• Clean Technology
• /
• 제29권2호
• /
• pp.87-94
• /
• 2023

The recovery of valuable metals from waste lithium-based secondary batteries is very important in terms of efficiently utilizing earth's limited number of resources. Currently, the cathode material of a LiFePO₄ battery, a type of battery which is widely used in automobiles, contains approximately 5% lithium. After use, the lithium in these batteries can be used again as a raw material for new batteries through lithium recycling. In this study, low-concentration sulfuric acid, a commonly used type of inorganic acid, was used to selectively leach the lithium contained in a waste LiFePO₄ cathode material powder. In addition, in order to compare and analyze the leaching efficiency and separation efficiency of each component, the optimalleaching conditions were derived by applying a two-step leaching process with pulp density being used as a variable during leaching. When leaching with pulp density as a variable, it was confirmed that at a pulp density of 200 g/L, the separation efficiency was approximately 200 times higher than at other pulp densities because the iron and phosphorus components were hardly leached at this pulp density. Accordingly, the pulp density of 200 g/L was used tooptimize the leaching conditions for the selective leaching and recovery of lithium.

• Journal of the Korean Electrochemical Society
• /
• 제13권3호
• /
• pp.157-162
• /
• 2010

The electrodes comprising nano-sized $LiFePO_4$, carbon black and binder are prepared with two different Al current collectors. One is the generally used normal Al foil and the other is the chemically etched Al foil. Surface characteristics of each Al foil and electrochemical performance of the cathodes using each foil are investigated. The electrode from the etched Al foil exhibits better physical and electrochemical properties as compared to those of the normal Al foil because the etched Al foil has rough surface with sub-micron pores which improve the adhesion between the electrode materials and the substrate. The electrode on the etched Al foil has such a strong peel strength that the impedance is smaller than that of normal one. Indeed the $LiFePO_4$ electrode from the etched Al foil exhibits a better rate capability and remains intact even after storage for 1 week at the charged state at the elevated temperature $60^{\circ}C$.

• Proceedings of the Korean Vacuum Society Conference
• /
• 한국진공학회 2009년도 제38회 동계학술대회 초록집
• /
• pp.306-306
• /
• 2010

일반적으로 가장 많이 사용되고 있는 양극재료 가운데 $LiCoO_2$는 비교적 용량이 크고, 우수한 수명특성의 장점을 가지고 있는 반면, 단점으로 원재료의 높은 가격과 독성이 있으며, 열적으로 불안정하다. 반면, 원재료의 높은 가격과 독성, 열적 불안정성은 단점으로 지적된다. 이러한 단점을 극복할 수 있는 양극재료로 원료 가격이 저렴하고 높은 용량(170 mAh/g)과 열적으로 안정한 올리빈 구조를 형성하고 있는 $LiFePO_4$가 가장 이상적으로 고려되어져 왔다. 하지만 낮은 이온, 전기전도도 때문에 다양한 연구가 이루어졌다. 특성향상을 위한 연구가 필요하며, 다양한 전이금속의 도핑과 카본 코팅을 통하여 전기전도도의 향상과 함께 구조적으로도 리튬 이온의 확산을 더 용이하게 한다는 결과가 최근 보고되어 있다. 최근 다양한 전이금속의 도핑과 카본코팅을 통하여 전기전도도의 향상과 함께 구조적으로도 리튬이온의 확산을 더 용이하게 한다는 결과가 보고되어 있다. 본 연구에서는 고상반응법을 이용하여 $LiFePO_4$를 합성하였고, 카본소스를 첨가하여 전기전도도의 향상과 함께 높은 용량의 $LiFePO_4$/C양극재료를 합성하였다. 제조된 분말은 XRD 회절시험을 통하여 결정구조를 분석 하였으며, SEM을 이용하여 분말의 형상과 크기를 관찰 하였고, 또한 전기화학적 특성도 평가하였다.

• Advances in materials Research
• /
• 제4권2호
• /
• pp.63-76
• /
• 2015

The energy crisis involving depletion of fossil fuel resource is not the sole driving force for developing renewable energy technologies. Another driving force is the ever increasing concerns on the air quality of our planet, associated with the continuous and dramatic increase of the concentration of greenhouse gas (mainly carbon dioxide) emissions. The internal combustion engine is a major source of distributed $CO_2$ emissions caused by combustion of gasoline derived largely from fossil fuel. Another major source of $CO_2$ is the combustion of fossil fuels to produce electricity. New technologies for generating electricity from sources that do not emit $CO_2$, such as water, solar, wind, and nuclear, together with the advent of plug-in hybrid electric vehicles (PHEV) and even all-electric vehicles (EVs), offer the potential of alleviating our present problem. Therefore, the relevant technologies in $LiFePO_4$ as cathode material for Li-ion batteries suitable to the friendly environment are reviewed aim to provide the vital information about the growing field for energies to minimize the potential environmental risks.

