• Resources Recycling
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• v.31 no.4
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• pp.26-33
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• 2022

Owing to the demand for lithium-ion batteries, the recovery of valuable metals from waste lithium-ion batteries is required in future. A pyrometallurgical treatment is appropriate for recycling a large number of waste lithium-ion batteries, but Li loss to slag and dust present a significant challenge. This research investigated carbonation roasting and water leaching behaviors in Li-ion batteries by graphite addition to recover Li from the NCM-based cathode materials of waste Li-ion batteries. When 10 wt% of graphite was added, CO and CO₂ gases were emitted with a rapid weight reduction at apporoximately 850 K, when heated in Ar and CO₂ atmosphere. After the rapid weight reduction, NCM was decomposed and reduced to metal oxides and pure metals. In the carbonation roasting of black powder (NCM+graphite), O₂ is generated via the decomposition of NCM, and an oxides, such as Li₂O and NiO were were also generated. Subsequently, Li₂O reacts with CO₂ to generate Li₂CO₃, and a part of NiO was reduced by graphite to produce metal Ni. In addition, up to 94.5 % Li₂CO₃ with ~99.95 % purity was recovered via water leaching after carbonation roasting.

• Journal of Power Electronics
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• v.16 no.2
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• pp.643-653
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• 2016

The conventional methods used to evaluate battery state-of-charge (SOC) cannot accommodate the chemistry nonlinearities, measurement inaccuracies and parameter perturbations involved in estimation systems. In this paper, an impedance-based equivalent circuit model has been constructed with respect to a LiFePO₄ battery by approximating the electrochemical impedance spectrum (EIS) with RC circuits. The efficiencies of approximating the EIS with RC networks in different series-parallel forms are first discussed. Additionally, the typical hysteresis characteristic is modeled through an empirical approach. Subsequently, a methodology incorporating an H-infinity observer designated for open-circuit voltage (OCV) observation and a hysteresis model developed for OCV-SOC mapping is proposed. Thereafter, evaluation experiments under FUDS and UDDS test cycles are undertaken with varying temperatures and different current-sense bias. Experimental comparisons, in comparison with the EKF based method, indicate that the proposed SOC estimator is more effective and robust. Moreover, test results on a group of Li-ion batteries, from different manufacturers and of different chemistries, show that the proposed method has high generalization capability for all the three types of Li-ion batteries.

• Resources Recycling
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• v.19 no.1
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• pp.27-32
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• 2010

To improve electronic conductivity of cathodic active materials of lithium ion battery, carbonaceous materials is usually added. New mixing method of abrasive milling has been investigated in mixing of graphite and $LiCoO_2$ powders. It would be expected that uniform mixing of graphite reduces capacity fading of cathode of lithium battery. Abrasion milled $LiCoO_2$ composite showed the best electrochemical performance as a cathode material with 1 wt% of graphite content, 300 rpm of milling speed, and 10 min of milling time. The improvement of the electrochemical performances such as cycleability and charge/discharge capacity retention would be mainly attributed to increase of the electronic conductivity and/or prevention of the active materials by uniform dispersion and coating of graphite on $LiCoO_2$.

• Journal of the Korean Ceramic Society
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• v.48 no.5
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• pp.379-383
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• 2011

This paper presents the synthesis of one-dimensional spinel $LiMn_2O_4$ nanostructures using a facile and scalable two-step process. $LiMn_2O_4$ nanorods with average diameter of 100 nm and length of 1.5 ${\mu}m$ have been prepared by solid-state lithiation of hydrothermally synthesized ${\beta}$-$MnO_2$ nanorods. $LiMn_2O_4$ nanowires with diameter of 10 nm and length of several micrometers have been fabricated via solid-state lithiation of ${\beta}$-$MnO_2$ nanowires. The precursors have been lithiated with LiOH and reaction temperature and pressure have been controlled. The complete structural transformation to cubic phase and the maintenance of 1-D nanostructure morphology have been evaluated by XRD, SEM, and TEM analysis. The size distribution of the spinel $LiMn_2O_4$ nanorods/wires has been similar to the $MnO_2$ precursors. By control of reaction pressure, cubic 1-D spinel $LiMn_2O_4$ nanostructures have been fabricated from tetragonal $MnO_2$ precursors even below $500^{\circ}C$.

