Embedding Co3O4 nanoparticles into graphene nanoscrolls as anode for lithium ion batteries with superior capacity and outstanding cycling stability

Co_3O_4 is a promising high-performance anode for lithium ion batteries(LIBs), but suffers from unsatisfied cyclability originating duo to low electrical conductivity and large volume expansion during charge and discharge process. Herein, we successfully constructed the Co_3O_4 nanoparticles embedded into graphene nanoscrolls(GNSs) as advanced anode for high-performance LIBs with large capacity and exceptional cyclability. The onedimensional(1 D) Co_3O_4/GNSs were synthesized via liquid nitrogen cold quenching of large-size graphene oxide nanosheets and sodium citrate(SC) modified Co_3O_4 nanoparticles, followed by freeze drying and annealing at400 °C for 2 h in nitrogen atmosphere. Benefiting from the interconnected porous network constructed by 1 D Co_3O_4/GNSs for fast electron transfer and rapid ion diffusion, and wrinkled graphene shell for significantly alleviating the huge volume expansion of Co_3O_4 during lithiation and delithiation. The resultant Co_3O_4/GNSs exhibited ultrahigh reversible capacity of 1200 mAh g~(-1) at 0.1 C, outperforming most reported Co_3O_4 anodes.Moreover, they showed high rate capability of 600 m Ah g-1 at 5 C, and outstanding cycling stability with a high capacity retention of 90% after 500 cycles. Therefore, this developed strategy could be extended as an universal and scalable approach for intergrating various metal oxide materials into GNSs for energy storage and conversion applications.     

Electrochemical properties of LaFeO3-rGO composite

LaFeO_3-xwt% r GO composite(x = 8, 10, 12) was synthesized by ultraphonic stirring and lyophilization method.SEM, TEM and XRD results show that the perovskite-type LaFeO_3 was dispersed by rGO to form special porous structure due to the gauze-shaped wrinkles and folds structure of rGO. It was found that the special porous structure can effectively increase the specific surface area and suppress particle aggregation of LaFeO_3, thus improving the electrical conductivity and appreciably enhancing the electrochemical properties of LaFeO_3. As compared with LaFeO_3, the maximum discharge capacity of the composite(x=10) increased from 209.5 mAhg~(–1) to 334.6 mAhg~(–1).The High rate dischargeability at a discharge current density of 1500 mAg~(–1)(HRD1500) and the capacity retention rate after 100 charge/discharge cycles(S100) of the composite increased by 9% and 17%, respectively.     

Morphological evolution and kinetic enhancement of Li2FexMn1-xSiO4/C cathodes for Li-ion battery

Li_2MnSiO_4-based cathode materials possess reasonable work potentials and high theoretical capacities,while the practical energy/power densities are constrained by their inferior kinetics of Li~+ diffusion.In this work,the Pmn2_1-structure Li_2Fe_xMn_(1-x)SiO_4/C materials were synthesized via a solvothermal method and evaluated as Liion cathode materials,with notable morphological evolutions and tunable crystallographic habits observed after solvothermal process.The Li_2Fe_(0.33)Mn_(0.67)SiO_4/C material delivers an initial reversible capacity of 250.2mAh g~(-1)at 0.1 C(～1.51 Li~+insertion/extraction,1 C=166 mA g~(-1)),excellent high-rate capability(52.2 mAh g~(-1)at 5 C),and good long-term cyclability(64.6%after 196 cycles at 2 C).The enhanced electrochemical properties are attributed to the boosted ion/electron transports induced by preferred morphological and structural characteristics of Li_2Fe_(0.33)Mn_(0.67)SiO_4/C.     

Synthesis of layered LiMnO2 byin situ oxidation-intercalation and a study of the reaction mechanism and electrochemical performance

Using Mn(OH)₂ as precursor, LiOH as lithiating agent and (NH₄)₂S₂O₈ as oxidant, layeredo-LiMnO₂ was obtained by a novel method—in situ oxidation-intercalation under mild conditions (80 °C). The product was characterized by XRD, ICP, TEM and⁷Li-NMR. The results reveal that orthorhombic LiMnO₂ with high purity and good crystallinity can be obtained by this method. During electrochemical tests, a LiMnO₂/Li cell shows an initial reversible capacity of 208 mAh · g⁻¹ and a reversible capacity of 180 mAh · g⁻¹ after 30 cycles at room temperature.     

