Layered LiNi0.83Co0.11Mn0.06O2 cathode materials single- and dual-doped by the rare-earth elements Ce and Nd are successfully fabricated by using a coprecipitation-assisted solid-phase method. For comparison purposes, nondoping pristine LiNi0.83Co0.11Mn0.06O2 cathode material is also prepared using the same method. The crystal structure, morphology, and electrochemical performances are characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) mapping, and electrochemical techniques. The XRD data demonstrates that all prepared samples maintain a typical α-NaFeO2-layered structure with the R-3m space group, and that the doped samples with Ce and/or Nd have lower cation mixing than that of pristine samples without doping. The results of SEM and EDS show that doped elements are uniformly distributed in all samples. The electrochemical performances of all doped samples are better than those of pristine samples without doping. In addition, the Ce/Nd dualdoped cathode material shows the best cycling performance and the least capacity loss. At a 10 C-rate, the electrodes of Ce/Nd dual-doped cathode material exhibit good capacity retention of 72.7, 58.5, and 45.2% after 100, 200, and 300 cycles, respectively, compared to those of pristine samples without doping (24.4, 11.1, and 8.0%).

In this study, an experiment is performed to recover the Li in Li2CO3 phase from the cathode active material NMC (LiNiCoMnO2) in waste lithium ion batteries. Firstly, carbonation is performed to convert the LiNiO, LiCoO, and Li2MnO3 phases within the powder to Li2CO3 and NiO, CoO, and MnO. The carbonation for phase separation proceeds at a temperature range of 600oC~800oC in a CO2 gas (300 cc/min) atmosphere. At 600~700oC, Li2CO3 and NiO, CoO, and MnO are not completely separated, while Li and other metallic compounds remain. At 800 oC, we can confirm that LiNiO, LiCoO, and Li2MnO3 phases are separated into Li2CO3 and NiO, CoO, and MnO phases. After completing the phase separation, by using the solubility difference of Li2CO3 and NiO, CoO, and MnO, we set the ratio of solution (distilled water) to powder after carbonation as 30:1. Subsequently, water leaching is carried out. Then, the Li2CO3 within the solution melts and concentrates, while NiO, MnO, and CoO phases remain after filtering. Thus, Li2CO3 can be recovered.

Lithium-ion batteries have been considered the most important devices to power mobile or small-sized devices due to their high energy density. LixCoO2 has been studied as a cathode material for the Li-ion battery. However, the limitation of its capacity impedes the development of high capacity cathode materials with Ni, Mn, etc. in them. The substitution of Mn and Ni for Co leads to the formation of solid solution phase LiNixMnyCo1-x-yO2 (NMC, both x and y < 1), which shows better battery performance than unsubstituted LiCoO2. However, despite a high discharge capacity in the Ni-rich compound (Ni > 0.8 in the metal site), poor cycle retention capability still remains to be overcome. In this study, aiming to improve the stability of the physical and chemical bonding, we investigate the stabilization effect of Ca in the Ni-rich layered compound Li(Ni0.83Co0.12Mn0.05)O2, and then Ca is added to the modified secondary particles to lower the degree of cationic mixing of the final particles. For the optimization of the final grains added with Ca, the Ca content (x = 0, 2.5, 5.0, 10.0 at.%) versus Li is analyzed.

전해환원공정의 금속전환체로부터 우라늄을 회수하는 전해정련공정의 수율을 높이기 위해 고수율 전해정련장치가 개발되 었다. 전해정련장치의 수율을 증대시키기 위해서는 고체음극에 전착되는 우라늄 덴드라이트를 음극 표면으로부터 효율적 으로 회수할 수 있어야 한다. 철강 재료의 음극을 고체음극으로 사용하면, 우라늄 덴드라이트가 전착되어 쉽게 떨어지고 않 고 고착 되어 점착계수(sticking coefficient)가 높아진다. 본 연구에서는 효율적으로 고체음극의 점착계수를 낮출 수 있는 진 동 탈리법을 개발하였고 이를 적용하였다. 고체음극에 진동을 가함으로써 고체 표면에서 우라늄 전착물이 흑연음극의 자발 특성과 유사하게 효율적으로 탈리됨을 확인하였다. 이러한 진동모드에 의한 고체음극에서의 전착물의 탈리 특성을, 고수율 전해정련장치 개념으로 개발한 흑연음극의 자발탈리 특성과 비교 검토하였다. 그리고 우라늄 덴드라이트의 진동 탈리에 대 한 인가전류밀도와 진동 스트로크에 의한 영향 등을 고찰하였다.

The production of nuclear fuel cladding tube is expected to increase with the nuclear power plant expansion. Zirconium(Zr) scrap that is generated during manufacturing is also expected to increase. Zr electrorefining experiment was carried out in the fluoride salt of LiF-KF-ZrF4 using multiple electrode for scale up and improving throughput Zr electrorefiner development. The Zr reduction peak observed at -0.8 V(vs.Ni). Polarization behavior showed that the amount of applied current increases because of decreasing cell resistance as the number of cathode increases. Experimental results showed the highest recovery rate about 98% at lowest current density of 25.64 mA/cm2 using 6 electrodes. XRD and TG analysis result show that pure Zr was recovered 99.92% and ICP analysis shows that lower impurity content than conventional impurity content of the Anode(97.8%). Electrorefining consumes energy about 7.15 kWh/kg less than 39.7% compared to the Kroll process using 6 electrode width of 20 mm and height of 65 mm. Because of increasing cell efficiency and recovery rate, using multiple cathode is determined as an efficient technique for scale up electrorefining Zr scrap.

