Highly safe lithium-ion batteries (LIBs) are required for large-scale applications such as electrical vehicles and energy storage systems. A highly stable cathode is essential for the development of safe LIBs. LiFePO4 is one of the most stable cathodes because of its stable structure and strong bonding between P and O. However, it has a lower energy density than lithium transition metal oxides. To investigate the high energy density of phosphate materials, vanadium phosphates were investigated. Vanadium enables multiple redox reactions as well as high redox potentials. LiVPO4O has two redox reactions (V5+/V4+/V3+) but low electrochemical activity. In this study, LiVPO4O is doped with fluorine to improve its electrochemical activity and increase its operational redox potential. With increasing fluorine content in LiVPO4O1-xFx, the local vanadium structure changed as the vanadium oxidation state changed. In addition, the operating potential increased with increasing fluorine content. Thus, it was confirmed that fluorine doping leads to a strong inductive effect and high operating voltage, which helps improve the energy density of the cathode materials.

Refined structured tin dioxide gets the amount of attraction because of its low cost and stability. The C@SnO2 nanospheres with mesoporous structures were produced using the hard template method in this work. The C@SnO2 is primarily gained attributed to the dehydration condensation of C6H12O6 and the hydrolysis of SnCl4 ·5H2O. The morphology of the C@SnO2 was analyzed by physical characterization and the diameter of the obtained C@SnO2 was around 138 nm. When C@SnO2 was applied to lithium-ion batteries as anode material, it performed outstanding electrochemical properties, with a capacity of 735 and 539 mA h g− 1 maintained at 1000 and 2000 mA g− 1, respectively. Furthermore, it exhibits favorable discharge/ charge cycle stability. This is probably because of the more chemically redox active sites provided by C@SnO2 nanocomposites and it also allows fast ion diffusion and electron migration.

In this study, we investigate the opportunity of using waste tire char as a cathode material for lithium-ion primary batteries (LPBs). The char obtained by carbonizing waste tires was washed with acid and thermally fluorinated to produce CFX. The structural and chemical properties of the char and CFX were analyzed to evaluate the effect of thermal fluorination. The carbon structure of the char was increasingly converted to CFX structure as the fluorination temperature increased. In addition, the manufactured CFX- based LPBs were evaluated through electrochemical analysis. The discharge capacity of the CFX reached a maximum of 800 mAh/g, which is comparable to that of CFX- based LPBs manufactured from other carbon sources. On the basis of these results, the use of waste tire char-based CFX as a cathode material for LPBs is presented as a new opportunity in the field of waste tire recycling.

전고체 전지는 전기 자동차의 안정성을 향상시키기 위해 기존의 리튬 이온 전지를 대체할 주요 후보로 간주되고 있 습니다. 그러나 전고체 전지에 사용되는 황화물계 고체 전해질은 산화 환원 안정성이 부족하며 양극복합전극과 표면 에서 부반응을 이르켜 문제를 야기시킵니다. 때문에 양극 표면 코팅법이 제안되었고 이는 충방전 사이클 안정성 및 속도 특성의 개선에 유용한 효과를 나타낼 수 있습니다. 본 논문에서는 결정학적 분석을 통하여 신규 Li-Zr-O 조성 탐색을 하였고, 다양한 양극 소재 코팅소재 후보군 중 리튬 이온 전도체인 Li6Zr2O7 구조가 매우 유망하다는 연구 결 과를 확인했습니다. 본 논문은 기존에 사용되는 LiNbO3, Li4Ti5O12가 아닌 새로운 다양한 구조 및 조성의 양극 코팅 소 재개발에 대한 필요성 및 가능성을 시사합니다.

