Columbic Efficiency Research Articles

Facile Strategy to Prepare Poly(ionic liquid)-Coated Solid Polymer Electrolytes through Layer-by-Layer Assembly.

The inability of solid polymer electrolytes to preserve strong mechanical strength with high ionic conductivity hinders the commercialization of lithium metal batteries (LMBs). The success of fabricating layer-by-layer (LbL)-assembled electrolytes has realized the application of flexible solid polymer electrolytes in electrochemical devices. Here, we demonstrate a rational strategy to construct solid electrolytes coated with multiple ultrathin layers of polyanions (poly(sodium 4-styrenesulfonate)) and polycations (linear poly(1-butyl-3-(4-vinylbenzyl)-1H-imidazolium chloride) (BVIC)/linear poly(PEG4-VIC)/SiO2-g-poly(PEG4-VIC)) using an LbL assembly method. Poly(ionic liquid) backbones and PEG side groups are employed to facilitate the transport of lithium ions via the segmental motion of the macromolecular matrix. The fabricated free-standing membranes exhibited good ionic conductivities of 9.03-10 × 10-4 S cm-1. Furthermore, a Li/LiFePO4 cell assembled with the LbL-membrane electrolytes exhibits an initial high discharge capacity of 143-158 mAhg-1 at 60 °C with high columbic efficiency. This approach, which combines polymer synthesis and LbL self-assembly, is an effective and facile route to fabricate solid polymer electrolyte membranes with superior ionic conductivity and mechanical robustness, which are useful for electrochemical devices and high-voltage battery applications.

Fabricating lithiophilic Sn nanolayer via vacuum evaporation coating for anode-free lithium metal battery

Lithium metal batteries (LMBs) have great advantages such like high energy density and capacity and low cost, which are widely studied by many researchers. As a type of LMBs, anode-free LMBs have zero Li excess, i.e., the entire Li is stripped from the cathode or current collector, obviously reducing the waste of excessive Li metal and improving the energy density of battery. However, the uneven deposition of Li will lead to the growth of Li dendrites, which reduces the columbic efficiency and cycling life of anode-free LMBs. In this work, the vacuum evaporation coating is used to synthesize a lithiophilic Sn nanolayer on Cu substrate, providing uniform deposition sites for Li. The polarization of Li deposition is reduced and the cyclability of anode-free LMBs is improved. As a result, a stable cycling performance for over 200 h at 3 mA cm−2 under 1 mAh cm−2 is achieved, demonstrating the superior Li-deposition regulation effect of Sn nanolayer.

Highly stable and nanoporous Na3V2(PO4)3@C cathode material for sodium-ion batteries using thermal management

Sodium vanadium phosphate (Na3V2(PO4)3-NVP) a NASICON-type material with exceptionally high ionic conductivity is acknowledged as a potential cathode for high-performance Na-ion batteries. Herein, we report a facile sol-gel process for the preparation of NVP@C. The NVP@C produced has rhombohedral NASICON crystal structure and exhibit 3D interlink microstructure with porous morphology and carbon network. The NVP@C prepared at 900 °C display an initial discharge capacity of 99 mAhg−1 at a current density of 1C and ultralong lifespan of 1400 cycles at 10C (73 mAhg−1) with 93 % capacity retention. This superior electrochemical performance is attributed to the synergistic effect of high crystallinity, porous structure & conducting carbon network. This provides a high contact area between electrode/electrolyte, better electronic conductivity, and high mechanical strength. Additionally, this will also responsible for easy diffusion of electrolyte and speedy transport of ions which ultimately helps to accelerate the electrochemical performance. It is noteworthy that the prepared NVP@C shows highly stable electrochemical performance at higher current density (10C) with 100 % columbic efficiency. More significantly, the full cell comprising NVP@C electrodes showed capacity retention of 80 % after 500 cycles at 2C rate. These prima fascia result shows the potential of the process which provides a new understanding to design other cathode material.

