Material For Lithium Secondary Batteries Research Articles

Synthesis of Lix[Ni0.225Co0.125Mn0.65]O2 as a positive electrode for lithium-ion batteries by optimizing its synthesis conditions via a hydroxide co-precipitation method

Lix[Ni0.225Co0.125Mn0.65]O2 cathode material for a lithium-ion battery was synthesized from metal hydroxide Ni0.225Co0.125Mn0.65(OH)2. The co-precipitated metal hydroxide was greatly influenced by synthesis conditions of pH, concentration of chelating agent, stirring speed, and co-precipitation temperature. The conditions were optimized by observing the spherical and uniform particles, as examined by scanning electron microscopy. The optimized pH, ammonia concentration stirring speed and co-precipitation temperature were determined to be 11–12, 0.36M, 1000rpm and 50°C, respectively. The final products, Lix[Ni0.225Co0.125Mn0.65]O2 had a well-ordered hexagonal super lattice layered structure as established by Rietveld refinement of X-ray diffraction pattern. As a result, the Lix[Ni0.225Co0.125Mn0.65]O2 compound may be considered as a excellent candidate for cathode material of Lithium secondary battery in terms of cycle life, both safety and energy density, lower cost and low environmental impact.

Synthesis and electrochemical properties of LiV3O8/PAn composite as a cathode material for lithium secondary batteries

A LiV3O8/polyaniline (PAn) composite was prepared by the in-situ polymerization method assisted by sodium dodecyl sulfate and ammonium persulfate. The as-prepared powders were investigated by XRD, SEM, and galvanostatic discharge/charge analysis. It was found that the introduction of PAn to LiV3O8 can effectively buffer the mechanical stress and restrain the number of phase changes of composite material during the electrochemical cycling. Compared with pristine LiV3O8, LiV3O8/PAn composite maintains a reversible capacity of 212.1 mAh g−1 at the current density of 30 mA g−1 after 50 cycles, approximately 22.6%, much higher than the former.

One‐Pot Facile Synthesis of Double‐Shelled SnO2 Yolk‐Shell‐Structured Powders by Continuous Process as Anode Materials for Li‐ion Batteries

Hollow and yolk-shell metal oxide powders used as energy storage materials exhibit good electrochemical properties at high current density because of their shortened diffusion length and increased amount of contact area between the electrolyte and the electrode for Li + insertion/extraction. [ 1–25 ] Although various types of hollow-structured oxide materials have been studied as anode and cathode electrode materials for lithium secondary batteries, [ 13–25 ] the hollow-structured powders cannot be readily applied as battery materials because of their low energy densities due to low tab density. The disadvantages of the hollow materials can be overcome using core@void@shellconfi gured yolk-shell-structured powder particles. The core of such yolk-shell-structured powder particles will improve the rate capability as well as the energy density of the powders by increasing the weight fraction of the electrochemically active component. [ 12 , 15 ]

Fe3O4–pyrolytic graphite oxide composite as an anode material for lithium secondary batteries

Fe3O4–pyrolytic graphite oxide (Fe3O4–PGO) composite has been prepared by solvothermal reaction at 200°C. The as-prepared Fe3O4–PGO composite displays excellent cycle stability and rate capability with the initial discharge capacity of 1275mAhg−1 and capacity retention of 81% after 50 cycles compared with pure Fe3O4. The reasons are as follows: (i) in situ synthesized Fe3O4 firmly anchors onto the exfoliated PGO sheets, and the PGO acts as a conductive agent to provide a fast path for electron transportation; and (ii) the interstitial cluster structure of microsphere-type Fe3O4 in Fe3O4–PGO composite facilitates more better percolation of the electrolyte, more efficient accommodation with the strain and stress of volume change upon cycling and faster Li-ion transfer.

