High nickel content Li(NixCoyMn1-x-y)O2 (NCM, x ≥ 0.9) cathode materials suffer from rapid capacity fading, a significant obstacle to their commercial application. To mitigate this issue, strategies such as doping and coating with various elements have been widely reported. In particular, multi-element doping has been explored as a potentially more effective alternative to single or dual element modification. Concurrently, the synthesis of high-entropy precursors via coprecipitation has gained significant attention. In this study, high nickel content precursors with nine components were synthesized by hydroxide coprecipitation under varying concentrations of ammonia that was employed as a chelating agent. The primary particle morphology of the precursors was found to be dependent on the ammonia concentration, which in turn influenced the physicochemical and electrochemical properties of the final cathode materials. At low ammonia concentration, the formation of secondary phases was detected. Notably, the cathode synthesized under high ammonia concentration exhibited excellent cycling stability, delivering a discharge capacity of 164.22 mAh/g after 100 cycles at 1 C, which corresponds to a capacity retention of approximately 91 % of its initial discharge capacity (180.50 mAh/g at 0.1 C).

It is addressed that the challenges of poor cyclic stability and low conductivity in metal–organic frameworks (MOFs) hinder their application in energy storage. Here, we synthesized binary metal MOFs through a one-step hydrothermal process, subsequently calcined to produce Co–Mn/reduced graphene oxide (rGO). This approach not only carbonized the organic framework but also enhanced its electrical conductivity and stability. Our findings demonstrated that the synergistic effects of Co and Mn within the assembled electrode resulted in remarkable performance, achieving a specific capacitance of 3558.65 F g− 1 at 1 A g− 1 and a rate capability of 1000 F g− 1 at 30 A g− 1. The Co–Mn/rGO anode in the asymmetric supercapattery exhibited a broadened operating potential window of 1.5 V, delivering an energy density of 54.65 W h kg− 1 at a power density of 125 W kg− 1, and maintaining 11.375 W h kg− 1 at a high power density of 12,500 W kg− 1. Notably, the capacitance retention rate reached 99.99% after 10,000 cycles at a current density of 10 A g− 1. These results suggest that the developed Co–Mn/rGO composite represents a promising candidate for advanced energy storage systems, offering both high performance and stability.

Sodium-ion batteries (SIBs) offer a viable alternative to partially or fully replace lithium ion batteries (LIBs) due to their lower cost and increased safety. This paper outlines the compositional optimizations, crystallographic evaluations, and electrochemical behavior of a novel mixed NASICON polyanionic compound, NaFe2PO4(SO4)2 (NFPS). X-ray photoelectron spectrometry (XPS) results showed that cobalt doping produces a higher concentration of oxygen defects compared to undoped samples. Scanning electron microscopy (SEM) analysis results revealed that the modified sample has more uniform pores and pore distribution. Brunauer-Emmett-Teller (BET) measurements showed that doping of Co2+ reduces the specific surface area of NFPS-Co0.08 compared to NFPS. This shortens the sodium ion diffusion pathway and promotes ion dynamics. The addition of Co2+ to the sample significantly improved its performance during galvanostatic charge-discharge tests. The electrochemical activity also is significantly enhanced by Co2+ doping. Na0.84Co0.08Fe2PO4(SO4)2 exhibits superior rate and cycling performance compared to pristine NFPS. After 80 cycles at 25 mA g-1, NFPS-Co0.08 retained discharge specific capacity of 60.8 mA h g-1, which is 1.24 times greater than that of NFPS.

Manganese dioxide, functioning as a cathode material for aqueous zinc-ion batteries (AZIBs), demonstrates a variety of benefits, such as elevated theoretical specific capacity, outstanding electrochemical performance, environmental compatibility, ample resource availability, and facile modification. These advantages make MnO2 one of the cathode materials that have attracted much attention for AZIBs. Nevertheless, manganese dioxide cathode in practical applications suffers from structural instability during the cycling process because of sluggish electrochemical kinetics and volume expansion, which hinder their large-scale application. Doping and compositing with conducting frameworks is an effective strategy for improving structural stability. Herein, homogeneously in situ growth of Yttrium-doped MnO2 nanorods on conductive reduced graphene oxide (Y-MnO2/rGO), were synthesized through a straightforward hydrothermal method. The Y-MnO2/rGO electrodes have an ultra-long cycle life of 179.2 mA h g− 1 after 2000 cycles at 1 A g− 1 without degradation. The excellent structural stability is attributed to the cooperative effect of yttrium doping and compositing with rGO, which is an effective approach to enhance the stability and mitigate the Jahn–Teller distortion associated with Mn ions.

