▎ 摘　　要

NOVELTY - Secondary structure of graphene cage comprises multiple capsule-shaped graphene cages with three-dimensional space of interconnected structure, which is provided with interconnected graphene layer and internal conducting cavity; where each capsule form graphene cage has length of 100-200 nm, diameter of 20-50 nm, 4-10 carbon atoms layer. USE - The secondary structure of graphene cage is useful for transfer of electrons and ion, as a lithium-ion battery cathode material, and in supercapacitors, electrochemical catalysis and electrochemical sensors. ADVANTAGE - The secondary structure of graphene cage has high specific capacity, good rate capability and good cycling stability. The process is simple, easy to operate, and conducive to mass production. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for preparing the secondary structure of graphene cage, comprising (i) adding soluble zinc salt and sodium hydroxide into a beaker, adding ethylenediamine and deionized water, ultrasonically dispersing to obtain white suspension, adding 50-80 volume% suspension into polytetrafluoroethylene substrate, and placing in a reactor, reacting under sealed condition at 150-200 degrees C for 6-12 hours, then cooling the reactor to room temperature, to obtain white precipitate, centrifuging, washing with anhydrous ethanol 3-5 times, drying at 50-80 degrees C for 8-12 hours, to obtain zinc oxide secondary structure; (ii) adding zinc oxide secondary structure and naphthalene in the mass ratio of 1:2-2:1 into dual-zone tubular furnace having high temperature zone and low temperature zone, under an inert gas atmosphere initially heating to deposition temperature at high temperature region, then heating to vaporization temperature in low temperature zone, carrying out chemical vapor deposition, and naturally cooling to produce surface wrapped zinc oxide graphene layer; and (iii) mixing surface wrapped zinc oxide graphene layer with 5-10% hydrochloric acid solution in the ratio of 1:100-1:200, ultrasonicating for 0.5-1 hour, to obtain a suspension, filtering, then centrifuging with anhydrous ethanol as solvent at 5000-9000 revolutions per minute for 5-10 minutes, washing until the pH is 6.5-7, and drying at 50-80 degrees C for 8-12 hours.