Facile synthesis of ZrO2 coated Li2CoPO4F cathode materials for lithium secondary batteries with improved electrochemical properties

A facile synthesis of a metal oxide (ZrO2) coating on the surface of high voltage type Li2CoPO4F cathode material using the conventional solution method is reported in this study. The Li2CoPO4F is prepared by a two step solid state method, followed by the application of wet coating containing various amounts of ZrO2. Among the samples, the 5 wt% ZrO2 coated Li2CoPO4F material shows the best performance with an initial discharge capacity of up to 144 mA h g−1 within the voltage range of 2–5.2 V vs Li at 10 mA g−1. Moreover, this ZrO2 coated cell demonstrates an enhanced capacity retention which is two times higher than that of the uncoated sample. The reversible extraction–insertion of one lithium unit from Li2CoPO4F is successfully carried out in a controlled environment, where the electrolyte decomposition is reduced using a highly durable ZrO2 coating. The nanosized coating over the Li2CoPO4F surface helps to attain a higher discharge capacity even at high current rates. As a consequence, the cell delivers a capacity of 104 mA h g−1 at a high current rate of 100 mA g−1.

Polyaniline/Poly[1,2]bis-thio[1,8]-naphthylidine 복합체 고분자 양극재료의 합성과 전기화학적 특성

충 방전 전압범위와 용량이 다른 두 고분자물질을 복합체로 만들어 전극에 사용하여 다른 전기화학적 현상과 용량증대 효과에 대해 연구하였다. 상대적으로 전압은 높으나 용량이 적은 polyaniline(PANI)과 전압은 낮으나 용량이 큰 poly[1,2]bis-thio[1,8]-naphthylidine(PTND)을 사용하여 두 물질의 복합체를 합성하였다. 먼저 PTND 고분자를 합성하고, 얻어진 PTND 고분자 표면위에 PANI를 합성하였다. 합성여부와 미세구조를 FT-IR, XPS, FE-SEM 및 FE-TEM을 이용하여 분석하였으며, 순환전압 전류법 측정과 충 방전 용량측정을 통하여 리튬이차전지 고분자 양극 활물질로서 전기화학적 성능을 측정하였다. 상온, 1.3~4.0 V 전압구간에서 PANI/PTND 복합체의 1, 5 그리고 10 사이클 후 방전용량은 167 mAh/g, 90 mAh/g 그리고 81 mAh/g로 측정되었고, 이것은 PANI만 사용한 전극(80, 67, 62 mAh/g)에 비해 10사이클 후 약 30% 용량이 향상된 것이다. 50 사이클 이후 PANI/PTND 복합체의 방전용량은 67 mAh/g로 측정되었다. We studied the electrochemical phenomena and increase of capacity according to the polymer composite electrode of two different polymeric materials with different the voltage range and capacity. Polyaniline (PANI) with relatively high voltage and small capacity and poly [1,2] bis-thio[1,8]-naphthylidine (PTND) with slightly low voltage and large capacity were used as polymer composite electrode materials. After PTND was synthesized, PANI was synthesized on the surface of PTND. The synthesis and the fine structure were analyzed by FT-IR, XPS, FE-SEM, and FE-TEM. Charge/discharge capacity and cyclic voltammetry measurements were carried out for the electrochemical performance as a polymer cathode active material for lithium secondary batteries. The discharge capacities of PANI/PTND after 1,5, and 10 cycles at 1.3~4.0 V voltage range and room temperature 167 mAh/g, 90 mAh/g, and 81 mAh/g. When we compared with PANI (80, 67, and 62 mAh/g), the discharge capacity after 10 cycles was improved about 30%. After 50 cycles, the discharge capacity of PANI/PTND was 67 mAh/g.

