Discharge Capacity Retention Research Articles

Macaroni‐Like Blue‐Gray Nb2O5 Nanotubes for High‐Reversible Lithium‐Ion Storage

Due to the high reliability and high theoretical capacity, lithium‐ion batteries (LIBs) have been widely studied in the world. Nevertheless, the existing LIB systems currently exhibit comparatively low capacities restricted by the anode materials. Herein, blue‐gray Nb2O5 (B‐Nb2O5) nanotubes are prepared which are rich in oxygen vacancy by a facile chemical vapor deposition (CVD) method and a further hydrogen annealing reduction as the anode material for LIBs, presenting a high discharge capacity of 375 mA h g−1 at 100 mA g−1 and a good rate performance up to 5 A g−1 with 126 mA h g−1. The detailed ex situ X‐ray diffraction (XRD) and X‐ray photoelectron spectra (XPS) characterizations verified the high‐reversible process, which Li+ should insert into/extract from the (001) planes of Nb2O5 crystal. Combined with a reversible PF6‐ intercalation into/deintercalation from graphite cathode, a B‐Nb2O5/graphite dual‐ion cell can run about 50 cycles with the discharge capacity retention approaching 23 mA h g−1 at 100 mA g−1. The importance of the modulation of morphology and vacancy in improving overall electrochemical performance is highlighted.

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.

Synergistic effect of nanofluid as catalyst with carbon foam electrode for improved rheological properties of aqueous electrolytes for vanadium redox flow battery

Enhancing the electrolyte flow characteristics of the electrode is essential in vanadium redox flow batteries. Herein, the design of hybrid electrode with improved flow characteristics is presented to enhance the battery lifetime, electrochemical reaction kinetics, and system efficiency. Further, an open-cell carbon foam is fabricated and experimentally evaluated. This foam acts as a conductor flow field and nanofluidic electrolyte, in which nanoparticles act as a catalyst for electrochemical reactions. The electrochemical performance of a conventional carbon felt electrode is directly compared with that of the hybrid electrode with carbon foam under the same operating conditions. The pumping efficiency of the fabricated hybrid electrode is 1.67 times higher than that of the conventional electrode. The electrochemical reaction is enhanced by the use of nanofluidic electrolytes. Results show that the hybrid electrode with 0.1 wt% nanofluidic electrolyte exhibits the largest discharge capacity (21.85 Wh L−1) and capacity retention (93.4%). The system efficiency can be improved by 2.3% using the hybrid electrodes with nanofluidic electrolytes. This new configuration provides insight into the benefits of replacing conventional carbon felt with carbon foam.

New O3-Type Layer-Structured Na0.80[Fe0.40Co0.40Ti0.20]O2 Cathode Material for Rechargeable Sodium-Ion Batteries.

Herein, we formulated a new O3-type layered Na0.80[Fe0.40Co0.40Ti0.20]O2 (NFCTO) cathode material for sodium-ion batteries (SIBs) using a double-substitution concept of Co in the parent NaFe0.5Co0.5O2, having the general formula Na1-x[Fe0.5–x/2Co0.5–x/2M4+x]O2 (M4+ = tetravalent ions). The NFCTO electrode delivers a first discharge capacity of 108 mAhg−1 with 80% discharge capacity retention after 50 cycles. Notably, the first charge–discharge profile shows asymmetric yet reversible redox reactions. Such asymmetric redox reactions and electrochemical properties of the NFCTO electrode were correlated with the phase transition behavior and charge compensation reaction using synchrotron-based in situ XRD and ex situ X-ray absorption spectroscopy. This study provides an exciting opportunity to explore the interplay between the rich chemistry of Na1–x[Fe0.5–x/2Co0.5–x/2M4+x]O2 and sodium storage properties, which may lead to the development of new cathode materials for SIBs.

