• Journal of the Korean Electrochemical Society
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• v.19 no.4
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• pp.129-133
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• 2016

In this study, a polymer-carbon composite material is prepared for environmental-friendly organic anode. On poly(styrenesulfonate)(PSS)-carbon composite anode, the carbon is coated by PSS as a core-shell structure and the PSS-carbon composite anode has $524mAh\;g^{-1}$ theoretical capacity with <0.6V voltage. Moreover, the PSS-carbon composite anode shows $519.6mAh\;g^{-1}$, $461.2mAh\;g^{-1}$, $411.8mAh\;g^{-1}$ and $315.9mAh\;g^{-1}$ discharge capacities at 0.1, 0.5, 1 and 10 C, respectively, and stable cycle performance up to 30 cycles. The PSS-carbon composite anode, containing polystyrene and sulfonate functional groups, is suitable for high electrochemical properties organic rechargeable battery.

• Applied Chemistry for Engineering
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• v.32 no.3
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• pp.243-252
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• 2021

With increasingly strict requirements for advanced energy storage devices in electric vehicles (EVs) and stationary energy storage systems (EES), the development of lithium-ion batteries (LIBs) with high power density and safety has become an urgent task. Because the performance of LIBs is determined primarily by the physicochemical characteristics of its electrode material, TiO₂, owing to its excellent stability, high safety levels, and environmentally friendly properties, has received significant attention as an alternative material for the replacement of commercial carbon-based anode materials. In particular, self-organized TiO₂ micro and nanostructures prepared by anodization have been intensively investigated as promising anode materials. In this review, the mechanism for the formation of anodic TiO₂ nanotubes and microcones and the parameters that influence their morphology are described. Furthermore, recent developments in anodic TiO₂-based composites as anode electrodes for LIBs to overcome the limitations of low conductivity and specific capacity are summarized.

• Particle and aerosol research
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• v.15 no.4
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• pp.127-137
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• 2019

Recently, high electrochemical performance anode materials for lithium ion secondary batteries are of interest. Here, we present silicon-carbon-graphene (Si-C-GR) composites for high performance anode materials of lithium ion secondary battery (LIB). Aerosol process and heat-treatment were employed to prepare the Si-C-GR composites using a colloidal mixture of silicon, glucose, and graphene oxide precursor. The effects of the size of the silicon particles in Si-C-GR composites on the material properties including the morphology and crystal structure were investigated. Silicon particles ranged from 50 nm to 1 ㎛ in average diameter were employed while concentration of silicon, graphene oxide and glucose was fixed in the aerosol precursor. Morphology of as-fabricated Si-C-GR composites was generally the shape of a crumpled paper ball and the Si particles were well wrapped in carbon and graphene. The size range of composites was about from 2.2 to 2.9 ㎛. The composites including silicon particles larger than 200 nm in size exhibited higher performance as LIB anodes such as capacity and coulombic efficiency than silicon particles less than 100 nm, which were about 1500 mAh/g at 100 cycles in capacity and 99% in coulombic efficiency, respectively.

• Journal of the Korean Electrochemical Society
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• v.22 no.3
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• pp.112-121
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• 2019

In this study, silicon / carbon nanotube / carbon composite particles with high capacity were fabricated by using micro-sized silicon particles and carbon nanotubes as an anode material for lithium ion batteries. The silicon / carbon nanotube / carbon composite particles were prepared by spray drying method to prepare spherical composite particles. The composite particles have the network structure of the carbon nanotubes around the silicon particles, in which the silicon particles and the carbon nanotubes are bonded by amorphous carbon. It appears that the volume expansion of silicon is effectively buffered and the electrical contact is maintained in the network structure of the composite particles during charge-discharge cycles.

• Transactions of the Korean hydrogen and new energy society
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• v.32 no.6
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• pp.612-617
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• 2021

In the case of a metal sulfide electrode, it is used as an anode or cathode active material in a lithium battery. The reason is that the voltage exists between 0.8 and 2.0 V via lithium electrode and the discharge and charge capacity is high. In order to manufacture nickel sulfide for electrode, which are widely used, nano-nickel powder was sulfided using ammonium polysulfide, and single-phase NiS electrodes were manufactured through heat treatment. The prepared NiS electrode had a high initial capacity of 500 mAh/g or more, and was stabilized after 20 cycles to maintain a capacity of 400 mAh/g or more until 100 cycles.

• Korean Chemical Engineering Research
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• v.57 no.6
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• pp.861-867
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• 2019

$Li_4Ti_5O_{12}$ is a promising next-generation anode material for lithium-ion batteries due to excellent cycle life, low irreversible capacity, and little volume expansion during charge-discharge process. However, it has poor charge capacity at high current density due to its low electrical conductivity. To improve this weakness, porous $Li_4Ti_5O_{12}$ was synthesized by sol-gel method with P123 as chelating agent. The physical characteristics of as-prepared sample was investigated by XRD, SEM, and BET analysis, and electrochemical properties were characterized by cycle performance test, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS). $Li_4Ti_5O_{12}$ synthesized by 0.01mol ratio of P123/Ti showed most unified particle size, high specific surface area, and relatively high porosity. EIS analysis showed that depressed semicircle size was remarkably reduced, which suggested resistance value in electrode was decreased. Capacity in rate performance showed 178 mAh/g at 0.2C, 170 mAh/g at 0.5C, 110 mA/h at 5C, and 90 mAh/g at 10C. Capacity retention also showed 99% after rate performance.

