• Korean Journal of Materials Research
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• v.32 no.4
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• pp.216-222
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• 2022

The capacity of high nickel Li(Ni_xCo_yMn_1-x-y)O₂ (NCM, x ≥ 0.8) cathodes is known to rapidly decline, a serious problem that needs to be solved in a timely manner. It was reported that cathode materials with the {010} plane exposed toward the outside, i.e., a radial structure, can provide facile Li⁺ diffusion paths and stress buffer during repeated cycles. In addition, cathodes with a core-shell composition gradient are of great interest. For example, a stable surface structure can be achieved using relatively low nickel content on the surface. In this study, precursors of the high-nickel NCM were synthesized by coprecipitation in ambient atmosphere. Then, a transition metal solution for coprecipitation was replaced with a low nickel content and the coprecipitation reaction proceeded for the desired time. The electrochemical analysis of the core-shell cathode showed a capacity retention of 94 % after 100 cycles, compared to the initial discharge capacity of 184.74 mA h/g. The rate capability test also confirmed that the core-shell cathode had enhanced kinetics during charging and discharging at 1 A/g.

• Environmental Engineering Research
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• v.25 no.1
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• pp.88-95
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• 2020

An investigation of rare metals recovery from LiNi_xCo_yMn_zO₂ cathode material of the end-of-life lithium-ion batteries is presented. To determine the influence of reductant on the leach process, the cathode material (containing Li 7.6%, Co 20.4%, Mn 19.4%, and Ni 19.3%) was leached in H₂SO₄ solutions either with or without H₂O₂. The optimal process parameters with respect to acid concentration, addition dosage of H₂O₂, temperature, and the leaching time were found to be 2.0 M H₂SO₄, 4 vol.% H₂O₂, 70℃, and 150 min, respectively. The yield of metal values in the leach liquor was > 99%. The leach liquor was subsequently treated by precipitation techniques to recover nickel as Ni(C₄H₇N₂O₂)₂ and lithium as Li₂CO₃ with stoichiometric ratios of 2:1 and 1.2:1 of dimethylglyoxime:Ni and Na₂CO₃:Li, respectively. Cobalt was recovered by solvent extraction following a 3-stage process using Na-Cyanex 272 at pH_eq ~5.0 with an organic-to-aqueous phase ratio (O/A) of 2/3. The loaded organic phase was stripped with 2.0 M H₂SO₄ at an O/A ratio of 8/1 to yield a solution of 114 g/L CoSO₄; finally recovered CoSO₄.xH₂O by crystallization. The process economics were analyzed and found to be viable with a margin of $476 per ton of the cathode material.

• Resources Recycling
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• v.30 no.6
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• pp.43-52
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• 2021

In this study, the optimal nitration process for selective lithium leaching from powder of a spent battery cell (LiNi_xCo_yMn_zO₂, LiCoO₂) was studied using Taguchi method. The nitration process is a method of selective lithium leaching that involves converting non-lithium nitric compounds into oxides via nitric acid leaching and roasting. The influence of pretreatment temperature, nitric acid concentration, amount of nitric acid, and roasting temperature were evaluated. The signal-to-noise ratio and analysis of variance of the results were determined using L₁₆(4⁴) orthogonal arrays. The findings indicated that the roasting temperature followed by the nitric acid concentration, pretreatment temperature, and amount of nitric acid used had the greatest impact on the lithium leaching ratio. Following detailed experiments, the optimal conditions were found to be 10 h of pretreatment at 700℃ with 2 ml/g of 10 M nitric acid leaching followed by 10 h of roasting at 275℃. Under these conditions, the overall recovery of lithium exceeded 80%. X-ray diffraction (XRD) analysis of the leaching residue in deionized water after roasting of lithium nitrate and other nitrate compounds was performed. This was done to determine the cause of rapid decrease in lithium leaching rate above a roasting temperature of 400℃. The results confirmed that lithium manganese oxide was formed from lithium nitrate and manganese nitrate at these temperatures, and that it did not leach in deionized water. XRD analysis was also used to confirm the recovery of pure LiNO₃ from the solution that was leached during the nitration process. This was carried out by evaporating and concentrating the leached solution through solid-liquid separation.