Development and Characterization of a New Solid Polymer Electrolyte for Supercapacitor Device

In this study, solid polymer electrolytes (SPEs) are based on methylcellulose (MC) used as a polymer host and sodium iodide (NaI) as a dopant. The SPE films are developed using different contents of ethyl carbonate (EC) as a plasticizer to enhance their properties via a solution casting method. The surface morphology of SPE films is shown using polarized optical microscopy (POM), which indicates the existence of amorphous patches due to the plasticizing effect of EC. The creation of a complex between MC, NaI, and EC was confirmed by Fourier transform infrared (FTIR) spectra. A tiny amount of EC applied to the MC-NaI polymer salt matrix increases the number of charge carriers and improves ionic conductivity. The ionic conductivity of the generated polymer electrolytes is examined using electrochemical impedance spectroscopy (EIS). The high-ion conducting PE of 5.06 × 10−3 S·cm−1 was found with the mixture MC + 50 wt% NaI + 10 wt% EC (room temperature). The linear speed voltammetry (LSV) test shows that the optimized polymer electrolyte can withstand decomposition up to 2.5 V. The optimized sample transmission numbers were calculated using a TNM (transference number measurement) approach, and the results show that 99% of the ions contribute to the conductivity, compared to only 1% of the electrons. A solid-state electrical double-layer capacitor (EDLC) was fabricated using the highest ion-conductive polymer electrolyte and graphene oxide (GO)-based electrodes. The galvanostatic charge-discharge (GCD) technique was performed, and the GCD graph shows the behavior of an ideal capacitor with a less Faradic process and a low ESR value. The GO-based cell’s columbic efficiency is 100%, and the system delivers the charge for a long duration. The EDLC cell demonstrates outstanding cyclability. The specific capacitance of the EDLC cell incorporated with MC + 50 wt. % NaI + 10 wt. % EC was found to be 154.66 F/g.

Sodium-Bismuth-Titanium glass–ceramic network: A high capacity anode network for Na+ ion storage

This article discusses 95[35Na2O-65Bi2O3]: 5TiO2 (mol%) glass-ceramic anode material system (abbreviated as GC-NBT5.0) in order to overcome major issues with Na-ion battery technology, such as inadequate reversible capacity, rate capability, electrical conductivity, and safety. After heat treatment for different heat treating regimes, the production of intense intermediate domains Na3Bi and Na3Ti results in flexible active centers with which heavier Na+ ions may react very easily for Na+ ion storage in the glass-ceramic anode network. As evaluated at 50mA/g over a longer cycle life of up to 3000 cycles, the GC-NBT5.0-8h glass ceramic anode beats both glass anode and traditional graphite anodes with a specific discharge capacity of 801mAh/g. However, the cell design is still backed by the best electrical conductivity because of the good interfacial contact between the glass-ceramic anode and electrolyte, and the lowest cycle-dependent complex impedance characteristics (Rct and Zw), which guarantee consistent capacity retention and the highest Columbic efficiency over longer cycle durations.

An Enduring Na-Ion Solar Battery Configured with Na2Co0.5Ni0.5Fe(CN)6 Positive and NaTi2(PO4)3 Negative Electrodes in Na2SO4-SiO2 Hydrogel Electrolyte

A successful solar energy storage is accomplished in a 5 V/5 mAh rated Na-ion battery, which is customized by series connection of three 1.8 V unit cells. The unit cell is constructed with open framework structured Na2Co0.5Ni0.5Fe(CN)6 positive and Natrium Super Ionic CONductor (NaSICON) type NaTi2(PO4)3 negative electrodes in 1 M Na2SO4-SiO2 hydrogel electrolyte. Both positive and negative active materials demonstrate Faradaic charge storage mechanism with appreciable diffusion coefficients, such as 5.17 × 10−15 and 1.13 10−15, respectively. The Na2Co0.5Ni0.5Fe(CN)6//NaTi2(PO4)3 full cell depicts a specific capacity of 48 mAh g−1 (@ 100 mA g−1), an energy density of 95.68 Wh kg−1 (@ 259.96 W kg−1) and a power density of 779.75 W kg−1 (@ 54.36 Wh kg−1). The cell also exhibits an excellent durability, i.e., 93% capacity retention with 99% Columbic efficiency at 200 mA g−1 upon 1000 cycles. However, the 5 V battery is performance tested under solar-charging cum constant-load-discharging experiment for one-month, and the device describes 85% capacity retention over the period. The good power capability and cycle life with moderate energy density make this battery chemistry suitable for solar energy storage applications.