• Applied Chemistry for Engineering
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• v.33 no.1
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• pp.58-63
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• 2022

Graphite has been used as an anode material for lithium-ion batteries for the past 30 years due to its low de-/lithiation voltage, high theoretical capacity of 372 mAh/g, low price, and long life properties. Recently, all-solid-state lithium-ion batteries (ASSLB), which are composed of inorganic solid materials with high stability, have received great attention as electric vehicles and next-generation energy storage devices, but research works on graphite that works well for ASSLB systems are insufficient. Therefore, we induced the performance improvement of ASSLB anode electrode graphite material by removing the amorphous carbon present in the carbon material surface, acting as a resistive layer from the graphite. As a result of X-ray diffraction (XRD) analysis using heat treated graphite in air at 400, 500, and 600 ℃, the full width at half maximum (FWHM) at (002) peak was reduced compared to that of bare graphite, indicating that the crystallinity of graphite was improved after heat treatment. In addition, the discharge capacity, initial coulombic efficiency (ICE) and cycle stability increased as the crystallinity of graphite increased after heat treatment. In the case of graphite annealed in air at 500 ℃, the high capacity retention rate of 331.1 mAh/g and ICE of 86.2% and capacity retention of 92.7% after 10-cycle measurement were shown.

• Journal of the Korean Electrochemical Society
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• v.2 no.2
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• pp.75-80
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• 1999

Li-ion cells employ lithium transtion metal oxide as the cathode material and carbon as anode material. To manufacture Li-ion cell with higher capacity and better cycle life, the utilization of electrode materials should be as high as possible without lithium deposition onto the carbon surface during charging. A careful design of cell balance between cathode and anode materials as well as a proper charge method is a key factor to design Li-ion cell with long cycle life. In this study, we investigated the effect of cathode/anode weight ratio on the performance of $LiCoO_2/MPCF$ cell. First we evaluated the charge-discharge behaviours of half-cells. And cylindrical Li-ion cells were fabricated using graphitized MPCF anode and $LiCoO_2$ cathode. The voltage profiles for each half-cell in $LiCoO_2/MPCF$ cell were measured by using lithium metal as a reference electrode. Also, we evaluated the cyclic performance of $LiCoO_2/MPCF$ cells according to weight ratio. From the result of experiment $LiCoO_2$ cathode utilization was independent of weight ratio, but MPCF anode utilization was dependant on weight ratio. Also, the optimal weight ratio of $LiCoO_2/MPCF$ cell was found to be $2.0\~2.2$.

• Clean Technology
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• v.18 no.2
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• pp.177-182
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• 2012

Mesoporous anatase $TiO_2$ nanoparticles have been synthesized by a hydrothermal method using a tri-block copolymer as a soft template. The resulting $TiO_2$ materials have a high specific surface area of $230\;m^2/g$, a predominant pore size of 6.8 nm and a pore volume of 0.404 mL/g. The electrochemical properties of mesoporous anatase $TiO_2$ for lithium ion battery (LIB) anode materials have been investigated by typical coin cell tests. The initial discharge capacity of these materials is 240 mAh/g, significantly higher than the theoretical capacity (175 mAh/g) of LTO ($Li_4Ti_5O_{12}$). Although the discharge capacity decreases with the C-rate increase, the mesoporous $TiO_2$ is very promising for LIB anode because the surface for the Li insertion is presented significantly with mesopores. Nitrogen doping has a certain effect to control the capacity decrease by improving the electron transport in $TiO_2$ framework.

• Korean Chemical Engineering Research
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• v.60 no.3
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• pp.327-333
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• 2022

In this study, silicon/carbon nanotube/carbon (Si/CNT/C) composites for anode were prepared to improve the volume expansion of silicon used as a high-capacity anode material. Si/CNT were prepared by electrostatic attraction of the positively charged Si and negatively charged CNT and then hydrothermal synthesis was performed to obtain the spherical Si/CNT/C composites. Poly(vinylidene fluoride) (PVDF), polyacrylic acid (PAA), and styrene butadiene rubber (SBR) were used as binders for electrode preparation, and coin cell was assembled using 1.0 M LiPF₆ (EC:DMC:EMC = 1:1:1 vol%) electrolyte and fluoroethylene carbonate (FEC) additive. The physical properties of Si/CNT/C anode materials were analyzed using SEM, EDS, XRD and TGA, and the electrochemical performances of lithium-ion batteries were investigated by charge-discharge cycle, rate performance, dQ/dV and electrochemical impedance spectroscopy tests. Also, it was confirmed that both capacity and rate performance were significantly improved using the PAA/SBR binder and 10 wt% FEC-added electrolyte. It is found that Si/CNT/C have the reversible capacity of 914 mAh/g, the capacity retention ratio of 83% during 50 cycles and the rate performance of 70% in 2 C/0.1 C.