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Hideka Ando, [Kenjiro Hashi](https://orcid.org/0000-0002-0320-4768), [Shinobu Ohki](https://orcid.org/0000-0002-7357-3833), Rika Matsumoto, Kazuma Gotoh

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This is a pre-copyedited, author-produced version of an article accepted for publication in Chemistry Letters following peer review. The version of record Hideka Ando, Kenjiro Hashi, Shinobu Ohki, Rika Matsumoto, Kazuma Gotoh, Strategic approaches to observing 39K NMR signals from potassium–graphite intercalation compounds, Chemistry Letters, Volume 53, Issue 11, November 2024, upae195, is available online at: https://doi.org/10.1093/chemle/upae195.[In Copyright](http://rightsstatements.org/vocab/InC/1.0/)

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[Strategic approaches to observing 39K NMR signals from potassium–graphite intercalation compounds](https://mdr.nims.go.jp/datasets/49d6c36a-c2e0-4426-9206-efbb03ed2ea7)

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For Peer ReviewStrategic approaches to observing 39K NMR signals from potassium–graphite intercalation compoundsJournal: Chemistry LettersManuscript ID CL-240369.R1Manuscript Type: LetterDate Submitted by the Author: n/aComplete List of Authors: Ando, Hideka; Okayama UniversityHashi, Kenjiro; National Institute for Materials Science, Solid-State NMR GroupOhki, Shinobu; National Institute for Materials Science, Solid-State NMR GroupMatsumoto, Rika; Tokyo Polytechnic UniversityGotoh, Kazuma; Japan Advanced Institute of Science and Technology, Center for Nano Materials and TechnologyCategories: Physical Chemistry, Inorganic Chemistry Japan Science and Technology Information Aggregator, Electronic (J-STAGE)innovative, web-based, database-driven peer review and online submission workflow solutionFor Peer Review1  Hideka Ando1, 2, Kenjiro Hashi3, Shinobu Ohki3, Rika Matsumoto4, and Kazuma Gotoh*2  1Graduate School of Natural Science & Technology, Okayama University, 3-1-1 Tsushima-naka, Okayama 700-8530, Japan 2Center for Nano Materials and Technology, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923-1292, Japan 3National Institute for Materials Science, 3-13 Sakura, Tsukuba, Ibaraki 305-0003, Japan 4Department of Engineering, Tokyo Polytechnic University, 5-45-1 Iiyamaminami, Atsugi, Kanagawa, 243-0297, Japan *Corresponding author: Center for Nano Materials and Technology, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923-1292, Japan. Email: kgotoh@jaist.ac.jpCarbon materials are known to take various forms and are used 1 in a wide range of fields.1,2 Development of new synthesis 2 methods and materials and evaluation of the properties of carbon 3 materials for various applications have been carried out.3–6 4 Graphite intercalation compounds (GICs) are interesting 5 materials in which several guest atoms or molecules are inserted 6 between the layers of graphite. GICs form various stage 7 structures described as stage n. The index “n” refers to the 8 number of graphene layers between the layers of intercalants. 9 Graphite and potassium form KC8, KC24, and KC36 GICs, 10 respectively, at stage 1, stage 2, and stage 3.7,8 Since they were 11 first reported in 1841, GICs have long been studied because they 12 exhibit excellent physical and chemical properties including high 13 electrical conductivity, superconductivity, and hydrogen 14 storage.9,10 Reversible intercalation–deintercalation of various 15 chemical species into graphite interlayers has been utilized as 16 electrode reactions for rechargeable batteries such as Li-ion 17 batteries (LIBs) and dual-graphite batteries (DGBs).11,12 18 Similarly, the intercalation–deintercalation of potassium into 19 graphite interlayers can be applied to K-ion batteries (KIBs).13 20 Actually, KIBs function according to the same mechanism as 21 LIBs and have some beneficial features including cost-22 effectiveness and high energy density. These KIB 23 characteristics have accelerated the study of KIBs for 24 application to next-generation batteries.  