode could effectively enhance safety and electrochemical performance of LMBs.

Time-intended effect on electrochemical performance of hydrothermally reduced graphene oxide nanosheets: Design and study of solid-state symmetric supercapacitor

Self-organized porous sheet-like assemblies have attracted extensive attention for the development of flexible high-performance electrodes. This work demonstrates the facile synthesis and effects of reduction time on the electrochemical performance of porous sheet-like assemblies of reduced graphene oxide (rGO) on carbon cloth. An rGO porous assembly with a reduction time of 4 h exhibited a superior specific capacitance of 456 F/g at a scan rate of 5 mV/s and 223 F/g at a current density of 1 mA/cm2, with ~ 93.9% initial capacity retention over 2000 cycles. A solid-state symmetric supercapacitor device constructed of a rGO4//rGO4 porous assembly achieved a specific capacitance of 45.86 F/g at a scan rate of 5 mV/s and yielded an energy density of 1.27 Wh/kg and specific power of 833.3 W/kg in a PVA-H2SO4 gel polymer electrolyte. Furthermore, the flexible solid-state symmetric device provides outstanding cyclic stability with a 95.3% retention of its initial capacity over 2000 cycles. Thus, electrodes constructed of rGO porous sheets show great potential for flexible and transparent solid-state symmetric energy storage devices.

A high-energy, long cycle life aqueous hybrid supercapacitor enabled by efficient battery electrode and widened potential window

For the development of high-performance aqueous hybrid supercapacitor, the exploration of high-rate battery electrode and breakthrough of potential window are urgently needed. In this work, N-doped carbon coated LiMn2O4 nanoparticles (LMO@C) have been designed and successfully fabricated, and “water-in-salt” electrolyte is applied. The as-prepared LMO@C delivers a high specific capacitance of 688 F g−1 at the scan rate of 0.5 mV s−1 and retains 258 F g−1 at 50 mV s−1 as cathode in 5 M LiTFSI aqueous electrolyte. With an enlarged working potential of 2.5 V, LMO@C//AC hybrid supercapacitor shows a high energy density of 95.3 W kg−1, and 95% of initial capacitance retention after 15,000 cycles. The excellent electrochemical performance suggests that the carbon coated lithium manganate nanocomposite and high-concentration electrolyte could be potential candidates for practical aqueous hybrid energy storage devices.

One-Pot Synthesis of Bismuth Sulfide Nanostructures as an Active Electrode Material for Aqueous Hybrid Capacitors

The high theoretical capacity of Bi2S3 shows high promise as a negative electrode material for energy storage devices. Herein, we investigate a facile, one-step chemical precipitation method using common organic solvents, such as acetone, ethanol, and isopropanol, for the synthesis of Bi2S3 nanostructures. The nanospherical Bi2S3 from acetone (Bi2S3-A) presents the most balanced electrochemical properties, exhibiting a high specific capacity of 181 mAh g−1 at 1 A g−1 and decent rate capability. Additionally, Bi2S3-A is used as a negative electrode in an aqueous hybrid system with an activated carbon positive electrode, demonstrating a capacitance of 86 F g−1, a specific energy of 7.6 Wh kg−1, and an initial capacity retention of 74% after 1000 cycles.

Ni/MnO2 doping pulping lignin-based porous carbon as supercapacitors electrode materials

Lignin extracted from pulping black liquor as carbon source, C4H6O4Ni·4H2O as acatalyst and KMnO4 as dopant, a lignin-based porous carbon material (PC-Ni/MnO2) co-doped with Ni and MnO2 was prepared and used in electrode materials for supercapacitors. During the high-temperature carbonization process, part of amorphous carbon generates a multi-layer graphene structure, causing the PC-Ni/MnO2 to has a high degree of graphitization. Meanwhile, KMnO4 gradually decomposes and reacts with C to produce MnO2. The lignin-based porous carbon material has a higher pseudocapacitance, the specific capacitance of PC-Ni/MnO2 can reach 267.34 F g−1 at a current density of 0.1 A g−1. After 5 000 cycles charge and discharge test, the specific capacitance retention rate kept 83.6% at a current density of 1 A g−1, showing good rate performance and electrochemical stability. A symmetrical supercapacitor prepared by PC-Ni/MnO2 as electrodes, its energy density can reach 28 Wh·kg−1 as the power density of the capacitor is 360 W kg−1. And the supercapacitor also exhibited good cyclic stability with 86.3% retention of initial capacitance after 5000 cycles at 1.0 A g−1. When two such supercapacitors in series, a LED lamp can be light. These induct that the doping of Ni and MnO2 can improve the capacitance characteristics, showing that the biomass porous carbon has great practical application value.

ZnO/CoO@NiCoS nanohybrids with double heterogeneous interface for high-performance hybrid supercapacitors

Hybrid supercapacitors (HSC) with high power density and long cycle life are received more attention in the field of energy storage devices, however, the wide application of HSC is limited by the low energy density owing to the insufficient active sites and poor electronic conductivity of electrode materials. Here, we successfully synthesize the ZnO/CoO@NiCoS nanohybrids with double-layer heterojunction by a three-step method. The conductivity of the as-prepared electrode can be improved by the built-in electric field formed between ZnO and CoO. The coating of amorphous NiCoS can provide sufficient active sites and strengthen the physical/chemical stability of ZnO/CoO nanowires. The obtained ZnO/CoO@NiCoS delivers a high specific capacity of 934 C g−1 (1868 F g−1), which is 5.5 times the pristine ZnO electrode. Furthermore, a HSC with ZnO/CoO@NiCoS shows an improved power density (3987.7 W kg−1), a high energy density of 39.2 Wh kg−1, and an excellent cycling stability (initial capacity retention rate of 81.7% after 6,000 cycles). This study not only proposes an effective strategy for the preparation of low-cost, deep-discharge electrodes for supercapacitors, but also provides a novel method to construct nanomaterials with double-layer heterostructure and built-in electric field.