Large-scale synthesis of Fe9S10/Fe3O4@C heterostructure as integrated trapping-catalyzing interlayer for highly efficient lithium-sulfur batteries

• A large-scale synthetic route to obtain core-shell Fe 9 S 10 /Fe 3 O 4 @C heterostructures. • Fe 9 S 10 /Fe 3 O 4 @C can effectively trap LiPS and promote the conversion kinetics. • The Fe 9 S 10 /Fe 3 O 4 heterointerface offers a moderate chemical bonding with LiPS. • The cell with Fe 9 S 10 /Fe 3 O 4 @C interlayer exhibits enhanced rate and cycling capability. The shuttle effect of soluble lithium polysulfides (LiPSs) and sluggish electrocatalysis of polysulfides conversion lead to severe capacity decay and poor rate capability, which is a determining factor for limiting the practical applications of lithium-sulfur (Li-S) batteries. To address such issues, a novel core-shell Fe 9 S 10 /Fe 3 O 4 @C architecture with well-defined heterointerfaces as a multifunctional polysulfides barrier for Li-S batteries is reported here. The spherical Fe 9 S 10 /Fe 3 O 4 @C heterostructure can be prepared by spray-drying technology on a large-scale and followed by a one-pot in-situ carbothermal reaction. With both physical entrapments by carbon shells and strong chemical interaction with Fe 9 S 10 /Fe 3 O 4 heterostructure cores, this constructed dense-packing architecture alleviates the shuttle effect. The mechanisms involved in the Fe 9 S 10 /Fe 3 O 4 @C trapping interlayer are confirmed by both experimental results and density functional theory (DFT) calculations. Moreover, due to its high conductivity and intrinsic catalytic activity, the Fe 9 S 10 /Fe 3 O 4 @C facilitates fast electron/ion transport and greatly improves the conversion of LiPSs. Benefit from the integrated trapping-catalyzing effect, the Li-S cell constructed with a Fe 9 S 10 /Fe 3 O 4 @C interlayer exhibits enhanced cycling stability (a low capacity fading rate of 0.08% per cycle for 500 cycles at 1 C) and outstanding rate performance (660 mAh g −1 at 5 C). Even under a high areal sulfur loading of 3 mg cm −2 , the high discharge capacity and capacity retention ratio can also be obtained. This work offers an insight into the construction of multi-functional heterostructures for high-performance Li-S batteries.

Surface tailoring of polypropylene separators for lithium-ion batteries via N-hydroxyphthalimide catalysis

Surface modification of polyolefine separators for high performance lithium-ion batteries has been a worthwhile research topic. In this work, poly (poly (ethylene glycol) methacrylate) (PPEGMA) was firstly grafted onto polypropylene (PP) separator based on N-hydroxyphthalimide (NHPI) catalysis and activators regenerated by electron transfer atom transfer radical polymerization (ARGET-ATRP). Bis(2,2,2-trichloroethyl) azodicarboxylate (BTCEAD) was anchored on the surface of PP separators in the presence of NHPI. Then BTCEAD functionalized PP separator initiated the polymerization of PEGMA by ARGET-ATRP. Thus, structure controllable PPEGMA was grafted on the surface of PP separators. The results of contact angle and electrolyte uptake tests demonstrated that electrolyte wettability of PPEGMA functionalized PP separator has been significantly improved. Electrochemical measurements indicated that the ionic conductivity and discharge capacity retention of cells assembled with PPEGMA functionalized PP separators were distinctly higher than that of cells with pristine PP separator. Herein, we presented a new methodology with high efficiency to modify PP separators under mild condition, which was also applied to other polyolefine separator for high performance lithium-ion batteries. The proposed approach might have many other potential applications in membrane modification field.

Water-based binder with easy reuse characteristics for silicon/graphite anodes in lithium-ion batteries

