COMPOSITIONS AND METHODS FOR ELECTRODE FABRICATION
Provided are compositions and methods of making and using free-standing electrode films for electrodes by processes that improve upon prior dry process fabrication techniques. Processes are provided for forming an initial free standing film. The initial free standing film is then compressed into an electrode film in the presence of a liquid processing aid whereby the presence of the liquid processing aid reduces the number of roll mill passes to achieve a robust electrode film suitable for use in an electrode with relatively increased film porosity and mechanical strength.
1 . A process for forming a film suitable for use in an electrode, the process comprising:
forming an initial free standing film, the step of forming optionally comprising
a) combining a fibrillizable binder and a solid processing additive (optionally carbon particles) or an active electrode material to form an electrode precursor material;
b) intermixing said electrode precursor material;
c) combining said electrode precursor material with said solid processing additive or said active electrode material; and
d) intermixing said fibrillizable binder or said active electrode material with said electrode precursor material to form an electrode film material wherein said electrode film material comprises said fibrillizable binder, and at least one of said processing additives and said active electrode material;
calendering said electrode film material into an initial free standing film;
contacting said initial free standing film with a liquid processing aid forming a wetted free standing film;
passing said wetted free standing film through a roll mill, wherein said step of passing said wetted free standing film through said roll mill is repeated one or more times until an electrode film is formed, the electrode film comprising a final desired thickness of about 75% or less, optionally 50% or less, optionally 25% or less, relative to the initial free standing film, wherein said step of passing said wetted free standing film through said roll mill requires fewer passes than passing an dry free standing film through said roll mill to form said electrode film comprising said thickness of about 75% or less relative to the initial free standing film.
2 . The process of claim 1 , wherein said fibrillizable binder and said active electrode material are combined and intermixed to form said electrode precursor material and said electrode precursor material and said processing additive are combined and intermixed to form said electrode film material.
3 . The process of claim 1 , wherein said fibrillizable binder and said solid processing additive are combined and intermixed to form said electrode precursor material and said electrode precursor material and said solid processing additive are combined and intermixed to form said electrode film material.
4 . The process of claim 1 , wherein said fibrillizable binder and said active electrode material are combined and intermixed to form said electrode precursor material and said electrode precursor material and said active electrode material are combined and intermixed to form said electrode film material.
5 . The process of claim 1 , wherein said step of passing said wetted free standing film through said roll mill requires 1 to 10 passes through said roll mill to achieve said thickness of about 100 micrometers or less.
6 . The process of claim 1 , wherein said step of passing said wetted free standing film through said roll mill requires 1-5 passes through said roll mill to achieve said thickness of about 100 micrometers or less.
7 . The process of claim 1 , said step of passing said wetted free standing film through said roll mill requires five fewer number of passes than passing said dry free standing film through said roll mill to achieve said thickness of about 400 micrometers or less.
8 . The process of claim 1 , wherein said electrode film comprises a porosity of about 35% to about 45%.
9 . The process of claim 1 , wherein said electrode film comprises a Young's modulus of about 9.1 N/mm 2 .
10 . The process of any one of claims 1 - 9 , wherein said liquid processing aid is an alcohol.
11 . The process of any one of claims 1 - 9 , wherein said liquid processing aid is a solvent, said solvent comprises a surface tension of about 30 dynes/cm or less at 20 degrees Celsius.
12 . The process of any one of claims 1 - 9 , wherein said liquid processing aid comprises an evaporation rate of greater than 1.
13 . The process of any one of claims 1 - 9 , wherein said liquid processing aid is acetone, dimethyl carbonate, ethyl alcohol, anisole, ethanol, anisole, isopropyl alcohol, or any combination thereof.
14 . The process of any one of claims 1 - 9 , wherein said liquid processing aid is isopropyl alcohol.
15 . The process of any one of claims 1 - 9 , wherein said step of calendering said electrode film material into said initial free standing film is in an environment of about 130 degree Celsius.
16 . The process of any one of claims 1 - 9 , wherein said step of passing said wetted free standing film through said roll mill comprises heating said wetted free standing film to about 50 degree Celsius.
17 . The process of claim 16 , wherein said heating said wetted free standing film comprises heating with IR heat.
18 . The process of any one of claims 1 - 9 , wherein said step of passing said wetted free standing film through said roll mill further comprises:
heating said wetted free standing film to 50 degree Celsius or greater; and
compressing said wetted free standing film with said roll mill at a pressure of about 4000 to about 7000 pounds per square inch.
19 . The process of any one of claims 1 - 9 , wherein said roll mill comprises a roll speed of about 0.65 meters per minute.
20 . The process of any one of claims 1 - 9 , further comprising laminating said electrode film to an current collector to form said electrode.
21 . The process of any one of claims 1 - 9 , wherein said electrode film material comprises a conductive carbon.
22 . The process of any one of claims 1 - 9 , wherein said step of intermixing is in the absence of a solvent at an amount greater than 1% by weight.
23 . The process of any one of claims 1 - 9 , wherein said electrode film comprises a thickness of 100 micrometers or less, optionally 50 micrometers or less.
24 . The process of any one of claims 1 - 9 , wherein said active electrode material is capable of lithiation and delithiation.
25 . The process of any one of claims 1 - 9 , further comprising sieving said electrode film material.
26 . The process of any one of claims 1 - 9 , wherein said active electrode material comprises a lithium metal oxide, a lithium metal phosphate (optionally lithium manganese iron phosphate), or combinations thereof.
27 . The process of any one of claims 1 - 9 , wherein said fibrillizable binder comprises polytetrafluoroethylene.
