Lithium Half-cells Research Articles

Solution-Phase Synthesis and Electrochemical Properties of Lepidocrocite Titanate-Reduced Graphene Oxide Composites

Stepped layered titanates can be used as anodes for lithium, sodium or potassium batteries in conventional or flow cell configurations. They are attractive due to their low cost, low toxicity, and high abundancy. However, their low conductivity and poor cycling performance are major hurdles for these materials.The addition of carbon can be used to overcome electronic transport limitations to some extent, but for nonconventional configurations, it is preferable to build in the conductivity by manipulating the structure. For example, in the case of layered materials, this can be done by incorporating a conductive component such as reduced graphene oxide (rGO) in the van der Waals gaps to make 2D heterostructures, the approach we are using here.In this presentation, solution-phase synthesis of K0.8[Ti1.73Li0.27]O4 (lepidocrocite titanate, LT)- rGO composite is demonstrated. After synthesis by conventional solid-state routes, K0.8[Ti1.73Li0.27]O4 is proton exchanged and ion-exchanged with bulky cations, causing expansion of the structure, and exfoliated by mechanical shaking. Exfoliated layered titania sheets are combined with reduced graphene oxide (rGO) to assemble into heterostructures through flocculation. Counter cations (e.g. Mg2+, Na+) are used for the self-assembly of negatively charged LT and rGO nanosheets via flocculation. Mg2+-coagulated composites with 15 wt% rGO have higher capacities than Na+-coagulated composites with the same rGO content in the lithium half-cell configurations, whereas Na+-coagulated composites deliver higher capacity than that of Mg2+-coagulated composites in the sodium half-cell configurations. Both Mg2+-coagulated and Na+-coagulated LT-rGO samples exhibit capacities which are more than two times higher than the capacities of pristine lepidocrocite titanate (K0.8[Ti1.73Li0.27]O4), and display good capacity retention after 50 cycles in both lithium and sodium half-cells configurations.

Preparation and the diffusion kinetic investigation of Zn3(OH)2V2O7·2H2O nanosheets anode for high performance lithium-ion battery

In this paper, two dimensional nanosheet (2D) Zn3(OH)2V2O7·2H2O has been synthesized by a facile hydrothermal method. The structure and morphology evolution of the resulting material are characterized by several technologies. Applied for anode of lithium-half cell, the as-synthesized sample delivers a high reversible capacity, long-cycling stability, and good rate capability due to intrinsically great area and the short diffusion distance. Notably, according to the equivalent electrical circuit and the non-linear least square regression method, the in-situ electrochemical impedance spectra during the initial discharge–charge cycle are simulated, which indicates that the kinetics property changes significantly when discharged to 0.5 V, and then keeps stability.

2-Carboxyethylgermanium Sesquioxide as A Promising Anode Material for Li-Ion Batteries.

Various forms of germanium and germanium-containing compounds and materials are actively investigated as energy-intensive alternatives to graphite as the anode of lithium-ion batteries. The most accessible form-germanium dioxide-has the structure of a 3D polymer, which accounts for its rapid destruction during cycling, and requires the development of further approaches to the production of nanomaterials and various composites based on it. For the first time, we propose here the strategy of using 2-carboxyethylgermanium sesquioxide ([O1.5 GeCH2 CH2 CO2 H]n , 2-CEGS), in lieu of GeO2 , as a promising, energy-intensive, and stable new source system for building lithium-ion anodes. Due to the presence of the organic substituent, the formed polymer has a 1D or a 2D space organization, which facilitates the reversible penetration of lithium into its structure. 2-CEGS is common and commercially available, completely safe and non-toxic, insoluble in organic solvents (which is important for battery use) but soluble in water (which is convenient for manufacturing diverse materials from it). This paper reports the preparation of micro- (flower-shaped agglomerates of ≈1 μm thick plates) and nanoformed (needle-shaped nanoparticles of ≈500×(50-80) nm) 2-CEGS using methods commonly available in laboratories and industry such as vacuum and freeze-drying of aqueous solutions of 2-CEGS. Lithium half-cell anodes based on 2-CEGS show a capacity of ≈400 mAh g-1 for microforms and up to ≈700 mAh g-1 for nanoforms, which is almost two times higher than the maximal theoretical capacity of graphite. These anodes are stable during the cycling at various rates. The results of DFT simulations suggest that Li atoms form the stable Li2 O with the oxygen atoms of 2-CEGS, and actual charge-discharge cycles involve deoxygenated GeC3 H5 molecules. Thus, C3 chains loosen the anode structure compared to pure Ge, improving its ability to accommodate Li ions.

