Exhibit B 

Case 2:23-cv-00334 Document 1-2 Filed 07/14/23 Page 1 of 12 PageID #: 24
(12) United States Patent 

Zhong et al. 

USOO85916O1B2 

(10) Patent No.: US 8.591,601 B2 

(45) Date of Patent: Nov. 26, 2013 

(54) ELECTRODE FOR ENERGY STORAGE 

DEVICE WITH MICROPOROUSAND 

MESOPOROUS ACTIVATED CARBON 

PARTICLES 

(75) Inventors: Linda Zhong, San Diego, CA (US); 

Xiaomei Xi, Carlsbad, CA (US) 

(73) Assignee: Maxwell Technologies, Inc., San Diego, 

CA (US) 

(*) Notice: Subject to any disclaimer, the term of this 

patent is extended or adjusted under 35 

U.S.C. 154(b) by 0 days. 

(21) Appl. No.: 13/601,567 

(22) Filed: Aug. 31, 2012 

(65) Prior Publication Data 

US 2013/OO56138A1 Mar. 7, 2013 

Related U.S. Application Data 

(62) Division of application No. 12/445.295, filed as 

application No. PCT/US2007/081698 on Oct. 17, 

2007, now Pat. No. 8,279,580. 

(60) Provisional application No. 60/852.459, filed on Oct. 

17, 2006. 

(51) Int. Cl. 

HOIG 9/00 

(52) U.S. Cl. 

USPC ......................................................... 29/25.03 

(58) Field of Classification Search 

None 

See application file for complete search history. 

(2006.01) 

(56) References Cited 

U.S. PATENT DOCUMENTS 

5,973,912 A 10, 1999 Kibi 

6,127.474. A 10, 2000 Andelman 

2001 N. 

2O5 current collector 

2O Active Electrode Film 

220 Porous separator 

23O Active Electrode Film 

235 Current Collector 

6,296,746 B1 10/2001 Broman 

6,359,769 B1 3/2002 Mushiake 

6,377,441 B1 4/2002 Ohya 

6.426,865 B2 7/2002 Kasahara 

6,456.484 B1 9, 2002 Matsuoka 

6,461,769 B1 10/2002 Ando et al. 

(Continued) 

FOREIGN PATENT DOCUMENTS 

JP 1992-148670 12/1993 

JP 1992-359777 T 1994 

(Continued) 

OTHER PUBLICATIONS 

Office Action dated May 29, 2012, in counterpart Jap. App. No. 

2009-533513, filed Oct. 17, 2007. 

(Continued) 

Primary Examiner — Seahvosh Nikmanesh 

(74) Attorney, Agent, or Firm — Knobbe Martens Olson & 

Bear LLP 

(57) ABSTRACT 

A method of making an active electrode material is provided. Activated carbon having between about 70 and 98 percent microporous activated carbon particles of a total amount of 

activated carbon by weight and between about 2 and 30 per 

cent mesoporous activated carbon particles of the total 

amount of activated carbon by weight is provided. Binder is 

provided. The activated carbon and the binder is mixed to 

form an active electrode material mixture. In some imple mentations, a method of making an electrode film includes 

forming a film of active electrode material comprising acti 

vated carbon having between about 70 and 98 percent microporous activated carbon particles of a total amount of 

activated carbon by weight and between about 2 and 30 per 

cent mesoporous activated carbon particles of the total 

amount of activated carbon by weight. The method further 

includes bonding the film to a current collector to form an 

electrode film. 

27 Claims, 2 Drawing Sheets 

 

 

 

 

 

