Flexible asymmetric electrochemical cells using nano graphene platelet as an electrode material

摘要

A flexible, asymmetric electrochemical cell comprising: (A) A sheet of graphene paper as first electrode comprising nano graphene platelets having a platelet thickness less than 1 nm, wherein the first electrode has electrolyte-accessible pores; (B) A thin-film or paper-like first separator and electrolyte; and (C) A thin-film or paper-like second electrode which is different in composition than the first electrode; wherein the separator is sandwiched between the first and second electrode to form a flexible laminate configuration. The asymmetric supercapacitor cells with different NGP-based electrodes exhibit an exceptionally high capacitance, specific energy, and stable and long cycle life.

主权项

1. A flexible, asymmetric electrochemical cell comprising:
(A) a sheet of spacer-modified graphene paper thinner than 1 mm as first electrode, said paper comprising (a) nano graphene platelets having a thickness smaller than 10 nm and (b) discrete, non-continuous, and non-metallic particles, having a size no less than 2 nm, bonded to a surface or both surfaces of said nano graphene platelets as spacer particles to produce electrolyte-accessible pores having a size greater than 2 nm and less than 10 nm and having a specific surface area greater than 100 m2/g, and (c) a binder that bonds said nano graphene platelets together and wherein said particles consist of a material selected from the group consisting of metal carbide, metal nitride, metal halide, and combinations thereof and wherein said first electrode has a first specific capacitance C1, (B) a thin-film first separator thinner than 1 mm and electrolyte; (C) a thin-film second electrode thinner than 1 mm which is different in composition than the first electrode wherein said second electrode comprises a lithium foil or lithium-intercalated material; and wherein said separator is sandwiched between the first and second electrode to form a flexible laminate configuration; D) a second separator containing electrolyte, wherein said second separator is in physical contact with said second electrode; and (E) a third thin-film electrode, having a thickness less than 1 mm, in contact with said second separator and having a second specific capacitance C2 and wherein the C1/C2 ratio is greater than 3.