Electrochemical behavior of nanostructured NiO@C anode in a lithium-ion battery using LiNi⅓Co⅓Mn⅓O2 cathode

A NiO@C composite anode is prepared through an alternative synthesis route involving precipitation of a carbon precursor on NiO nanopowder, annealing under argon to form a Ni core, and oxidation at moderate temperature to get metal oxide particles whilst retaining carbon and metallic Ni in traces. The electrode reversibly reacts in lithium cells by the typical conversion process occurring in a wide potential range with the main electrochemical activity at 1.3 V vs. Li+/Li during discharge and at 2.2 V vs. Li+/Li during charge. The NiO@C material exhibits highly improved behavior in a lithium half-cell compared to bare NiO due to faster electrode kinetics and superior stability over electrochemical displacement, leading to a reversible capacity approaching 800 mAh g−1, much enhanced cycle life and promising rate capability. The applicability of the NiO@C anode is further investigated in a lithium-ion NiO@C/LiNi⅓Co⅓Mn⅓O2 cell, which operates at about 2.5 V delivering about 160 mAh g−1 with respect to the cathode mass. The cell exhibits stable response upon 80 cycles at a C/2 rate with coulombic efficiency ranging from 97% to 99%.

Alternative lithium-ion battery using biomass-derived carbons as environmentally sustainable anode

Disordered carbons derived from biomass are herein efficiently used as an alternative anode in lithium-ion battery. Carbon precursor obtained from cherry pit is activated by using either KOH or H3PO4, to increase the specific surface area and enable porosity. Structure, morphology and chemical characteristics of the activated carbons are investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermogravimetry (TG), Raman spectroscopy, nitrogen and mercury porosimetry. The electrodes are studied in lithium half-cell by galvanostatic cycling, cyclic voltammetry, and electrochemical impedance spectroscopy (EIS). The study evidences substantial effect of chemical activation on the carbon morphology, electrode resistance, and electrochemical performance. The materials reveal the typical profile of disordered carbon with initial irreversibility vanishing during cycles. Carbons activated by H3PO4 show higher capacity at the lower C-rates, while those activated by KOH reveal improved reversible capacity at the high currents, with efficiency approaching 100% upon initial cycles, and reversible capacity exceeding 175 mAh g−1. Therefore, the carbons and LiFePO4 cathode are combined in lithium-ion cells delivering 160 mAh g−1 at 2.8 V, with a retention exceeding 95% upon 200 cycles at C/3 rate. Hence, the carbons are suggested as environmentally sustainable anode for Li-ion battery.

Scalable Route to Electroactive and Light Active Perylene Diimide Dye Polymer Binder for Lithium-Ion Batteries.

Developing multifunctional polymeric binders is key to the design of energy storage technologies with value-added features. We report that a multigram-scale synthesis of perylene diimide polymer (PPDI), from a single batch via polymer analogous reaction route, yields high molecular weight polymers with suitable thermal stability and minimized solubility in electrolytes, potentially leading to improved binding affinity toward electrode particles. Further, it develops strategies for designing copolymers with virtually any desired composition via a subsequent grafting, leading to purpose-built binders. PPDI dye as both binder and electroactive additive in lithium half-cells using lithium iron phosphate exhibits good electrochemical performance.

