Method of fabricating electrodes including high-capacity, binder-free anodes for lithium-ion batteries
View Patent ↗An electrode ( 110 ) is provided that may be used in an electrochemical device ( 100 ) such as an energy storage/discharge device, e.g., a lithium-ion battery, or an electrochromic device, e.g., a smart window. Hydrothermal techniques and vacuum filtration methods were applied to fabricate the electrode ( 110 ). The electrode ( 110 ) includes an active portion ( 140 ) that is made up of electrochemically active nanoparticles, with one embodiment utilizing 3d-transition metal oxides to provide the electrochemical capacity of the electrode ( 110 ). The active material ( 140 ) may include other electrochemical materials, such as silicon, tin, lithium manganese oxide, and lithium iron phosphate. The electrode ( 110 ) also includes a matrix or net ( 170 ) of electrically conductive nanomaterial that acts to connect and/or bind the active nanoparticles ( 140 ) such that no binder material is required in the electrode ( 110 ), which allows more active materials ( 140 ) to be included to improve energy density and other desirable characteristics of the electrode. The matrix material ( 170 ) may take the form of carbon nanotubes, such as single-wall, double-wall, and/or multi-wall nanotubes, and be provided as about 2 to 30 percent weight of the electrode ( 110 ) with the rest being the active material ( 140 ).
1. A method of making a binderless electrode material, the method comprising:
combining an electrochemically active precursor material comprising iron oxyhydroxide nanoparticles and an electrically conductive material comprising carbon nanoparticles to form a material;
mixing the material with a sodium dodecyl sulfate solution to form a mixed material;
filtering the mixed material to form a mixed electrode material;
transferring the mixed electrode material to a conductive substrate; and
heating the transferred mixed electrode material and the conductive substrate in an inert atmosphere, such that at least a portion of the iron oxyhydroxide nanoparticles is converted to iron oxide nanoparticles suspended within the electrically conductive material.
2. The method of claim 1 , wherein the carbon nanoparticles comprise at least one of boron or nitrogen.
3. The method of claim 1 , wherein the heating is performed such that the transferred mixed electrode material reaches a temperature up to 450° C.
4. The method of claim 1 , wherein the mixing further comprises sonicating the mixed material.
5. The method of claim 1 , wherein the conductive substrate is a metal foil.
6. The method of claim 1 , wherein the inert atmosphere comprises argon.
7. The method of claim 1 , wherein the carbon nanoparticles comprise at least one of single-wall carbon nanotubes, double-wall carbon nanotubes, multi-wall carbon nanotubes, boron-doped carbon nanotubes, or nitrogen-doped carbon nanotubes.
8. The method of claim 1 , further comprising, prior to the combining, reacting a mixture comprising iron (III) chloride, sodium hydroxide, and water to produce the iron oxyhydroxide nanoparticles.
9. The method of claim 8 , wherein the reacting is performed at a temperature of 160° C.
10. The method of claim 1 , wherein the iron oxyhydroxide nanoparticles comprise nanorods.
11. The method of claim 1 , wherein the iron oxide nanoparticles comprise Fe 3 O 4 .