To optimize the electrochemical properties of Ni-rich cathode materials, CPAN@SC-NCM811 is prepared via surface modification of single-crystalline LiNi0.8Co0.1Mn0.1O2 cathode material by adding 1, 2 and 3 wt.% of polyacrylonitrile, respectively. Significantly, the results obtained from X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM) verify the successful synthesis of CPAN@SC-NCM811 cathode, which exhibits better electrochemical properties compared to SC-NMC811. After thorough milling and calcination of 2 wt.% polyacrylonitrile with SC-NCM811, the initial discharge specific capacity of prepared S2 sample is 197.7 mAh g− 1 and the capacity retention reached 89.2% after 100 cycles at a rate of 1.0 C. Furthermore, the S2 sample exhibits superior rate performance compared to the other three samples, in which these superior electrochemical properties are largely attributed to the optimal ratio of conductive cyclized polyacrylonitrile coatings. Overall, this work offers guidelines for modifying the surface of SC-NCM811 cathode materials for lithium-ion batteries with exceptional cycling and rate performance.

Lithium- and manganese-rich layered oxide (LMRO) is considered a promising cathode material for lithium-ion batteries owing to its high capacity and energy density. However, operation at a high voltage of 4.8 V leads to several issues including low Coulombic efficiency, poor cycle life, slow kinetics, and voltage decay due to spinel phase transition, hindering commercialization. Herein, we synthesized a cobalt-free LMRO cathode and studied the effect of Nb2O5 and Sb2O3 coating layers on electrochemical performance. The Nb2O5 coating facilitated the formation of a LiNbO3 layer, which enhanced the initial electrochemical performance, including Coulombic efficiency and energy density. Meanwhile, Sb2O3 not only coated the surface but also doped into the bulk structure, thereby increasing capacity and improving rate capability. Comparative analysis using materials with different structural solubility revealed how oxide coatings influenced lithium-ion transport and electrochemical behavior. This study highlights the importance of interfacial engineering for optimizing LMRO cathodes for high-performance lithium-ion batteries.

LiFePO4/C has been successfully synthesized using surfactant-assisted solid-state reaction method to investigate the effects of non-polar solvents on structural properties and electrochemical performance. Petroleum jelly, oleic acid, and sucrose were used as non-polar solvents, surfactants and carbon sources. The ratio of petroleum jelly and oleic acid were 0.5:1 (LFP A), 1:1 (LFP B), and 2:1 (LFP C). The XRD, FE-SEM, and HR-TEM results show that adding petroleum jelly in LFP C enhances crystallinity and improves the morphology of nanoplates in LiFePO4 material. The EDS and Raman Spectroscopy tests show that the higher addition of petroleum jelly increases carbon percentage and carbon layer defects. The highest Li-ion diffusion coefficient was calculated by LFP C of 4.21 × 10– 15 cm2. s−1. Furthermore, the highest discharge test results at 0.1 C of LFP A, LFP B, and LFP C were 125 mAh.g−1, 103 mAh.g−1, and 144 mAh.g−1, respectively. However, C-rate performance shows that the specific capacity of LFP A, LFP B, and LFP C at 5 C were 74 mAh.g−1, 35 mAh.g−1, and 59 mAh.g−1, respectively. The cyclability test results showed that LFP A capacity retention after testing for 100 cycles was better than LFP C, and the lowest stability was obtained by LFP B. The addition of petroleum jelly improved the performance of LiFePO4/ C but resulted in excess carbon in active material which decreased battery stability and specific capacity at high C-rate. Our results suggest that non-polar solvents can be added to LiFePO4/ C synthesis to improve electrochemical performance but less carbon chains must be chosen.