28 . The process of any one of claims 1 - 9 , wherein said electrode film material comprises a single fibrillizable binder, said fibrillizable binder comprising or consisting of polytetrafluoroethylene.
29 . An electrochemical cell comprising a cathode comprising said electrode film formed by the process of any one of claims 1 - 9 .
30 . An electrochemical cell comprising an anode comprising said electrode film formed by the process of any one of claims 1 - 9 .
31 . A process for forming an electrode comprising:
obtaining an electrode film material;
calendering said electrode film material into an initial free standing film;
contacting said initial free standing film with a liquid processing aid forming a wetted free standing film;
passing said wetted free standing film through a roll mill, wherein said step of passing said wetted free standing film through said roll mill is performed one or more times until an electrode film comprising a thickness of about 50% or less, optionally 25% or less, optionally 100 micrometers or less, relative to the initial free standing film is formed, wherein said step of passing said free standing film through said roll mill requires about 1 to 10 fewer passes than passing an initial free standing film absent said liquid processing aid through said roll mill to form said electrode film comprising a thickness of about 50% or less relative to the initial free standing film.
32 . The process of claim 31 , wherein said step of obtaining said electrode film material further comprises:
combining a fibrillizable binder and carbon particles or an active electrode material to form an electrode precursor material;
intermixing said electrode precursor material;
combining said electrode precursor material with said carbon particles or said active electrode material;
intermixing said fibrillizable binder or said active electrode material with said electrode precursor material to form said electrode film material wherein said electrode film material comprises said fibrillizable binder, and at least one of said carbon particles and said active electrode material.
33 . The process of claim 32 , wherein said fibrillizable binder and said active electrode material are combined and intermixed to form said electrode precursor material and said electrode precursor material and said carbon particles are combined and intermixed to form said electrode film material.
34 . The process of claim 32 , wherein said fibrillizable binder and said carbon particles are combined and intermixed to form said electrode precursor material and said electrode precursor material and said carbon particles are combined and intermixed to form said electrode film material.
35 . The process of claim 32 , wherein said fibrillizable binder and said active electrode material are combined and intermixed to form said electrode precursor material and said electrode precursor material and said active electrode material are combined and intermixed to form said electrode film material.
36 . The process of claim 32 , wherein repeating said step of passing said wetted free standing film through said roll mill requires three fewer number of passes than passing said dry free standing film through said roll mill to achieve said thickness of about 50% or less.
37 . The process of claim 32 , wherein repeating said step of passing said wetted free standing film through said roll mill requires four fewer number of passes than passing said dry free standing film through said roll mill to achieve said thickness of about 50% or less.
38 . The process of claim 32 , wherein repeating said step of passing said wetted free standing film through said roll mill requires five fewer number of passes than passing said dry free standing film through said roll mill to achieve said thickness of about 50% or less.
39 . The process of any one of claims 31 - 38 , wherein said liquid processing aid is an alcohol.
40 . The process of any one of claims 31 - 38 , wherein said liquid processing aid comprises a surface tension of about 30 dynes/cm or less at 20 degree Celsius.
41 . The process of any one of claims 31 - 38 , wherein said liquid processing aid comprises an evaporation rate of greater than 1.
42 . The process of any one of claims 31 - 38 , wherein said liquid processing aid is at least one of acetone, dimethyl carbonate, ethyl alcohol, ethanol, anisole, isopropyl alcohol, or combinations thereof.
43 . The process of any one of claims 31 - 38 , wherein said liquid processing aid is isopropyl alcohol.
44 . The process of any one of claims 31 - 38 , wherein said step of calendering said electrode film material into said initial free standing film is in an environment of about 130 degrees Celsius.
45 . The process of any one of claims 31 - 38 , wherein said step of passing said wetted free standing film through said roll mill comprises heating said wetted free standing film to about 50 degree Celsius.
46 . The process of claim 45 , wherein said heating said wetted free standing film comprises heating with IR heat.
47 . The process of any one of claims 31 - 38 , wherein said step of passing said wetted free standing film through said roll mill further comprises:
heating said wetted free standing film to 50 degrees Celsius or greater; and
compressing said wetted free standing film with said roll mill at a pressure of about 4000 to about 7000 pounds per square inch.
48 . The process of any one of claims 31 - 38 , wherein step of compressing is at a roll speed of about 0.65 meters per minute.
49 . The process of any one of claims 31 - 38 , further comprising laminating said electrode film to a current collector to form said electrode.
50 . The process of any one of claims 31 - 38 , wherein said electrode film material comprises a conductive carbon.
51 . The process of any one of claims 31 - 38 , wherein said step of intermixing is in the absence of a solvent greater than 1%.
52 . The process of any one of claims 31 - 38 , wherein said electrode film comprises a thickness of 100 micrometers or less, optionally 50 micrometers or less.
53 . The process of any one of claims 32 - 38 , wherein said active electrode material is capable of lithiation and delithiation.
54 . The process of any one of claims 31 - 38 , further comprising sieving said electrode film material.
55 . The process of any one of claims 32 - 38 , wherein said active electrode material comprises a lithium metal oxide, a lithium metal phosphate (optionally lithium manganese iron phosphate), or combinations thereof.
56 . The process of any one of claims 32 - 38 , wherein said fibrillizable binder comprises polytetrafluoroethylene.
57 . The process of any one of claims 32 - 38 , wherein said electrode film material comprises a single fibrillizable binder, said fibrillizable binder comprising or consisting of polytetrafluoroethylene.
58 . An electrochemical cell comprising a cathode comprising said electrode film formed by a process of any one of claims 31 - 38 .
59 . An electrochemical cell comprising an anode comprising said electrode film formed by a process of any one of claims 31 - 38 .