Electroch emical properties and interfacial reactions of LiNi0.5Mn1.5O4-δ nanorods

LiNi0.5Mn1.5O4-δ which possesses a high voltage of 4.7 V vs.Li+/Li and stable structure has been considered as a promising cathode material for high energy Li-ion batteries.In this study,well-crystalli...     

Filter Paper-Derived Three-Dimensional Carbon Fibers Film Supported Fe<Subscript>3</Subscript>O<Subscript>4</Subscript> as a Superior Binder-Free Anode Material for High Performance Lithium-Ion Batteries

Highly uniform and tight adhering of Fe₃O₄ particles on carbon fiber film (Fe₃O₄/CFF) is achieved through a simple in-situ thermal oxidation method. Particularly, 3D CFF with interconnected structure can shorten transfer path and buffer the volume expansion during charge-discharge cycling. Herein, the obtained Fe₃O₄/CFF anode exhibits a stable cycling performance and excellent high rate capability. The cell delivers a reversible capacity of 1 711 mAh·g^–1 at a current density of 100 mA·g^–1 after 100 cycles. Even at a high rate density of 2 A·g^–1, the specific capacity also can maintain 1 034 mAh·g^–1 after 100 cycles. The simplified fabrication is featured with low-cost and this binder-free perspective holds great potential in mass-production of high-performance metal oxide electrochemical devices.     

Cobalt coordination modified double-schiff-base with low solubility as a long-cycle life anode for sodium-ion batteries

Sodium-ion batteries (SIBs) have been recently considered as an intriguing candidate for next-generation battery systems with their advantages in large-scale energy storage applications. However, the design of electrode materials of SIBs still suffers from severe volume expansion and low capacity caused by the larger ion radius, high re-dox potential and heavy atom weight of Na. Organic electrode materials with structural flexibility have attracted great attention recently for their potential in alleviating volume expansion. However, most organic electrode materials suffer from dissolution in electrolytes and consequent capacity fading during the long-term cycling process. In this work, a method coordinating with Co²⁺ was applied to solve the shuttle effect of H₄salphdc (N, N’-phenylene-bis-(salicylideneimine) dicarboxylic acid). By virtue of the Co²⁺ coordination, the Co(H₂salphdc) electrode delivered a desirable discharge capacity of 123 mAh g^?1 after 1500 cycles at the current density of 200 ?mA ?g^?1, while the H₄salphdc electrode exhibited severe capacity fading. Such excellent electrochemical performance can be credited to the Co²⁺ coordination repressing the electrode dissolution and improving the structure stability.     

Zr~(4+)/F~– co-doped TiO_2(anatase) as high performance anode material for lithium-ion battery

Zr~(4+) and F~– co-doped TiO_2 with the formula of Ti_(0.97)Zr_(0.03)O_(1.98)F_(0.02) was facilely synthesized by a sol-gel template route.The crystal structure,morphology,composition,surface area,and conductivity were characterized by Raman spectroscopy,energy-dispersive X-ray analysis,scanning electron microscopy,Brunauer-Emmett-Teller measurements,X-ray photoelectron spectroscopy,and electrochemical impedance spectroscopy.The results demonstrate that Zr~(4+)and F~–homogeneously incorporated into TiO_2,forming solid solution with an anatase structure.Ti_(0.97)Zr_(0.03)O_(1.98)F_(0.02)shows outstanding electrochemical properties as Li-ion battery anode in comparison with Ti_(0.97)Zr_(0.03)O_2.In particular,upon 35-fold cycling at 1C-rate Zr~(4+)/F~–co-doped TiO_2delivers a reversible capacity of 163 mAh g~(–1),whereas Zr~(4+)-doped TiO_2gives only 34 mA h g~(–1).Additionally,Zr~(4+)/F~–co-doped TiO_2retains a capacity of 138 mA h g~(–1)during cycling even at 10 C.The enhance performance originates from improved conductivity of Zr~(4+)/F~–co-doped TiO_2material through generation of Ti~(3+)(serving as electron donors)into the crystal lattice and,possibly,due to F-doping blocked the anode surface from attack of HF formed as electrolyte decomposition product.     