Study of [EMIM] [EtSO4] ionic liquid-based gel polymer electrolyte mediated with hydroquinone redox additive for flexible supercapacitors

Gel Polymer Electrolytes (GPEs) are considered as suitable candidates in the design of energy storage devices like flexible supercapacitors due to their higher safety and flexibility. Incorporating small quantity of redox additives in GPE significantly improves their conductivity and is considered as an innovative method to enhance the capacitance of supercapacitors, because both electrolyte and electrode materials contribute to the capacitance. In this work, performance of Flexible Supercapacitor's (FSCs) using symmetrical Laser Induced Graphene (LIG) as electrodes and ionic liquid 1-Ethyl-3-Methylimidazolium Ethyl Sulfate [EMIM] [EtSO4] incorporated in Gel Polymer Electrolyte (GPE) with and without redox additive Hydroquinone (HQ) is presented. Upon electrochemical characterization using Galvanostatic Charge Discharge (GCD), it was found that the FSC with redox additive showed highest areal capacitance and energy density of 15.1 mFcm−2 and 1.54 μWhcm−2 respectively and FSC without redox additive showed an areal capacitance and energy density of 1.94 mFcm−2 and 0.14 μWhcm−2 respectively at 2 mAcm−2. The device with redox additive also showed 100 % columbic efficiency after 50 cycles and maintained 80 % capacitance for 5000 charge-discharge cycles. Additionally, the electrolyte with the redox additive showed superior conductivity of 10.8 mScm−1, demonstrating that modifying electrolyte by adding redox additive has been a simple yet effective method to enhance the overall performance of FSCs. Also, the synthesized LIG was characterized by X-ray Diffraction (XRD), Raman and Scanning Electron Microscopy techniques which confirmed the formation of bi-layer porous graphene.

Cost effective, high proton conductive and low oxygen crossover novel modified biochar doped microbial fuel cell membrane

The current study focuses on synthesizing a cost-effective high proton conductive and low oxygen crossover proton exchange membrane. The membrane is prepared using modified biochar from chili stalk waste in a sulfonated polyether sulfone polymer for microbial fuel cell applications for tamarind wastewater treatment. The membrane shows desired modification confirmed through instrumental characterization using FTIR, XRD, TGA, and SEM. The ultimate analysis confirmed the high carbon and nitrogen content in modified biochar that induces elevated proton conductivity (0.098 Scm−1) and less oxygen diffusivity (3.33 × 10-8 m2 s−1) in a 5% modified biochar doped sulfonated polyether sulfone membrane with a desired mechanical strength, IEC, and moisture content. The high oxygen reduction reaction due to nitrogen content in modified char enhances columbic efficiency and bacterial activity that eventually improves the MFC performance in terms of high-power density (0.148 Wcm−2) and 82.2% of COD elimination. The presence of graphitic and pyridinic, pyrrolic, and N groups accompanying carbon structures favor oxygen reduction via the 2e− or 4e− pathway, respectively. Finally, molecular dynamics simulation also confirmed the low oxygen diffusion and reduced fraction-free volume for oxygen diffusion after including modified biochar in SPES. The economic assessment shows a five times lower cost of modified biochar doped membrane than Nafion 117 membrane.

Enhancement of Columbic Efficiency and Capacity of Li-Ion Batteries using a Boron Nitride Nanotubes-Dispersed-Electrolyte with High Ionic Conductivity

Enhancement of Columbic Efficiency and Capacity of Li-Ion Batteries using a Boron Nitride Nanotubes-Dispersed-Electrolyte with High Ionic Conductivity

Regenerated Ni-Rich Cathode Materials from Spent Li-Ion Batteries by a Closed Loop Process

The demand for rechargeable lithium-ion batteries (LIBs) has increased exponentially since they were first commercialized by Sony in 1991.[1] Due to the high energy density and excellent cycle stability, LIBs have been widespread utilized in electric vehicles and other applications. However, the lifespan of LIBs is limited. Thus, tons of spent LIBs are generated during the recent decades. More importantly, the price of raw materials, including lithium and cobalt salts, for producing LIBs grows significantly.[2, 3] Therefore, recycling these End-of-Life LIBs becomes a non-negligible part in the whole manufacturing process and hydrometallurgical process is the most common recycling method. Here, our group has demonstrated a closed loop recycling process, combining inorganic acid etching and coprecipitation reaction, to produce regenerated Ni-rich cathode materials. The regenerated LiNi0.83Mn0.06Co0.11O2 shows excellent performance: the first cycle discharge capacity is 214.1mAh/g at 0.05C in the voltage range of 2.8 - 4.3V and the initial columbic efficiency is 90.9%. The performance of our regenerated cathode materials is comparable to commercial cathode materials. In order to further optimize the properties of the regenerated LiNi0.83Mn0.06Co0.11O2, different elements, like Al, with various doping or coating methods will be utilized. Manthiram A. A reflection on lithium-ion battery cathode chemistry. Nature Communications 2020; 11(1):1550.Li W, Lee S, Manthiram A. High‐Nickel NMA: A Cobalt‐Free Alternative to NMC and NCA Cathodes for Lithium‐Ion Batteries. Advanced materials (Weinheim) 2020; 32(33):2002718-n/a.Hou J, Ma X, Fu J, Vanaphuti P, Yao Z, Liu Y, et al. A green closed-loop process for selective recycling of lithium from spent lithium-ion batteries. Green Chemistry 2022; 24(18):7049-7060.