Potato Chip-Like 0D Interconnected ZnCo2O4 Nanoparticles for High-Performance Supercapacitors

Zinc cobaltite (ZnCo2O4) is an emerging electrode material for supercapacitors due to its rich redox reactions involving multiple oxidation states and different ions. In the present work, potato chip-like 0D interconnected ZnCo2O4 nanoparticles (PIZCON) were prepared using a solvothermal approach. The prepared material was characterized using various analytical methods, including X-ray powder diffraction and scanning electron microscopy. The possible formation mechanism of PIZCON was proposed. The PIZCON electrode material was systematically characterized for supercapacitor application. The areal capacitance of PIZCON was 14.52 mF cm−2 at 10 µA cm−2 of current density, and retention of initial capacitance was 95% at 250 µA cm−2 following 3000 continuous charge/discharge cycles. The attained measures of electrochemical performance indicate that PIZCON is an excellent supercapacitor electrode material.

Maximized crystal water content and charge-shielding effect in layered vanadate render superior aqueous zinc-ion battery

Emerging as a promising candidate for grid-scale energy storage, aqueous zinc-ion batteries are challenged by both sluggish Zn2+ migration kinetics and poor cyclic stability of cathode materials. Herein, a maximized crystal water content of 14.8 wt% is reported for layered Na5V12O32·11.9H2O as the new cathode material. Such a content has enlarged the lattice space up to 12.75 Å providing spacious channels for rapid Zn2+ migration. The charge-shielding effect of crystal water alleviates the electrostatic interactions between Zn2+ and the cathode framework, enhancing ionic conductivity. The density functional theory calculation reveals that the high crystal water content facilitates the electrical conductivity. These should promote the Zn2+ migration kinetics and cyclic stability. Through characterizations by ex situ X-ray photoelectron spectroscopy and near edge X-ray absorption fine structure analysis, the high crystal water content is found to associate with two-electron redox reactions during Zn2+ (de)intercalation. As a result, the Na5V12O32·11.9H2O cathode presents a reversible capacity of 430.52 mA h/g at 0.1 A/g with 103.7% retention of initial capacity over 3,862 cycles at 1 A/g.

A novel ternary Fe3O4@Fc-GO/PANI nanocomposite for outstanding supercapacitor performance

This work introduced a novel ternary electrode material (Fe3O4@Fc1-GO/PANI2:1) for battery-type supercapacitor applications. This high performance electrode material was designed and synthesized via simple processes that involves a simple co-precipitation of magnetic nanoparticles (MNPs), surface modification of MNPs with ferrocene (Fc) moieties through hydrogen-bonded interaction, and preparation of nanohybrids and nanocomposites via physical mixing strategy. Different appropriate structural analyses were then applied for characterization of the synthesized materials. The supercapacitor properties of the materials were investigated by means of cyclic voltammetry (CV),galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS), tests. After electrochemical evaluations, the Fe3O4@Fc1-GO/PANI2:1nanocomposite was selected as optimal combination. This nanocomposite shows a 640mAh g−1 at 1 A g−1. Also, the selected nanocomposite was exhibited 86.68 % retention of initial capacity after 5000 CV cycles. Finally, this ternary nanocomposite was adopted for symmetric two-electrode system fabrication. The Fe3O4@Fc1-GO/PANI2:1-based symmetric cell delivered a high energy density of 106.2 Wh Kg−1 and a high power density of 6657 W Kg−1. These excellent electrochemical performances can be described to the synergistic effects between nanocomposite components.

Research on High-Value Utilization of Carbon Derived from Tobacco Waste in Supercapacitors.

Large quantities of tobacco stalks residues are generated and discarded as crop waste or combusted directly every year. Thus, we need to find an appropriate way to dispose of this type of waste and recycle it. The conversion of biomass waste into electrode materials for supercapacitors is entirely in line with the concept of sustainability and green. In this paper, tobacco-stalk-based, porous activated carbon (TC) was successfully synthesized by high-temperature and high-pressure hydrothermal pre-carbonization and KOH activation. The synthesized TC had a high pore volume and a large surface area of 1875.5 m2 g−1, in which there were many mesopores and interconnected micro-/macropores. The electrochemical test demonstrated that TC-1 could reach a high specific capacitance of up to 356.4 F g−1 at a current density of 0.5 A g−1, which was carried in 6M KOH. Additionally, a symmetrical supercapacitor device was fabricated by using TC-1 as the electrode, which delivered a high energy density up to 10.4 Wh kg−1 at a power density of 300 W kg−1, and excellent long-term cycling stability (92.8% of the initial capacitance retention rate after 5000 cycles). Therefore, TC-1 is considered to be a promising candidate for high-performance supercapacitor electrode materials and is a good choice for converting tobacco biomass waste into a resource.