Flat panel display devices are mainly used as information display devices in the 21st century. The worldwide waste flat panel displays are expected at 2-3 million units but most of them are land-filled for want of a proper recycling technology More specifically, rare earth metals of La and Eu are used as fluorescent materials of Cold Cathode Flourscent Lamp(CCFL)s in the waste flat panel displays and they are critically vulnerable and irreplaceable strategic mineral resources. At present, most of the waste CCFLs are disposed of by land-filling and incineration and proper recovery of 80-plus tons per annum of the rare earth fluorescent materials will significantly contribute to steady supply of them. A dearth of Korean domestic research results on recovery and recycling of rare earth elements in the CCFLs prompts to initiate this status report on overseas research trends and noteworthy research results in related fields.

A three dimensional numerical analysis was performed to study the effect of cathode inlet relative humidity on PEMFC performance characteristics. As cathode inlet relative humidity increases from 0 percent to 60 percent, the current density increases. Then, as cathode inlet relative humidity increases from 60 percent to 100 percent, the current density decreases. The two dimensional contour map analysis shows that the flooding phenomenon in cathode gas channel, gas diffusion layer, and catalyst layer leads to the decrease of current density.

FeS2 has been widely used for cathode materials in thermal battery because of its high stability and currentcapability at high operation temperature. Salts such as a LiCl-KCl were added as a binder for improving electrical per-formance and formability of FeS2 cathode powder. In this study, the effects of the addition of Li2O in LiCl-KCl binderon the formability of FeS2 powder compact were investigated. With the increasing amount of Li2O addition to LiCl-KClbinder salts, the strength of the pressed compacts increased considerably when the powder mixture were pre-heat-treatedabove 350oC. The heat-treatment resulted in promoting the coating coverage of FeS2 particles by the salts as Li2O wasadded. The observed coating as Li2O addition might be attributed to the enhanced wettability of the salt rather than itsreduced melting temperature. The high strength of compacts by the Li2O addition and pre-heat-treatment could improvethe formability of FeS2 raw materials.

Cathode materials and their precursors are prepared with transition metal solutions recycled from the thewaste lithium-ion batteries containing NCM (nickel-cobalt-manganese) cathodes by a H2 and C-reduction process. Therecycled transition metal sulfate solutions are used in a co-precipitation process in a CSTR reactor to obtain the tran-sition metal hydroxide. The NCM cathode materials (Ni:Mn:Co=5:3:2) are prepared from the transition metal hydroxideby calcining with lithium carbonate. X-ray diffraction and scanning electron microscopy analyses show that the cathodematerial has a layered structure and particle size of about 10 µm. The cathode materials also exhibited a capacity ofabout 160 mAh/g with a retention rate of 93~96% after 100 cycles.

용융염 전해정련공정은 사용후핵연료로부터 전기화학적인 방법을 통해 음극에서 우라늄을 회수 하는 공정이다. 이 때 우라 늄은 약 30wt%의 염을 포함하고 있어 순수한 우라늄을 얻기 위해서는 염을 제거하는 Cathode Process (CP)가 필수적이다. CP는 대량의 우라늄을 처리해야 하므로 파이로공정의 난관중의 하나로 인식되고 있으며, 우라늄의 순도가 최종적으로 결정 되는 단계이므로 매우 중요한 공정이다. 현재, 이에 대한 연구는 주로 실험적 방법에 근거 하고 있어 염 제거 공정 중 온도, 압력, 염 가스의 거동을 관찰하기 어렵다. 따라서 본 연구에서는, 공정의 운전 조건에 대해 적합한 수학적 모델을 이용하여 전산모사 해석을 진행하였다. 본 연구는 증류부에서 염 가스의 증류 량, 확산계수에 의해 계산된 장치 내 염 가스의 이동 그 리고 응축부에서의 응결속도를 중점적으로 연구하였다. 장치내의 각각의 염 가스 거동을 정의하기 위해 Hertz-Langmuir 관 계식, Chapman-Enskog Theory, ANSYS-CFX의 상용 코드를 사용하였다. 그리고 HSC Chemistry에서 염의 물성 값을 이용 하여 모델을 구성하였다. 본 연구의 전산모사 해석을 통해 얻은 연구 결과를 이용하여 염 가스의 거동과 장치의 최적 운전 조건을 예측하였다. 따라서 본 해석 결과는 CP의 물리적 현상을 깊게 이해하는데 쓰일 뿐 아니라, 공학규모의 CP 장치를 상 용규모로 확장하는데 이용 할 수 있다.