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US 8,591,601 B2 

Page 2 

(56) References Cited JP 2003-054524 2, 2003 

JP 2003-341526 12/2003 

U.S. PATENT DOCUMENTS JP 2004-221523 8, 2004 

JP 2005-379763 3, 2005 

6,500,770 B1 12/2002 Cheng JP 2005-104676 4/2005 

6,532,144 B2 3/2003 Ohya JP 2005-104.701 4/2005 

6,565,701 B1 5/2003 Jerabek JP 2005-104709 4/2005 

6,627,252 B1 9/2003 Nanjundiah JP 2005-104.735 4/2005 

6,631,073 B1 10/2003 Sakata et al. JP 2005-121571 5, 2005 

6,631,074 B2 10/2003 Bendale JP 2005-125707 5, 2005 

6,740,454 B1 5/2004 Ando et al. JP 2005-12871.4 5, 2005 

6,862,168 B2 3/2005 Ando et al. JP 2005-160529 6, 2005 

7,147,674 B1 12/2006 Zhong JP 2005-196723 7/2005 

7,317,609 B2 1/2008 Zhong et al. JP 2005-249763 9, 2005 

7,443,651 B2 10/2008 Ando et al. JP 2005-249927 9, 2005 

7,697.264 B2 4/2010 Tasaki et al. JP 2005-25.0022 9, 2005 

7,733,629 B2 6/2010 Tasaki et al. JP 2005-251586 9, 2005 

7,768,769 B2 8/2010 Matsui et al. JP 2005-286170 10/2005 

8,279.580 B2 * 10/2012 Zhong et al. .................. 361,502 JP 2005-302342 10/2005 

2003/O161781 A1 8/2003 Cabasso et al. JP 2005-3294.55 12/2005 

2004/0246658 A1 12/2004 Adrianov et al. JP 2005-3554.09 6, 2007 

2005, OO14643 A1 1/2005 Lini JP 2005-379698 7/2007 

2005/0057888 A1 3, 2005 Mitchell JP 2005-379741 7/2007 

2005/0233183 A1* 10/2005 Hampden-Smith et al. ... 429/12 JP 2005-379798 7/2007 

2006, OO57433 A1 3, 2006 Ando et al. 

2006/O115723 A1 6, 2006 Ando et al. OTHER PUBLICATIONS 

2006, O188784 A1 8, 2006 Sudoh 

2007/0048521 A1 3f2007 Istvan ........................... 428,367 Office Action dated Sep. 1, 2010 Received from Chinese Patent 

39.99. A. 3. (SA, etal Office for co-pending Chinese Application No. 200780038879.7. 

2009, O127129 A1* 5, 2009 Nazri et al. o 205/477 International Search Report and Written Opinion for International 

Application No. PCT/US07/81698. 

FOREIGN PATENT DOCUMENTS European Extended Search Report in European Application No. 

07854143.0, filed Oct. 17, 2007, dated Jun. 6, 2013. 

JP 2001-044082 2, 2001 

JP 2001-143973 5, 2001 * cited by examiner 

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U.S. Patent Nov. 26, 2013 Sheet 1 of 2 US 8,591,601 B2 

| -61

 

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U.S. Patent Nov. 26, 2013 Sheet 2 of 2 US 8,591,601 B2 

2001 Y 

205 Current Collector 

21 O Active Electrode Film 

220 Porous Separator 

230 Active Electrode Film 

235. Current Collector 

 

 

 

 

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US 8,591,601 B2 

1. 

ELECTRODE FOR ENERGY STORAGE 

DEVICE WITH MICROPOROUSAND 

MESOPOROUS ACTIVATED CARBON 

PARTICLES 

CROSS-REFERENCE TO RELATED 

APPLICATIONS 

This application is a divisional of U.S. patent application 

Ser. No. 12/445,295, filed on Apr. 15, 2009, now U.S. Pat. No. 

8.279,580, issued Oct. 2, 2012, which is a national stage application under 35 U.S.C. S371 of international PCT Appli 

cation No. PCT/US2007/081698 designating the United 

States, filed on Oct. 17, 2007 and claiming priority to U.S. 

Provisional Application No. 60/852.459, filed on Oct. 17, 

2006, the entire contents of these applications are incorpo 

rated herein by reference in their entirety. 

BACKGROUND 

The present invention generally relates to electrodes and 

the fabrication of electrodes. More specifically, the present 

invention relates to electrodes used in energy storage devices, 

Such as electrochemical double layer capacitors and hybrid capacitor and battery devices. 

