准二维原子晶体的离子储能机制分析

Quasi-two dimensional (2D) few-layer atomic crystals including few-layer graphene (1-9 atomic layer) are new matters that have quantum structures different from their mother material layered compounds, unusual physical and chemical properties, and thus possibly support conceptual and advanced energy storage. I, the project applicant, have invented a new method of efficient and non-oxidative exfoliation of graphite into high-quality of few-layer graphene flakes and also applied them for the anode of lithium ion secondary battery with a preliminary result of good and flat charge/discharge curves in contrast with the one of reduced graphene oxide's. Based on these, I propose here the investigation of the energy storage mechanism of electrochemical interaction between metal ions and quasi-2D few-layer atomic crystals, or say, the mechansim of metal ion diffusion related to electrochemical energy storage into quasi-2D few-layer atomic crystals. A hypothesis of the diffusion mechanism related to energy storage of either lithium ion intercalation into the interlayer of each few-layer graphene flake or absorption onto the surface of few-layer graphene flakes stacked in a limited distance was suggested. The experiments to obtain the relationship between the performances (such as specific capacity) of both lithium ion battery and aluminum ion battery and the factors of the layer number of few-layer graphene flake and the inter-distance of the flakes stacked will be carried out to validate the hypothesis, which is based on the rule that Li+ ion is so small and can intercalate into the interlayer of each few-layer graphene flake while Al3+ ion is too large to intercalate into it. This project will also involve the study of few-layer graphene and other quasi-2D oxide crystals (such as few-layer V2O5 and CoO2) working as new type of electrodes of secondary ion batteries, the comparison of the performances of lithium ion battery and renewable aluminum ion battery with theoretically higher energy density, and fundamental issues of the application of quasi-2D atomic crystals to advanced secondary ion battery. To clarify the energy storage mechanism of electrochemical interaction between metal ions and quasi-2D atomic crystals, it will be carried out for the comparative study of the relationships between the performances of batteries and the factors of the compositions and the layer number of quasi-2D atomic crystal nanosheet, the direction and the inter-distance range of the nanosheets stacked, and the size and the valence of ions. According to the mechansim illustrated, new printable film battery will be fabricated, and new theory for energy storage will be expected, too.

以若干层(1-9原子层)石墨烯为代表的准二维原子晶体新型材料具有与层状化合物母材料不同的量子结构和物化性能（如胶体分散性），可能带来能量储存新形态。申请人在发明石墨非氧化层离高效制备若干层石墨烯及其为负极的锂离子电池具有可逆的充放电平台的基础上，提出其离子电化学储能机制的研究。先假定锂离子扩散机理为Li+插层于若干层石墨烯单片的层间或者石墨烯片堆砌后限域性的表面吸附，后拟研究锂离子和铝离子电池的比容量与石墨烯层数及堆砌方式等因素的关联来求证鉴别，因为小的Li+能插层而大的Al3+不能。以若干层氧化物（如V2O5、CoO2）片层和石墨烯分别作为离子电池的正极和负极材料，系统地类比和比较性研究电池比容量等性能与准二维原子晶体的成分和层数、组装的取向及片与片的间距、离子的大小和价态等因素的内在关系，界定其离子电化学储能机理的边界条件，构造可印刷的新型薄膜电池，并期待构建新的存储理论。

本课题以若干层(1-9原子层)石墨烯为代表的准二维原子晶体新型材料的制备为突破口，成功研究了石墨烯等与层状化合物母材料不同的量子结构和物化性能（如良好的胶体分散性），成功研究了合成的新材料在能量储存应用中的新形态、新原理和新机制。申请人首先发明了电化学法从微晶石墨原矿中直接电解和机械剥离制备若干层小石墨烯微米片的方法，并发现了其良好的分散性和作为锂电池负极和导电剂的应用价值，获得了国家发明专利授权，并许可企业进行了石墨烯制备的中试放大。该小石墨烯还可以储硫作为长寿命锂硫电池，2000循环库伦效率99%以上。另外，还发现了同时制备石墨烯和负载的单分散金属原子的方法，获得了良好的电化学催化性能。研究证实了Li+能插层若干层石墨烯而大的Al3+不能若干层石墨烯的假设。系统地研究了锂电池比容量等性能与准二维原子晶体的成分和层数、组装的取向及片与片的间距、离子的大小和价态等因素的内在关系，界定了其离子电化学储能机理的边界条件，构造了高性能锂电池和空气电池。由于石墨烯的极大关注和广阔的应用价值以及石墨烯制备的重要突破，本课题着重于石墨烯的应用基础研究，获得了众多创新性成果。申请国家发明专利4项，授权3项，技术许可费500万，发表学术论文13篇，参加国内外学术会议26人次，培养毕业研究生2名和副研究员1名。