Self-Assembled 2D VS2 /Ti3 C2 Tx MXene Nanostructures with Ultrafast Kinetics for Superior Electrochemical Sodium-Ion Storage.

Constructing nanostructures with high structural stability and ultrafast electrochemical reaction kinetics as anodes for sodium-ion batteries (SIBs) is a big challenge. Herein, the robust 2D VS2 / Ti3 C2 Tx MXene nanostructures with the strong Ti─S covalent bond synthesized by a one-pot self-assembly approach are developed. The strong interfacial interaction renders the material of good structural durability and enhanced reaction kinetics. Meanwhile, the enlarged and few-layered MXene nanosheets can be easily obtained according to this interaction, providing a conductive network for sufficient electrolyte penetration and rapid charge transfer. As predicted, the VS2 /MXene nanostructures exhibit an extremely low sodium diffusion barrier confirmed by DFT calculations and small charge transfer impedance evidenced by electrochemical impedance spectroscopy (EIS) analysis. Therefore, the SIBs based on the VS2 /MXene electrode present first-class electrochemical performance with the ultrahigh average initial columbic efficiency of 95.08% and excellent sodium-ion storage capacity of 424.6mAhg-1 even at 10Ag-1 . It also shows an outstanding sodium-ion storage capacity of 514.2mAhg-1 at 1Ag-1 with a capacity retention of nearly 100% within 500 times high-rate cycling. Such impressive performance demonstrates the successful synthesis strategy and the great potential of interfacial interactions for high-performance energy storage devices.

Ultrasounds-assisted solvothermal synthesis of Ni-Co-Mn MOFs/PANI-CNTs nanocomposites with enhanced electrochemical energy storage performance

Among various energy storage devices, one of the emerging classes to be considered nowadays is advanced eco-friendly supercapacitors. Despite vast research regarding their electrochemical performance, there is still room for further refinement. Here, such an attempt has been made by producing nanocomposites of NiCoMn ternary transition metal-organic frameworks (MOFs) with conductive-natured carbon nanotubes (CNTs) functionalized with polyaniline (PANI). A rather different approach i.e., ultrasounds assisted solvothermal method has been employed to prepare the MOFs and their nanocomposites with varying concentrations (0, 20, 40, 60 mg) of PANI functionalized CNTs (PC). A comparison analysis suggests that NiCoMn/PC-40 (40 mg PANI-CNTs) has shown excellent electrochemical performance. In the material of worth attention, the formation of flower-like morphology and crystallinity was explored and confirmed by SEM and XRD characterizations. FT-IR analysis facilitated the exploration of compositional and functional groups of the best-performing material. The large cyclic area, highest specific capacity, excellent stability, less ion transport resistance, and excellent morphology proved NiCoMn/PC-40 as an excellent next-generation supercapacitor battery-grade material with the dominance of diffusive response (71.7%). It has been shown 1194 C/g of specific capacity with an extraordinary energy density of 82 Wh/kg and 1105 W/kg of power density by the NiCoMn/PC-40. At 20 A/g, 100% cyclic stability after 5000 charge/discharge cycles with 97.5% columbic efficiency was achieved. In essence, the excellent electrochemical performance, ease of fabrication, and affordable cost can provide a breakthrough in value addition of NiCoMn/PC-40 worth as a proficient energy storage material.