Electrodes are widely used in many devices that store elec 

trical energy, including primary (non-rechargeable) battery 

cells, secondary (rechargeable) battery cells, fuel cells, and 

capacitors. Important characteristics of electrical energy Stor 

age devices include energy density, power density, maximum 

charging and discharging rate, internal leakage current, 

equivalent series resistance (ESR), and/or durability, i.e., the 

ability to withstand multiple charge-discharge cycles. For a 

number of reasons, double layer capacitors, also known as 

Supercapacitors and ultracapacitors, are gaining popularity in 

many energy storage applications. The reasons include avail 

ability of double layer capacitors with high power densities 

(in both charge and discharge modes), and the long life of 

double layer capacitors compared to conventional recharge 

able cells. 

Double layer capacitors typically use as their energy stor 

age element electrodes immersed in an electrolyte (an elec 

trolytic solution). As such, a porous separator immersed in 

and impregnated with the electrolyte may ensure that the 

electrodes do not come in contact with each other, preventing 

electronic current flow directly between the electrodes. At the 

same time, the porous separator allows ionic currents to flow 

through the electrolyte between the electrodes in both direc 

tions. As discussed below, double layers of charges are 

formed at the interfaces between the solid electrodes and the 

electrolyte. 

When electric potential is applied between a pair of elec 

trodes of a double layer capacitor, ions that exist within the 

electrolyte are attracted to the surfaces of the oppositely 

charged electrodes, and migrate towards the electrodes. A 

layer of oppositely-charged ions is thus created and main 

tained near each electrode surface. Electrical energy is stored 

in the charge separation layers between these ionic layers and 

the charge layers of the corresponding electrode surfaces. In 

fact, the charge separation layers behave essentially as elec 

trostatic capacitors. Electrostatic energy can also be stored in 

the double layer capacitors through orientation and alignment 

of molecules of the electrolytic solution under influence of 

the electric field induced by the potential. This mode of 

energy storage, however, is secondary. 

In comparison to conventional capacitors, double layer 

capacitors have high capacitance in relation to their Volume 

10 

15 

25 

30 

35 

40 

45 

50 

55 

60 

65 

2 

and weight. There are two main reasons for these Volumetric 

and weight efficiencies. First, the charge separation layers are 

very narrow. Their widths are typically on the order of 

nanometers. Second, the electrodes can be made from a 

porous material, having very large effective surface area per unit Volume. Because capacitance is directly proportional to 

the electrode area and inversely proportional to the widths of 

the charge separation layers, the combined effect of the large 

effective Surface area and narrow charge separation layers is 

capacitance that is very high in comparison to that of conven 

tional capacitors of similar size and weight. High capacitance 

of double layer capacitors allows the capacitors to receive, 

store, and release large amount of electrical energy. Electrical energy stored in a capacitor is determined using a well-known formula: 

C. V. (1) 

In this formula, E represents the stored energy, C Stands for 

the capacitance, and V is the Voltage of the charged capacitor. 

Thus, the maximum energy (E) that can be stored in a 

capacitor is given by the following expression: 

C: V (2) 

En = 2 

where V, stands for the rated voltage of the capacitor. It 

follows that a capacitors energy storage capability depends 

on both (1) its capacitance, and (2) its rated Voltage. Increas 

ing these two parameters may therefore be important to 

capacitor performance. 

SUMMARY 

Over a number of charge-discharge cycles, ions within an 

electrolyte of an energy storage device may migrate within an 

electrode of the energy storage device. Over time, ions may 

get “stuck within pores (e.g., micropores) of an electrode 

and become unavailable for further charge-discharge cycles. 

This reduction in available ions within a localized region of 

the electrode results in a condition of “local electrolyte starv 

ing in that region of the electrode. As regions of an electrode 

lose the availability of ions in those regions, the energy Stor 

age device undergoes a reduction in performance. It would be 

desirable to improve reliability and durability of energy stor 

age devices, as measured by the number of charge-discharge 

cycles that an energy storage device can withstand without a 

significant deterioration in its operating characteristics. Addi 

tionally, it would be desirable to provide energy storage 

devices using these electrodes. 

The use of both microporous and mesoporous activated 

carbons together is provided. The mesoporous activated car 

bons provide excess capacity for electrolytes (and the ions 

within the electrolytes). Microporous activated carbons, how 

ever, have Smaller capacities for electrolytes and ions. Thus, 

when ions may not be available due to the microporous acti 

vated carbons, the mesoporous activated carbons may pro vide additional electrolyte in a localized region to provide additional ions for charge-discharge cycles. 