Synthesis of layered–layered xLi2MnO3·(1−x)LiMO2 (M = Mn, Ni, Co) nanocomposite electrodes materials by mechanochemical process

A strategy of facile route to prepare the Li2MnO3-stabilized LiMO2 (M = Mn, Ni, Co) electrode materials, cathode materials for Lithium secondary batteries that can be operated at the high voltage greater than 4.5 V, is proposed using the method of mechanochemical process. Li2MnO3 was synthesized at 400 °C, followed by the mechanochemical process with LiMO2 to form nanocomposite with the layered–layered structure. Structures and morphologies of xLi2MnO3·(1−x)LiMO2 are investigated to confirm the layered–layered structural integration. Various mole ratios of our xLi2MnO3·(1−x)LiMO2 electrode materials exhibit a large discharge capacity about 200 mAh g−1 at the room temperature. The cycle performances and the specific discharge capacities are improved by the secondary heat treatment for the xLi2MnO3·(1−x)LiMO2 composite electrodes where x ≤ 0.5. Our experimental results suggest the mechanochemical process is an easy and effective tool to form the nanocomposite of two components with controlled composition, especially, for the layered–layered integrated structure of xLi2MnO3·(1−x)LiMO2 system.

A microporous carbon derived from phenol–melamine–formaldehyde resin by K2CO3 activation for lithium ion batteries

A microporous carbon material with large surface area was prepared by carbonizing and activating of phenol–melamine–formaldehyde resin, using K2CO3 as activation reagent. The textural characteristics of the carbon materials were characterized by scanning electron microscope, X-ray diffraction, Raman spectra, Brunauer–Emmett–Teller, elemental analyses, respectively. Results showed that the surface area and pore diameter of the activated carbon were 1,610 m2 g−1 and less than 2 nm. Electrochemical lithium insertion properties were also investigated. At a current density of 100 mA g−1, the activated carbon showed an enormous first-discharge capacity of 2,610 mAh g−1 and the first charge capacity of 992 mAh g−1. From the second cycle, the coulombic efficiency went up rapidly to above 95 %. The results indicated it may be a promising candidate as an anode material for lithium secondary batteries.

Electrochemical Properties and Thermal Stability of LiNi0.8Co0.15 Al0.05O2-LiFePO4 Mixed Cathode Materials for Lithium Secondary Batteries

ABSTRACT: We prepared various LiNi 0.8 Co 0.15 Al 0.05 O 2 -LiFePO 4 mixed-cathode electrodes by changing the con-tent of LiNi 0.8 Co 0.15 Al 0.05 O 2 and LiFePO 4 used, and we analyzed the electrochemical characteristicsof the cathodes. We found that the reversible specific capacity of the cathodes increased and thatthe capacity retention ratios of the cathodes decreased during cycling as the content ofLiNi 0.8 Co 0.15 Al 0.05 O 2 increased. Conversely, we found that although the reversible specific capacityof the cathodes decreased because of the material composition, the cycle property of the cathodesincreased when the LiFePO 4 content increased. We analyzed the thermal stability of theLiNi 0.8 Co 0.15 Al 0.05 O 2 -LiFePO 4 mixed-material cathodes by differential scanning calorimetry andfound that it increased as the LiFePO 4 content increased.Keywords: LiNi 0.8 Co 0.15 Al 0.05 O 2 , LiFePO 4 , Thermal stability, Mixed-cathode, Cycle property Received May 8, 2012 : Accepted June 22, 2012

Indigo carmine (IC) doped polypyrrole (PPy) as a free-standing polymer electrode for lithium secondary battery application

Flexible free-standing polypyrrole-indigo carmine (PPy-IC) films were designed as additive-free anode material for lithium secondary batteries and were produced via the electropolymerization method. The films are soft, lightweight, mechanically robust, and electrically conductive. The films display a cauliflower-like structure consisting of micron-scale spherical grains, which are related to dopant intercalation in the polymeric chains. The morphologies and electrochemical behaviour of the free-standing PPy-IC films were affected by the electropolymerization conditions. Electrochemical tests demonstrated that the discharge capacity and initial coulombic efficiency increased as the thickness of the films decreased. The PPy-IC films prepared at lower deposition time (30min) and lower deposition current density (0.4mAcm−2) exhibited higher discharge capacity (83mAhg−1 beyond 100cycles) in the voltage range of 0.01–3.0V. These free-standing films can be used as possible anode materials to satisfy the new market demand for flexible/bendable lithium polymer or polymer batteries that are suitable for roll-up displays, wearable devices, and implanted medical devices used in biological and biomedical systems.

