Polyimide-based composite films with high thermal conductivity,good mechanical property and electrical insulating performance are urgently needed in the electronics and microelectronics fields.As one of the key techni...Polyimide-based composite films with high thermal conductivity,good mechanical property and electrical insulating performance are urgently needed in the electronics and microelectronics fields.As one of the key technical challenges to be solved,interfacial compatibility between filler and matrix plays an important role for composite film.Herein,boron nitride was modified by grafting polyimide brushes via a twostep method,and a series of thermally conductive polyimide/boron nitride composite films were prepared.Both characterization and performance results proved that the interfacial interaction and compatibility was greatly enhanced,resulting in a significant reduction in defects and interfacial thermal resistance.The interphase width of transition zone between two phases was also efficiently enlarged due to polyimide brushes grafted on filler surface.As a result,composite films based on polyimide-grafted boron nitride exhibited significantly improved properties compared with those based on pristine filler.Tensile strength can reach up to 80 MPa even if the filler content is as high as 50 wt%.The out-of-plane and in-plane thermal conductivity of composite film increased to 0.841 and 0.850 W·m^(-1)·K^(-1),respectively.In addition,thermal and dielectric properties of composite films were also enhanced to some extent.The above results indicate that surface modification by chemically grafting polymer brushes is an effective method to improve two-phase interfacial compatibility so as to prepare composite film with enhanced properties.展开更多
Lithium(Li) metal batteries have received extensive research focusing on the dendrite growth issue on account of the high chemical activity of Li anode. While, thermal safety, as one of the important security concerns...Lithium(Li) metal batteries have received extensive research focusing on the dendrite growth issue on account of the high chemical activity of Li anode. While, thermal safety, as one of the important security concerns facing the further application, gets little attention. Here, the high-performance polyimide film is successfully developed to enhance the safety margin based on the excellent mechanical strength and heat resistance corresponding to the traditional separator. And, the polyimide film with the Mo S2 coating made by spraying method as the composite separator can not only improve the wettability to the electrolyte, but also in-situ form an artificial layer with the low nucleation barrier for the Li ions. When used in both the coin cell and the pouch cell, all achieve the outstanding cycling stability and the coulombic efficiency. Specially, the in-situ Li ions nucleation behaviors are investigated by optical microscopy in the capillary cell. The electric field intensity at the Li anode surface is also simulated by COMSOL Multiphysics to further elucidate the effect of the coating.展开更多
基金financially supported by the Natural Science Foundation of Beijing(No.2202068)the National Natural Science Foundation of China(No.51803221)National Key Research and Development Program(No.2022YFB3603105).
文摘Polyimide-based composite films with high thermal conductivity,good mechanical property and electrical insulating performance are urgently needed in the electronics and microelectronics fields.As one of the key technical challenges to be solved,interfacial compatibility between filler and matrix plays an important role for composite film.Herein,boron nitride was modified by grafting polyimide brushes via a twostep method,and a series of thermally conductive polyimide/boron nitride composite films were prepared.Both characterization and performance results proved that the interfacial interaction and compatibility was greatly enhanced,resulting in a significant reduction in defects and interfacial thermal resistance.The interphase width of transition zone between two phases was also efficiently enlarged due to polyimide brushes grafted on filler surface.As a result,composite films based on polyimide-grafted boron nitride exhibited significantly improved properties compared with those based on pristine filler.Tensile strength can reach up to 80 MPa even if the filler content is as high as 50 wt%.The out-of-plane and in-plane thermal conductivity of composite film increased to 0.841 and 0.850 W·m^(-1)·K^(-1),respectively.In addition,thermal and dielectric properties of composite films were also enhanced to some extent.The above results indicate that surface modification by chemically grafting polymer brushes is an effective method to improve two-phase interfacial compatibility so as to prepare composite film with enhanced properties.
文摘Lithium(Li) metal batteries have received extensive research focusing on the dendrite growth issue on account of the high chemical activity of Li anode. While, thermal safety, as one of the important security concerns facing the further application, gets little attention. Here, the high-performance polyimide film is successfully developed to enhance the safety margin based on the excellent mechanical strength and heat resistance corresponding to the traditional separator. And, the polyimide film with the Mo S2 coating made by spraying method as the composite separator can not only improve the wettability to the electrolyte, but also in-situ form an artificial layer with the low nucleation barrier for the Li ions. When used in both the coin cell and the pouch cell, all achieve the outstanding cycling stability and the coulombic efficiency. Specially, the in-situ Li ions nucleation behaviors are investigated by optical microscopy in the capillary cell. The electric field intensity at the Li anode surface is also simulated by COMSOL Multiphysics to further elucidate the effect of the coating.