In a double layer capacitor, for example, local electrolyte 

starvation can lead to capacitance fade, where the capacitance of the double layer capacitor decreases over multiple charge discharge cycles. It would be desirable to improve reliability 

Case 2:23-cv-00334 Document 1-2 Filed 07/14/23 Page 6 of 12 PageID #: 29
US 8,591,601 B2 

3 

and durability of energy storage devices double layer capaci 

tors, as measured by the number of charge-discharge cycles 

that a double layer capacitor can withstand without a signifi 

cant deterioration in its operating characteristics (e.g., capaci 

tance). Since an end of life of a double layer capacitor can be 

defined for a particular application by reaching an unaccept 

able capacitance level for that application, slowing a fade in 

capacitance can directly increase the life of a double layer capacitor. 

Various implementations hereof are directed to methods, 

electrodes, electrode assemblies, and electrical devices that 

may be directed to or may satisfy one or more of the above 

needs. An exemplar implementation herein disclosed is a 

method of making particles of active electrode material. In 

accordance with Such a method, particles of activated carbon, 

optional conductive carbon, and binder may be mixed. In 

aspects hereof, the activated carbon may comprise between 

about 70 and 98 percent microporous activated carbon par 

ticles and between about 2 and 30 percent mesoporous acti 

vated carbon particles by weight. In aspects hereof, the 

optional conductive particles may include conductive carbon 

materials such as carbon black, graphite, carbon fiber, carbon 

nanotubes, and the like. 

In accordance with Some alternative aspects hereof, the 

binder is an electrochemically inert binder, such as PTFE. 

The proportion of the inert binder may be between about 3 

and about 20 percent by weight, and in some other instances 

between about 9 and about 11 percent by weight, or may be, 

for example, about 10 percent by weight. In accordance with 

Some aspects hereof, the proportion of the optional conduc 

tive particles in the resultant mixture may be between about 0 

and about 15 percent by weight, and in some instances does 

not exceed about 0.5 percent by weight. In accordance with 

further alternative aspects hereof, mixing of the activated 

carbon, optional conductive carbon, and binder may be per 

formed by dry-blending these ingredients. In accordance with 

Some further alternative aspects hereof, the mixing may be 

carried out by Subjecting the activated carbon, optional con 

ductive carbon, and binder to a non-lubricated high-shear 

force technique. In accordance with still further alternative 

aspects hereof, films of active electrode material may be made 

from the particles of active electrode material made as is 

described herein. The films may be attached to current col 

lectors and used in various electrical devices, for example, in 

double layer capacitors. Other binders that may be used 

include, but are not limited to, polyvinylidene difluoride 

(PVDF), polyethylene (PE), high molecular weight polyeth 

ylene (HMWPE), ultra high molecular weight polyethylene 

(UHMWPE), polypropylene (PP), carboxymethyl cellulose 

(CMC), polyvinylphenol, polyvinylpyrrolidine, polyvinyl 

acetate, polyvinyl alcohol, and polyacetylene. 

In one implementation, a method of making an active elec 

trode material may include providing activated carbon with 

between about 70 and 98 percent microporous activated car 

bon particles of a total amount of activated carbon by weight 

and between about 2 and 30 percent mesoporous activated 

carbon particles of a total amount of activated carbon by weight; providing binder; and mixing the activated carbon 

and the binder to obtain a an active electrode material mix 

ture. The method may in Some options further include pro viding conductive particles, such as conductive carbon par ticles. In one implementation, the binder may include PTFE. 

In one implementation, the operation of mixing may include 

dry blending the activated carbon and the binder, or activated 

conductive, conductive carbon, and the binder. In one imple mentation, the operation of mixing may be performed without 

10 

15 

25 

30 

35 

40 

45 

50 

55 

60 

65 

4 

processing additives. In another implementation, the opera 

tion of mixing may be performed with one or more processing 

additives. 