Electrochemical performance of a nickel-rich LiNi<Subscript>0.6</Subscript>Co<Subscript>0.2</Subscript>Mn<Subscript>0.2</Subscript>O<Subscript>2</Subscript> cathode material for lithium-ion batteries under different cut-off voltages

A spherical-like Ni_0.6Co_0.2Mn_0.2(OH)₂ precursor was tuned homogeneously to synthesize LiNi_0.6Co_0.2Mn_0.2O₂ as a cathode material for lithium-ion batteries. The effects of calcination temperature on the crystal structure, morphology, and the electrochemical performance of the as-prepared LiNi_0.6Co_0.2Mn_0.2O₂ were investigated in detail. The as-prepared material was characterized by X-ray diffraction, scanning electron microscopy, laser particle size analysis, charge-discharge tests, and cyclic voltammetry measurements. The results show that the spherical-like LiNi_0.6Co_0.2Mn_0.2O₂ material obtained by calcination at 900℃ displayed the most significant layered structure among samples calcined at various temperatures, with a particle size of approximately 10 μm. It delivered an initial discharge capacity of 189.2 mAh·g-1 at 0.2C with a capacity retention of 94.0% after 100 cycles between 2.7 and 4.3 V. The as-prepared cathode material also exhibited good rate performance, with a discharge capacity of 119.6 mAh·g-1 at 5C. Furthermore, within the cut-off voltage ranges from 2.7 to 4.3, 4.4, and 4.5 V, the initial discharge capacities of the calcined samples were 170.7, 180.9, and 192.8 mAh·g-1, respectively, at a rate of 1C. The corresponding retentions were 86.8%, 80.3%, and 74.4% after 200 cycles, respectively.     

Rational construction of NiCo_2O_4@Fe_2O_3 core-shell nanowire arrays for high-performance supercapacitors

Fe_2O_3 electrode materials exhibit excellent electrochemical performance in electrochemical energy storage system. However, its poor electrical conductivity limits its future practical application. The binder-free Ni Co_2O_4@Fe_2O_3 composites was reasonably designed and fabricated on carbon fiber paper with NiCo_2 O_4 nanowires as conductive scaffold in the present investigation. The three-dimensional nanostructure of the porous Fe_2O_3 nanorods coated the Ni Co2 O4 nanowire arrays showed the fascinating electrochemical performance, including high specific capacitance of 262 m F/cm2 at a current density of 1 m A/cm2, and remarkable cycle stability with～74.2% capacitance retention after 4000 cycles. The excellent pseudocapacitance performance of NiCo_2O_4@Fe_2O_3 composite materials is due to synergistic effect between NiCo_2O_4 and Fe_2O_3. The results of the present work show that NiCo_2O_4@Fe_2O_3 core-shell composite electrode is expected to exhibit excellent performance in the field of supercapacitors.     

Properties of garnet-type Li6La3ZrTaO12 solid electrolyte films fabricated by aerosol deposition method

The garnet-type Li_6La_3ZrTaO_(12)(LLZT) solid electrolyte films were fabricated by aerosol deposition(AD)method.Ball-milled LLZT powder with a cubic garnet structure and a particle size of 1-2 urn was used as raw material and deposited directly on a SUS316L or a glass substrate via impact consolidation.As-deposited LLZT film has a cubic garnet structure but contains Li_2CO_3 and La_2Zr_2O_7 phases.SEM observation revealed that the film consists of LLZT particles fractured into submicron size.The impurity phase formation during AD process was caused by the local heating by the collision between LLZT particles and deposition surface and reaction with CO_2.The Li~+ ion conductivity of LLZT film was estimated to be 0.24 × 10~(-5)S cm~(-1) at room temperature.Electronic conductivity of LLZT film was confirmed to be around 10~(-12) S cm~(-1),indicating the dominant Li~+ ion conduction of LLZT film.     

Bionic titania coating carbon multi-layer material derived from natural leaf and its superior photocatalytic performance

Bionic titania coating carbon multi-layer material was fabricated by employing canna leaves as substrate and carbon precursor. Titania nanocrystals were assembled and coated on the natural films. The carbonation treatment under pure N_2 atmosphere yielded the ultrathin multi-film hybrid material. The carbon layer was coated with small anatase titania crystallite(8–10 nm) and possessed a highly specific surface area of 248.3 m~2 g~(-1). Examination using UV–visible spectrophotometer(UV–vis) showed that the band gap of the multi-layer material was reduced to 2.75 eV, and the hydrogen production by photocatalytic splitting of water under visible light irradiation was about 302 μmol g~(-1) after six hour.     

