研究等業績 - 原著論文 - 安部 勇輔
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Takuya EGUCHI, Taiki NAGANUMA, Reiichi CHIBA, Kimitaka WATANABE, Yusuke ABE, Seiji KUMAGAI
International Journal of the Society of Materials Engineering for Resources ( 日本素材物性学会 ) 27 ( 1 ) 663 2024年11月 [査読有り]
研究論文（学術雑誌） 国内共著
Biochar produced from bio-waste of cellulose-extracted kenaf residue was utilized as a conductive additive for electrodes in electric double-layer capacitors (EDLCs). The EDLC cells were assembled using electrodes with varying mixing ratios of kenaf-derived carbon (KC), and hydrocarbons-derived carbon black (CB) which had been industrially utilized as the conductive additive. Although the sole use of KC could not provide a sufficient electronic conduction in the EDLC electrodes, the combinational use of KC and CB attained a formation of stable conductive path therein. The energy density of the EDLC cell utilizing electrodes composed of KC and CB at a mixing ratio of 50:50 in mass under the use of 8 M KOH electrolytic solution and the cell voltage range of 0−1.0 V was found to be approximately equivalent to that of electrodes composed solely of CB, particularly at power densities below 100 W kg−1. Through the application of KC to the conductive electrode additive, we discovered new potential uses for kenaf residue.
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Graphite/Nanosilicon Composite Anode for Lithium-Ion Capacitors with Improved Energy Density and Cyclability
Cheng Jie Chng, Yusuke Abe, Seiji Kumagai
Advanced Energy and Sustainability Research ( WILEY ) 6 ( 1 ) 2400238 2024年09月 [査読有り]
研究論文（学術雑誌） 国内共著
The current energy density of Li-ion capacitors (LICs) is unfavorable for industrial applications, due to the asymmetrical electrochemical kinetics between the anode and cathode. Herein, the energy density of composite anode materials is increased by optimizing the mass ratio between graphite (Gr) and nano-Si to enable the solid electrolyte interface (SEI) to effectively buffer the large volume changes of Si during lithiation/delithiation. A twice-repeated prelithiation method is used to stabilize the SEI and eliminate the irreversible capacity of the composite anodes. Variation of the Gr:nano-Si mass ratio of the composite anode from 0 to 40 mass% shows that, although the LIC with a Gr:nano-Si mass ratio of 80:20 (Gr80Si20) exhibits the highest energy density (91.9 Wh kg−1), its energy density deteriorates drastically after 10 000 cycles, retaining only 34.8% of its initial energy density. Conversely, the LIC with the composite anode with a Gr:nano-Si mass ratio of 60:40 (Gr60Si40) has slightly lower energy density (87.3 Wh kg−1) but demonstrates outstanding cycling performance with energy density retention of 87.2% after 10 000 cycles. These findings highlight the potential of incorporating Gr/nano-Si composite anodes into LICs for high-energy-density industrial applications.
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Hard carbon/graphite composite anode for durable lithium-ion capacitor
Cheng Jie Chng, Xinyu Ma, Yusuke Abe, Seiji Kumagai
Journal of Energy Storage ( ELSEVIER ) 92 112913 2024年05月 [査読有り]
研究論文（学術雑誌） 国内共著
Li-ion capacitors (LICs), characterized by high energy and power densities, are widely regarded as promising electrochemical energy-storage devices. However, the application of these devices is limited by the poor stability of anode materials and inferior electrochemical performance owing to asymmetrical kinetics between the anode and cathode. To address these concerns, this study aimed at developing a highly stable composite anode material by tuning the mass ratio between graphite (Gr) and hard carbon (HC). When subjected to thrice-repeated deep prelithiation, the composite anode exhibited enhanced cycling performance without significant deterioration in the capacity. The incorporation of HC in the anode effectively improved the cyclability of Gr, and the thrice-repeated deep prelithiation strategy facilitated the increase in LIC capacity. The LIC using the composite anode exhibited an energy density of 48.5 Wh kg−1 at a power density of 2170 W kg−1, surpassing those of Gr (33.8 Wh kg−1 at 2030 W kg−1) and HC (35.7 Wh kg−1 at 2230 W kg−1) LICs. The enhanced LIC retained 80.5 % of its initial energy density after 10,000 cycles, a significantly higher value than those of LICs based on Gr (26.1 %) and HC (73.3 %). In summary, deep prelithiation can enhance the overall performance of LICs to achieve improved cyclability and capacity compared with its semi-shallow prelithiated counterpart. This study provides a cost-effective solution for the design of LIC anode materials with high rate and long cycling performances. © 2024 The Authors