Rapid microwave synthesis of Zn3(OH)2V2O7·2H2O nanosheets for enhanced lithium storage performances

Zn3V2O7(OH)2·2H2O has attracted much attention due to its fascinating properties. However, the reported methods need a long reaction time. Little attention has been paid to the energy consumption cost and time saving in the manufacturing process. This paper develops the microwave approach to synthesize Zn3V2O7(OH)2·2H2O nanosheets with about 25 nm thickness only in 10 min, which greatly saves the energy compared to the traditional routes, and easily be extended to fabricate other metal pyrovanadate compounds. Nanosheets shape implies a totally different reaction in the similar microwave system. As cathode of lithium-half cells, The as-prepared Zn3V2O7(OH)2·2H2O nanosheets holds the high capacity of 962.4 mAh g−1 after 100 cycles at 20 mA g−1. It can retain 98.9% of the eighth reversible capacity and shows a promising application in cathode of lithium power batteries. In comparison, the capacity is 392.6 mAh g−1 after 100 cycles and the retention is only 50.9% of the eighth for the thicker plate-like Zn3V2O7(OH)2·2H2O. The electrochemical impedance spectroscopy reveals that Li+ (de) intercalation process in this system is mix-controlled by charge-transfer and diffusion steps, which indicates that 2 dimensional structure plays a vital role in improving the electrochemical performances of Zn3V2O7(OH)2·2H2O.

Morphology engineering of silicon nanoparticles for better performance in Li-ion battery anodes.

Amorphous silicon nanoparticles were synthesized through pyrolysis of silane gas at temperatures ranging from 575 to 675 °C. According to the used temperature and silane concentration, two distinct types of particles can be obtained: at 625 °C, spherical particles with smooth surface and a low degree of aggregation, but at a higher temperature (650 °C) and lower silane concentration, particles with extremely rough surfaces and high degree of aggregation are found. This demonstrates the importance of the synthesis temperature on the morphology of silicon particles. The two types of silicon nanoparticles were subsequently used as active materials in a lithium half cell configuration, using LiPF6 in an alkylcarbonate-based electrolyte, in order to investigate the impact of the particles morphology on the cycling performances of silicon anode material. The difference in morphology of the particles resulted in different volume expansions, which impacts the solid electrolyte interface (SEI) formation and, as a consequence, the lifetime of the electrode. Half-cells fabricated from spherical particles demonstrated almost 70% capacity retention for over 300 cycles, while the cells made from the rough, aggregated particles showed a sharp decrease in capacity after the 20th cycle. The cycling results underline the importance of Si particle engineering and its influence on the lifetime of Si-based materials.

Atomic layer deposition and structure optimization of ultrathin Nb2O5 films on carbon nanotubes for high-rate and long-life lithium ion storage

Niobium pentoxides (Nb2O5) as anode materials has attracted tremendous research interest due to its great potential in rate capability and cyclic durability. Nevertheless, the low electrical conductivity and weak structural controllability of Nb2O5 hinders its practical application. Herein, amorphous Nb2O5 thin films are conformally deposited on carbon nanotubes (CNTs) by controlled atomic layer deposition (ALD) and three types of crystalline Nb2O5@CNTs composites are obtained by post-deposition annealing. Moreover, the effects of deposition temperature and annealing temperature on the crystal structure and surface morphology of Nb2O5@CNTs are investigated. Based on these, the electrochemical performances of Nb2O5@CNTs composites as anode materials are compared in lithium half cells. Impressively, ultrathin and uniform Nb2O5 nanocrystal film with hexagonal (TT) phase on CNTs delivers a capacity of 325.1 mAh g−1 at 0.2 A g−1. Even at a high current density of 3 A g−1, a stable capacity of 170 mAh g−1 is still achieved over 4000 cycles. Its high-rate and long-life lithium ion storage is mainly attributed to the synergistic effects of carbon nanotubes, TT-phase Nb2O5, and ultrathin film structure. Therefore, this synthetic strategy facilitates the development of Nb2O5 as anode materials for high-rate and long-life lithium/sodium ion batteries.