As increasing markets for Lithium‒ion battery (LiB), several environmental issues have attained great attention. Especially, the organic solvent N‒Methyl‒2‒Pyrrolidone (NMP), commonly used in the traditional slurry casting process for fabricating LiB electrodes, will be about to be regulated due to its toxicity and the environmental concerns. Therefore, the production of LiB electrodes by a dry process without using NMP organic solvents is of special interest nowadays. In the dry process, it is generally accepted that 1‒dimensional carbon materials like carbon nanotubes (CNT) are beneficial than conventional carbon conductor such as carbon blacks (CB). However, CB is inevitably included during the CNT production, simultaneously as an impurity. Refining CNT from CNT/CB mixture can cause another cost obviously. On the other hand, there have been limited information to study dispersion of carbon materials in electrode with respect to dispersion method and types of carbon conductor. Here, we systematically test the effect of dispersibility of carbon conductor in electrode according to dispersion method and type of carbon conductors. In addition, effect of CB amount in carbon conductor are also elucidated on manufacturing procedure, properties of electrode and their electrochemical performances.

Lithium-ion batteries (LIBs) are widely used as essential power sources for electric vehicles and energy storage systems. Among various cathode materials, Li[Ni0.9Mn0.1]O2 (NM90) has gained significant attention for enhancing the performance of LIBs due to its high energy density and nontoxicity. However, increasing the nickel content introduces challenges, including structural instability and cation mixing. To address these issues, we propose a surface coating strategy using nitrogendoped carbon quantum dots (NCQDs). NCQDs provide high electrical conductivity and electrochemically active sites, so the NCQDs coating effectively enhanced both structural stability and electrical/ionic conductivity. The NCQDs were synthesized via a hydrothermal method, and NM90 were synthesized by co-precipitation. The fabricated NCQD/NM_5 electrode exhibited superior electrochemical properties, including a high initial capacity of 189.6 mAh/g, excellent rate performance, and an outstanding capacity retention of 81.5 % after 200 cycles in 1C. These superior results demonstrate that surface modification using the NCQDs strategy for Li[Ni0.9Mn0.1]O2 cathode materials will contribute to the further development of cycle stability and ultrafast performance in energy storage systems.

In this study, ferric phosphate precursors were prepared by controlling precipitation time, and the resulting LiFe PO4 active materials were thoroughly investigated. Microscale LiFePO4 cathode materials, designed for high energy density at the cell level, were successfully synthesized through a 10 h co-precipitation. As the reaction time increased, smaller primary particles were aggregated more tightly, and the secondary particles exhibited a more spherical shape. Meanwhile, ammonia did not work effectively as a complexing agent. The carbon coated LiFePO4 (LiFePO4/C) synthesized from the 10 h ferric phosphate precursor exhibited larger primary and secondary particle sizes, a lower specific surface area, and higher crystallinity due to the sintering of the primary particles. Enhanced battery performance was achieved with the LiFePO4/C that was synthesized from the precursor with the smaller size, which exhibited the discharge capacity of 132.25 mAh ‧ g-1 at 0.1 C, 70 % capacity retention at 5 C compared with 0.1 C, and 99.9 % capacity retention after the 50th cycle. The better battery performance is attributed to the lower charge transfer resistance and higher ionic conductivity, resulting from smaller primary particle sizes and a shorter Li+ diffusion path.