25 In studies of LIBs and Na-ion batteries, solid-state nuclear 26 magnetic resonance (NMR) has played an important role in 27 elucidating the mechanisms.14,15 Solid-state NMR can observe 28 target nuclei directly and reveal the structure and dynamics of 29 materials at atomic and molecular levels. Particularly, NMR 30 has contributed to the development of high energy density 31 and safer anode materials by revealing the states of quasi-32 metallic clusters and dendritic alkali metals in carbon 33 materials.16–18 Also in KIBs, NMR can be expected to contribute 34 to elucidating potassium storage mechanisms in carbon materials 35 such as graphite and hard carbon, which are promising anode 36 Strategic approaches to observing 39K NMR signals from potassium–graphite intercalation compounds Abstract Solid-state nuclear magnetic resonance (NMR) is an invaluable tool for potassium–graphite intercalation compounds (K-GICs), promising anode materials of K-ion batteries, but it has not yet been applied because of several issues. We attempted 39K NMR measurements of K-GICs sealed in glass using an 18.8 T NMR spectrometer with an NMR probe adjusted to the samples. The first observed 39K NMR signal of K-GICs showed the possibility of evaluating intralayer density, which cannot be ascertained from Raman measurements.  Keywords: Graphite intercalation compound, Solid-state nuclear magnetic resonance, Potassium Graphical abstract  Page 1 of 5Japan Science and Technology Information Aggregator, Electronic (J-STAGE)innovative, web-based, database-driven peer review and online submission workflow solutionFor Peer Review2   materials for KIBs. Despite growing demand for NMR analysis 1 for the study of KIBs, no report of the relevant literature has 2 described the use of potassium NMR for KIB research. This gap 3 in the literature has occurred because potassium nuclei are 4 difficult to measure as a result of their low sensitivity attributed 5 to their small gyromagnetic ratio γ and a nuclear quadrupole 6 interaction.19 Potassium has three NMR active isotopes: 39K, 40K, 7 and 41K. Of these isotopes, 39K has the highest potential for 8 measurement because of its high natural abundance (93.3%) and 9 relatively small nuclear quadrupole moment Q. However, the 10 low Larmore frequency of 39K (28.05 MHz in a static magnetic 11 field of 14.1 T, which corresponds to 1H resonance frequency of 12 600 MHz) leads to low sensitivity. Additionally, the high 13 conductivity of K-GICs makes NMR measurement with general 14 probes difficult because adjustment of a circuit in NMR probes 15 (tuning and matching) might not match well. Reliable NMR 16 spectra are not obtained using a standard sample rotor for Magic 17 Angle Spinning (MAS) experimentation because K-GICs 18 decompose during NMR measurement as a result of their high 19 reactivity, even if nitrogen gas is used for driving and rotating 20 for MAS. Because of these various difficulties, 39K NMR 21 measurements have not been applied to KIB research, although 22 39K NMR can be expected to make an important contribution to 23 KIB development. 24 For this study, we attempted to obtain reference 39K NMR 25 spectra of KC8, KC24, and KC36 as a first step toward using 39K 26 NMR in KIBs research. Samples were measured in the static 27 magnetic field at 18.8 T to increase sensitivity. To reduce the 28 effects of high conductivity and high reactivity, the samples were 29 sealed in 8 mm glass tubes with fluoropolymer. In addition, 30 NMR probes were adjusted by changing the number of turns of 31 the coil to match each sample. Optimal measurement conditions 32 were explored. Among the results, 39K NMR signals of 33 potassium metal, KC8, KC24, and KC36 were observed. This 34 report is the first of observed K-GIC signals showing different 35 chemical shifts depending on the samples. 