A numerical analysis was performed to study PEMFC performance characteristics depending on the flow direction of cathode reactant gas, cathode relative humidity, and porosity of gas diffusion layer. As cathode relative humidity decreases and porosity increases, current density increases due to better diffusion of reactant gas to cathode surface. As current density increases, power density increases initially and then decreases with its maximum located around current density value of 2.2 Amperes per square centimeter. From the analysis of current density distribution inside membrane, the counter-flow cases show more uniform profile across the membrane than the co-flow cases due to more uniform reactant gas supply.

경제적이고 우수한 핵확산저항성을 갖는 파이로공정의 핵심 단위공정인 전해제련 공정에서 U와 TRU를 동시에 회수하기 위해 환원전극으로써 LCC가 사용된다. 한가지 원소만을 회수하는 금속음극과는 달리 LCC는 전기화학적으로 U와 TRU의 선택적 분리가 어려워 핵확산저항성을 높이는 기술의 핵심이라고 할 수 있다. LCC를 담아놓는 LCC 도가니는 U나 TRU로만 전착되어야하기 때문에 도가니는 전기적으로 절연되어야 한다. LCC와의 안정성과 회수된 TRU 및 용융염과의 화학적 안전성은 물론 공정 중 전착될 수 있는 금속 Li과의 반응성도 고려되어야하므로 LCC 도가니의 소재 특성은 매우 중요하다. 본 연구에서는 Al2O3, MgO, Y2O3, BeO 네 가지 대체 세라믹 소재의 화학적 안정성을 500℃에서 모의 LCC로 열역학적 및 실험적으로 평가하였다. 세라믹 기판 위의 LCC 접촉각은 화학적 반응성을 예측하기 위해 시간에 따라 측정하였다. Al2O3는 가장 낮은 화학적 안정성 갖고 BeO는 재료 내에 존재하는 기공은 접촉각감소에 영향을 주었다. MgO, Y2O3는 우수한 화학적 안정성을 나타내었다.

A numerical analysis was performed to study PEMFC characteristics depending on the flow direction of reactant gas in cathode gas channel using the Fluent. As cathode relative humidity increases, water mass fraction increases due to back diffusion from cathode. For the both of co-flow and counter-flow cases, water mass fraction is higher near the hydrogen inlet region where the chemical reaction rate is high. In overall, counter-flow case gives higher current density compared to co-flow case for the same operating conditions. However, the difference in the current density is not high. The temperature is also higher near the hydrogen inlet region due to the chemical reaction rate for the both of co-flow and counter-flow cases.

A numerical analysis was performed to study PEMFC characteristics depending on GDL porosity and the inlet direction in cathode gas channel using the FLUENT. As GDL porosity increases, temperature increases. For the both of co-flow and counter-flow cases, temperature is higher near the hydrogen inlet region where the chemical reaction rate is high. As GDL porosity increases, current density increases. In overall, counter-flow case gives higher current density compared to co-flow case for the same operating conditions. However, the difference in the current density is not high. The water mass fraction is also higher near the hydrogen inlet region due to the chemical reaction rate for the both of co-flow and counter-flow cases.

In this paper, the PEMFC performance was studied using three dimensional numerical analysis. The effect of GDL porosity and cathode inlet humidity on the cell polarization curve was analyzed. The GDL porosity of 0.3, 0.5, 0.7 and cathode inlet humidity of 20, 40, 60, 80, 100 percent were selected as simulation cases while the anode inlet humidity was maintained as 100 percent. For a constant cell voltage condition, the highest current density was obtained at GDL porosity of 0.7 and cathode inlet humidity of 20 percent. As GDL porosity increases, the amount of hydrogen diffusion to membrane from the anode increases and chemical reaction also increases. As cathode inlet humidity decreases, oxygen mass fraction of cathode gas channel increases and chemical reaction also increases.

고분자 전해질막 연료전지는 연료극의 연료와 공기극의 공기에 각각 H2S와 SO2이 포함되어 있을 때 그 성능이 심각하게 감소한다. 본 연구는 고분자전해질막 연료전지의 공기극과 연료극에 1 ppm에서 10 ppm의 불순물 가스를 공급하여 전기적 성능측정을 통해 복합적인 황불순물이 단위전지에 미치는 영향을 확인하였다. 최적의 운전조건에서 불순물가스를 피독하였을 때 SO2와 H2S의 농도가 증가할수록 성능이 급격히 감소하였다(단위전지 온도 65℃, 상대습도 100%). 그리고 황의 흡착은 MEA의 백금 촉매층 표면서 일어나며, 불순물 가스가 MEA에 누적되는 것을 확인하였다. 1, 3, 5, 및 10 ppm 4회의 연속적인 피독 후 연료전지의 성능이 0.71 V에서 0.54 V(76 %)로 감소하였다.

In this study, fine cathode materials and were synthesized using the simple, convenient process of mechanical alloying (MA). In order to improve the cell properties, wet milling processes were conducted using low-energy ball milling to decrease the mean particle size of both materials. The cells of Na/ and Na/ show a high initial discharge capacity of 425 mAh/g and 577 mAh/g respectively using wet milled powder particles, which is much larger than commercial ones, providing some potential as new cathode materials for rechargeable sodium-ion batteries.