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Cathode active materials using rare metals recovered from waste lithium-ion batteries: A review
Yusuke Abe, Ryoei Watanabe, Tatsuya Yodose, Seiji Kumagai
Heliyon ( ELSEVIER ) 10 ( 7 ) e28145 2024年03月 [査読有り]
研究論文（学術雑誌） 国内共著
Large-scale lithium-ion batteries (LIBs) are overtaking as power sources for electric vehicles and grid-scale energy-storage systems for renewable sources. Accordingly, large amounts of LIBs are expected to be discarded in the near future. Recycling technologies for waste LIBs, particularly for valuable rare metals (Li, Co, and Ni) used in cathode active materials, need to be developed to construct continuous LIB supply chains. Various recovery methodologies, such as pyrometallurgy, hydrometallurgy, and direct recycling, as well as their advantages, disadvantages, and technical features, are briefly introduced. We review the electrochemical performances of these cathode active materials based on recycled rare metals from LIB waste. Moreover, the physicochemical properties and electrochemical performance of the cathode active materials with impurities incorporated during recycling, which have high academic significance, are outlined. In hydrometallurgy-based LIB recycling, the complete removal of impurities in cathode active materials is not realistic for the mass and sustainable production of LIBs; thus, optimal control of the impurity levels is of significance. Meanwhile, the studies on the direct recycling of LIB showed the necessity of almost complete impurity removal and restoration of physicochemical properties in cathode active materials. This review provides a survey of the technological outlook of reusing cathode active materials from waste LIBs.
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Takuya Eguchi, Keiichiro Sawada, Yusuke Abe, Seiji Kumagai
Journal of Power Sources ( Elsevier ) 580 233407 2023年07月 [査読有り]
研究論文（学術雑誌） 国内共著
Si is utilized as the active anode material of lithium-ion capacitors (LICs) to increase their energy and power densities. The main drawback of industrial Si-based LICs is their insufficient cycling stability resulting from the limited life of Si anodes. In this study, cell design parameters required for 10,000 stable cycles were determined using inexpensive unmodified 2 μm Si particles and a polyimide binder. Three cathode-to-anode capacity ratios were investigated by varying the thickness of a Si coating layer at a constant mass of the cathode fabricated from activated carbon (AC). The thickest Si coating with a thickness of 48 μm resulted in the anode/cathode capacity ratio of 56.4, which was calculated based on the apparent Si specific capacity of 3000 mAh g-1 and AC specific capacity of 60 mAh g-1. Conversely, the thinnest Si coating with a thickness of 10 μm exhibited a capacity ratio of 14.2 and highest energy density of 97.4 Wh kg-1 at a power density of ~1 kW kg-1 during the first cycle, and the highest cycling stability corresponding to a retention of 78.3% after 30,000 cycles. Additionally, the aging behavior of the produced anodes and cathodes was examined via postmortem material characterization.
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Effects of Excessive Prelithiation on Full-Cell Performance of Li-Ion Batteries with a Hard-Carbon/Nanosized-Si Composite Anode
Yusuke Abe, Ippei Saito, Masahiro Tomioka, Mahmudul Kabir, Seiji Kumagai
Batteries ( MDPI ) 8 ( 11 ) 210 2022年11月 [査読有り]
研究論文（学術雑誌） 国内共著
The effects of excessive prelithiation on the full-cell performance of Li-ion batteries (LIBs) with a hard-carbon/nanosized-Si (HC/N-Si) composite anode were investigated; HC and N-Si simply mixed at mass ratios of 9:1 and 8:2 were analyzed. CR2032-type half- and full-cells were assembled to evaluate the electrochemical LIB anode behavior. The galvanostatic measurements of half-cell configurations revealed that the composite anode with an 8:2 HC/N-Si mass ratio exhibited a high capacity (531 mAh g−1) at 0.1 C and superior current-rate dependence (rate performance) at 0.1–10 C. To evaluate the practical LIB anode performance, the optimally performing composite anode was used in the full cell. Prior to full-cell assembly, the composite anodes were prelithiated via electrochemical Li doping at different cutoff anodic specific capacities (200–600 mAh g−1). The composite anode was paired with a LiNi0.5Co0.2Mn0.3O2 cathode to construct full-cells, the performance of which was evaluated by conducting sequential rate and cycling performance tests. Prelithiation affected only the cycling performance, without affecting the rate performance. Excellent capacity retention was observed in the full-cells with prelithiation conducted at cutoff anodic specific capacities greater than or equal to 500 mAh g−1.
