▎ 摘　　要

NOVELTY - Electrode comprises first active material, second active material and graphene compound, where the first active material comprises silicon having particle diameter of less than or equal to 1 mu m, the second active material comprises graphite larger than that of first active material, the first active material is located on surface of second active material, and the graphene compound is in contact with first active material and second active material. USE - The electrode is used for secondary battery, such as lithium ion secondary battery, lithium ion capacitor and electric double layer capacitor, which is used in mobile body and electronic device (all claimed), such as power storage device, electro-optical device having the power storage device and information terminal device, used in semiconductor device, display device, light emitting device, power storage device, lighting device and electronic device, portable information terminals such as mobile phones, smartphones, or notebook computers, portable music players, digital cameras, medical devices, or hybrid vehicles (HVs), and electric vehicles, the secondary batteries are used for moving objects such as electric vehicles and hybrid vehicles, and the electronic devices are used for television devices, such as televisions or television receivers, monitors for computers, digital cameras, digital video cameras, digital photo frames, mobile phones for e-mails, text viewing and writing, music playback, internet communication and computer games, portable game machine, mobile information terminal, sound reproduction device, large game machine, such as a pachinko machine and mobile information terminals, such as notebook personal computers, tablet terminals, electronic books and mobile phones. ADVANTAGE - The electrode provides lithium-ion secondary batteries with high output, high energy density and high capacity, and is not susceptible to deterioration. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following: (1) a secondary battery comprising electrode and electrolyte; and (2) a method for preparing the electrode, involving uniformly mixing silicon and solvent to obtain first mixture, uniformly mixing obtained first mixture with graphite to obtain second mixture, uniformly mixing obtained second mixture with graphene compound to obtain third mixture, uniformly mixing obtained third mixture with polyimide precursor and solvent to obtain fourth mixture, and applying obtained fourth mixture to metal foil, drying obtained fourth mixture, and heating obtained fourth mixture in reduced pressure environment to obtain the electrode.