Synthesis and characterization of LiNi0.8Co0.2O2 as cathode material for lithium-ion batteries by a spray-drying method

Layered structure LiNi_0.8Co_0.2O₂ cathode material for lithium-ion batteries was synthesized by sintering the precursor, which was obtained from the corresponding metal acetate solution via a spray-drying method. The structure, morphology and reaction mechanism of the powders were characterized by means of XRD, SEM and TG-DTA. The electrochemical properties of the LiNi_0.8Co_0.2O₂ cathode were also investigated by using a coin-type cell containing Li metal as the anode in a potential range of 3.0–4.3 V. Upon sintering the spray-dried powders at 750 °C for 24 h, the LiNi_0.8Co_0.2O₂ particles obtained are fine, narrowly distributed and well crystallized. As a result, the synthesized LiNi_0.8Co_0.2O₂ has excellent electrochemical properties. The simple synthesis procedure is time and energy saving, and thus is promising for commercial application.     

In situ electrochemical synthesis of lithiated silicon–carbon based composites anode materials for lithium ion batteries

Most composite anode systems research on lithium ion batteries to date focus on pristine unalloyed Si as the electrochemically active component combined with a suitable matrix component that is electrochemically inactive or relatively inactive to lithium ions. Herein, we report the generation of composites by electrochemical synthesis in situ, denoted as Li–Si/C based on Li–Si alloys synthesized as dispersoids in a carbon (C) matrix, as potential anode materials for lithium ion batteries. The electrochemical performance of the Li–Si/C composite of different compositions generated has been systematically studied in order to identify a suitable Li–Si–C composition that could be most effective as a lithium ion anode. The resultant alloy would also exhibit stable electrochemical capacities while expecting to deliver high energy density during discharge with suitable cathode systems. This study shows that the Li–Si/C composite of composition 64 at.% C–21.6 at.% Li–14.4 at.% Si, comprised of Li–Si alloy of compositions in the vicinity of Li–40 at.% Si dispersed in the C matrix cycled within the stable potential window of 0.02–0.5 V, has the potential characteristics of being a promising anode material displaying excellent capacity retention (0.13% loss per cycle) with high specific capacity (700 mA h g⁻¹), and also expected to deliver high energy density during discharge in the full cell configuration employing a suitable cathode.     

Development of long life lithium ion battery for power storage

With the aim of developing lithium ion batteries with a long life and high efficiency for power storage, we experimentally evaluated combinations of cathode and anode active materials, in which batteries are able to obtain over 4000 cycles or 10 years of life. An acceleration method was evaluated using coin cells. We found that changing the current density was effective for evaluating battery life, since the logarithm of the cycle life showed a linear relationship to current density. Based on the current density increasing method, various combinations of cathode and anode active materials were tested. The cell system of LiCoO₂/Li_4/3Ti_5/3O₄ clearly showed a long life of about 4000 cycles. The energy density of the cell using the Li_4/3Ti_5/3O₄ anode is obviously smaller than that using a graphite anode, the cell with Li_4/3Ti_5/3O₄ anode was thought to have some merit especially in the large-scale-layer-built type battery by the applicability of the Al anode collector and a light weight battery case.     

Thin-film rechargeable lithium batteries

Thin-film rechargeable batteries with a lithium metal anode, an amorphous inorganic electrolyte, and cathodes of amorphous V₂O₅ and crystalline and amorphous Li_xMn₂O₄ have been fabricated and characterized. The performance of the thin-film cells was evaluated at different current densities and, in the case of LiV₅, at several temperatures. Electrical measurements show that the current density of the thin-film cells is limited by the lithium-ion mobility in the cathodes. The resistance of LiLi_xMn₂O₄ cells with crystalline cathodes is about two orders of magnitude lower than that of LiV₅ cells with amorphous cathodes.     

Enhanced performance of direct peroxide/peroxide fuel cell by using ultrafine Nickel Ferric Ferrocyanide nanoparticles as the cathode catalyst

Direct peroxide-peroxide fuel cell (DPPFC) employing with H₂O₂ both as the fuel and oxidant is an attractive fuel cell due to its no intermediates, easy handling, low toxicity and expense. However, the major gap of DPPFC is the cathode performance as a result of the slow reaction kinetics of H₂O₂ electro-reduction and thus the target issue is to design cathode catalysts with high performance and low cost. Herein, different with using noble metal of state-of-the-art, we have successfully synthesized ultra-fine NiFe ferrocyanide (NiFeHCF) nanoparticles (the mean particles size is 2.5 nm) through a co-precipitation method, which is used as the cathode catalyst towards H₂O₂ reduction in acidic medium. The current density of H₂O₂ reduction on the resultant NiFeHCF electrode after the 1800 s test period at ?0.1, 0 and 0.1 V are 121, 93 and 76 mA cm², respectively. Meanwhile, a single two-compartment DPPFC cell with NiFeHCF nanoparticles as the cathode and Ni/Ni foam as the anode is assembled and displayed a stable OCP of 1.09 V and a peak power density of 36 mW cm^?2 at 20 °C, which is much higher than that of a DPPFC employed with Pd nano-catalyst as cathode.     