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Electrochemical performance of LiNi1/3Co1/3Mn1/3O2 cathode recovered from pyrolysis residue of waste Li-ion batteries
Yusuke Abe, Kensuke Sawa, Masahiro Tomioka, Ryoei Watanabe, Tatsuya Yodose, Seiji Kumagai
Journal of Electroanalytical Chemistry 922 116761 2022年09月 [査読有り]
研究論文（学術雑誌） 国内共著
A methodology for time-effective, automatic, and safe extraction of cathode active materials from waste lithium-ion battery (LIB) stacks without complex mechanical disassembly and using electrically and chemically harmless processes can be beneficial for the sustainable fabrication of LIB. Herein, we present a feasibility study on the recovery of ternary Li transition metal oxide (LTMO) cathode active materials from the residue of a waste automotive LIB stack using pyrolysis at 800 °C without exposure to air. Sequential processes from pyrolysis, residue grinding, classification (sieving), wet magnetic separation, acid leaching, hydroxide precipitation, and desalination to drying were used to prepare the precursor of the cathode active material. The precursor was mixed with Li2CO3 and sintered in air at 800 °C, which yielded LiNi1/3Co1/3Mn1/3O2 (NCM) with metallic impurities of Al, Cu, and Fe at a total of 4 mass% as well as excess Li and residual F. The electrochemical performance of waste LIB-derived LiNi1/3Co1/3Mn1/3O2 (W-NCM) cathode active materials was evaluated in half-cell and full-cell configurations and compared with that of a commercial LIB cathode active material of LiNi0.5Co0.2Mn0.3O2 (NCM) used in automobile applications. The Li-ion extraction/insertion specific capacity of W-NCM in the half-cell was 120 mAh/g at 15 mA g−1, which was 70.4 % that of NCM. The specific capacity of W-NCM in a full-cell using a graphite anode at 0.1 C was 85 mAh/g, which was 69.1 % that of NCM. However, W-NCM in the full-cell exhibited much higher capacity retention (91.2 %) after 1000 charge–discharge cycles at 2 C, while the capacity retention of NCM was 34.0 %. The excellent cycling performance of W-NCM was attributed to the co-existence of metallic impurities. The proposed cathode recovery method may be further explored for applications in large-scale and automatic recycling of waste LIBs.
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Takuya Eguchi,Ryoichi Sugawara,Yusuke Abe,Masahiro Tomioka,Seiji Kumagai
Batteries ( MDPI ) 8 ( 6 ) 49 2022年05月 [査読有り]
研究論文（学術雑誌） 国内共著
The impact of full prelithiation on the rate and cycle performance of a Si-based Li-ion capacitor (LIC) was investigated. Full prelithiation of the anode was achieved by assembling a half cell with a 2 µm-sized Si anode (0 V vs. Li/Li+) and Li metal. A three-electrode full cell (100% prelithiation) was assembled using an activated carbon (AC) cathode with a high specific surface area (3041 m2/g), fully prelithiated Si anode, and Li metal reference electrode. A three-electrode full cell (87% prelithiation) using a Si anode prelithiated with 87% Li ions was also assembled. Both cells displayed similar energy density levels at a lower power density (200 Wh/kg at ≤100 W/kg; based on the total mass of AC and Si). However, at a higher power density (1 kW/kg), the 100% prelithiation cell maintained a high energy density (180 Wh/kg), whereas that of the 87% prelithiation cell was significantly reduced (80 Wh/kg). During charge/discharge cycling at ~1 kW/kg, the energy density retention of the 100% prelithiation cell was higher than that of the 87% prelithiation cell. The larger irreversibility of the Si anode during the initial Li-ion uptake/release cycles confirmed that the simple full prelithiation process is essential for Si-based LIC cells.
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Role of SiOx in rice-husk-derived anodes for Li-ion batteries
Yusuke Abe, Masahiro Tomioka, Mahmudul Kabir, Seiji Kumagai
Scientific Reports 12 ( 975 ) 2022年01月 [査読有り]
研究論文（学術雑誌） 国内共著
The present study investigated the role of SiOx in a rice-husk-derived C/SiOx anode on the rate and cycling performance of a Li-ion battery. C/SiOx active materials with different SiOx contents (45, 24, and 5 mass%) were prepared from rice husk by heat treatment and immersion in NaOH solution. The C and SiOx specific capacities were 375 and 475 mAh g−1, respectively. A stable anodic operation was achieved by pre-lithiating the C/SiOx anode. Full-cells consisting of this anode and a Li(Ni0.5Co0.2Mn0.3)O2 cathode displayed high initial Coulombic efficiency (~ 85%) and high discharge specific capacity, indicating the maximum performance of the cathode (~ 150 mAh g−1). At increased current density, the higher the SiOx content, the higher the specific capacity retention, suggesting that the time response of the reversible reaction of SiOx with Li ions is faster than that of the C component. The full-cell with the highest SiOx content exhibited the largest decrease in cell specific capacity during the cycle test. The structural decay caused by the volume expansion of SiOx during Li-ion uptake and release degraded the cycling performance. Based on its high production yield and electrochemical benefits, degree of cycling performance degradation, and disadvantages of its removal, SiOx is preferably retained for Li-ion battery anode applications.