Investigating the effect of electrolyte and its concentration dependence on WO3 nanosheet as an efficient electrode for supercapacitors: Effect of Redox Additive

This research aimed to synthesize non-uniform nanosheet-like tungstate oxide (WO3) using a simple hydrothermal process, which would result in an effective and environment-friendly material for use in supercapacitors (SCs). The resulting materials are thoroughly examined using physio-chemical techniques. The supercapacitive properties of the WO3–Ni-Foam (NF) were examined using 1 M KOH, NaOH, and LiOH electrolytes and further, the electrochemical performance of the WO3–NF electrode was assessed by changing the concentration of KOH electrolytes from 1 to 4 M respectively. The WO3–NF electrode demonstrated the highest specific capacity (Csp) of 70 mAh/g and capacitance (Cs) of 563 F/g with a high energy density of 16 Wh/kg, and power density of 281 W/kg in 2 M KOH electrolyte respectively. Additionally, the WO3–NF electrode showed excellent Columbic efficiency of 98% and long-term capacitive retention of 88% over 5000 cycles in 2 M KOH electrolyte. Additionally, the effect of redox additive (0.01 M of potassium ferrocyanide) improves the electrochemical performance of WO3–NF; the Csp and Cs values were 137 mAh/g, 618 F/g and 100 mAh/g, 800 F/g at 5 mV/s and 5 mA/cm2, respectively. Furthermore, the WO3–NF electrode exhibits good stability retention of 94% over the 2000 cycles. The electrochemical performance of WO3 nanosheets for energy storage applications was improved by this straightforward hydrothermal method and evaluating the effect of redox additive electrolyte.

Customized poly (aniline-co-o-aminobenzoic acid) by functionalizing with n/p dopants and its application in symmetrical redox supercapacitor

The chemically synthesized poly (aniline-co-o-aminobenzoic acid) copolymer was functionalized electrochemically by cationic and anionic doping and tailored its property for suitable redox behavior. The mechanism during this process has been proposed using cyclic voltammetry studies, and the doping was confirmed in FTIR and UV studies. In the electrochemical impedance spectroscopy, undoped and doped behavior revealed the possibility of fine-tuning of conditions that are required for redox supercapacitor. A symmetrical supercapacitor was fabricated with an optimized doped co-polymer-based electrode and the specific capacitance values were 107 Fg−1 for n-doped polymer and 140 Fg−1 for p-doped polymer. The electrochemical characterization of n/p 1 cm2 cells in terms of specific power, specific energy, specific capacitance, columbic efficiency, IR drop, and ESR was calculated from charge/discharge studies. Data were analyzed in terms of complex power versus complex capacitance, and hence, active region of n/p supercapacitor was obtained. This concept paves way for future tailoring of dopants during the synthesis of conducting polymer and its copolymers.Graphical abstract

Microwave-etched V2C MXene-activated carbon hybrid as a high-performance anode material for lithium-ion batteries

Activated carbon (AC) has been widely utilized as an active material in lithium-ion batteries (LIB) due to its stability and abundance. Nevertheless, the performance of AC anode materials alone falls short of competing with hybrid anode materials, which can attain maximum discharge capacity. Recently, a new two-dimensional (2D) transition metal carbide, MXene, has shown promising performance as an anode in LIB applications. The combination between AC and MXene has proved to improve battery performance previously. Thus, in this study, the electrode was prepared using a hybrid of activated carbon with vanadium carbide MXene (V2C), which was synthesized by etching V2AlC with in situ of hydrochloric acid (HCl) and lithium fluoride (LiF) at 90 °C for 30 min via microwave-assisted hydrothermal technique. The characterization by XRD pattern shows the appearance of V2C MXene peak at 7.23°, indicating the successful etching from V2AlC MAX. The as-prepared AC/V2C_D at ratio 9:1 revealed excellent electrochemical properties as anode LIB, owned capacity up to 562 mAh g−1 (at 50 mA g−1) with cycling stability and columbic efficiency of 95.87 % and 98.2 %, respectively after 50 cycles. Moreover, AC/V2C_D exhibited the smallest Rct (18.50 Ω), and the discharge capacity of 370.25 mAh g−1 was restored after 60 cycles when the current density returned to 50 mAg−1, implying a good reversibility performance and high endurance for LIB. Furthermore, the fabricated full cell of AC/V2C_D//LiFePO4 exhibits initial discharge and charge capacity at 159.6 and 199.8 mAh g−1, respectively, with 79.9 % of CE and delivers a stable cycling performance with reversible discharge specific capacity of 82.72 mAh g−1 after 100 cycles. These promising results prove that the hybrid of AC/V2C_D MXene can be good potential as an anode material in future LIBs applications.