Electrospinning synthesis of C/Fe3O4 composite nanofibers and their application for high performance lithium-ion batteries

Carbon-based nanofibers can be used as anode materials for lithium-ion batteries. Both pure carbon nanofiber and C/Fe₃O₄ composite nanofibers were prepared by electrospinning and subsequent carbonization processes. The composition and structures were characterized by Fourier transformation infrared spectroscopy, X-ray diffraction, scanning and transmission electron microscopy. The electrochemical properties were evaluated in coin-type cells versus metallic lithium. It is found that after an annealing temperature of 500–700 °C, the carbon has disordered structure while Fe₃O₄ is nanocrystalline with a particle size from 8.5 to 52 nm. Compared with the pure carbon nanofiber, the 600 °C-carbonized C/Fe₃O₄ composite nanofiber exhibits much better electrochemical performance with a high reversible capacity of 1007 mAh g⁻¹ at the 80th cycle and excellent rate capability. A beneficial powderization phenomenon is discovered during the electrochemical cycling. This study suggests that the optimized C/Fe₃O₄ composite nanofiber is a promising anode material for high performance lithium-ion batteries.     

Imidazolium ionic liquids as electrolytes for manganese dioxide free Leclanché batteries

A set of four imidazolium ionic liquids (solid at room temperature) and one imidazolium ionic solid was screened for its potential as electrolytes in manganese dioxide free Leclanché batteries, equipped with a zinc anode and graphite cathode. Electrical impedance spectroscopy allowed to determine the room-temperature ionic solids (RTISs) ionic conductivities, which was the highest for carboxylic acid functionalized RTIS 3 [C₂O₂MIm][Cl]. The toxic manganese dioxide was substituted by benzoquinone. A systematic ionic conductivity optimization of RTIS 3–benzoquinone–ZnSO₄–H₂O mixtures at room temperature resulted in the identification of the following conditions for the Leclanché battery studies: 50 mg of a 50:50 RTIS:benzoquinone mixture and 96 mg of water. The chronopotentiometric experiments with a constant current of 5 μA showed a remarkable performance for the RTIS 3 based battery. The potential (1.47 V) and stability is comparable to that of the commercial Rayovac^® battery filling (model AA). Furthermore, linear potentiodynamic voltammetry (0.01 V/s) and chronoamperometric analysis at short-circuit conditions (0.0 V) validated the RTIS 3–benzoquinone–water battery as a promising alternative for manganese dioxide free Leclanché batteries.     

Infiltrated Pr2NiO4 as promising bi-electrode for symmetrical solid oxide fuel cells

In-situ growth of nanoparticles on electrode surface for high temperature energy conversion devices is one of efficient ways for new electro-catalyst design. Here, perovskite-related Pr₂NiO₄ (PNO) has been evaluated as a novel symmetrical electrode for intermediate-temperature solid oxide fuel cells (IT-SOFCs). Nickel nanoparticles are exsolved and dispersed on the surface of PNO after exposed in H₂ at 800 °C as an efficient electrocatalyst for hydrogen oxidation reaction (HOR) as anode. The electro-activity towards oxygen reduction reaction (ORR) at cathode side is further improved by infiltration process. A synergetic effect of in-situ exsolved nanoparticles as well as infiltrated ionic conducting particles have improved HOR and ORR activity at anode and cathode side, respectively. Furthermore, symmetrical SOFC (SSOFC) with infiltrated Pr₂NiO₄ as bi-electrode exhibits excellent short-term stability and reliable redox stability in repeated H₂/air cycles.     

High performance hybrid supercapacitors with LiNi1/3Mn1/3Co1/3O2/activated carbon cathode and activated carbon anode

Hybrid supercapacitors have been studied as a next generation energy storage device that combines the advantages of supercapacitors and batteries. One important challenge of hybrid supercapacitors is to improve energy density (8.9–42 Wh/kg) with maintaining excellent power density (800–7989 W/kg) and cyclability (98.9% after 9000 cycles). Herein, we demonstrate an approach to design hybrid supercapacitors based on LiNi_1/3Mn_1/3Co_1/3O₂ (NMC)/activated carbon (AC) cathode and AC anode (NMC/AC//AC). The NMC/AC//AC hybrid supercapacitors shows outstanding electrochemical performances due to the enhanced energy and power densities. These findings suggest that the NMC/AC cathode is an effective method for high performance hybrid supercapacitors.     