In one implementation, an electrode may include a current 

collector; and a film of active electrode material attached to 

the current collector, wherein the active electrode material 

may include particles of activated carbon with between about 

70 and 98 percent microporous activated carbon particles and 

between about 2 and 30 percent mesoporous activated carbon 

particles by weight. The active electrode material further 

includes binder. The active electrode material may also 

include conductive particles, such as conductive carbon par 

ticles. In one implementation, the activated carbon may have 

between about 80 and 98 percent microporous activated car 

bonparticles and between about 2 and 20 percent mesoporous 

activated carbon particles by weight. In another implementa 

tion, the activated carbon may have between about 85 and 95 

percent microporous activated carbon particles and between 

about 5 and 15 percent mesoporous activated carbon particles by weight. 

In one implementation, a method of making an electrode 

film is provided. The method includes foaming a film of 

active electrode material comprising activated carbon having 

between about 70 and 98 percent microporous activated car 

bon particles of a total amount of activated carbon by weight 

and between about 2 and 30 percent mesoporous activated 

carbon particles of the total amount of activated carbon by 

weight. The method further includes bonding the film to a 

current collector to form an electrode film. 

In one implementation, an electrochemical double layer 

capacitor may include a first electrode comprising a first 

current collector and a first film of active electrode material, 

the first film comprising a first Surface and a second surface, 

the first current collector being attached to the first surface of 

the first film; a second electrode comprising a second current 

collector and a second film of active electrode material, the 

second film comprising a third Surface and a fourth Surface, 

the second current collector being attached to the third surface 

of the second film; a porous separator disposed between the 

second surface of the first film and the fourth surface of the 

second film; a container; an electrolyte; wherein: the first 

electrode, the second electrode, the porous separator, and the 

electrolyte are disposed in the container; the first film is at 

least partially immersed in the electrolyte; the second film is 

at least partially immersed in the electrolyte; the porous sepa 

rator is at least partially immersed in the electrolyte; each of 

the first and second films may include a mixture comprising 

activated carbon, wherein the activated carbon has between 

about 70 and 98 percent microporous activated carbon par ticles and between about 2 and 30 percent mesoporous acti 

vated carbon particles by weight. In one implementation, the 

electrode films further may include conductive particles, such 

as conductive carbon. In one implementation, the electrode 

films further may include binder. In one implementation, the 

films are attached to respective collectors via a conductive 

adhesive layer. 

These and other features and aspects of the present inven 

tion will be better understood with reference to the following description, drawings, and appended claims. 

BRIEF DESCRIPTION OF THE DRAWINGS 

FIG. 1 illustrates selected operations of a process for mak 

ing active electrode material in accordance with Some aspects 

hereof, and 

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US 8,591,601 B2 

5 

FIG. 2, which includes sub-part FIGS. 2A and 2B, illus 

trates a cross-section of respective electrode assemblies 

which may be used in an ultracapacitor. 

DETAILED DESCRIPTION 

In this document, the words “implementation' and “vari 

ant’ may be used to refer to a particular apparatus, process, or 

article of manufacture, and not necessarily always to one and 

the same apparatus, process, or article of manufacture. Thus, 

“one implementation’ (or a similar expression) used in one 

place or context can refer to one particular apparatus, process, 

or article of manufacture; and, the same or a similar expres sion in a different place can refer either to the same or to a 

different apparatus, process, or article of manufacture. Simi 

larly, 'Some implementations.” “certain implementations.” or 

similar expressions used in one place or context may refer to 

one or more particular apparatuses, processes, or articles of 

manufacture; the same or similar expressions in a different 

place or context may refer to the same or a different apparatus, 

process, or article of manufacture. The expression “alterna 

tive implementation' and similar phrases are used to indicate 

one of a number of different possible implementations. The 

number of possible implementations is not necessarily lim 

ited to two or any other quantity. Characterization of an 

implementation as “an exemplar' or “exemplary' means that 

the implementation is used as an example. Such characteriza 

tion does not necessarily mean that the implementation is a 

preferred implementation; the implementation may but need 

not be a currently preferred implementation. 

