Abstract：
The energy stability and electronic structural of graphene and defective graphene oxide (GO) parallel to the surface of LiFePO4 (010) were theoretically investigated by using first-principles density functional theory calculations within the DFT + U framework. The calculated formation energy shows that GO coating on the surface of LiFePO4 (010) is energetically favorable and has higher bond strength compared to graphene. The calculation of the electronic structure indicates that the emergence of band in-gap states originates from graphene coating, with adsorbed O atoms contributing significantly above the Fermi level. Electron density difference indicate that GO stands on the LFP (010) surface through C-O and Fe-O bonds, rather than relying on van der Waals forces placed parallel to the LFP crystal, with the chemical bond at the LFP/GO interface (Fe-O-C) both anchoring the coated carbon layer and promoting electron conductivity at the interface. In addition, LFP/GO shows superior electrochemical performance, Atomic Populations suggests that the average Fe-O bonding on the surface of LiFePO4 (010) was clearly changed after graphene or GO coating, which led to the expansion of Li+ channels and favored the migration insertion and extraction of Li+.
摘要：
通过在DFT+U框架内使用第一性原理密度泛函理论计算，从理论上研究了平行于LiFePO4(010)表面的石墨烯和缺陷氧化石墨烯(GO)的能量稳定性和电子结构。计算的形成能表明，与石墨烯相比，在LiFePO4（010）表面上的GO涂层在能量上是有利的，并且具有更高的粘结强度。电子结构的计算表明，带隙态的出现源于石墨烯涂层，吸附的O原子大大超过费米能级。电子密度差表明GO通过C-O和Fe-O键位于LFP(010)表面,而不是依靠平行于LFP晶体的范德华力，LFP/GO界面处的化学键(Fe-O-C)既锚定涂覆的碳层又促进界面处的电子传导性。此外,LFP/GO表示出优越的电化学机能，原子群表明，在石墨烯或GO涂覆后，LiFePO4（010）表面上的平均Fe-O键明显改变，这导致了Li+通道的扩展，有利于Li+的迁移插入和提取。