Fullerene C<SUB>60</SUB> Coated Silicon Nanowires as Anode Materials for Lithium Secondary Batteries

A Fullerene C60 film was introduced as a coating layer for silicon nanowires (Si NWs) by a plasma assisted thermal evaporation technique. The morphology and structural characteristics of the materials were studied by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). SEM observations showed that the shape of the nanowire structure was maintained after the C60 coating and the XPS analysis confirmed the presence of the carbon coating layer. The electrochemical characteristics of C60 coated Si NWs as anode materials were examined by charge-discharge tests and electrochemical impedance measurements. With the C60 film coating, Si NW electrodes exhibited a higher initial coulombic efficiency of 77% and a higher specific capacity of 2020 mA h g(-1) after the 30th cycle at a current density of 100 microA cm(-2) with cut-off voltage between 0-1.5 V. These improved electrochemical characteristics are attributed to the presence of the C60 coating layer which suppresses side reaction with the electrolyte and maintains the structural integrity of the Si NW electrodes during cycle tests.

Resynthesis of LiCo1−xMnxO2 as a cathode material for lithium secondary batteries

A recycling process involving chemical, mechanical, and electrochemical steps has been applied to recover cobalt from spent lithium ion batteries and resynthesize cathode active materials. LiCo1−xMnxO2 powders using Co salt including Mn from the leach liquor were resynthesized by solid-state reaction as cathode active materials. When the powder mixture with added Li salt was calcined at 950 °C for 8 hours, well crystallined LiCo1−xMnxO2 was successfully obtained. The LiCo1−xMnxO2 powders with a ratio of Co:Mn=10:1 has a discharge capacity of 156.3 mAh/g at a rate of 20 mA/g with no perceptible capacity loss, in sharp contrast to the pure LiCoO2 as active materials. The resynthesized LiCo1−xMnxO2 was proven to have good characteristics as cathode active materials in charge/discharge capacity and cyclic performance.

The Improved Electrochemical Properties of Silicon Thin Film Anodes Using Boron Doped Fullerene C60 as Coating Material in Lithium Secondary Batteries

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A novel amorphous Fe2V4O13 as cathode material for lithium secondary batteries

Amorphous Fe2V4O13 has been synthesized by the liquid precipitation method. The compound showed nano-lamellar structure with the average thickness of layer was about 40nm, which leads to an enhanced lithium ion transport and sustained volume variations. The initial specific capacity is 235mAh/g, and the specific capacity still remained 201mAh g−1 after 40 cycles at the rate of 0.25C in the range of 2.0–4.0V, which only brought about an 14% reduction of the capacity. The results show that the amorphous nanostructured Fe2V4O13 is a novel promising cathode material due to its high specific capacity, power density and good cycle performance.

Wire Explosion Synthesis of a Sn/C Nanocomposite as an Anode Material for Li Secondary Batteries

As a top-down approach for nanomaterial synthesis, a “wire explosion in liquid media” process was applied to the preparation of a Sn/C nanocomposite as an alternative anode material for lithium secondary batteries. Using a highly-dispersed Sn nanoparticle suspension produced by electrical explosion of Sn wires in ethanol followed by gravimetric sedimentation for size separation and by addition of a carbon precursor and pyrolysis, we prepared nano-sized Sn particles embedded in a carbon matrix. The physical properties of the nano-sized Sn and its carbon composite were characterized by using scanning electron microscopy, transmission electron microscopy, X-ray diraction and dierential scanning calorimetry. The electrochemical property was analyzed by using cycled charge/discharge tests. The resulting Li storage performance of the Sn/C nanocomposite showed an initial discharge capacity of over 400 mAhg 1 and improved capacity retention of 340 mAhg 1 after 40 cycles. The simplicity and the scalability of nanocomposite synthesis provided by the “wire explosion in a liquid medium” process make this method a promising tool not only for new nanomaterial investigations but also for commercial production of nanomaterials.