The expression “active electrode material' and similar 

phrases signify material that provides or enhances the func 

tion of the electrode beyond simply providing a contact or 

reactive area approximately the size of the visible external 

surface of the electrode. In a double layer capacitor electrode, 

for example, a film of active electrode material includes par 

ticles with high porosity, so that the surface area of the elec 

trode exposed to an electrolyte in which the electrode is 

immersed may be increased well beyond the area of the 

visible external surface; in effect, the surface area exposed to 

the electrolyte becomes a function of the volume of the film 

made from the active electrode material. 

The meaning of the word “film is similar to the meaning of 

the words “layer” and “sheet': the word “film” does not 

necessarily imply a particular thickness or thinness of the 

material. When used to describe making of active electrode 

material film, the terms “powder,” “particles, and the like 

refer to a plurality of small granules. As a person skilled in the 

art would recognize, particulate material is often referred to 

as a powder, grain, specks, dust, or by other appellations. 

References to carbon and binder powders throughout this 

document are thus not meant to limit the present implemen 

tations. 

The references to “binder within this document are 

intended to convey the meaning of polymers, co-polymers, 

and similar ultra-high molecular weight Substances capable 

of providing a binding for the carbon herein. Such substances 

are often employed as binder for promoting cohesion in 

loosely-assembled particulate materials, i.e., active filler 

materials that perform some useful function in a particular application. 

The words “calendar.” “nip,” “laminator, and similar 

expressions mean a device adapted for pressing and com 

pressing. Pressing may be, but is not necessarily, performed 

using rollers. When used as verbs, “calendar and “laminate’ 

mean processing in a press, which may, but need not, include 

rollers. Mixing or blending as used herein may mean process 

10 

15 

25 

30 

35 

40 

45 

50 

55 

60 

65 

6 

ing which involves bringing together component elements 

into a mixture. High shear or high impact forces may be, but 

are not necessarily, used for Such mixing. Example equip 

ment that can be used to prepare/mix the dry powder(s)hereof 

may include, in non-limiting fashion: a ball mill, an electro 

magnetic ball mill, a disk mill, a pin mill, a high-energy impact mill, a fluid energy impact mill, an opposing nozzle jet 

mill, a fluidized bed jet mill, a hammer mill, a fritz mill, a 

Warring blender, a roll mill, a mechanofusion processor (e.g., 

a Hosokawa AMS), or an impact mill. 

Other and further definitions and clarifications of defini 

tions may be found throughout this document. The definitions 

are intended to assist in understanding this disclosure and the 

appended claims, but the scope and spirit of the invention 

should not be construed as strictly limited to the definitions, 

or to the particular examples described in this specification. 

Reference will now be made in detail to several implemen 

tations of the invention that are illustrated in the accompany ing drawings. The same reference numerals are used in the 

drawings and the description to refer to the same or Substan 

tially the same parts or operations. The drawings are in sim 

plified form and not to precise scale. For purposes of conve 

nience and clarity only, directional terms, such as top, bottom, 

left, right, up, down, over, above, below, beneath, rear, and 

front may be used with respect to the accompanying draw 

ings. These and similar directional terms, should not be con 

strued to limit the scope of the invention. 

Referring more particularly to the drawings, FIG. 1 illus 

trates selected operations of a dry process 100 for making active electrode material. Although the process operations are 

described Substantially serially, certain operations may also 

be performed in alternative order, in conjunction or in paral 

lel, in a pipelined manner, or otherwise. There is no particular requirement that the operations be performed in the same 

order in which this description lists them, except where 

explicitly so indicated, otherwise made clear from the con 

text, or inherently required. Not all illustrated operations may be strictly necessary, while other optional operations may be 

added to the process 100. A high level overview of the process 100 is provided immediately below. A more detailed descrip 

tion of the operations of the process 100 and variants of the 

operations are provided following the overview. 

In operation 105, activated carbon particles with different 

porosities may be provided. For the purposes of this applica 

tion, micropores refer to pores in activated carbon having a 

pore diameter of less than 2 nanometers, mesopores refer to 

pores in activated carbon having a pore diameter from 2 

nanometers to 50 nanometers, and macropores refer to pores in activated carbon having a pore diameter of greater than 50 

nanometers. A bulk activated carbon material may also be 

classified as microporous activated carbon material, mesopo 

rous activated carbon material, and macroporous activated 

carbon material. A microporous activated carbon material 

refers to a bulk activated carbon material having a majority of 

micropores (i.e., greater than 50 percent of its pores being 

micropores). A mesoporous activated carbon material refers 

to a bulk activated carbon material having a majority of meso 

pores. A macroporous activated carbon material refers to a 

bulk activated carbon material having a majority of 

macropores. 