36 For this study, K-GIC samples were prepared by purchase or 37 synthesis. The KC8 sample was purchased from FUJIFILM 38 Wako Pure Chemical Corp. The KC24 sample and KC36 sample 39 were synthesized using the following procedure. Natural 40 Graphite (SNO30; SEC Carbon Ltd.) and potassium metal 41 (99.5% purity) were mixed at a stoichiometric ratio of KC24 or 42 KC36 composition ratios. After these materials were placed into 43 glass tubes, they were heated at 300 C under vacuum for 1 week.  44 Raman spectra of the prepared samples were measured to 45 confirm synthesis of the target compounds. Raman spectroscopy 46 was carried out using a laser Raman spectrometer (NRS-5500; 47 JASCO Corp.) with a 532 nm laser. The spot size of the laser for 48 Raman measurement of KC8, KC8-air, KC24, and KC36 samples 49 was approximately 20, 20, 2, and 1 μm in diameter, respectively. 50 Spectra were obtained at several locations per sample. For NMR 51 measurements, 40–50 mg of a K-GIC sample were mixed with a 52 similar volume of polyvinylidene difluoride (PVDF) to reduce 53 the sample conductivity. Then they were placed in a 8 mm 54 Pyrex tube in an argon-filled glove box. After the Pyrex tube was 55 taken out from the glove box without exposing the sample to air, 56 it was sealed (Fig. S1(a)). In addition, a KC8 sample degraded by 57 air exposure was prepared for comparison: “KC8-air” denotes the 58 air-exposed sample. A potassium metal sample was also 59 prepared for NMR measurements. 27 mg of potassium metal was 60 cut into 2–3 mm square pieces in an argon-filled glove box and 61 was sealed in a 8 mm Pyrex tube with PVDF. The 39K NMR 62 spectra were recorded using a spectrometer (18.79 T magnet, 63 JNM-ECZ800R; JEOL/JASTEC or 18.79 T magnet, JNM-64 ECA800; JEOL/JASTEC). A general MAS probe was used to 65 measure the potassium metal, KC24, and KC36 samples. To 66 measure the KC8 samples, a resonance circuit of a homebuilt 67 NMR probe was adjusted for the samples because of a mismatch 68 between the resonance frequency of the MAS probe and the 69 samples caused by the sample’s high conductivity. All samples 70 were measured under static conditions with a single pulse 71 sequence with pulse length of 10 μs or 5 μs, a delay of 1 s, and 72 overnight accumulation. KBr aqueous solution was used as a 73 reference at 0 ppm. 74 The prepared K-GIC samples were evaluated to determine if 75 they were the desired samples before NMR measurements. K-76 GICs are known to exhibit characteristic colors depending on 77 their composition. The samples used for this experiment were 78 also colored: the purchased KC8 sample was a golden powder, 79 the synthesized KC24 sample was a bright blue powder, and the 80 KC36 sample was a dark blue powder (Figs. S1(b–d)). Each 81 sample was evaluated using Raman spectroscopy (Fig. S2). As 82 shown in Fig. S2(a), the Raman spectrum of the KC8 sample 83 showed an asymmetric Fano-line at 1600 cm-1 with a Cz mode 84 around 540 cm-1, which shows good agreement with the reported 85 Raman spectra of KC8.20,21 The Raman spectrum of the KC24 86 sample showed a single line around 1600 cm-1, as presented in 87 Fig. S2(b). This line corresponds to the Gc-line, related to the 88 charged graphene layers next to an intercalant layer.21 The 89 Raman spectrum of the KC24 sample is similar to the reported 90 Raman spectra of KC24, confirming that the chemical 91 composition of the synthesized sample is surely KC24. For the 92 Raman spectrum of the KC36 sample, two peaks were observed 93 at 1580 and 1600 cm-1, as shown in Fig. S2(c). These peaks at 94 1580 and 1600 cm-1 were assigned respectively to the Guc-line, 95 which is related to the uncharged