Amorphous Sb2S3 Anodes by Reactive Radio Frequency Magnetron Sputtering for High‐Performance Lithium‐Ion Half/Full Cells

Herein, amorphous Sb2S3 (a‐Sb2S3) anodes are prepared on 3D conductive networks by a simple reactive radio frequency (RF) magnetron sputtering process, and their application feasibility in both a lithium half cell and LiFePO4 full cell is assessed. The a‐Sb2S3 electrodes exhibit excellent cycling performance and rate capacity in the half cells, owing to the amorphous phase and 3D structure, and thus yield a high discharge capacity of 585.4 mAh g−1 at a current density of 0.2 C after 250 cycles. Moreover, the assembled a‐Sb2S3/LiFePO4 full cell can deliver 467.1 mAh g−1 at a high current density of 1000 mA g−1 even after 100 cycles. The prepared a‐Sb2S3 shows great potential to be a promising alternative anode in the application of high‐electrochemical‐performance lithium‐ion batteries.

Ce-doped Mn3O4 as high-performance anode material for lithium ion batteries

A series of Ce-doped Mn3O4 (Mn3-xCexO4, x = 0, 0.01, 0.02, 0.03, and 0.04) samples have been successfully synthesized by using a facile hydrothermal method. The composition, phase, structure and morphologies of the as-prepared compounds were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Scanning electron microscopy (SEM). The cell parameters and the electronic conductivity increase with the increasing of x. The amount x of Ce doping can not exceed 0.03 in order to keep the pure tetragonal structure of Mn3O4. As anode of lithium half cell, Ce-doping improved obviously the electrochemical performances of the pristine Mn3O4 at the expense of the first discharge capacity. Particular, The compound Mn2.98Ce0.02O4 displayed the highest capacity (754.2 mAh g−1) up to 100 cycles at 100 mA g−1, accompanied with good rate capability (238 mAh g−1 even at 5C), which can be attributed to that Ce-doping resulted into the bigger diffusion channels, the more robust structure and the reduced charge transfer impedances. This study provides a new insights into promoting the application of Mn3O4 into lithium ion batteries.

Geminal pyrrolidinium and piperidinium dicationic ionic liquid electrolytes. Synthesis, characterization and cell performance in LiMn2O4 rechargeable lithium cells

Dicationic ionic liquids are promising solvents for safe high performance Li-ion battery applications. In this work, we report on the synthesis and characterization of new electrolytes based on geminal dicationic pyrrolidinium and piperidinium bis(trifluoromethane)sulfonimide ionic liquids, where the two cations are linked by variable length oxyethylene chain spacers. All 1 M LiTFSI doped synthesized electrolytes are thermally stable up to 300 °C, and they exhibited remarkable electrochemical stability window up to 6.0 V vs. Li/Li+.Electrolytes were assembled with LiMn2O4 (LMO) spinel in lithium half-cells. Electrochemical cell performance in terms of cyclic voltammetry, rate capability and galvanostatic cycling studies have been studied at 60 °C. Results obtained indicate that both the cationic structure and the length of the oxyethylene chain spacer has a significant influence on the electrochemical performance of LMO-cells. The cell based on the pyrrolidinium electrolyte with the two cationic structures linked by two oxyethylene units exhibit the faster rate capability, with a capacity retention of 45% at 5C, and the highest reversible capacity (ca. 80 mAhg-1).

Structural Degradation of Cu Current Collector During Electrochemical Cycling of Sn-Based Lithium-Ion Batteries

It is an open question whether there exists structural degradation of current collectors, which likely can lead to the capacity loss of lithium-ion batteries. In this work, we investigate the cycling-induced structural degradation/damage of the Cu current collector used in Sn-based lithium half cells. Electrochemical cycling causes the formation of a layer of porous structure even after the first cycle and the formation of Li2SnCu. The thickness of the porous structure increases with the increase of the cycle number, and local separation between the porous layer and the “solid” Cu layer occurs after prolonged cycling. The nominal contact moduli of the porous layers formed after one and five electrochemical cycles are slightly larger than the pristine Cu current collector. For the porous layers formed after twenty or more electrochemical cycles, the normal contact modulus is generally less than the pristine Cu. The indentation hardnesses of the porous structures are generally less than the pristine Cu except for the porous structure formed after five electrochemical cycles.