With a rapid expansion in electric vehicles, a huge amount of the spent Li-ion batteries (LIBs) could be discharged in near future. And thus, the proper handling of the spent LIBs is essential to sustainable development in the industry of electrical vehicles. Among various approaches such as pyrometallurgy, hydrometallurgy, and direct recycling, the hydrometallurgical manner has gained interest in recycling the spent LIBs due to its high effectiveness in recycling raw materials (e.g., lithium, nickel, cobalt, and manganese). However, the hydrometallurgical process not only requires the use of large amounts of acids and water resources but also produces toxic gases and wastewater leading to environmental and economic problems, considering potential economic and environmental problems. Thus, this review aims to provide an overview of conventional and state-of-the-art hydrometallurgical processes to recover valuable metals from spent LIBs. First, we briefly introduce the basic principle and materials of LIBs. Then, we briefly introduce the operations and pros-and cons- of hydrometallurgical processes. Finally, this review proposes future research directions in hydrometallurgy, and its potential opportunities in the fundamental and practical challenges regarding its deployment going forward.

The inclusion of conductive carbon materials into lithium-ion batteries (LIBs) is essential for constructing an electrical network of electrodes. Considering the demand for cells in electric vehicles (e.g., higher energy density and lower cell cost), the replacement of the currently used carbon black with carbon nanotubes (CNTs) seems inevitable. This review discusses how CNTs can contribute to the development of advanced LIBs for EVs. First, the reason for choosing CNTs as a conducting agent for the cathode is discussed in terms of energy density. Second, the reinforcing effect of CNTs on the anode is described with respect to the choice of silicon as the active material. Third, the development of water-based cathode fabrication as well as dry electrode fabrication with aid of CNTs is discussed. Fourth, three technical hurdles, that is, the price, dispersion issue, and entrapped metal impurities, for widespread use of CNTs in LIBs are discussed.

Silicon oxide (SiOx) has been considered one of the most promising anode materials for lithium-ion batteries due to having a higher capacity than the commercial graphite anodes. However, its practical application is hampered by very large volume variations. In this work, pyrolysis fuel oil is the carbon coating precursor, and physical vapor deposition (PVD) is performed on SiOx at 200 and 400 °C (SiOx@C 200 and SiOx@C 400), followed by carbonization at 950 °C. SiOx@C 200 has a carbon coating layer with a thickness of ~ 20 nm and an amorphous structure, while that of SiOx@C 400 is approximately 10 nm thick and has a more semigraphitic structure. The carbon-coated SiOx anodes display better charge–discharge performance than the pristine SiOx anode. In particular, SiOx@C 200 shows the highest reversible capacity compared with the other samples at high C-rates (2.0 and 5.0 C). Moreover, SiOx@C 200 exhibits excellent cycling stability with a capacity retention of 90.2% after 80 cycles at 1.0 C. This result is ascribed to the suppressed volume expansion by the PFO carbon coating on SiOx after PVD.

Despite having a low electrical conductivity, graphene oxide (GO) is used as an anode material in lithium-ion batteries (LIBs) owing its good processability in large quantities. GO is reduced by chemical or thermal treatments to enhance its electrical conductivity. In this study, high-performance GO anodes with polydopamine (PDA) and polyethylenimine (PEI) as binders were fabricated. Gamma (γ)-ray irradiation was applied to the GO–PDA–PEI hybrid sheets to covalently cross-link the GO sheets and binders with an amide bond. The covalent crosslinking was confirmed by Fourier-transform infrared spectroscopy analysis. Further, X-ray photoelectron spectroscopy results showed that γ-ray irradiation produced a reduced GO sheet, which resulted in an increase in the electrical conductivity by 30%. By characterizing the electrochemical properties, we found that the γ-ray irradiation facilitates the stability and increases the charge/discharge capacity by crosslinking GO and PDA–PEI binders and reducing the GO sheets.