graphene layers surrounded by 96 the charged graphene layers, and the Gc-line. However, the 97 intensity of the Guc-line of the KC36 sample differed depending 98 on the measurement spot, suggesting that the KC36 contains some 99 compositionally different structures from KC36. Because several 100 particles of different colors were included in the KC8-air sample, 101 the Raman spectrum was obtained for each color particle. The 102 Raman spectrum of the golden color particles in the KC8-air 103 sample is shown in Fig. S2(d). Signals observed at 1259 and 104 1550 cm-1 were assigned respectively to the D-band and E2g 105 mode or G-band, based on spectra similar to the Raman spectrum 106 of stage 1 KC8. Figure S2(e) shows that the Raman spectrum of 107 the bluish particles in the KC8-air samples was similar to that of 108 KC24. These results suggest that the KC8-air sample has a stage 109 1 structure but that it is partially broken down into a stage 2 or 110 higher stage structure. 111 The 39K NMR spectrum of the potassium metal is presented in 112 Fig. S3(a). Two peaks were observed at 2468 and 2637 ppm. The 113 signal at 2468 ppm appeared even when the sample was not set, 114 suggesting that the signal originates from the NMR probe (Fig. 115 S3(b)). This signal is assigned to the spectral aliasing of silver 116 because the NMR probe uses silver wire, which has a similar 117 resonance frequency to that of potassium (Ag, 37.5 MHz; K, 37.3 118 Page 2 of 5Japan Science and Technology Information Aggregator, Electronic (J-STAGE)innovative, web-based, database-driven peer review and online submission workflow solutionFor Peer Review3   MHz). In fact, the signal at 2468 ppm disappeared in 1 measurement with the homebuilt probe without silver wire. The 2 signal at 2637 ppm is regarded as that of potassium metal 3 because this signal was observed in measurements with both 4 probes. The Knight shift for potassium metal particles dispersed 5 in paraffin has been reported as 0.248% (2480 ppm),22 which is 6 in reasonable agreement with results of this work. 7  Initially, we tried the NMR measurement of K-GICs using a 8 general 8 mm MAS sample rotor. However, no reliable 9 spectrum was obtained because of sample degradation that 10 occurred during measurement. The certain spectra of the K-GICs 11 were obtained by sealing off the samples into the Pyrex tube to 12 keep them from degradation. Figure 1(a) presents that the NMR 13 spectrum of the KC8 sample showed only one peak at 411 ppm. 14 The KC8-air sample was also measured using 39K NMR, which 15 is displayed in Fig. 1(b). The NMR spectrum showed three peaks 16 at -483, -429, and 413 ppm. Because the KC8 signal was 17 confirmed to appear at 411 ppm, the signal at 413 ppm is 18 regarded as KC8, whereas the signals at -429 and -483 ppm are 19 ascribed to degradation products. The Raman spectrum also 20 suggests that the KC8-air sample contains some KC8 compound, 21 which is consistent with NMR findings. These signals at -483 22 and -429 ppm are assignable to stage 2 or higher stage K-GIC 23 because the Raman spectra of the KC8-air sample indicated the 24 presence of stage 2 or higher stage compounds. In prior reports, 25 7Li NMR signals of lithium-stored carbon materials have 26 been also observed without MAS,18, 23 and our results are 27 reasonable. 28 The 39K NMR spectra of the KC24 and KC36 samples are 29 displayed in Fig. 2. The NMR signal of the KC24 sample was 30 observed at -1075, -80, 508, 817, and 2460 ppm (Fig. 2(a)), 31 whereas that of the KC36 was observed at -1087, -97, 500, and 32 2460 ppm (Fig. 2(b)). In Fig. 2(a), it seems that there are three 33 peaks at 336, 401, and 508 ppm around 500 ppm. However, 34 NMR measurements of another lot of KC24 samples showed only 35 a peak at 516 ppm (Fig. S4), suggesting that only the peak at 508 36 ppm is a signal of the sample and the other two peaks are noise. 