Development and performance of a rechargeable thin-film solid-state microbattery

A thin-film solid-state Li/TiS₂ microbattery has been developed at Eveready Battery Company (EBC). It is fabricated using sputtering for deposition of the metal contacts, TiS₂ cathode, and oxide/sulfide glassy electrolyte. High vacuum evaporation is used to deposit a LiI layer and Li anode. EBC Microbatteries range from 8 to 12 μm in thickness and have a capacity between 35 and 100 μAh/cm², depending on the amount of anode and cathode deposited. The microbattery open-circuit voltage is approximately 2.5 V. EBC Microbatteries routinely go more than 1000 cycles between 1.4 and 2.8 V, with greater than 90% cathode utilization, at current densities as high as 300 μA/cm². Several EBC Microbatteries have gone over 10 000 cycles at 100 μA/cm² with greater than 90% cathode utilization on each cycle. The microbatteries will cycle at temperatures as low as −10 °C at a current density of 100 μA/cm², are capable of supplying pulse currents of several mA/cm², and have excellent long-term stability both on shelf and while cycling. Sets of five microbatteries have been assembled in either a series or parallel configuration and cycled more than 1000 times. EBC Microbatteries as large as 10 cm² have been fabricated and cycled over 1000 times at close to 100% cathode efficiency.     

In situ fabrication of porous graphene electrodes for high-performance lithiumoxygen batteries

These years, LiO₂ batteries attract wide interest because of its high theoretical energy density. However, the catalytic activity and porous structure of cathode remains a great challenge. In this work, we developed a hierarchical porous graphene foam to serve as a battery cathode, which has much richer active sites for cathodic reaction and channels for Li⁺ transfer and O₂ diffusion. The cathode exhibits a superior specific capacity as high as 9559 mAh g^?1 at 57 mA g^?1 and remains a high-rate capability of 3988 mAh g^?1 at an increased current density of 285 mA g^?1. Benefiting from the well-designed cathode structure, the battery can be stably operated for 150 cycles with a stable voltage profile and voltage efficiency up to 65%. The well-designed graphene has a potential to be a superior free-standing cathode to other carbon-based materials due to its good combination of its hierarchical and porous structure, large surface area, abundant defects and excellent mechanical stability.     

Effect of conditioning method on direct methanol fuel cell performance

We investigated the effect of the conditioning methods on improving the direct methanol fuel cell (DMFC) performance. The DMFC performance after the conditioning was measured using a newly developed single cell having an Ag/Ag₂SO₄ reference electrode, which is not influenced by methanol. As a result, we succeeded in developing an original two-step conditioning method in which the conditioning by fueling H₂ gas is conducted prior to a conventional DMFC conditioning. The anode and cathode characteristics after the two-step conditioning were measured with respect to a reference electrode. Based on the obtained i-E curves, the two-step conditioning is found to improve the methanol oxidation performance at the anode and also suppress the decline of the O₂ reduction performance at the cathode. The high DMFC performance based on the two-step conditioning is well explained by the anode and cathode characteristics.     

The lithium-sulfuryl chloride battery: Discharge behaviour

The properties of the lithium-sulfuryl chloride battery have been examined in terms of discharge performance and characteristics. The results indicate that the Li/SO₂Cl₂ system is intrinsically capable of delivering large current outputs at high voltages. Upon storage and long term discharge, however, the cell is affected by the two major polarization phenomena typical of lithium-inorganic electrolyte batteries, i.e., the passivation of the anode and the inactivation of the cathode.     

The influence of sodium ion on the solid polymer electrolyte water electrolysis

A study of the influence of sodium ions on the solid polymer electrolyte (SPE) water electrolysis is reported. Different poisoning modes (anode poisoning and cathode poisoning) and different cathode catalysts (Pt/C, Pd/C and RuO₂) were compared. The results showed that the anode poisoning had more severe effects than cathode poisoning. The cell voltages increased by 0.730 V and 0.250 V respectively. In the anode poisoning, the cathode potential descended dramatically by 0.570 V. Meanwhile, the pH of cathode feed water increased to above 11.0 due to the reaction of 2H₂O+2e⁻=H₂+2OH⁻$2{\text{H}}_2\text{O}+2{\text{e}}^{-}={\text{H}}_2+2{\text{OH}}^{-}$ taking place. However, the cell voltage increased mainly caused by the anode potential in the cathode poisoning. The results also showed that the poisoning results were similar for different cathode catalysts.     