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Suitable binder for Li-ion battery anode produced from rice husk
Seiji Kumagai, Yusuke Abe, Masahiro Tomioka, Mahmudul Kabir
Scientific Reports 11 ( 15784 ) 2021年08月 [査読有り]
研究論文（学術雑誌） 国内共著
Rice husk (RH) is a globally abundant and sustainable bioresource composed of lignocellulose and inorganic components, the majority of which consist of silicon oxides (approximately 20% w/w in dried RH). In this work, a RH-derived C/SiOx composite (RHC) was prepared by carbonization at 1000 °C for use in Li-ion battery anodes. To find a suitable binder for RHC, the RHC-based electrodes were fabricated using two different contemporary aqueous binders: polyacrylic acid (PAA) and a combination of carboxymethyl cellulose and styrene butadiene rubber (CMC/SBR). The rate and cycling performances of the RHC electrodes with respect to the insertion/extraction of Li ions were evaluated in a half-cell configuration. The cell was shorted for 24 h to completely lithiate the RHC. Impedance analysis was conducted to identify the source of the increase in the resistance of the RHC electrodes. The RHC electrode fabricated using PAA exhibited higher specific capacity for Li-ion extraction during the cycling test. The PAA binder strengthened the electrode and alleviated the increase in electrode resistance caused by the formation of the interphase film. The high affinity of PAA for SiOx in RHC was responsible for the stabilization of the anodic performance of Li-ion batteries.
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Yusuke Abe, Natsuki Hori, Seiji Kumagai
Energies ( MDPI ) 12 ( 23 ) 4507 2019年11月 [査読有り]
研究論文（学術雑誌） 国内共著
Lithium-ion batteries (LIBs) using a LiFePO4 cathode and graphite anode were assembled in coin cell form and subjected to 1000 charge-discharge cycles at 1, 2, and 5 C at 25 °C. The performance degradation of the LIB cells under different C-rates was analyzed by electrochemical impedance spectroscopy (EIS) and scanning electron microscopy. The most severe degradation occurred at 2 C while degradation was mitigated at the highest C-rate of 5 C. EIS data of the equivalent circuit model provided information on the changes in the internal resistance. The charge-transfer resistance within all the cells increased after the cycle test, with the cell cycled at 2 C presenting the greatest increment in the charge-transfer resistance. Agglomerates were observed on the graphite anodes of the cells cycled at 2 and 5 C; these were more abundantly produced in the former cell. The lower degradation of the cell cycled at 5 C was attributed to the lowered capacity utilization of the anode. The larger cell voltage drop caused by the increased C-rate reduced the electrode potential variation allocated to the net electrochemical reactions, contributing to the charge-discharge specific capacity of the cells.
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Seiji Kumagai, Yusuke Abe, Tomoaki Saito, Takuya Eguchi, Masahiro Tomioka, Mahmudul Kabir, Daisuke Tashima
Journal of Power Sources ( Elsevier ) 437 226924 2019年10月 [査読有り]
研究論文（学術雑誌） 国内共著
Rice husk (RH), agricultural waste produced from rice harvest, is investigated as a potential source for cathode and anode active materials in lithium-ion capacitors (LICs). A carbonized mixture composed of pre-heated RH and beet sugar is subjected to silica removal via immersion in NaOH solution followed by activation using CO2 gas. This yields activated carbon with a specific surface area of 1801 m2 g−1 as the cathode active material. The anode active material is produced by carbonizing RH and partly removing 41 mass% of silica. The charge-discharge performances of a three-electrode LIC full-cell, using the RH-derived cathode and anode active materials with Li metal as the reference electrode, are evaluated under the uncontrolled full-pre-lithiation in comparison with similar three-electrode LIC full-cells using a commercial cathode and anode (graphite or hard carbon) active materials. The results of charge-discharge tests reveal that excellent rate and cycling stabilities are obtained from the LIC using RH-derived active materials in comparison with those using commercial active materials. Postmortem material characterizations suggest that the performance stability of the RH-derived LIC is attributed to the passivation ability of silica for excessive Li delivered via the full pre-lithiation process.