본 연구는 대기 중 장기간 노출로 인해 열화된 Ni-rich NCM811(LiNi₀.₈Co₀.₁Mn₀.₁O₂) 양극 소재의 계면 저항 증가 및 전기화학적 성능 저하 문제를 해결하기 위해, 물리적 열처리 방법을 제안하였다. NCM811 양극 소재는 대기 중 수분 및 이산화탄소와의 반응에 의해 표면에 불순물이 형성되기 쉬우며, 이는 고체전해질과의 계면 저항을 증가시켜 전고 체전지 시스템에서의 성능 저하를 초래한다. 이러한 문제를 해결하기 위해, 열화된 NCM811 양극 소재를 O₂ 분위기 에서 열처리하여 표면의 불순물을 효과적으로 제거하고 양극 표면의 전도성을 향상시킴으로써, 양극-고체전해질 간의 계면 저항을 현저히 감소시키는 결과를 얻었다. SEM, XRD, ICP 분석을 통해 열화된 NCM811 양극 소재의 표면 특성 변화를 분석하였으며, 열처리 후 NCM811 소재의 계면 특성이 개선됨에 따라 전기화학적 성능 또한 상용 NCM811 소재와 유사한 수준으로 회복되는 것을 확인하였다. 특히, O₂ 분위기의 물리적 열처리 방법은 Ni-rich NCM811 양극 소재의 열화를 효과적으로 억제하고 고체전해질과의 계면 접촉을 개선하여, 황화물계 전고체전지의 전기화학적 성능 을 획기적으로 향상시킬 수 있는 유망한 기술임을 입증하였다. 이러한 결과는 전고체전지 상용화를 위한 핵심 전략으 로 적용될 수 있을 것으로 기대된다.

Na4MnV(PO4)3 (NMVP) cathode materials have attracted significant attention as potential candidates for grid applications due to their distinctive structure and high theoretical capacity. However, their inadequate electronic conductivity compromises both cycling stability and rate capability, presenting a challenge for practical implementation. To address this issue, we employed a strategy involving Zr4+ doping and dual-carbon coating to enhance the electrochemical performance of NMVP. The resulting Na3.8MnV0.8Zr0.2( PO4)3/C/rGO composite demonstrated markedly improved rate capability (71.9 mAh g− 1 at 60 °C) and sustained cyclic stability (84.8% retention at 2 C after 1000 cycles), as validated through comprehensive kinetics assessments. The enhanced performance can be attributed to the expanded Na-ion pathways facilitated by large size ion doping and the improved electronic conductivity enabled by the dual-layer coating.

As the demand for lithium-ion batteries for electric vehicles is increasing, it is important to recover valuable metals from waste lithium-ion batteries. In this study, the effects of gas flow rate and hydrogen partial pressure on hydrogen reduction of NCM-based lithium-ion battery cathode materials were investigated. As the gas flow rate and hydrogen partial pressure increased, the weight loss rate increased significantly from the beginning of the reaction due to the reduction of NiO and CoO by hydrogen. At 700 °C and hydrogen partial pressure above 0.5 atm, Ni and Li2O were produced by hydrogen reduction. From the reduction product and Li recovery rate, the hydrogen reduction of NCM-based cathode materials was significantly affected by hydrogen partial pressure. The Li compounds recovered from the solution after water leaching of the reduction products were LiOH, LiOH·H2O, and Li2CO3, with about 0.02 wt% Al as an impurity.

최근 전기차 및 전력저장 시스템과 같은 대형 전지 시장의 성장으로 인해 리튬 이온 배터리에 대한 수요가 급증하 고 있다. 이에 따라 폐전지의 발생이 빠르게 증가할 것 으로 예상되며, 이에 대한 처리가 사회적 문제가 될 것 으로 예상된다. 폐전지 처리의 가장 효과적인 방법은 폐전지의 소재를 재활용하는 방법이다. 이 중 고가의 금속 물질로서, 재활용 시 경제성이 가장 높은 양극 소재 재활용 연구가 가장 활발히 이뤄지고 있다. 하지만 폐전지로부터 회수된 블 랙 파우더에는 도전재 및 바인더가 포함되어 있는데 양극 소재를 재활용하기 위해서는 이를 제거하는 공정이 필요하 다. 본 연구에서는 폐전지에서 추출된 폐양극 소재의 재활용을 위한 소재 전처리 연구를 제시한다. 열처리 및 화학 처리의 두 가지 전처리 공정을 사용하여 불순물을 제거하였고, 이에 따른 제거 정도를 SEM 분석을 통해 확인하였고, 불순물의 정량 분석을 TGA, EA 분석을 통해 확인하였으며, 전기화학 성능을 분석하였다.

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.

