Abstract: An electrochemical device includes a negative electrode sheet. The negative electrode sheet includes a current collector, a first coating layer, and a second coating layer. The first coating layer is located between the current collector and the second coating layer. The second coating layer includes a negative active material. The first coating layer includes a conductive carbon material. The conductive carbon material includes at least one of carbon nanotubes or graphene. Based on a mass of the first coating layer, a mass percent of the conductive carbon material is 20% to 60%. The main material of the first coating layer is at least one of carbon nanotubes or graphene.

Abstract: A micro-vibration sensor and preparation method thereof. The method includes a metal sheet is coated with first curing material, and first curing material is cured into first cured layer; piezoelectric thin film element is attached to edge of first cured layer; one side, attached with piezoelectric thin film element, of first cured layer is vertically placed into second curing material, and second curing material is cured into second cured layer; and metal sheet is removed to obtain micro-vibration sensor. Due to fact that piezoelectric thin film element is arranged at a crack tip, during micro-vibration, stress in stress field of crack tip is rapidly increased due to crack stress deformation, and stress signal is efficiently converted into electric signal; and micro-vibration sensor has characteristics of being low in detection limit and high in accuracy.

Abstract: A bionic nested structure fiber composite material includes a first fiber resin layer and a second fiber resin layer which are arranged in parallel, the first fiber resin layer and the second fiber resin layer are formed by a fiber bundle infiltrated with resin, and a bonded fiber unit is arranged between the first fiber resin layer and the second fiber resin layer, the bonded fiber unit are evenly distributed in a radial direction and a weft direction, the bonded fiber unit includes an inner core layer bonded fiber bundle, a middle core layer bonded fiber bundle and an outer core layer bonded fiber bundle, and the bonded fiber unit is performed 3D integrated layer-by-layer inner and outer nesting-and-weaving to form bionic nested structure.

Abstract: A micro-vibration sensor and preparation method thereof. The method includes a metal sheet is coated with first curing material, and first curing material is cured into first cured layer; piezoelectric thin film element is attached to edge of first cured layer; one side, attached with piezoelectric thin film element, of first cured layer is vertically placed into second curing material, and second curing material is cured into second cured layer; and metal sheet is removed to obtain micro-vibration sensor. Due to fact that piezoelectric thin film element is arranged at a crack tip, during micro-vibration, stress in stress field of crack tip is rapidly increased due to crack stress deformation, and stress signal is efficiently converted into electric signal; and micro-vibration sensor has characteristics of being low in detection limit and high in accuracy.