Direct electrodeposition of ionic liquid-based template-free SnCo alloy nanowires as an anode for Li-ion batteries

SnCo alloy nanowires were successfully electrodeposited from SnCl₂-CoCl₂-1-ethyl-3-methylimidazolium chloride (EMIC) ionic liquid without a template. The nanowires were obtained from the molar ratio of 5:40:60 for SnCl₂:CoCl₂:EMIC at -0.55 V and showed a minimum diameter of about 50 nm and lengths of over 20 μm. The as-fabricated SnCo nanowires were about 70 nm in diameter and featured a Sn/Co weight ratio of 3.85:1, when used as an anode for a Li-ion battery, they presented respective specific capacities of 687 and 678 mAh·g-1 after the first charge and discharge cycle and maintained capacities of about 654 mAh·g-1 after 60 cycles and 539 mAh·g-1 after 80 cycles at a current density of 300 mA·g-1. Both the nanowire structure and presence of elemental Co helped buffer large volume changes in the Sn anode during charging and discharging to a certain extent, thereby improving the cycling performance of the Sn anode.     

High temperature electrochemical discharge performance of LaFeO3 coated with C/Ni as anode material for NiMH batteries

Perovskite LaFeO₃ is considered as a promising new anode material for nickel/metal hydride batteries due to its low cost, environmental friendliness and high temperature resistance. However, the poor conductivity of LaFeO₃ material restricts the discharge ability, which is problematic for its future widespread application. To solve the above issue, in this study, we prepared C/Ni-coated LaFeO₃ composite in view of the excellent electrical conductivity of carbon and nickel metal. Results show that the C/Ni-coated LaFeO₃ composite delivers remarkably increased discharge capacity of ～345 mAh g^?1 at 60 ?°C in contrast to ～267 mAh g^?1 for pure LaFeO₃. Furthermore, the carbon and nickel not only increase the electrical conductivity of the LaFeO₃ but also reduces the agglomeration of the LaFeO₃, therefore, the C/Ni-coated LaFeO₃ composite serves superior long cycle-life, which maintains 60.9% after 100 cycles (52.9% for the LaFeO₃ sample). In overall, the electrochemical behavior of the C/Ni-coated LaFeO₃ composite confirms its high potential as nickel/metal hydride batteries for energy storage applications.     

钴掺杂Mn3O4作为模板制备锂离子电池正极LiMn2O4

以水热合成的钴掺杂Mn₃O₄作为模板,通过固相反应制备尖晶石LiMn₂O₄。XRD谱图和SEM照片显示制备的LiMn₂O₄具有岩石状结构并呈现良好的结晶性,同时Co的引入能够引起LiMn₂O₄晶格的收缩。作为锂离子电池正极材料,Co含量的增加能够提高循环稳定性但降低材料放电比容量,3% Co掺杂的LiMn₂O₄在0.5 C的电流密度下,经过100次循环后,剩余放电比容量达101.6 mAh·g^-1;在10 C的电流密度下,放电比容量可维持在81.0 mAh·g^-1,优于未掺杂的LiMn₂O₄。这是由于Co的引入能够稳定LiMn₂O₄晶体结构并抑制循环中的姜-泰勒扭曲。     

Synthesis of amorphous SeP2/C composite by plasma assisted ball milling for high-performance anode materials of lithium and sodium-ion batteries

To promote substantially the performances of red phosphorous (P) anode for lithium and sodium-ion batteries, a simple plasma assisted milling (P-milling) method was used to in-situ synthesize SeP₂/C composite. The results showed that the amorphous SeP₂/C composite exhibits the excellent lithium and sodium storage performances duo to the small nano-granules size and complete combination of selenium (Se) and phosphorous (P) to generate Se–P alloy phase. It was observed that inside the granules of SeP₂/C composite the nanometer size of the SeP₂ particles ensured the fast kinetics for Li⁺ and Na⁺ ​transfer, and the amorphous carbon wrapping the SeP₂ particles relieved volume expansion during lithium/sodium storage processes and enhances electric conductivity. Therefore, the SeP₂/C electrode retained reversible capacities of 700 ​mA ​h ​g⁻¹ at 2 ​A ​g⁻¹ after 500 cycles and 400 ​mA ​h ​g⁻¹ at 0.5 ​A ​g⁻¹ after 400 cycles as anode for LIBs and SIBs, respectively. The result proves that the amorphous SeP₂/C composite can be a new type of anode material with great potential for lithium and sodium-ion batteries.     