A new binder, poly(2-propenoic acid, 2-methyl-, 3-[(2-aminoethyl) amino]-2-hydroxypropyl ester) (P-HAEAPMA), is synthesized and applied to silicon/graphite (Si/graphite) anodes in lithium-ion batteries. The Si/graphite anode with the binder exhibits good electrochemical stability. Furthermore, the materials on the discarded Si/graphite/P-HAEAPMA electrode can be recycled for use based on water because the P-HAEAPMA binder is easily soluble in water. The discharge capacity and capacity retention rate of the electrode with reused materials are slightly lower than those of the original Si/graphite/P-HAEAPMA electrode. The binder is rich in polar amino and hydroxyl groups, which not only helps to form strong adhesion between the electrode active material and copper foil but also promotes the transport of Li ions. The electrochemical performance of the electrode with the P-HAEAPMA binder is significantly enhanced compared with that of the electrode with the traditional PVDF binder or water-based LA133 binder. After 305 cycles, a specific capacity of 485.0 mA h g−1 and a capacity retention rate of 74.8% are achieved for the Si/graphite/P-HAEAPMA electrode. A binder, poly(2-propenoic acid, 2-methyl-, 3-[(2-aminoethyl) amino]-2-hydroxypropyl ester) (P-HAEAPMA), is synthesized and applied to silicon/graphite anodes in lithium-ion batteries, which exhibits good electrochemical stability. After 305 cycles, a specific capacity of 485.0 mA h g−1 and a capacity retention rate of 74.8% are achieved. Moreover, the discarded electrode with P-HAEAPMA binder can be reused just based on water because the P-HAEAPMA binder is easily soluble in water, and the electrochemical properties of the electrode with reused materials are slightly lower than those of the original electrode.

Polypyrrole Modification of High Sulfur-Loaded Three-Dimensional Aluminum Foam Cathode in Lithium–Sulfur Batteries for High-Rate Capability

A low-resistance polypyrrole (PPy) film that can achieve high rates (rates of >1C) while suppressing polysulfide dissolution is developed in this study. To achieve high-rate characteristic in a sulfur cathode with high sulfur loading, a three-dimensional (3D) aluminum foam current collector is used and the Li+ concentration of the PPy film is enhanced by a glyme–Li equimolar complex as the polymerization electrolyte. A PPy–sulfur/ketjenblack (S/KB) 3D aluminum foam laminated cell with a sulfur loading of 5 mg cm−2 is prepared. Consequently, a high discharge capacity of 794 mAh g−1-sulfur at 3.0C is achieved using 1 M lithium bis-(trifluoromethylsulfonyl)imide (LiTFSI) with dimethoxyethane (DME) and 1,3-dioxolane (DOL), (DME/DOL = 1/1 vol.) as the electrolyte and Li foil as the anode. In the cycling test, PPy-S/KB 3D Al foam cathode achieved a significant improvement in discharge capacity retention compared to bare S/KB 3D Al foam cathode without PPy coating. Moreover, almost no polysulfide dissolution is confirmed from the ultraviolet–visible spectrum of the electrolyte after the cycle evaluation. Here, we prepare a 3D structure S/KB cathode that can support high rates while suppressing sulfur dissolution by PPy coating, and reveal its potential for lithium–sulfur battery application.

Nondestructive measurement method for binder content and performance of lithium-ion battery based on electrode deflection under bending deformation

To confirm the durability and reliability of lithium-ion batteries, a fundamental study for the development of nondestructive measurement method for binder content and performance of the batteries prior to cell assembly is presented herein. This study focuses on the deflection of the electrode, consisting of a current collector and an electrode film on the current collector. Bending deformation is used as a representative measurement for the binder content because it can easily be induced and measured during the production process of the electrode. The correlation between the binder content and the Young's modulus of the electrode film is characterized via tensile testing. Furthermore, the correlation between the Young's modulus of the electrode film affected by the binder content and the electrode deflection under bending deformation is experimentally confirmed and verified using finite element analysis (FEA). Additionally, it is confirmed that the charge-transfer resistance and discharge capacity retention of the cells assembled with different binder contents vary. Ultimately, it is shown that the binder content, discharge capacity retention, and charge-transfer resistance of the cells with different binder contents can be predicted from electrode deflection prior to cell assembly.