• Journal of the Korean Ceramic Society
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• v.38 no.8
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• pp.755-760
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• 2001

본 연구에서는 카본전극의 표면개질에 따른 리튬이온 전지의 전지특성 변화에 대해서 연구하였다. 즉, mesocarbon microbeads(MCMB) 카본에 에폭시 수지(resin)를 코팅시킴으로서 카본전극 표면에 개질시켰으며, 이에 따른 전극의 전기화학적 특성을 고찰하였다. 에폭시 수지에 의한 카본의 표면코팅은 30%의 H$_2$SO$_4$용액에서 2시간 동안 refluxing한 MCMB를 에폭시 수지를 용해시킨 THF(tetrahydrofuran) 용액에 넣어 혼합함으로써 MCMB 표면에 에폭시 수지가 코팅되도록 하였다. 이렇게 에폭시 수지가 코팅된 MCMB를 약 1000-130$0^{\circ}C$로 열처리하여 고분해능 투과전자현미경으로 관찰한 결과, 코팅층은 비정질 카본 구조를 갖게됨을 알 수 있었다. 또한, 에폭시 수지에 의하여 코팅된 MCMB는 코팅되지 않은 MCMB보다 더 높은 BET 비표면적을 나타내었다. Li/MCMB 전지 cell을 만들어 충방전시험을 수행한 결과, 에폭시 수지에 의하여 코팅된 MCMB로 만든 전극이 더 우수한 충방전 용량과 싸이클 특성을 나타내었다. 에폭시 수지 코팅으로 전극 표면을 개질시킴으로서 전지특성이 개선된 원인에 관하여 에폭시 코팅의 결정구조와 전극계면에서의 부동태 피막(passivation film) 형성과 연계하여 논의하였다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.2
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• pp.142-147
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• 2005

In this work, a gel polymer electrolyte (GPE) was prepared using polyoxyalkylene glycol acrylate (POAGA) as a macromonomer LiCoO$_2$/GPE/graphite cells were prepared and their electrochemical properties were evaluated at various current densities and temperatures. The ionic conductivity of the GPE was more than 6.2${\times}$10$^{-3}$ S$.$$cm^{-1}$ / at room temperature. The GPE had good electrochemical stability up to 4.5 V vs. Li/Li$^{+}$. POAGA-based cells were showed good electrochemical performances such as rate capability, low-temperature performance, and cycleability. The cells, also, passed a safety test such as the overcharge and nail-penetration test.t.

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

• Bulletin of the Korean Chemical Society
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• v.30 no.7
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• pp.1607-1610
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• 2009

The carbon-coated Si/Cu powder has been prepared by mechanical ball milling and hydrocarbon gas decomposition methods. The phase of Si/Cu powder was analyzed using X-ray diffraction (XRD), dispersive Raman spectroscopy, electron probe microanalysis (EPMA) and transmission electron microscope (TEM). The carbon-coated Si/Cu powders were used as anode active material for lithium-ion batteries. Their electrochemical properties were investigated by charge/discharge test using commercial LiCo$O_2$ cathode and lithium foil electrode, respectively. The surface phase of Si/Cu powders consisted of carbon phase like the carbon nanotubes (CNTs) with a spacing layer of 0.35 nm. The carbon-coated Si/Cu/graphite composite anode exhibited a higher capacity than commercial graphite anode. However, the cyclic efficiency and the capacity retention of the composite anode were lower compared with graphite anode as cycling proceeds. This effect may be attributed to some mass limitations in LiCo$O_2$ cathode materials during the cycling.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2004.11a
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• pp.106-106
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• 2004

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