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Yusuke Abe, Tomoaki Saito, Seiji Kumagai
Batteries ( MDPI ) 4 ( 4 ) 71 2018年12月 [査読有り]
研究論文（学術雑誌） 国内共著
Two prelithiation processes (shallow Li-ion insertion, and thrice-repeated deep Li-ion insertion and extraction) were applied to the hard carbon (HC) negative electrode (NE) used in lithium-ion batteries (LIBs). LIB full-cells were assembled using Li(Ni0.5Co0.2Mn0.3)O2 positive electrodes (PEs) and the prelithiated HC NEs. The assembled full-cells were charged and discharged under a low current density, increasing current densities in a stepwise manner, and then constant under a high current density. The prelithiation process of shallow Li-ion insertion resulted in the high Coulombic efficiency (CE) of the full-cell at the initial charge-discharge cycles as well as in a superior rate capability. The prelithiation process of thrice-repeated Li-ion insertion and extraction attained an even higher CE and a high charge-discharge specific capacity under a low current density. However, both prelithiation processes decreased the capacity retention during charge-discharge cycling under a high current density, ascertaining a trade-off relationship between the increased CE and the cycling performance. Further elimination of the irreversible capacity of the HC NE was responsible for the higher utilization of both the PE and NE, attaining higher initial performances, but allowing the larger capacity to fade throughout charge-discharge cycling.
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Yusuke Abe, Seiji Kumagai
Journal of Energy Storage ( Elsevier ) 19 96 - 102 2018年10月 [査読有り]
研究論文（学術雑誌） 国内共著
The influence of the capacity ratio of the negative to positive electrode (N/P ratio) on the rate and cycling performances of LiFePO4/graphite lithium-ion batteries was investigated using 2032 coin-type full and three-electrode cells. LiFePO4/graphite coin cells were assembled with N/P ratios of 0.87, 1.03 and 1.20, which were adjusted by varying the mass of the graphite negative electrode. Three-electrode cells were also assembled with similar N/P ratios to understand the potential variations of the positive and negative electrodes. The cycling performances of the coin cells were evaluated by repeating the charge-discharge cycle 5000 times (1 C-rate for the 1st–1000th cycle and 2 C-rate for the 1001st–5000th cycle) at cell voltages of 2.5–4.2 V, during which their rate performances were intermittently evaluated (0.1–10 C-rate). Prior to the charge-discharge cycling test, the highest cell specific capacity was obtained from the lowest N/P ratio of 0.87. The coin cell with the highest N/P ratio of 1.20 exhibited the highest capacity retention of 86.5% at 1 or 2 C-rate in the 5000 cycle test. The results obtained using the three-electrode cells showed that the higher N/P ratio elevated the working potential ranges of the positive and negative electrodes. The lower N/P ratio led to deeper Li-ion intercalation for the negative electrode, lowering the potential of both the positive and negative electrodes. The lower N/P ratio was beneficial for achieving full performances from the initial service, but caused larger capacity fading due to the aging by cycling. The higher N/P ratio rather restricted the performances at the initial service, which was useful to prevent the cycling-derived capacity fading. The lowering of rate performance owing to the charge-discharge cycling, particularly at the high current densities of 5 and 10 C-rates, was enhanced by the decrease in the N/P ratio.
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Tomoaki Saito, Hiroaki Fujiwara, Yusuke Abe, Seiji Kumagai
International Journal of the Society of Materials Engineering for Resources ( 日本素材物性学会 ) 23 ( 2 ) 142 - 146 2018年09月 [査読有り]
研究論文（学術雑誌） 国内共著
The composite negative electrode active material of Li-ion batteries (LIBs) was fabricated using phenolic resin (PR) and agricultural waste of rice husk (RH). Because silicates were intrinsically composed in RH, the composite of hard carbon (HC) and SiOx (HC/SiOx composite) was readily prepared by carbonizing the mixture of PR and RH. Li-ion insertion and extraction capacity of the HC/SiOx composite was evaluated in a half-cell configuration using Li metal as the counter electrode, in comparison with those of the carbonized RH and the commercial HC. It was revealed the HC/SiOx composite exhibited 30% higher specific capacity of Li-ion insertion/extraction than did the commercial HC. In addition to this, its capacity retention was found to be approximately equal to that of the commercial HC. The performance comparison of the HC/SiOx composite and the carbonized RH suggested that hybridization of HC and SiOx was useful to alleviate the capacity fading of the SiOx part with maintaining the increased specific capacity attributed to the SiOx part. Cost-effective active material for the LIB negative electrode with acceptable performances could be realized by the simple carbonization of the mixture of PR and RH. The produced HC/SiOx composite was promising for vehicle applications requiring excellent cycle performance and high cost effectiveness.