• Journal of the Korean Chemical Society
• /
• v.67 no.6
• /
• pp.429-440
• /
• 2023

1,1-Dialkyl-2,5-bis(trimethylsilylethynyl)-3,4-diphenylsiloles (R=Et, i-Pr, n-Hex; 3a-c) were prepared and utilized as anode active materials for lithium-ion batteries; 3a was also used as a filler for the solid-state electrolytes (SSE). Siloles 3a-c were prepared by substitution reactions in which the two bromine groups of 1,1-dialkyl-2,5-dibromo-3,4-diphe- nylsiloles, used as precursors, were substituted with trimethylsilylacetylene in the presence of palladium chloride, copper iodide, and triphenylphosphine in diisopropylamine. Among siloles 3a-c, 3a had the best electrochemical properties as an anode material for lithium-ion batteries, including an initial capacity of 758 mAhg^-1 (0.1 A/g), which was reduced to 547 mAhg^-1 and then increased to 1,225 mAhg^-1 at 500 cycles. A 3a-composite polymer electrolyte (3a-CPE) was prepared using silole 3a as an additive at concentrations of 1, 2, 3, and 4 wt.%. The 2 wt.% 3a-CPE composite afforded an excellent ionic conductivity of 1.09 × 10^-3 Scm^-1 at 60℃, indicating that silole 3a has potential applicability as an anode active material for lithium-ion batteries, and can also be used as an additive for the SSE of lithium-ion batteries.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.11 no.9
• /
• pp.727-732
• /
• 1998

Ag-deposited graphite powder was prepared by a chemical reduction method of metal particles onto graphite powder. X-ray diffraction observation of Ag-deposited graphite powder revealed that silver existed in a metallic state, but not in an oxidized one. From SEM measurement, ultrafine silver particles were highly dispersed on the surface of graphite particles. Cylindrical lithium ion secondary battery was manufactured using Ag-deposited graphite anodes and $LiCoO_2$ cathodes. The cycleability of lithium ion secondary battery using Ag-deposited graphite anodes was superior to that of original graphite powder. The improved cycleability may be due to both the reduction of electric resistance between electrodes and the highly durable Ag-graphite anode.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1999.05a
• /
• pp.362-365
• /
• 1999

The electrochemical properties of flyash obtained from combustion of fuel in fossil power plants and their performance as anode material of secondary battery have been investigated Various flysh pellets molded at various molding pressure have been used as anode lithium secondary battery. The best Performance was achieved when flyash pellet molded at pressure of 400kgf/$\textrm{cm}^2$ is utilized, that is, charge capacity of 300kgf/$\textrm{cm}^2$ and Coulombic efficiency of larger than 95% have been achieved. In addition, this battery exhibited good cycling performance. Considering these results, we predicted that utilization of the flyash as anode material and polyaniline conducting polymer as cathode material in a secondary will show capacity of 300mAh/g and Coulombic efficiency of higher than 95%.

• Korean Journal of Materials Research
• /
• v.28 no.6
• /
• pp.337-342
• /
• 2018

Using a high pressure homonizer, we report on the electrochemical performance of $Li_4Ti_5O_{12}(LTO)$ particles manufactured as anode active material for lithium ion battery. High-pressure synthesis processing is performed under conditions in which the mole fraction of Li/Ti is 0.9, the synthesis pressure is 2,000 bar and the numbers of passings-through are 5, 7 and 10. The observed X-ray diffraction patterns show that pure LTO is manufactured when the number of passings-through is 10. It is found from scanning electron microscopy analysis that the average size of synthesized particles decreases as the number of passings-through increases. $LiCoO_2-based$ active cathode materials are used to fabricate several coin half/full cells and their battery characteristics such as lifetime, rate capability and charge transfer resistance are then estimated, revealing quite good electrochemical performance of the LTO particles as an effective anode active material for lithium secondary batteries.