Simultaneous removal of sulfide and bicarbonate from synthetic wastewater using an algae-assisted microbial fuel cell

ABSTRACT The anaerobic digestion (AD) process is one of the most practiced technologies for the remediation of organic waste and maximization of energy recovery in terms of biogas or biomethane. The presence of other gaseous components in biogas, e.g. CO2 and H2S, often makes its direct application in engines and electricity production unsuitable. This work aimed to develop and utilize an algae-assisted microbial fuel cell (AMFC) for the purification of biogas by removing both CO2 and H2S and simultaneous bioelectricity generation. In addition to biogas clean-up, elemental sulfur recovery and CO2 utilization for algae cultivation add value to the proposed AMFC process. Experiments were performed with both sulfide and bicarbonate in their dissolved form, in the respective anodic and cathodic chambers of the AMFC. The sulfide concentration was varied from 100 to 800 mg/l and the AMFC exhibited a sulfide removal efficiency exceeding 97% at all concentrations tested. The process efficiency dropped, however, at sulfide concentrations above 300 mg/l in terms of both sulfide removal and power output. The AMFC performed best at 400 mg/l sulfide by exhibiting a power density of 24.99 mW/m3 and sulfide removal efficiency of 98.87%. The system exhibited columbic efficiency (CE %) in the range of 7.85–80%. The total alkalinity representing CO2, carbonate and bicarbonate levels in the algae-based system was reduced by 49.54%. The electrical energy recovered from the AMFC was 0.1 kWh/m3 and the total energy recovery, which is the sum of the electrical and algal lipid energy, amounted to 7.25 kWh/m3.

Improved energy storage performance of sonochemically synthesized Ni-Co-Zn ternary metal phosphate composites by incorporating PANI functionalized CNTs

The multi-walled carbon nanotubes (MWCNTs) were initially functionalized with polyaniline (PANI) through an in-situ polymerization approach. The ternary transition metal phosphate of Ni0.50Co0.25Zn0.25 (PO4)2 was then chemically grafted onto different masses of PANI/CNTs (20, 40, 60, 100, and 130 mg) aided with probe sonication. The structural morphology and elemental analysis of the nanocomposites were evaluated by scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM), whereas chemical grafting and compositional analysis were evaluated by EDX, XRD, Raman spectroscopy and FTIR. The hierarchical structure of ternary metal phosphates and 100 mg PANI/CNTs nanocomposites provides excellent specific capacity of 1438 Cg−1 (2400 Fg−1, at 1.5 Ag−1). An asymmetric supercapacitor device (ASC) of Ni0.50Co0.25Zn0.25 (PO4)2-100 mg PANI/CNT//AC demonstrated excellent electrochemical performance with an energy density of 104 Whkg−1 (@540 Wkg−1 and very good cyclic stability and columbic efficiency (100 %)). According to a capacitive-diffusive investigation, the ASC device has 63.5 % diffusive and 33.5 % capacitive behavior at low scan rates. The reason for the excellent electrochemical performance of nanocomposite is the combined contribution of uniform chemically grafted structures of tri-metallic phosphate and PANI/CNTs. As a result, the Ni0.50Co0.25Zn0.25 (PO4)2-100 mg PANI/CNTs provides good potential to be used in energy storage devices.

Surface Modification of Micro-Silicon Anode for High-performance Lithium-Ion Batteries

Advanced lithium-ion batteries are urgently needed in consumer electronic products, electric vehicles, and energy storage, while the traditional carbonaceous anode materials with relatively low specific capacity gradually become difficult to meet the practical requirements in the market. Silicon-based anodes are considered one of the most promising alternatives in LIBs with high specific energy due to their considerable theoretical specific capacities. However, the large volume variation and severe surface parasitic reactions still limit the practical application of silicon anode. In this work, to suppress the surface side reactions and great volume changes, the electrochemical inert Li3PO4 is proposed to be coated as the physical barrier between the silicon and electrolyte. The as-coated micro-silicon has been successfully prepared via a facile spray drying method with a low-temperature thermal treatment. Li3PO4 coating layer with high shear modules can not only passivate the surface but also enable to suppression of the severe volumetric expansion and shrinkage of the silicon particle, thus enhancing the initial columbic efficiency and structural integrity of the silicon materials during long-term cycling. The optimized silicon anode with the proper amount of Li3PO4 displays a superior initial columbic efficiency higher than 90% and a highly reversible capacity of 1394 mAh g-1 after charging and discharging 200 times. It is hoped this work should shed light on the modification of high-capacity anode materials.