37 The peak at 2460 ppm is assigned to the spectral aliasing of silver. 38 Although the KC24 sample was confirmed from Raman 39 measurements to have a stage 2 structure, the NMR spectrum 40 showed four signals aside from the silver signal. By contrast, for 41 the KC36 sample, the NMR spectrum was similar to that of the 42 KC24 sample, even though the Raman measurement confirmed 43 that the KC36 structure was partially heterogeneous. These 44 samples were not degraded by air. Therefore, the NMR spectra 45 of the KC24 and KC36 samples were more complicated than those 46 expected from the Raman measurement, suggesting that 39K 47 NMR is likely to be a powerful tool for distinguishing 48 Fig. 1. 39K NMR spectra of (a) KC8, and (b) KC8-air. Fig. 2. 39K NMR spectra of (a) KC24, and (b) KC36. Page 3 of 5Japan Science and Technology Information Aggregator, Electronic (J-STAGE)innovative, web-based, database-driven peer review and online submission workflow solutionFor Peer Review4   differences in the in-plane density of interlayer potassium that 1 cannot be detected by Raman spectroscopy. Additionally, as 2 noted earlier, the Raman results for the KC8-air sample suggest 3 that it contains stage 2 and higher stage compounds. However, 4 the NMR spectra of the KC24 and KC36 samples differed from 5 that of the KC8-air sample. The causes for the different NMR 6 signals of each sample might be the different host carbon types 7 of the purchased KC8 and the synthesized KC24 and KC36 8 samples. In fact, the chemical composition of the degradation 9 products of K-GICs depends on the types of host carbon and the 10 duration of exposure to air.24 Further sample data acquisition is 11 necessary for the accurate assignment of NMR signals. 12 In conclusion, we present the first observations of the 39K 13 NMR signals of K-GICs using an 18.8 T NMR system, by 14 adjusting the resonance circuit of the NMR probe for each 15 sample. The signal of stage 1 K-GIC (KC8) is assigned clearly. 16 Although some higher stage GICs, showed more complicated 17 NMR spectra than expected from Raman measurements, our 18 findings reveal that 39K NMR can be a powerful tool for 19 distinguishing differences in the in-plane density of interlayer 20 potassium, which are not detected using Raman spectroscopy. 21 The results are expected to contribute to the analysis of 22 heterogeneous and disordered electrochemically intercalated 23 carbon electrodes for KIBs. 24  25 Acknowledgments 26 This work was supported by "Advanced Research Infrastructure 27 for Materials and Nanotechnology in Japan (ARIM)" of the 28 Ministry of Education, Culture, Sports, Science and Technology 29 (MEXT). Proposal Number JPMXP1224NM0135. 30  31 Supplementary data 32 Supplementary material is available at Chemistry Letters 33  34 Funding 35 This work was supported by JST SPRING, Grant No. 36 JPMJSP2126, JST GteX, Grant No. JPMJGX23S4, and 37 KAKENHI 23K04535 and 20H00399. 38  39 Conflict of interest statement. None declared. 40  41 References 42 1. M. S. Mauter, M. Elimelech, Environ. Sci. Technol. 2008, 42, 43 5843. https://doi.org/10.1021/es8006904 44 2. D. S. Su, S. Perathoner, G. Centi, Chem. Rev. 2013, 113, 5782. 45 https://doi.org/10.1021/cr300367d 46 3. K. Nakabayashi, Y. Matsuo, K. Isomoto, K. Teshima, T. 47 Ayukawa, H. Shimanoe, T. Mashio, I. Mochida, J. Miyawaki, S.-48 H. Yoon, ACS Sustainable Chem. Eng. 2020, 8, 3844. 49 https://doi.org/10.1021/acssuschemeng.9b07253 50 4. K. Kira, T. Yamamoto, Y. Sugimoto, I. Shimabukuro, A. 51 Hikosaka, T. Irisawa, Carbon 2024, 228, 119417. 52 https://doi.org/10.1016/j.carbon.2024.119417 53 5. K. Ishii, T. Ogiyama, K. Fumoto, Y. Nishina, Appl. Phys. Lett. 54 2024, 125, 023104. https://doi.org/10.1063/5.0210446 55 6. W. Yu, Z. Shen, T. Yoshii, S. Iwamura, M. Ono, S. Matsuda, M. 56 Aoki, T. Kondo, S. R. Mukai, S. Nakanishi, H. Nishihara, Adv. 57 Energy Mater. 