• Journal of the Korean Chemical Society
• /
• 제19권5호
• /
• pp.325-330
• /
• 1975

Complex formation between ferric ion and phosphoric acid has been studied in the wide range of the acid concentration(0${\sim}40{\%}$) by uv-visible spectroscopy and by characterization of the isolated products. The electronic spectra of Fe(III)-containing phosphoric acid solutions exhibit two visible bands at 19.2 and 24.1 kK, which are characteristic of Fe(III)-phosphate complex formation. The measurements of acid concentration dependence of the opical density of the 24.1 kK band indicates the presence of two distinct forms of Fe(Ⅲ)-phosphate complexes possibly $[Fe(H_xPO_4)]^{x+}\;and\;[Fe_2 (H_xPO_4)]^{(3+x)+}$. The 1:1 complex has been isolated for characterization, and the phosphate ion was found to be coordinated to the metal in monobasic state whereas the isolation of the dimeric species was unsuccessful.

• Proceedings of the KIPE Conference
• /
• 전력전자학회 2011년도 추계학술대회
• /
• pp.51-52
• /
• 2011

전류 적산법(Coulomb counting, Ampere counting)을 이용한 배터리 SOC(State of Charge) 추정 방식은 초기 SOC 값에 존재하는 오차와 SOC를 추정하는 시간동안 누적되는 전류값의 오차로 인해 추정이 실패할 수 있는 단점이 존재한다. 하지만 알고리즘이 직관적이며 단시간 내에서는 그 오차가 크지않고, 상용화된 배터리 SOC 추정 IC가 존재하여 구현이 간단하다는 장점 또한 있다. 본 논문에서는 전류 적산법 기반의 배터리 SOC 추정 IC를 사용하여 $LiFePO_4$ 리튬 폴리머 배터리의 SOC 추정 회로를 구현하는 과정을 제안한다. 또한 실험을 통해 제안된 배터리 SOC 추정 회로의 성능을 확인해본다.

• Journal of Power Electronics
• /
• 제18권5호
• /
• pp.1585-1594
• /
• 2018

The estimation of $LiFePO_4$/graphite battery states suffers from the prominent hysteresis phenomenon between the respective open-circuit voltage curves towards charging and discharging. A lot of hysteresis models have been documented to investigate the hysteresis mechanism. This paper reviews and deeply interprets four non-electrochemical hysteresis models and some improvements. These models can be conveniently incorporated into commonly used equivalent circuit models to reproduce battery behaviors. Through simulation and experimental comparisons of voltage predictions and state-of-charge estimations, the pros and cons of these models are presented.

• Journal of the Korean Applied Science and Technology
• /
• 제28권3호
• /
• pp.329-334
• /
• 2011

The electrochemical performances of an asymmetric hybrid capacitor were investigated using $LiFePO_4$ as the positive electrode and active carbon fibers(ACF) as the negative electrode. The electrochemical behaviors of a nonaqueous hybrid capacitor were characterized by constant current charge/discharge test. The specific capacitance using $LiFePO_4$/ACF electrode turned out to be $0.87F/cm^2$ and the unit cell showed excellent cycling performance. This hybrid capacitor was able to deliver a specific energy as high as 178 Wh/kg at a specific power of 1,068 W/kg.

• Bulletin of the Korean Chemical Society
• /
• 제33권7호
• /
• pp.2315-2319
• /
• 2012

To improve the performance of $LiFePO_4F$, a novel sol-gel process is developed. For comparison, ceramic process is also implemented. From X-ray diffraction results we know that each sample adopts a triclinic $P{\bar{1}}$ space group, and they are isostructural with amblygonite and tavorite. The scanning electron microscope images show that the homogeneous grains with the dimension of 300-500 nm is obtained by the sol-gel process; meanwhile the sample particles obtained by ceramic process are as big as 1000-3000 nm. By galvanostatic tests and at electrochemical impedance spectroscopy method, the sample obtained by sol-gel process presents better electrochemical properties than the one obtained by ceramic process.

• Proceedings of the KIPE Conference
• /
• 전력전자학회 2017년도 전력전자학술대회
• /
• pp.463-464
• /
• 2017

다른 리튬계열 전지와 달리, 인산철($LiFePO_4$) 배터리는 중간 동작 영역에서 개방전압(OCV; open-circuit voltage)의 히스테리시스(hysteresis) 영역이 존재한다. 그러므로, 인산철 배터리 관리시스템, 특히 충전상태(SOC; state-of-charge)와 수명상태(SOH; state-of-health)의 정확한 모니터링을 위해서는 OCV의 정밀성이 요구된다. 본 논문에서는, 충전 및 방전 OCV-SOC의 SOC 간격에 따른 인산철 배터리의 SOH를 비교하기 위해 전기적 등가회로 모델(ECM; electrical-circuit modeling)적응제어 알고리즘 기반 실시간 내부저항(DCIR; direct current internal resistance)을 모니터링 하였다.