• Journal of the Korean Electrochemical Society
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• v.15 no.4
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• pp.230-235
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• 2012

Polymer electrolytes consisted of $BF_3LiMA$ and 300 (PEGMA300) or 1100 (PEGMA1100) g $mol^{-1}$ of PEGMA were prepared and the electrochemical properties were characterized. Interestingly, the AC-impedance measurement shows $1.22{\times}10^{-5}S\;cm^{-1}$ of room temperature ionic conductivity from PEGMA1100 based solid polymer electrolytes while $8.54{\times}10^{-7}S\;cm^{-1}$ was observed in PEGMA300 based liquid polymer electrolytes. The more suitable coordination between lithium ion and ethylene oxide (EO) unit might be the reason of higher ionic conductivity which can be possible in PEGMA1100 based electrolytes since it has 23 EO units in monomer. The lithium ion transference number was found to be 0.6 due to the side reactions between $BF_3$ and lithium metal expecially for longer time but 0.9 was observed within 3000 seconds of measuring time which is strong evidence of a single-ion conductor.

• Journal of the Korean Magnetics Society
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• v.24 no.6
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• pp.197-201
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• 2014

As the importance of rare metal is increasing globally, Japan introduced the concept of Strategic Elements in 2004, and started Strategic Elements Project in 2007. The Goal of this project run by MEXT (Ministry of Education, Culture, Sports, Science and Technology) is to develop high-function materials and components that do not use rare or harmful elements by studying the role and characteristics of the elements that compose materials and components and decide their functions and characteristics. In September 2010, Japanese coast guard arrested a Chinese fishing boat near Senkaku Islands (Diaoyudao Islands by China), which escalated to the territory issue and eventually a big diplomatic and economic conflict. In order to put pressure on Japanese Government, China used an economic option, which is the ban of rare earth export to Japan. This incident doubled Japan's motivation to develop Strategic Elements and put more efforts into this Project. MEXT set the following three research areas in February 2012: Study of alternative materials using sufficient and harmless elements, Study of applications for the high-functions of Strategic Elements, Study of practical design for components using Strategic Elements. Through a course of gathering the opinion of professionals, MEXT settled down with the following 4 research and study areas for the Strategic Elements Project in June 2012. 1. Magnetic materials to replace Dy, Nd. 2. Catalyst/Battery materials to replace Pt, Rh/Li, Co. 3. Electronic materials to replace In, Ta. 4. Structural materials to replace Nb, Mo. This paper deals with the first area and reviews the results of the research and study as of now.

• Transactions of the Korean hydrogen and new energy society
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• v.28 no.2
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• pp.156-165
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• 2017

This study quantitatively assessed the environmental impacts of fuel cell (FC) systems by performing life cycle assessment (LCA) and analyzed their energy efficiencies based on energy return on investment (EROI) and electrical energy stored on investment (ESOI). Molten carbonate fuel cell (MCFC) system and polymer electrolyte membrane fuel cell (PEMFC) system were selected as the fuel cell systems. Five different paths to produce hydrogen ($H_2$) as fuel such as natural gas steam reforming (NGSR), centralized naptha SR (NSR(C)), NSR station (NSR(S)), liquified petroleum gas SR (LPGSR), water electrolysis (WE) were each applied to the FCs. The environmental impacts and the energy efficiencies of the FCs were compared with rechargeable batteries such as $LiFePO_4$ (LFP) and Nickel-metal hydride (Ni-MH). The LCA results show that MCFC_NSR(C) and PEMFC_NSR(C) have the lowest global warming potential (GWP) with 6.23E-02 kg $CO_2$ eq./MJ electricity and 6.84E-02 kg $CO_2$ eq./MJ electricity, respectively. For the impact category of abiotic resource depletion potential (ADP), MCFC_NGSR(S) and PEMFC_NGSR(S) show the lowest impacts of 7.42E-01 g Sb eq./MJ electricity and 7.19E-01 g Sb eq./MJ electricity, respectively. And, the energy efficiencies of the FCs are higher than those of the rechargeable batteries except for the case of hydrogen produced by WE.

• Journal of the Korean Electrochemical Society
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• v.15 no.3
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• pp.198-205
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• 2012

Carbon-supported manganese oxide composite were fabricated as an air cathode material for Li-air batteries by hydrothermal method. The composite materials of carbon and manganese oxide were investigated by the implementation of X-ray diffraction, FE-SEM and BET surface area measurer. The manganese oxide synthesized at $170^{\circ}C$ for 12 h has a rod like shape morphology with 40-50 nm long in size. A Lithium-air battery with coin type, of which electrodes are composed of cathode composite materials synthesized $170^{\circ}C$-12 h and lithium metal anode, reveals its first discharge capacity of 3,852 mAh/g and four discharge-charge cycles.