Ni-rich계 양극 소재는 낮은 가격과 높은 용량으로 인해 고용량 달성을 위한 상용화 소재로 주목받고 있지만, 이 소재의 경 우 전기화학적 불안정성으로 인한 한계를 가진다. 그래서 다양한 표면 코팅 방법을 통해 성능향상을 이루고 있지만, 성능향상이 소 재와 코팅 방법때문인지 또는 코팅 범위가 넓어진 것 때문인지는 모호하게 남아 있다. 본 연구에서는 전이금속으로 양극 활물질을 코팅할 때 전구체 코팅 범위에 따른 리튬이온배터리 전기화학 성능평가를 분석하였다. 상업용 LiNi0.8Co0.1Mn0.1O2 양극 소재 표면을 에탄올 용액에 용해된 리튬-코발트와 리튬-주석 아세테이트 전구체를 코팅하였고, 교반속도를 다르게 하여 (200 rpm 및 600 rpm) 전구체 코팅 범위를 다르게 하였다. 리튬-코발트 아세테이트 전구체의 경우 교반속도가 증가할수록 코팅 범위가 증가하였지만, 리튬 -주석 아세테이트 전구체의 경우 교반속도가 증가할수록 코팅 범위가 감소하였다. 하지만 원소의 종류에 관계없이 코팅 범위가 넓 은 경우에 상대적으로 우수한 전기화학적 성능을 나타내었다. 코팅된 양극 활물질의 물리적 특성은 SEM 및 XRD를 이용하여 분석하 였으며, 전기화학적 성능은 초기 충·방전 용량, 사이클 안정성 및 율속특성 테스트를 통해 조사하였다.

In this study, multilayered SnO nanoparticles are prepared using oleylamine as a surfactant at 165oC. The physical and chemical properties of the multilayered SnO nanoparticles are determined by transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Interestingly, when the multilayered SnO nanoparticles are heated at 400oC under argon for 2 h, they become more efficient anode materials, maintaining their morphology. Heat treatment of the multilayered SnO nanoparticles results in enhanced discharge capacities of up to 584 mAh/g in 70 cycles and cycle stability. These materials exhibit better coulombic efficiencies. Therefore, we believe that the heat treatment of multilayered SnO nanoparticles is a suitable approach to enable their application as anode materials for lithium-ion batteries.

This study examined the effects of micro- (crystallinity) and macro (orientation)-crystalline properties of graphite on the initial efficiency, discharge capacity, and rate performance of anodic materials. Needle coke and regular coke were selected as raw materials and pulverized to 2–25 μm to determine the effects of crystalline properties on particle shape after pulverization. Needle coke with outstanding crystallinity had high initial efficiency, and smaller particles with larger specific surface areas saw increased irreversible capacity due to the formation of SEI layers. Because of cavities existing between crystals, the poorer the crystalline properties were, the greater the capacity of the lithium ions increased. As such, regular coke had a 30 mAh/g higher discharge capacity than that of needle coke. Rate performance was more affected by particle size than by crystalline structure, and was the highest at a particle distribution of 10–15 μm.

논문에서 리튬이온전지용 양극 소재의 개발 동향과 함께 앞으로 필요한 양극 소재의 연구 방향을 제시한다. 현재 리튬이온 전지는 지구 환경 개선을 위한 친환경 에너지로 주목받고 있으며, 전기차와 에너지저장 시스템 등에서의 다양한 활용으로 고용량 및 고안정성 소재 개발에 초점을 맞추어 연구가 진행되고 있다. 특히, 리튬이온전지 양극 소재의 경우 전지의 가격 및 성능을 결정하기 때문에 활발한 연구가 이루어지며, 그중 높은 이론 용량을 가지는 Ni-rich 계 layered 구조의 양극 소재에 대한 연구가 집중되고 있다. 그러나, 고용량 특성을 달성하기 위한 Ni-rich 계 양극 소재는 높은 Ni 조성에 의해 비용량이 증가함에 따라 전기화학적 불안정성 또한 증가하는 문제를 가지기 때문에 활용에 한계를 가진다. 이를 해결하기 위한 방법으로 본 논문에서는 양극 소재의 표면 개질 방법 과 원소치환 방법에 대해 언급하며, 이에 진일보하여 리튬이온전지의 가격 경쟁력을 확보하기 위한 양극 소재의 연구 방향을 제안한다.

Nanostructured ZnO materials have been studied extensively because of their functional properties. This paper presents a composite material of zinc oxide quantum dots (ZnO QDs) and porous carbon using a one-step carbonization process. The direct carbonization of a metal–organic complex generates mesostructured porous carbon with a homogeneous distribution of ZnO QDs. The structural and morphological properties are investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The resulting ZnO QDs@porous carbon composite delivers a high specific capacity of 990 mAh g−1 at 100 mA g−1, 357 mAh g−1 at 2 A g−1, and high reversibility when evaluated as an anode for lithium ion batteries.