Facile metal complex-derived Ni/NiO/Carbon composite as anode material for Lithium-ion battery

In the present work, nickel/nickel oxide/carbon matrix (Ni/[email protected]) was generated using [Ni(salen)] complex by a facile pyrolysis method. The formation of the Ni/[email protected] was confirmed by several physico-chemical analyses. Subsequently, the Ni/NiO/cm was explored as anode material for lithium-ion battery in each of half-cell and full-cell. The CR2032-type lithium-ion half-cell (Ni/[email protected]∣LiPF6∣Li) delivered a stabilized discharge capacity of 330 mAh g−1 with excellent cycling stability (200 cycles) as well as Columbic efficiency. The stable lithium-ion storage performance of the Ni/[email protected] anode is attributed to the occurrence of conversion/re-conversion reactions. The presence of the carbon matrix acted as both conductive network as well as cushion during volume change. Consequently, the lithium storage performances of the Ni/[email protected] as anode was verified in the form of CR2032-type full-cell that exhibted discharge capacity of 400 mA h g−1 at 0.1C-rate and stabilized capacity of 100 mA h g−1 at high 0.3C-rate for 500 cycles. Even at 500th cycle, the full-cell delivered 70% retention of discharge capacity. A proto-type full cell was demonstrated to power a commercial (3.0 V) green LED bulb for more than 9 h continuously on single charge.

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.

Amphoteric Nafion membrane with tunable cationic and anionic ratios for vanadium redox flow battery prepared via atom transfer radical polymerization

Nafion is currently the most stable ion exchange membrane for vanadium redox flow battery (VRB). In order to decrease the high vanadium permeability of Nafion while still keeping its high ionic conductivity and stability, in this study, solution atom transfer radical polymerization (ATRP) method is used with Nafion as initiator to prepare amphoteric Nafion membrane with tunable cationic and anionic ratios. Polymers of [2-(methacryloyloxy)ethyl] trimethylammonium chloride (METAC) and sodium 4-styrenesulfonate (NaSS) are chosen as cationic and anionic monomers, respectively. FT-IR (Fourier transform infrared) and 1H NMR (nuclear magnetic resonance) tests prove that the METAC and NaSS have been successfully bonded on the Nafion molecules. The solution-casted amphoteric Nafion membrane M-1:1 has shown the highest ion selectivity among all the grafted Nafion membranes. The VRB with M-1:1 membrane has shown the highest average energy efficiency of 83.9% at current density of 40–80 mA cm−2, which is 4.2% higher than that of Nafion 212 (79.7%). One hundred cycles dynamic charge-discharge test proves that the M-1:1 membrane possesses enough stability and good discharge capacity retention ability. On-line self-discharge test further proves that the M-1:1 membrane has lower vanadium ions permeation than that of Nafion 212 membrane. All the results prove that ATRP is an effective method for preparation of novel amphoteric materials for VRB application.

Assessment of Li-S Battery Performance as a Function of Electrolyte-to-Sulfur Ratio

Lithium-Sulfur (Li-S) battery performance is greatly sensitive to cell design as a result of the highly complex reaction and shuttle mechanisms within the cathode. Electrolyte-to-sulfur (E/S) ratio is one of the key design parameters that have a great impact on the performance of Li-S batteries. Here, an integrated research methodology coupling experimental characterization and electrochemical modeling is applied to forecast the relation between the E/S ratio and the discharge capacity, cycling performance and cell- and system-level specific energy and energy density of the Li-S battery. The highest initial discharge capacity is achieved with an E/S ratio of 20 μl mg−1, whereas, the best capacity retention is observed for 13 μl mg−1. This experimentally obtained link between the E/S ratio and the discharge performance is taken into consideration in the proposed cell- and system-level performance models. Lower E/S ratios lead to higher battery performance at the cell and system level. Consequently, an E/S ratio of 13 μl mg−1 presents the best performance as the impact of E/S ratio not only on the peak discharge capacity and capacity retention but also on the specific energy and energy density at the cell and system level are all considered.