Lithium-Ion Transport and Cycling Characteristics of Fluorinated Electrolytes

Electrical energy is ubiquitous in the modern world, and in order to continue pushing boundaries on consumer wearables, electric vehicles, and grid storage, secondary lithium-based rechargeable batteries need to be enhanced. The performance of binary electrolytes is governed by the electrolyte thermodynamic factor and three transport properties: conductivity, salt diffusion coefficient, and transference number. Rigorous methods for measuring conductivity and the salt diffusion coefficient are well established in literature. NMR and the steady-state current method are often used to measure the transference number, but are predicated on the dilute solution assumption and do not fully consider the non-ideality of the electrolyte. Within this work, we elucidate a complete set of lithium-ion transport properties for mixtures of dimethyl carbonate terminated perfluorinated tetraethylene ether and lithium bis(fluorosulfonyl)imide (LiFSI). The steady-state current transference number is positive across all concentrations and decreases with salt concentration, while the NMR transference number is approximately 0.5 everywhere. In contrast, we find that the transference number using Newman’s concentrated solution theory is negative across all concentrations. We show that Newman’s concentrated solution theory allows for accurate potential and limiting current modeling of lithium half cells whereas the steady-state current transference number severely over-estimates the electrolyte’s limiting current. The disparity between the dilute solution theory measurements and that of Newman’s concentrated solution theory approach indicates the dominance of ion clustering. Figure 1

New tetraazapentacene-based redox-active material as a promising high-capacity organic cathode for lithium and potassium batteries

We report a facile synthesis of octahydroxytetraazapentacene (OHTAP) and the application of this redox-active material as a cathode for lithium- and potassium-ion batteries. While testing in lithium half-cells, OHTAP was used in the form of lithium salt and delivered the specific discharge capacity of >400 mAh g−1 and the energy density of ~700 Wh kg−1, which are impressive values achieved for organic electrode materials and can also be favorably compared with the characteristics of the current commercial benchmark cathodes based on LiFePO4 (~155 mAh g−1 and 543 Wh kg−1). The potassium half-cells fabricated using pristine OHTAP depending on the electrode deposition technique showed specific capacities of 120–220 mAh g−1, which are among the record values reported so far for this type of batteries. Quantum chemical DFT modelling provided insights in the mechanistic aspects of metallation of OHTAP and revealed that lithium- and potassium-ion storage might involve both the hydroquinone-quione chemistry as well as the redox transformations of pyrazine rings.

Polyphenylamine-Based Cathode Material for Ultrafast Charging Lithium, Sodium and Potassium Batteries