• Korean Chemical Engineering Research
• /
• v.56 no.6
• /
• pp.901-908
• /
• 2018

Graphite is used as a sample anode active material. However, since the maximum theoretical capacity is limited to $372mA\;h\;g^{-1}$, a new anode active material is required for the development of a high capacity lithium ion battery. The maximum theoretical capacity of Si is $4200mA\;h\;g^{-1}$, which is higher than that of graphite. However, it is not suitable for direct application to the anode active material because it has a volume expansion of 400%. In order to minimize the decrease of the discharge capacity due to the volume expansion, the Si was pulverized by the dry method to reduce the mechanical stress and the volume change of the reaction phase, and the change of the volume was suppressed by coating the carbon layers to the particle size controlled Si particles. And carbon fiber is grown like a thread on the particle surface to control secondary volume expansion and improve electrical conductivity. The physical and chemical properties of the materials were measured by XRD, SEM and TEM, and their electrochemical properties were evaluated. In this study, we have investigated the synthesis method that can be used as anode active material by improving cycle characteristics of Si.

• Journal of Electrochemical Science and Technology
• /
• v.10 no.2
• /
• pp.244-249
• /
• 2019

SiO has a high theoretical capacity as a promising anode material candidate for high-energy-density Li-ion batteries. However, its practical application is still not widely used because of the large volume change that occurs during cycling. In this report, an active material containing a mixture of SiO and graphite was used to improve the insufficient energy density of the conventional anode with the support of multidimensional conducting agents. To relieve the isolation of the active materials from volume changes of SiO/graphite electrode, two types of conducting agents, namely, 1-dimensional VGCF and 0-dimensional Super-P, were introduced. The combination of VGCF and Super-P conducting agents efficiently maintained electrical pathways among particles in the electrode during cycling. We found that the electrochemical performances of cycleability and rate capability were greatly improved by employing the conducting agent combinations of VGCF and Super-P compared with the electrode using only single VGCF or single Super-P. We investigated the detailed failure mechanisms by using systematic electrochemical analyses.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.11b
• /
• pp.513-516
• /
• 2001

In this study, the properties of MCMB anode Mixed with KCF were evaluated, KCF material was used as not only conducting agent but also active material, The Electirc conductivity of MCMB and KCF were 23.7S/cm and 45.8S/cm. Characteristics of anode with different KCF contents were the best effect at 2wt%. The 1st Ah efficiency of cells were increased with increment of KCF contents. The internal resistance and the rate capability were $1.59{\Omega}$ and 135mAh/g at 2C, The discharge capacity was gradually faded with the charge-discharge cycling to about 50th cycles.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.11a
• /
• pp.513-516
• /
• 2001

In this study, the properties of MCMB anode Mixed with KCF were evaluated. KCF material was used as not only conducting agent but also active material. The Electric conductivity of MCMB and KCF were 23.7S/cm and 45.8S/cm. Characteristics of anode with different KCF contents were the best effect at 2wt%. The 1st Ah efficiency of cells were increased with increment of KCF contents. The internal resistance and the rate capability were 1.59Ω and 135mAh/g at 2C. The discharge capacity was gradually faded with the charge-discharge cycling to about 50th cycles.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2003.05c
• /
• pp.88-90
• /
• 2003

The purpose of this study is to research and develop tin oxide-flash composite for lithium Ion polymer battery. Tin oxide is one of the promising material as a electrode active material for lithium Ion polymer battery (LIPB). Tin-based oxides have theoretical volumetric and gravimetric capacities that are four and two times that of carbon, respectively. We investigated cyclic voltammetry and charge/discharge cycling of SnO-flyash/SPE/Li cells. The first discharge capacity of SnO-flyash composite anode was 720 mAh/g. The discharge capacity of SnO-flyash composite anode 412 and 314 mAh/g at cycle 2 and 10 at room temperature, respectively. The SnO-flyash composite anode with PVDF-PMMA-PC-EC-$LiClO_4$ electrolyte showed good capacity with cycling.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.17 no.11
• /
• pp.1224-1229
• /
• 2004

The purpose of this study is to research and develop tin oxide-flyash composite for lithium Ion polymer battery. Tin oxide is one of the promising material as a electrode active material for lithium Ion polymer battery (LIPB). Tin-based oxides have theoretical volumetric and gravimetric capacities that are four and two times that of carbon, respectively. We investigated cyclic voltammetry, AC impedance and charge/discharge cycling of SnO$_2$-flyash/SPE/Li cells. The first discharge capacity of SnO$_2$-flyash composite anode was 639 mAh/g. The discharge capacity of SnO$_2$-flyash composite anode was 563 and 472 mAh/g at 6th and 15th cycle, respectively. The SnO$_2$-flyash composite anode with PVDF-PMMA-PC-EC-LiClO$_4$ electrolyte showed good capacity with cycling.