Synthesis of cathode material with different dosage of maleic acid-leachate of spent lithium-ion batteries

In this paper, LiNi1/3Co1/3Mn1/3O2 cathode materials were synthesized by sol-gel with different dosage of maleic acid-leachate of spent lithium ion batteries (LIBs). Electrochemical performance test was performed on the re-synthesised materials to explore the effect of leachate dosage. The results show that the degree of Li+/Ni2+ mixing increased while initial discharge capacities and capacity retention decreased significantly with leachate dosage increasing. Therefore, the leachate dosage is preferably 65% which can achieve a win-win situation in economy and performance when the LiNi1/3Co1/3Mn1/3O2 cathode materials were synthesized with maleic acid-leachate of spent LIBs in our work.

Y and Sb co-doped Li7La3Zr2O12 electrolyte for all solid-state lithium batteries

Li7La3Zr2O12 (LLZO) with high ionic conductivity and excellent chemical and electrochemical stability with metallic Li is considered to be one of the most promising candidates for solid-state batteries. In this work, Li6.925La3-xYxZr1.925Sb0.075O12 (0 ≤ x ≤ 0.1) garnets were prepared through solid-state reaction method, and effects of the co-dopant on the structure and ionic property are studied. The co-doping of Y3+ (0–0.075) and Sb5+ (0.075) accelerates the formation of cubic phase structure. Meanwhile, Li6.925La2.95Y0.05Zr1.925Sb0.075O12 (relative density ~ 95.1%) showed the highest total conductivity (3.20 × 10−4 S/cm) and the lowest activation energy of 0.30 eV at 30 °C. Moreover, the high discharge capacity and capacity retention of solid-state battery of LiFePO4/Li6.925La2.95Y0.05Zr1.925Sb0.075O12/Li indicate that Y and Sb co-doped Li7La3Zr2O12 ceramic should be a promising electrolyte.

A high-voltage rechargeable alkaline Zn–MnO4− battery with enhanced stability achieved by highly reversible MnO4−/MnO42− redox pair

Development of rechargeable alkaline Zn–Mn batteries has been facing big challenges for low working voltage and poor cycling stability, although they have advantages of low cost, high safety, and simple maintenance. For the first time, this work demonstrates a record high voltage (1.78 V) for rechargeable alkaline Zn–MnO4− battery achieved by a high reversible redox pair of MnO4−/MnO42−, which shows excellent cycling stability up to 1,500 cycles at a high current density of 20 mA cm−2 without obvious capacity attenuation. The MnO4−/MnO42− redox reaction investigated by ex-situ scanning electron microscope as well as ultraviolet and visible absorption spectrum indicates high reversibility of the MnO4−/MnO42− redox couple after the activation during the first discharge process. Furthermore, benefiting from the liquid-phase reaction nature of MnO4−/MnO42−, a flow battery is further prototyped to show highly stable cycles with 95.8% of discharge capacity retention for 600 cycles at the current density of 40 mA cm−2.

Room Temperature to 150 °C Lithium Metal Batteries Enabled by a Rigid Molecular Ionic Composite Electrolyte

AbstractMolecular ionic composites (MICs), made from ionic liquids and a rigid‐rod polymer poly(2,2′‐disulfonyl‐4,4′‐benzidine terephthalamide) (PBDT), are a new type of rigid gel electrolyte that combine fast ion transport with high thermal stability and mechanical strength. In this work, a MIC electrolyte membrane is prepared that is composed of PBDT, lithium bis(trifluoromethylsulfonyl)imide (LiTFSI), and 1‐butyl‐1‐methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (Pyr14TFSI) in a mass ratio of 10:10:80. The ionic conductivity at 25 °C is 0.56 mS cm−1 with no added flammable/volatile components. Although the polymer content is only 10 wt%, this MIC membrane is rigid with a tensile modulus of 410 MPa at room temperature. The MIC membrane remains stable and rigid at 200 °C with the shear storage modulus (G′) only slightly decreasing by 35%. Li/MIC/LiFePO4 cells demonstrate stable cycling performance over a wide temperature range from 23 to 150 °C. The specific discharge capacity at 100 and 150 °C at 1 C rate exceeds 160 mAh g−1. The discharge capacity retention is 99% after 50 cycles at 150 °C. This stable battery performance shows that this low polymer content MIC membrane qualifies for use as a solid electrolyte in lithium metal batteries operating over a wide temperature range.