Effect of temperature on carrier transport and photoconductivity of Mn-doped FeS2 thin films

Thin-film of Mn-doped iron disulfide (FeS₂) has been prepared using the thermal evaporation method. This work reports the Hall measurements, temperature and light intensity-dependent photoconductivity, electrical transport mechanism, and photodetection properties of Mn-doped FeS₂ thin film. The transient photoconductivity measurements of p-type Mn-doped FeS₂ thin film show a consistent dependence upon temperature and light intensity. Charge transport mechanism was illustrated using different models. In region-I (303–393 ?K) deposited film followed the thermally activated transport mechanism. Nearest neighbour hopping (NNH) transport mechanism was followed by region-II (274–293 ?K), and Mott's variable range hopping (VRH) mechanism was dominant in region-III (108–273 ?K). The fabricated device resulted in higher photoconductivity due to collecting charge carriers through electrodes under light illumination. The results also revealed that Mn-doped thin film possessed good photoresponsivity (～19 ?mA/W) as well as photo-detectivity (～3.4 ?× ?10¹² Jones) due to the occupation of localized states formed by Mn-doping. Light intensity-dependent photodetection properties suggested the potential for real-time photodetection applications.     

Efficient and selective recovery of Ni,Cu, and Co from low-nickel matte via a hydrometallurgical process

Low-nickel matte was intensively characterized, and Ni, Cu, and Co were determined to exist mainly as (Fe,Ni)₉S₈ and FeNi₃, Cu₅FeS₄, and (Fe,Ni)₉S₈ and Fe₃O₄ (in isomorphic form), respectively. The efficient and selective extraction of Ni, Cu, and Co from the low-nickel matte in an (NH₄)₂S₂O₈/NH₃·H₂O solution system was studied. The effects of (NH₄)₂S₂O₈ and NH₃·H₂O concentrations, leaching time, and leaching temperature on the metal extraction efficiency were systematically investigated. During the oxidative ammonia leaching process, the metal extraction efficiencies of Ni 81.07%, Cu 93.81%, and Co 71.74% were obtained under the optimal conditions. The relatively low leaching efficiency of Ni was mainly ascribed to NiFe alloy deactivation in ammonia solution. By introducing an acid pre-leaching process into the oxidative ammonia leaching process, we achieved the high extraction efficiencies of 98.03%, 99.13%, and 85.60% for the valuable metals Ni, Cu, and Co, respectively, from the low-nickel matte.     

Preparation and electrochemical properties of carbon-coated LiFePO4 hollow nanofibers

Carbon-coated LiFePO₄ hollow nanofibers as cathode materials for Li-ion batteries were obtained by coaxial electrospinning. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Brunauer–Emmett–Teller specific surface area analysis, galvanostatic charge–discharge, and electrochemical impedance spectroscopy (EIS) were employed to investigate the crystalline structure, morphology, and electrochemical performance of the as-prepared hollow nanofibers. The results indicate that the carbon-coated LiFePO₄ hollow nanofibers have good long-term cycling performance and good rate capability: at a current density of 0.2C (1.0C = 170 mA·g-1) in the voltage range of 2.5–4.2 V, the cathode materials achieve an initial discharge specific capacity of 153.16 mAh·g-1 with a first charge–discharge coulombic efficiency of more than 97%, as well as a high capacity retention of 99% after 10 cycles; moreover, the materials can retain a specific capacity of 135.68 mAh·g-1, even at 2C.     

Fabrication and electrochemical properties of 3D nano-network LiFePO_4@multiwalled carbon nanotube composite using risedronic acid as the phosphorus source

LiFePO_4@multiwalled carbon nanotubes(LFP@MWCNTs) nanocomposite has been fabricated using risedronic acid(RDA) as a new eco-friendly phosphorus source. Microscopic, spectroscopic, and electrochemical characterization demonstrate that the MWCNTs are in the form of coiled and cross-linking nanoribbon, which wrapped and encrusted around LiFePO_4 particles to form a three-dimensional(3D) nano-network composite.This microstructure of 3D nano-network is obtained due to the reactions between RDA's special functional groups with Fe~(2+) and C-OH,-C=O or-COOH on the surface of the functionalized MWCNTs. The results also show that the particle size of the fabricated LiFePO_4@MWCNTs composite is below 300 nm with the pure crystal of olivine. This nanocomposite indicates an enhanced reversible capacity of 162.2 mAh g~(-1) at 0.2C, and high capacity retention of 76.5% even at 10C after the 800 th cycles. The electric conductivity and Li~+ diffusion coefficient(D_(Li)~+) of the LiFePO_4@MWCNTs are 3.79 × 10~(-2)S cm~(-1) and 4.46 × 10~(-11) cm~2s~(-1), respectively.These improved electrochemical parameters can be attributed to the nano-sized effect of particles, MWCNTs' wrapping effect and 3D nano-network microstructure of the LFP@MWCNTs resulted from using RDA as a new phosphorus source.