{"title":"State change of Na clusters in hard carbon electrodes and increased capacity for Na-ion batteries achieved by heteroatom doping","authors":"Hideka Ando , Kenjiro Hashi , Shinobu Ohki , Yoshikiyo Hatakeyama , Yuta Nishina , Norihiro Kowata , Takahiro Ohkubo , Kazuma Gotoh","doi":"10.1016/j.cartre.2024.100387","DOIUrl":null,"url":null,"abstract":"<div><p>Although heteroatom doping is an effective method to improve the capacity of hard carbon (HC) anodes in Na-ion batteries (NIBs), the complicated structure of HC leads to uncertainty when understanding the effects of heteroatom doping on sodium storage. This study shows the effects of phosphorus and sulfur doping to HC on sodium storage using solid-state NMR to improve the capacity of HC prepared by the carbonization of resorcinol formaldehyde (RF) resin at 1100 °C. Heteroatom doping increased the battery capacity of the HC, especially the plateau capacity, but the interlayer distance of the carbon layers in the HC did not expand considerably. <sup>23</sup>Na solid-state NMR revealed that heteroatom doping facilitates the formation of quasi-metallic sodium clusters, thereby contributing to the plateau capacity increase. The metallicity of the sodium clusters in heteroatom-doped HC samples was controlled by the amount of doped-phosphorous. XPS and <sup>31</sup>P NMR detected various phosphorus sites such as phosphine and phosphine oxide in the carbon structure.</p></div>","PeriodicalId":52629,"journal":{"name":"Carbon Trends","volume":"16 ","pages":"Article 100387"},"PeriodicalIF":3.1000,"publicationDate":"2024-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2667056924000683/pdfft?md5=8b6dbbe64c9c84408757db5e1481d11d&pid=1-s2.0-S2667056924000683-main.pdf","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Carbon Trends","FirstCategoryId":"1085","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S2667056924000683","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"MATERIALS SCIENCE, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
Abstract
Although heteroatom doping is an effective method to improve the capacity of hard carbon (HC) anodes in Na-ion batteries (NIBs), the complicated structure of HC leads to uncertainty when understanding the effects of heteroatom doping on sodium storage. This study shows the effects of phosphorus and sulfur doping to HC on sodium storage using solid-state NMR to improve the capacity of HC prepared by the carbonization of resorcinol formaldehyde (RF) resin at 1100 °C. Heteroatom doping increased the battery capacity of the HC, especially the plateau capacity, but the interlayer distance of the carbon layers in the HC did not expand considerably. 23Na solid-state NMR revealed that heteroatom doping facilitates the formation of quasi-metallic sodium clusters, thereby contributing to the plateau capacity increase. The metallicity of the sodium clusters in heteroatom-doped HC samples was controlled by the amount of doped-phosphorous. XPS and 31P NMR detected various phosphorus sites such as phosphine and phosphine oxide in the carbon structure.
虽然掺杂杂原子是提高纳离子电池(NIBs)中硬碳(HC)阳极容量的有效方法,但由于 HC 结构复杂,在理解掺杂杂原子对钠储存的影响时存在不确定性。本研究利用固态核磁共振显示了掺入磷和硫的碳氢化合物对钠储存的影响,以提高间苯二酚甲醛(RF)树脂在 1100 °C 下碳化制备的碳氢化合物的容量。杂原子掺杂提高了碳氢化合物的电池容量,尤其是高原容量,但碳氢化合物中碳层的层间距离并没有显著扩大。23Na 固态核磁共振显示,杂原子掺杂促进了准金属钠簇的形成,从而推动了高原容量的增加。掺杂杂原子的 HC 样品中钠团簇的金属性受掺磷量的控制。XPS 和 31P NMR 在碳结构中检测到了各种磷位点,如膦和氧化膦。