• Journal of the Microelectronics and Packaging Society
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• v.12 no.3 s.36
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• pp.267-274
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• 2005

This paper presents the fabrication of surface acoustic wave (SAW)-based pressure sensor for long-term stable mechanical compression force measurement. SAW pressure sensor has many attractive features for practical pressure measurement: no battery requirement, wireless pressure detection especially at hazardous environments, and easy other functionality integrations such as temperature, humidity, and RFID. A $41^{\circ}$ YX $LiNbO_3$ piezoelectric substrate was used because of its high SAW propagation velocity and large values of electromechanical coupling factors $K^2$. A silicon substrate with $\~200{\mu}m$ deep cavity was bonded to the diaphragm with epoxy, in which gold was covered all over the inner cavity in order to confine electromagnetic energy inside the sensor, and provide good isolation of the device from its environment. The reflection coefficient $S_{11}$ was measured using network analyzer. High S/N ratio, sharp reflected peaks, and clear separation between the peaks were observed. As a mechanical compression force was applied to the diaphragm from top with extremely sharp object, the diaphragm was bended, resulting in the phase shifts of the reflected peaks. The phase shifts were modulated depending on the amount of applied mechanical compression force. The measured $S_{11}$ results showed a good agreement with simulated results obtained from equivalent admittance circuit modeling.

• Journal of the Korean Electrochemical Society
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• v.24 no.4
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• pp.93-99
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• 2021

In order to decrease the weight of stretchable energy storage devices, interest in developing lightweight materials to replace metal current collectors is increasing. In this study, nanofibers prepared by electrospinning a conductive polymer, PEDOT:PSS, were used as current collectors for lithium ion batteries. The nanofiber showed improved electrical conductivity by using DMSO, a dopant, and indicated a stretch rate of 30% or more from the elasticity evaluation result. In addition, the use of the nanofiber current collector facilitates penetration of the liquid electrolyte and exhibits the effect of increasing the electronic conductivity through the nanofiber network. The lithium-ion battery using the DMSO-doped PEDOT:PSS@PAM nanofiber current collector indicated a high discharge capacity of 135mAh g^-1, and indicated a high capacity retention rate of 73.5% after 1000 cycles. Thus, the excellent electrochemical stability and mechanical properties of conductive nanofibers showed that they can be used as lightweight current collectors for stretchable energy storage devices.

• Economic and Environmental Geology
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• v.56 no.6
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• pp.781-797
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• 2023

Recently, there has been a rapid response from mineral-demanding countries for securing critical minerals in a high tech industries. Graphite, while overwhelmingly dominated by China in production, is changing in global supply due to the exponential growth in EV battery sector, with active exploration in East Africa. Rare earth elements are essential raw materials widely used in advanced industries. Globally, there are ongoing developments in the production of REEs from three main deposit types: carbonatite, laterite, and ion-adsorption clay types. While China's production has decreased somewhat, it still maintains overwhelming dominance in this sector. Recent changes over the past few years include the rapid emergence of Myanmar and increased production in Vietnam. Nickel has been used in various chemical and metal industries for a long time, but recently, its significance in the market has been increasing, particularly in the battery sector. Worldwide, nickel deposits can be broadly classified into two types: laterite-type, which are derived from ultramafic rocks, and ultramafic hosted sulfide-type. It is predicted that the development of sulfide-type, primarily in Australia, will continue to grow, while the development of laterite-type is expected to be promoted in Indonesia. This is largely driven by the growing demand for nickel in response to the demand for lithium-ion batteries. The global lithium ores are produced in three main types: brine lake (78%), rock/mineral (19%), and clay types (3%). Rock/mineral type has a slightly higher grade compared to brine lake type, but they are less abundant. Chile, Argentina, and the United States primarily produce lithium from brine lake deposits, while Australia and China extract lithium from both brine lake and rock/mineral sources. Canada, on the other hand, exclusively produces lithium from rock/mineral type. Vanadium has traditionally been used in steel alloys, accounting for approximately 90% of its usage. However, there is a growing trend in the use for vanadium redox flow batteries, particularly for large-scale energy storage applications. The global sources of vanadium can be broadly categorized into two main types: vanadium contained in iron ore (81%) produced from mines and vanadium recovered from by-products (secondary sources, 18%). The primary source, accounting for 81%, is vanadium-iron ores, with 70% derived from vanadium slag in the steel making process and 30% from ore mined in primary sources. Intermediate vanadium oxides are manufactured from these sources. Vanadium deposits are classified into four types: vanadiferous titanomagnetite (VTM), sandstone-hosted, shale-hosted, and vanadate types. Currently, only the VTM-type ore is being produced.