Department of Energy Systems Engineering, Daegu Gyeongbuk Institute of Science and Technology , Daegu 42988, South Korea.
Graduate School of Energy, Environment, Water, and Sustainability and KAIST Institute NanoCentury, Korea Advanced Institute of Science and Technology , Daejeon 34141, South Korea.
ACS Appl Mater Interfaces. 2016 Jun 8;8(22):13973-81. doi: 10.1021/acsami.6b04109. Epub 2016 May 20.
Despite two decades of commercial history, it remains very difficult to simultaneously achieve both high rate capability and thermal stability in the graphite anodes of Li-ion batteries because the stable solid electrolyte interphase (SEI) layer, which is essential for thermal stability, impedes facile Li(+) ion transport at the interface. Here, we resolve this longstanding challenge using a mussel-inspired polydopamine (PD) coating via a simple immersion process. The nanometer-thick PD coating layer allows the formation of an SEI layer on the coating surface without perturbing the intrinsic properties of the SEI layer of the graphite anodes. PD-coated graphite exhibits far better performances in cycling test at 60 °C and storage test at 90 °C than bare graphite. The PD-coated graphite also displays superior rate capability during both lithiation and delithiation. As evidenced by surface free energy analysis, the enhanced performance of the PD-coated graphite can be ascribed to the Lewis basicity of the PD, which scavenges harmful hydrofluoric acid and forms an intermediate triple-body complex among a Li(+) ion, solvent molecules, and the PD's basic site. The usefulness of the proposed PD coating can be expanded to various electrodes in rechargeable batteries that suffer from poor thermal stability and interfacial kinetics.
尽管已有二十年的商业历史，但要在锂离子电池的石墨阳极中同时实现高倍率性能和热稳定性仍然非常困难，因为稳定的固体电解质界面（SEI）层对于热稳定性至关重要，但它会阻碍界面处 Li(+)离子的传输。在这里，我们通过简单的浸渍工艺使用受贻贝启发的聚多巴胺（PD）涂层解决了这一长期存在的挑战。纳米厚的 PD 涂层允许在涂层表面形成 SEI 层，而不会干扰石墨阳极 SEI 层的固有特性。与裸石墨相比，PD 涂层石墨在 60°C 的循环测试和 90°C 的存储测试中表现出更好的性能。PD 涂层石墨在锂化和脱锂过程中均表现出优异的倍率性能。通过表面自由能分析证明，PD 涂层石墨的增强性能可归因于 PD 的路易斯碱性，它可以清除有害的氢氟酸并在 Li(+)离子、溶剂分子和 PD 的碱性位之间形成中间三体络合物。所提出的 PD 涂层的用途可以扩展到各种在热稳定性和界面动力学方面存在问题的可充电电池中的电极。