Novel cobalt-free cathode materials BaCexFe1−xO3−δ for proton-conducting solid oxide fuel cells

A series of cobalt-free and low cost BaCe_xFe_1−xO_3−δ (x = 0.15, 0.50, 0.85) materials are successful synthesized and used as the cathode materials for proton-conducting solid oxide fuel cells (SOFCs). The single cell, consisting of a BaZr_0.1Ce_0.7Y_0.2O_3−δ (BZCY7)-NiO anode substrate, a BZCY7 anode functional layer, a BZCY7 electrolyte membrane and a BaCe_xFe_1−xO_3−δ cathode layer, is assembled and tested from 600 to 700 °C with humidified hydrogen (3% H₂O) as the fuel and the static air as the oxidant. Within all the cathode materials above, the cathode BaCe_0.5Fe_0.5O_3−δ shows the highest cell performance which could obtain an open-circuit potential of 0.99 V and a maximum power density of 395 mW cm⁻² at 700 °C. The results indicate that the Fe-doped barium cerates can be promising cathodes for proton-conducting SOFCs.     

Facile synthesis of highly conducting and mesoporous carbon aerogel as platinum support for PEM fuel cells

We report novel method for synthesis of carbon aerogel as platinum support for PEM fuel cells applications. The sol gel polymerization has been carried out using resorcinol and furfuraldehyde in non-aqueous medium followed by gelation at high pressure. This resulted in highly conducting and mesoporous carbon aerogel under ambient drying conditions. Platinum nano-particles are impregnated in the mesoporous carbon aerogel using microwave assisted polyol process. The support material and the catalyst are characterized by different analytical techniques like surface area analyzer, X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy. Cyclic voltammetry and linear sweep voltammetry are used to evaluate the electro–catalytic activity of the Pt/carbon aerogel catalyst using rotating disk electrode technique. Well dispersed Pt nano-particles of size ∼3 nm on carbon aerogel showed good catalytic activity with onset potential of 964 mV and half wave potential of 814 mV towards oxygen reduction reaction kinetics. A membrane electrode assembly fabricated with the prepared Pt/carbon aerogel catalyst as a cathode and anode is tested in PEMFCs (H₂O₂) single cell, the power density of 536 mW cm⁻² at 0.6 V is obtained at 60 °C under atmospheric pressure.     

Exploration of aqueous zinc–hydrogen peroxide batteries

In zinc–hydrogen peroxide batteries, an active metal ? zinc piece is used as the anode and ammonium chloride is used as the electrolyte in the anode zone. A soluble oxidant, hydrogen peroxide, is used as the active cathode substance, and sulfuric acid as an electrolyte in the cathode zone. Carbon felt, the sum of two apparent areas of which is 24 cm², is used as an inert cathode with a PE‐01 homogeneous membrane between the anode and cathode zones and 50 mL of solution in both the anode and cathode zones. The discharge characteristics of the batteries at 5 Ω were investigated for various concentrations of hydrogen peroxide, sulfuric acid and ammonium chloride solutions. When a 5‐M ammonium chloride solution was used in the anode zone with a 3.2‐M sulfuric acid and 3.52‐M hydrogen peroxide mixed solution in the cathode zone, an average discharge current of 190 mA, an average output voltage of approximately 0.95 V and an actual gravimetric energy density of 42.73 W h kg^?1 were obtained, and the discharge time of the batteries was more than 30 h. Copyright © 2011 John Wiley & Sons, Ltd.     

Investigation of new types of lithium-ion battery materials

This paper reports part of the activities in progress in our laboratory in the investigation of electrode and electrolyte materials which may be of interest for the development of lithium-ion batteries with improved characteristics and performances. This investigation has been directed to both anode and cathode materials, with particular attention to convertible oxides and defect spinel-framework Li-insertion compounds in the anode area and layered mixed lithium–nickel–cobalt oxide and high voltage, metal type oxides in the cathode area. As for the electrolyte materials, we have concentrated the efforts on composite polymer electrolytes and gel-type membranes. In this work we report the physical, chemical and electrochemical properties of the defect spinel-framework Li-insertion anodes and of the high voltage, mixed metal type oxide cathodes, by describing their electrochemical properties in cells using either “standard” liquid electrolytes and “advanced” gel-type, polymer electrolytes.The results illustrated here demonstrate that the spinel-framework anodes of the Li[Li_1/3Ti_5/3]O₄ type can be combined with high voltage cathodes of the Li₂M_xMn_(4−x)O₈ family for the fabrication of new types of lithium-ion battery systems cycling around 3.5 V. The development of this interesting concept is however still limited by the availability of highly stable electrolytes.