Electrochemical performance of spherical LiCoO2 with high stability in neutral aqueous electrolyte

Layer-structured lithium cobalt oxide (LCO) is one of promising electrode materials for secondary aqueous lithium-ion batteries, yet the effect of structural proton insertion in LCO in neutral aqueous electrolytes cannot be ignored. Present study investigates the electrochemical performance of polycrystalline spherical LCO in neutral aqueous saturated Li2SO4 solution. Herein, we for the first time demonstrate the dependence of LCO stability on the discharge cutoff potential. The applied LCO electrodes show good cycling stability within the potential window of 0.65–1.1 V vs. SCE, while electrochemical impedance spectrum (EIS) analysis detects no sign of proton intercalation. Moreover, the spherical LCO free from the proton intercalation exhibits a superior rate capability with 78% discharge capacity retention at 80 C. The lithium-ion chemical diffusion coefficient being seven times than that of irregular shaped LCO sample can be responsible for such significant rate capability. The cyclability testing depicts the better performance of spherical LCO in comparison with the counterpart, especially in terms of electrode activation time. Post cycling electrode characterization displays that the discharge capacity fading of LCO mainly results from the crystal grain deformation due to high potential cycling and can be alleviated by reducing the depth of charge.

Enhanced electrolyte retention capability of separator for lithium-ion battery constructed by decorating ZIF-67 on bacterial cellulose nanofiber

The separator is a key component of the lithium-ion battery (LIB), which not only prevents the anode and the cathode from contacting, but is also related to the performance of the LIB. However, the widely used polyolefin separator has the disadvantages of inferior electrolyte retention capability and poor electrolyte wettability. Therefore, the development of high-performance separators for LIB has attracted widespread attention. In order to enhance the electrolyte retention capacity of the separator, the bacterial cellulose (BC)/zeolitic imidazolate framework-67 (ZIF-67) composite separator was prepared by introducing ZIF-67 on the BC nanofibers. It was found that the introduction of ZIF-67 in BC membrane significantly improved the pore structure and enhanced the electrolyte retention capability, thus contributing to the transfer of lithium-ion, increasing the ionic conductivity (0.837 mS cm−1). In terms of ionic conductivity, BC/ZIF-67 separator has achieved a great improvement compared to polypropylene (PP) separator (0.096 mS cm−1). Besides, the prepared BC/ZIF-67 composite separators hardly shrink at high temperatures. The discharge capacity retention of the LIB using BC/ZIF-67 separator was 91.41% after 100 cycles (0.2 C). Meanwhile, LIB with BC/ZIF-67 separator showed a large discharge capacity (156 mAh g−1) and improved rate performance. Therefore, the BC/ZIF-67 composite membrane has good development potential in the direction of LIB separator.

Synthesis and Li-ion diffusion kinetic of Zn2(OH)3VO3 nanosheets with ultra-high electrochemical activity

It has been reported that 2-dimension Zn2(OH)3VO3 possesses the higher electrochemical activity. However, its morphology evolution, formation mechanism and electrochemical kinetics remain elusive. In this study, Zn2(OH)3VO3 nanosheets with a thickness of 20 ~ 50 nm were synthesized by a facile one-pot hydrothermal route without any post heat treatment. We reveal the morphology evolution through the reaction time manipulation and formation mechanism in terms of nucleation, crystallization and growth. Lithium storage performances of the obtained nanosheets were investigated, featuring a discharge capacity retention of 863 mAh g−1 after 100 cycles at 0.1 A g−1 and Coulombic efficiency of 99%. The reversible specific capacity reached 477 mAh g−1 even at 10 A g−1, indicating an analyzed diffusion-controlled mechanism. Furthermore, for the first time, the electrochemical kinetics of Zn2(OH)3VO3 nanosheets electrode during the first cycle were studied in detail by in situ Electrochemical impedance technology, which certified that the solid electrolyte interface (SEI) layer experienced the formation, dissolution and reformation process upon cycling. The present work might greatly promote the application of Zn2(OH)3VO3 in Li-ion batteries and other fields.