In operation 110, optional conductive particles, such as 

conductive carbon particles with low contamination level and 

high conductivity or other conductive particles may be pro 

vided. In operation 115, binder may be provided. In one or 

more implementations, and although one or more of a variety 

of binders may be used as described elsewhere herein, the 

binder may include polytetrafluoroethylene (also known as 

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US 8,591,601 B2 

7 

PTFE or by the tradename, “Teflon R”). In operation 120, one 

or more of the activated carbon, conductive carbon, and 

binder may be blended or mixed; typically two or more may 

be mixed together. Alternatively, in certain implementations 

one or more of these ingredients and/or operations may be 

omitted. 

More detailed descriptions of individual operations of the 

process 100 in preferred and alternative forms are now set 

forth. As a first example, operation 105, in which activated 

carbon particles with between about 70 and 98 percent 

microporous activated carbon particles and between about 2 

and 30 percent mesoporous activated carbon particles by 

weight, is first described. Electrodes made from activated 

carbon particles with between about 70 and 98 percent 

microporous activated carbon particles and between about 2 

and 30 percent mesoporous activated carbon particles by 

weight tend to have better mobility of electrolyte in which the 

electrodes are immersed and ions within the electrolyte to 

reduce or prevent local electrolyte starvation from occurring, 

than in the case of activated carbon particles with a higher 

percentage of microporous activated carbon. Accordingly, in 

Some implementations the activated carbon particles pro 

vided in operation 105 have between about 70 and 98 percent microporous activated carbon particles and between about 2 

and 30 percent mesoporous activated carbon particles by 

weight. In some more specific implementations, activated 

carbon particles provided in the operation 105 have between 

about 80 and 98 percent microporous activated carbon par ticles and between about 2 and 20 percent mesoporous acti 

vated carbon particles by weight of the activated carbon par 

ticles may. In another implementation, the activated carbon 

particles provided in the operation 105 have between about 85 

and 95 percent microporous activated carbon particles and 

between about 5 and 15 percent mesoporous activated carbon 

particles by weight 

In operation 115, binders may be provided, for example: 

PTFE in granular powder faun, and/or various fluoropolymer particles, polypropylene, polyethylene, co-polymers, and/or 

other polymer blends. It has been identified, that the use of 

inert binders such as PTFE, tends to increase the voltage at 

which an electrode including Such an inert binder may be 

operated. Such increase occurs in part due to reduced inter 

actions with electrolyte in which the electrode is subse 

quently immersed. In one implementation, typical diameters 

of the PTFE particles may be in the five hundred micron 

range. 

In the operation 120, activated carbon particles and binder 

particles may be blended or otherwise mixed together. In 

various implementations, proportions of activated carbon 

(comprising both microporous activated carbon and mesopo 

rous activated carbon as described above) and binder may be 

as follows: about 80 to about 97 percent by weight of acti 

vated carbon, about 3 to about 20 percent by weight of PTFE. 

Optional conductive carbon could be added in a range of 

about 0 to about 15 percent by weight. An implementation 

may contain about 89.5 percent of activated carbon, about 10 

percent of PTFE, and about 0.5 percent of conductive carbon. 

Other ranges are within the scope hereofas well. Note that all 

percentages are here presented by weight, though other per 

centages with other bases may be used. Conductive carbon 

may be preferably held to a low percentage of the mixture 

because an increased proportion of conductive carbon may 

tend to lower the breakdown voltage of electrolyte in which 

an electrode made from the conductive carbon particles is 

Subsequently immersed (alternative electrolyte examples are 

set forth below). 