The development of functional carbon materials using waste biomass as raw materials is one of the research hotspots of lithium-sulfur batteries in recent years. In this work, used a natural high-quality carbon source—coffee grounds, which contain more than 58% carbon and less than 1% ash. Honeycomb-like S and N dual-doped graded porous carbon (SNHPC) was successfully prepared by hydrothermal carbonization and chemical activation, and the amount of thiourea used in the activation process was investigated. The prepared SNHPC showed excellent electrochemical energy storage characteristics. For example, SNHPC-2 has a large pore volume (1.85 cm3·g− 1), a high mesoporous ratio (36.76%), and a synergistic effect (S, N interaction). As the cathode material of lithium-sulfur batteries, SNHPC-2/S (sulfur content is 71.61%) has the highest specific capacity. Its initial discharge-specific capacity at 0.2 C is 1106.7 mAh·g−1, and its discharge-specific capacity after 200 cycles is still as high as 636.5 mAh·g−1.

Rechargeable zinc-based batteries (RZBs) with the advantages of high safety, low cost, abundant resources and environmental friendliness, are considered as advanced secondary battery systems that can be applied to large-scale energy storage. As an important cathode material for RZBs, NASICON-type Na3V2( PO4)3 (NVP) possesses three-dimensional and large-scale ion channels that facilitate the rapid diffusion of Zn2+, and has a higher average operating voltage compared with other vanadiumbased compounds, thus exhibiting the possibility of realizing RZBs with high energy density. However, NVP still has some problems, such as poor electronic conductivity and spontaneous dissolution in aqueous solution. The sluggish kinetics of Zn2+ (de)intercalation in NVP and dendritic growth on the Zn anode also contribute to the poor rate performance and short cycle life of the batteries. In this review, optimization strategies for the electrochemical performance of RZBs with NVP as cathode are systematically elaborated, including modification of NVP cathode and optimization of electrolyte. Several mainstream energy storage mechanisms and analysis methods in this battery system are sorted out and summarized. On this basis, the development direction of NVP–RZB system is further prospected.

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.

본 연구는 코팅 방법을 활용한 단결정 양극 소재 연구로서 Ni-rich계 다결정 양극 소재로 부터 단결정 양극 소재를 합 성하여 사이클 구동 시 양극 소재의 안정성을 향상시키고자 한다. 양극 소재에 LixCoO2와 LixSnO3 를 각각 코팅하여 이차입자 내부 혹은 외부에 코팅층이 형성된 양극 소재를 합성한 후 이를 소결하여 단결정 형성에 대한 영향을 비교 하였다. 입자 외부에 LixSnO3가 코팅되어 열처리 된 Ni0.8Co0.1Mn0.1O2(NCM811)의 경우 코팅 처리 없이 열처리된 양극 소재 보다 개선된 수명특성을 보였으나, 단결정화가 이뤄지지 않았다. 입자 내부에 LixCoO2 코팅층이 형성된 NCM811 을 열처리 한 결과 이차입자 내부에 형성된 Co 코팅층이 결정화되어 50회 사이클 후 기준 단결정 양극 소재의 방전용 량인 117.34 mAh·g-1 대비 129.11 mAh·g-1의 높은 방전용량을 나타내었고, 형상제어를 통해 이성적인 단결정화가 이뤄 졌다. 본 연구는 다결정체인 Ni-rich 양극소재의 단결정화에 대한 유요한 통찰력을 제공할 것으로 예상한다.

Here, we have demonstrated the successful exfoliation of graphite into a layered material with scotch tape-like exfoliation. Sulfur acts as an exfoliating agent and exfoliates the loosely bounded graphite stacks. The shear force by ball milling provides the force required to overcome the van der Waals force between the layers. The MnO2 nanorods were synthesized using a KMnO4 precursor in a hydrothermal arrangement, and due to their intrinsic chemisorption capability, they were doped for polysulfide trapping. With an initial capacity of 1150 mAh/g achieved by the MnO2 nanorod-doped exfoliate-graphite/sulfur composite material, the material has displayed its application in lithium–sulfur batteries, but its use is not limited; it can be a low-cost eco-friendly solution to various energy storage systems with extensive structural qualities.