Organic redox-active compounds are considered as one of the most promising alternatives to conventional inorganic electrode materials. Organic cathodes, comprising of abundant elements (C, H, N, O), can be obtained from renewable resources and also have a number of other advantages. [1] In particular, batteries based on certain groups of organic materials have higher rate capabilities due to their fast oxidation-reduction kinetics and soft amorphous structure which facilitates ion diffusion. The diversity of organic molecules allows for tailoring their structure and properties to improve specific capacity, rate capability and operation stability of batteries. Inorganic intercalation-type compounds are usually constrained by their crystal lattice to a certain ion (e.g. Li+) with a specific ionic radius. On the contrary, the vast majority of known organic cathode materials are, in principle, electroactive with respect to a variety of metal ions since they are soft solids and have simple redox chemistry. Therefore, there is also a considerable potential in the development of potassium, sodium, magnesium, zinc and aluminium ion batteries if appropriate organic electrode materials and electrolytes are provided. This feature opens up wide opportunities for switching from scarce Li+ to some more abundant metal ions such as Na+ or K+. The recent flow of publications highlights four promising families of organic cathode materials represented by conjugated carbonyl compounds, free radical polymers, organosulfides, and conducting polymers. [2] The nitroxyl-based radical ion polymers and other redox-active conjugated polymers demonstrated impressive performances in terms of rate capabilities due to their high porosity, insolubility in conventional electrolytes and high operation voltages, while their capacity in batteries is typically limited by ~100 mA h g-1. Polytriphenylamine [3] and its analogues represent emerging group of redox-active polymers, which are expected to deliver superior gravimetric and volumetric capacities as well as high rate capability and good operational stability. [4] Herein, we report the synthesis and investigation of a novel redox-active poly(N,N’-diphenyl-p-phenylenediamine) (PDPPD) polymer obtained via Buchwald-Hartwig C-N cross-coupling reaction. PDPPD has a high density of redox-active amine groups enabling the theoretical specific capacity of 209 mA h g-1, which is nearly twice higher compared to all other materials of this family reported so far. The obtained polymer was evaluated as a cathode material for dual-ion batteries and demonstrated promising operation voltages of 3.5-3.7 V and decent practical gravimetric capacities of 97, 94 and 63 mA h g-1 in lithium, sodium and potassium half-cells, respectively, while being tested at the moderate current density of 1C. A specific capacity of 84 mA h g-1 was obtained for the ultrafast lithium batteries operating at 100C (full charge and discharge takes 36 seconds only), which is, to the best of our knowledge, the highest battery capacity reported so far for such high current densities. The PDPPD//Li batteries also showed promising stability reflected in 67% capacity retention after 5000 cycles. The obtained results prove that the designed PDPPD polymer indeed represents a highly promising organic cathode material for metal-ion batteries. Further rational design and exploration of this family of compounds might result in the development of a new generation of organic redox-active materials for advanced energy storage devices. In particular, the demonstrated in this work ultrafast batteries are of special interest in the view of multiple applications in the “electric push” devices emerging at the interface between the metal-ion batteries and supercapacitors.

Synthesis and Investigation of Surface-Modified Silicon Nanoparticles As Advanced Anodes for Li-Ion Batteries

Since their invention in the 1990s, Li-ion batteries (LIBs) have been the emergent battery technology, and have been instrumental towards widespread technological revolution in the present-day society. Commercial success aside, the energy density and the cycle life of state-of-the-art LIBs still cannot keep up with the needs of the modern world, e.g. in elctromobility [1]. Thus, there is a strong thrust towards development of advanced LIBs and Si based systems are one of the more promising technology[2], as they have significantly high theoretical specific capacity (3579 mAh/g) more than 10 times that of commercial graphite.[3] Furthermore, Si being low cost and environmentally friendly, makes them quite attractive for applications. Unfortunately, with regards to silicon chemistry, significant challenges inhibiting long term performance are still unresolved which act as hurdles toward broad commercialization. Si undergoes a large volume change (~300 %) during lithiation/delithiation, causing significant degradation of electrode with cycling in the form of cracking, contact loss and delamination. This inevitably leads to loss of active material and low cycling efficiency [3]. Nanostructuring of Si anodes has proven to be a successful strategy towards mitigating the stress involved, thereby minimizing the electrode degradation [4,5]. However, in nanoscale materials with high surface to volume ratio, the solid-electrolyte interphase (SEI) becomes a critical factor. Moreover, the SEI formed on silicon surface, in conjunction with common electrolytes, is relatively unstable and undergoes increasing resistance and acts as the bottleneck towards stable performance. In this work, we present our results on synthesis and functionalization of silicon nanoparticles (SiNPs). The aim is to influence the formation of the SEI by selectively modifying the surface of SiNPs Hydrogen silsesquioxane, obtained from hydrolysis of trichlorosilane, was subsequently annealed and etched to obtain sub-10nm sized SiNPs. The silicon surface was then modified with linear hydrocarbons containing different functional groups. Different functional groups (carboxyl group and amine group) were chosen to systematically study the effects on SEI formation and binder-interaction. Detailed characterization at different steps of the synthesis was done using FTIR, XRD and SEM. XPS and TEM was used to study the structure and morphology of the surface modified SiNPs. The SiNPs were prepared as electrodes and their electrochemical performance was evaluated versus lithium (half-cells) using LP30 as an electrolyte (Figure 1). Thus, an insight into the interaction of functional surface towards SEI formation, shall be instrumental towards development of a highly efficient and stable SEI for nanostructured Si anodes with high energy density and long term cycling stability. We thus present a relatively new approach, with large possibilities for further work, which is interesting and promising to leverage the power of silicon towards LIBs. Figure 1: a) Specific capacities (open symbol indicates discharge capacity and filled symbol indicates charge capacity) and b) Coulombic efficiencies for different functionalized SiNP anodes along with non-functionalized SiNP anodes in half cells with LP30 (1M LiPF6 in Ethylene carbonate:Dimethyl carbonate 1:1 v/v) as an electrolyte.

