“…Although the incorporation of single 2D nanofillers enhances the energy density to a certain degree, the nanocomposites are still unsuitable for energy storage because of high energy loss of high ϵ r fillers or low polarization of highly insulating fillers. To further enhance the energy density and meet the need for energy storage applications, multiphase 2D nanofillers are introduced into the polymer matrix in single-layered polymer nanocomposites ( Liu et al., 2020 ; Wang et al., 2018b ; Ke et al., 2019 ; Zhu et al., 2020 ; Feng et al, 2019 ; Deng et al, 2019; He et al., 2018 ; Luo et al., 2018 ; Li et al., 2019 ; Song et al., 2020 ) or different 2D materials are filled separately into multilayer-structured nanocomposites ( Guo et al., 2020 ; Chi et al., 2019 ; Wu et al., 2018a ; Liu et al., 2017b ; Shen et al., 2015 ).…”