Synthesis and electrochemical properties of submicron sized sheet-like LiV 3O 8 crystallites for lithium secondary batteries

Submicron sized sheet-like LiV 3O 8 cathode materials for lithium secondary batteries were synthesized via a simple processing, microwave hydrothermal improved low temperature solid-state reaction, with LiOH·H 2O, NH 4VO 3 and PVP as raw materials. The LiV 3O 8 crystallites prepared without PVP consists of smaller particle size than that prepared with PVP, and it exhibits relatively better electrochemical performance. The LiV 3O 8 crystallites prepared without PVP delivers an initial discharge capacity of 282.2 mAh/g at a current density of 100 mA/g. After 20 cycles, the discharge capacity retains 228.4 mAh/g corresponded to 80.9% of the initial value. The small submicron sized sheet-like LiV 3O 8 crystallites are expected to shorten the Li + ions diffusion path for its electrochemical properties. The good electrochemical properties of the as-synthesized LiV 3O 8 make them a promising candidate as a cathode material for lithium secondary batteries.

A novel activated nitrogen-containing carbon anode material for lithium secondary batteries

A novel activated nitrogen-containing carbon anode material has been prepared by carbonization and activation of phenol-melamine-formaldehyde resin which is synthesized by the condensation polymerization method. The physicochemical properties of the carbon were characterized by scanning electron microscope, X-ray diffraction, Raman spectra, Brunauer–Emmett–Teller, elemental analysis and X-ray photoelectron spectroscopy measurement. Lithium storage performances have been analyzed by galvanostatic charge/discharge and cycle performance. The carbonization sample shows a first discharge capacity of 515 mAh g −1. After activation, the first discharge capacity is up to 917 mAh g −1, the reversible capacity is still as high as 251 mAh g − 1 after 20 cycles. It may be a promising candidate as anode material for lithium secondary batteries.

Synthesis and electrochemical performance of LiMnxFex−1PO4/C cathode material for lithium secondary batteries

Carbon-coated LiMn0.8Fe0.2PO4/C (C = 5 wt.%, 10 wt.%, 15 wt.%, and 20 wt.%) cathode material is synthesized using a solid-state method. No impurity is found within the synthesized active material, which is confirmed to have an olivine structure with particle sizes in the range of 100 nm to 200 nm. The LiMn0.8Fe0.2PO4/C (C = 10 wt.%) active material shows an outstanding discharge capacity of 121.7 mAh·g−1, along with a high capacity maintenance rate of 87.9 % at 2 C against the 0.2 C rate. In addition, this sample shows the most outstanding discharge capacity and coulombic efficiency in the cycling performance tests.

Electrochemical Characteristics Of Manufactured Material Li4Ti5O12

The article deals with manufactured electrode materials for lithium secondary batteries - nanostructured Li4Ti5O12. Material was chosen for research by virtue of very good intercalation / insertion characteristics, possibility utilization high charge and discharge rate and for his environmental safety.

Lithium storage performance of carbon nanotubes prepared from polyaniline for lithium-ion batteries

Carbon nanotubes with large surface area and surface nitrogen and oxygen functional groups are prepared by carbonizing and activating of polyaniline nanotubes, which is synthesized by polymerization of aniline with the self-assembly method in aqueous media. The physicochemical properties of the carbon nanotubes are characterized by scanning electron microscope, transmission electron microscopy, X-ray diffraction, Brunauer–Emmett–Teller, elemental analyses and X-ray photoelectron spectroscopy measurements. The surface area and pore diameter are 618.9 m 2 g −1 and 3.10 nm. The electrochemical properties of the carbon nanotubes as anode materials in lithium ion batteries are evaluated. At a current density of 100 mA g −1, the activated carbon nanotube shows an enormously first discharge capacity of about 1370 mAh g −1 and a charge capacity of 907 mAh g −1. After 20 cycling tests, the activated carbon nanotube retains a reversible capacity of 728 mAh g −1. These indicate it may be a promising candidate for an anode material for lithium secondary batteries.