Ultrastable and high-performance 3D core-shell NiCo2S4@Bi2O3 nanorod arrays as anode for Li[sbnd]S batteries

In spite of the low specific capacity of Bi2O3 (∼386 mA h g−1), it lies among auspicious contenders to be utilized as anode for future generation lithium-ion batteries (LIBs). Conversely, the persistently low valued capacity is causing the restrictions on its superb anticipated electro-chemical properties and obscuring their useful applications/devices. Similarly bimetallic transition metal sulfides with superior electro-chemical performances have gained the attention due to the existence of synergistic effect among bimetallic cations. Herein, a novel template-assisted, two-step hydrothermal method followed by electrodeposition technique is employed to fabricate hybrid 3D core-shell NiCo2S4@Bi2O3 nanorod arrays (NRAs). The fabricated hybrid-structure comprises the qualities of both materials; NiCo2S4 presents the backbone for structural stability, while Bi2O3 provides the high specific capacity. Hybrid core-shell structure has provided the integrating facile strain relaxation, along with the fast electron and ion transport. Hybrid 3D core-shell NiCo2S4@Bi2O3 NRAs with the possession of high Bi2O3 mass loading has exhibited the excellent capacity of ∼2344 mA h g−1 with a columbic efficiency of 96 %, which is much improved compare to pristine NiCo2S4 NRAs (∼1865 mA h g−1) with columbic efficiency of 89 % and Bi2O3 nanosheet arrays (∼1160 mA h g−1) with columbic efficiency of 54 % respectively, demonstrating that hybrid 3D core-shell NiCo2S4@Bi2O3 NRAs have presented decent rate capability at current density 0.4 A g−1 and particularly significant cycle stability (∼1930 mA h g−1) even after 100 successive cycles. Achieved outcomes not only highlight the innovative opportunity for novel core-shell formation, but also provide the vision of rational design for innovative electrode materials for LIBs.

Acid substitutions for WO3 nanostructures synthesis by the hydrothermal route and its effect on physio-chemical and electrochemical properties for supercapacitors

In this study, we have developed a feasible and eco-friendly electrode material for supercapacitor (SCs) application by effectively synthesizing different morphological structures of tungsten oxide nanostructures (WO3-NSs). The concentrated acids play a crucial role in the synthesis of WO3-NSs and are employed to evaluate the electrochemical activity. The stable phase formation and the crystal structures of WO3-NSs were confirmed by thermogravimetric and X-ray analysis. From the field emission scanning electron microscope (FE-SEM), the hexagonal-shaped nanosheets, one-dimensional nanorods (1D NRs), and heterogeneous non-uniform agglomerated nanosheets were observed for the WO3-NSs. The presence of functional groups and the stretching-bending vibrations of WO bonds were detected by Fourier transform infrared, and Raman spectroscopy respectively. The transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS) offers a more in-depth morphological, structural, and elemental composition and electronic states investigation of the optimized WO3-NRs. Additionally, the electrochemical properties of the WO3-NSs have been examined in 1 M KOH electrolyte using Nickel Foam (NF) as a current collector. Furthermore, the M-WO3-NF electrode reveals higher specific capacity (Csp) and gravimetric capacitance (Cg) of 72 mAh/g and 600 F/g with high energy density (Ed) of 17 Wh/kg, and power density (Pd) of 321 W/kg as well as the superior Columbic efficiency (96.9 %) at 5 mA/cm2. The M-WO3 electrode exhibits 91 % capacitive retention over 5000 cycles. The M-WO3-NF is used as the cathode and activated carbon (AC) as the anode in the design of an aqueous hybrid supercapacitor (AHSC) device. Notably, the M-WO3-NF//AC-NF device offers a Pd of 1060 W/kg at an Ed of 9 Wh/kg and remarkable electrochemical stability of 80 % over 3000 charge-discharge cycles. These results highlight the excellent electrochemical functionality and advantages of the M-WO3-NRs as a promising cathode for practical energy-storage systems.