Rapid microwave preparation of Zn2(OH)3VO4 nanosheets with high lithium electroactivity

Abstract A rapid microwave route has been developed for the synthesis of electrochemically active Zn2(OH)3VO4 nanosheets just in 10 min. The crystalline phase, structure, composition and morphology with ∼22 nm thickness are characterized by X-ray powder diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, Scanning electron microscopy and Transmission electron microscopy. Used as anode of lithium half-cell, the as-prepared Zn2(OH)3VO4 nanosheets display a reversible discharge capacity of 887 mAh g−1 at a current density of 0.1 A g−1 for 100 cycles, even 280 mAh g−1 at 10 A g−1. The discharge capacity is about 777 mAh g−1 when the current density backed to 0.1 A g−1. A superior rate capacity and kinetic property are achieved, which demonstrate a high electrochemical activity and stable structure of the Zn2(OH)3VO4 nanosheet prepared by a quick and straightforward microwave technique.

Surface properties enhancement of battery separator by micro-plasma treatments

The aim of this work is to test the wettability enhancement of a low-wetting and low-cost commercial polymer separator by cold microplasma treatments. Liquid and gas ammonia are tested as precursors in a pulsed microreactor at low pressure. Two modes of plasma producing are used, i.e., with and without bias. Optical emission spectroscopy, contact angle technique, and cycling tests are performed to characterize the process and the separator. Best results are obtained with liquid ammonia precursor without bias (contact angle between water and a polyethylene separator being 10° ± 2° compared to 111° ± 2° without any treatment). Cycling tests of lithium half-cells incorporating plasma-treated separator show drastic improvements to capacity retention at high rates (after 100 cycles at a 2C rate, the discharge capacity of a Li4Ti5O12 is almost three times higher, i.e., 38 mA h g−1 and 113 mA h g−1 with an untreated separator and a treated one, respectively).

A green and facile hydrothermal synthesis of γ-MnOOH nanowires as a prospective anode material for high power Li-ion batteries

In the present work, an oxidation-crystallization-reduction route in the hydrothermal systems has been demonstrated to be facile and feasible in the large-scale production of γ-MnOOH nanowires. The whole is green and cheap only using Mn2+ and polyvinylpyrrolidone without adding any oxide agent or template. The structure and morphology of the as-synthesized samples are characterized by X-ray diffraction, scanning electron microscopy, Transmission electron microscopy, Infrared active spectrum, Raman spectrum, thermogravimetry, cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectroscopy. As anode of lithium-half cells, γ-MnOOH nanowires exhibit enhanced cycling performance and rate capacity in comparison with the previous reports. A high capacity of up to 393.9 mAh g−1 with a Coulombic efficiency of nearly 100% is obtained at 0.1C after 100 cycles, which presents a promising application as anode materials for lithium power batteries.