2024, 14, 2303055. 58 https://doi.org/10.1002/aenm.202303055 59 7. W. Rüdorff, E. Schulze, Z. Anorg. Allg. Chem. 1954, 277, 156. 60 https://doi.org/10.1002/zaac.19542770307 61 8. D. E. Nixon, G. S. Parry, J. Phys. D: Appl. Phys. 1968, 1, 291. 62 https://doi.org/10.1088/0022-3727/1/3/303 63 9. M. S. Dresselhaus, G. Dresselhaus, Adv. Phys. 2002, 51, 1. 64 https://doi.org/10.1080/00018730110113644 65 10. M. Inagaki, J. Mater. Res. 1989, 4, 1560. 66 https://doi.org/10.1557/JMR.1989.1560 67 11. H. Zhang, Y. Yang, D. Ren, L. Wang, X. He, Energy Stor. Mater. 68 2021, 36, 147. https://doi.org/10.1016/j.ensm.2020.12.027 69 12. Y. Ito, C. Lee, Y. Miyahara, K. Miyazaki, T. Abe, ACS Energy 70 Lett. 2024, 9, 1473. 71 https://doi.org/10.1021/acsenergylett.4c00130 72 13. T. Hosaka, K. Kubota, A. S. Hameed, S. Komaba, Chem. Rev. 73 2020, 120, 6358. https://doi.org/10.1021/acs.chemrev.9b00463 74 14. O. Pecher, J. Carretero-González, K. J. Griffith, C. P. Grey, Chem. 75 Mater. 2017, 29, 213. 76 https://doi.org/10.1021/acs.chemmater.6b03183 77 15. K. Gotoh, Batteries Supercaps 2021, 4, 1267. 78 https://doi.org/10.1002/batt.202000295 79 16. J. M. Stratford, P. K. Allan, O. Pecher, P. A. Chater, C. P. Grey, 80 Chem. Commun. 2016, 52, 12430. 81 https://doi.org/10.1039/C6CC06990H 82 17. H. Au, H. Alptekin, A. C. S. Jensen, E. Olsson, C. A. O’Keefe, T. 83 Smith, M. Crespo-Ribadeneyra, T. F. Headen, C. P. Grey, Q. Cai, 84 A. J. Drew, M.-M. Titirici, Energy Environ. Sci. 2020, 13, 3469. 85 https://doi.org/10.1039/D0EE01363C 86 18. K. Gotoh, T. Yamakami, I. Nishimura, H. Kometani, H. Ando, K. 87 Hashi, T. Shimizu, H. Ishida, J. Mater. Chem. A 2020, 8, 14472. 88 https://doi.org/10.1039/D0TA04005C 89 19. M. E. Smith, Magn. Reson. Chem. 2021, 59, 864. 90 https://doi.org/10.1002/mrc.5116 91 20. J. C. Chacón-Torres, A. Y. Ganin, M. J. Rosseinsky, T. Pichler, 92 Phys. Rev. B 2012, 86, 075406. 93 https://doi.org/10.1103/PhysRevB.86.075406 94 21. J. C. Chacón-Torres, L. Wirtz, T. Pichler, Physica Status Solidi 95 (b) 2014, 251, 2337. https://doi.org/10.1002/pssb.201451477 96 22. W. van der Lugt, J. S. Knol, Physica Status Solidi (b) 1967, 23, 97 K83. https://doi.org/10.1002/pssb.19670230164 98 23. K. Gotoh, M. Maeda, A. Nagai, A. Goto, M. Tansho, K. Hashi, T. 99 Shimizu, H. Ishida, J. Power Sources 2006, 162, 1322. 100 https://doi.org/10.1016/j.jpowsour.2006.09.001 101 24. R. Matsumoto, M. Arakawa, H. Yoshida, N. Akuzawa, Synthetic 102 Metals 2012, 162, 2149. 103 https://doi.org/10.1016/j.synthmet.2012.10.010 104 Page 4 of 5Japan Science and Technology Information Aggregator, Electronic (J-STAGE)innovative, web-based, database-driven peer review and online submission workflow solutionhttps://doi.org/10.1021/es8006904https://doi.org/10.1021/cr300367dhttps://doi.org/10.1021/acssuschemeng.9b07253https://doi.org/10.1016/j.carbon.2024.119417https://doi.org/10.1063/5.0210446https://doi.org/10.1002/aenm.202303055https://doi.org/10.1002/zaac.19542770307https://doi.org/10.1088/0022-3727/1/3/303https://doi.org/10.1080/00018730110113644https://doi.org/10.1557/JMR.1989.1560https://doi.org/10.1016/j.ensm.2020.12.027https://doi.org/10.1021/acsenergylett.4c00130https://doi.org/10.1021/acs.chemrev.9b00463https://doi.org/10.1021/acs.chemmater.6b03183https://doi.org/10.1002/batt.202000295https://doi.org/10.1039/C6CC06990Hhttps://doi.org/10.1039/D0EE01363Chttps://doi.org/10.1039/D0TA04005Chttps://doi.org/10.1002/mrc.5116https://doi.org/10.1103/PhysRevB.86.075406https://doi.org/10.1002/pssb.201451477https://doi.org/10.1002/pssb.19670230164https://doi.org/10.1016/j.jpowsour.2006.09.001https://doi.org/10.1016/j.synthmet.2012.10.010For Peer Review5    Page 5 of 5Japan Science and Technology Information Aggregator, Electronic (J-STAGE)innovative, web-based, database-driven peer review and online submission workflow solution