10 

15 

25 

30 

35 

40 

45 

50 

55 

60 

65 

8 

In an implementation of the process 100, the blending operation 120 may be a “dry-blending operation, i.e., blend 

ing of activated carbon, conductive carbon, and/or binder is 

performed without the addition of any solvents, liquids, pro cessing aids, or the like to the particle mixture. Dry-blending 

may be carried out, for example, for about 1 to about 10 

minutes in a mill, mixer or blender (such as a V-blender 

equipped with a high intensity mixing bar, or other alternative 

equipment as described further below), until a uniform dry 

mixture is formed. Those skilled in the art will identify, after 

perusal of this document, that blending time can vary based 

on batch size, materials, particle size, densities, as well as 

other properties, and yet remain within the scope hereof. 

In another implementation, the blending operation 120 

may blendactivated carbon, conductive carbon, and/or binder 

together with the addition of any solvents, liquids processing 

aids, or the like. Such additives, for example, may be helpful informing an electrode film depending on the process used to 

ultimately form the film. Coating or extrusion film processes, 

for example, may require one or more additives to be blended or otherwise mixed with the other materials. 

As introduced above, the blended dry powder material or 

other blended materials (e.g., including one or more dry or 

wet additive) may also or alternatively be formed/mixed/ 

blended using other equipment. Such equipment that can be 

used to prepare/mix the dry powder(s) or other materials 

hereof may include, for non-limiting examples: blenders of 

many sorts including rolling blenders and warring blenders, 

and mills of many sorts including ball mills, electromagnetic 

ball mills, disk mills, pin mills, high-energy impact mills, 

fluid energy impact mills, opposing nozzle jet mills, fluidized 

bedjet mills, hammer mills, fritz mills, roll mills, mechano 

fusion processing (e.g., a Hosokawa AMS), or impact mills. 

In an implementation, the dry powder material may be dry 

mixed using non-lubricated high-shear or high impact force 

techniques. In an implementation, high-shear or high impact 

forces may be provided by a mill such as one of those 

described above. The dry powder material or other blended 

material may be introduced into the mill, wherein high-ve 

locities and/or high forces could then be directed at or 

imposed upon the dry powder material to effectuate applica 

tion of high shear or high impact to the binder within the dry 

powder material or other blended material. The shear or 

impact forces that arise during the dry mixing process may 

physically affect the binder, causing the binder to bind the 

binder to and/or with other particles within the material. 

Moreover, although additives, such as solvents, liquids, 

and the like, are not necessarily used in some implementa 

tions of the manufacture of certain electrode films disclosed 

herein, a certain amount of impurity, for example, moisture, 

may be absorbed by the active electrode material from the 

surrounding environment. Those skilled in the art will under 

stand, after perusal of this document, that the dry particles used with implementations and processes disclosed herein 

may also, prior to being provided by particle manufacturers as 

dry particles, have themselves been pre-processed with addi 

tives and, thus, contain one or more pre-process residues. For 

these reasons, one or more of the implementations and pro 

cesses disclosed herein may utilize a drying operation at Some 

point before a final electrolyte impregnation operation, so as 

to remove or reduce the aforementioned pre-process residues 

and impurities. Even after one or more drying operations, 

trace amounts of moisture, residues and impurities may be 

present in the active electrode material and an electrode film 

made therefrom. 

It should also be noted that references to dry-blending, dry particles, and other dry materials and processes used in the 

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US 8,591,601 B2 

manufacture of an active electrode material and/or film do not 

exclude the use of other than dry processes, for example, this 

may be achieved after drying of particles and films that may 

have been prepared using a processing aid, liquid, solvent, or 

the like. 

A product obtained through a process like process 100 may 

be used to make an electrode film. The films may then be 

bonded to a current collector, such as a foil made from alu 

minum or another conductor. The current collector can be a 

continuous metal foil, metal mesh, or nonwoven metal fabric. 

The metal current collector provides a continuous electrically 

conductive substrate for the electrode film. The current col 

lector may be pretreated prior to bonding to enhance its adhe 

sion properties. Pretreatment of the current collector may 

include mechanical roughing, chemical pitting, and/or use of 

a Surface activation treatment, Such as corona discharge, active plasma, ultraviolet, laser, or high frequency treatment 

methods known to a person skilled in the art. In one imple 

mentation, the electrode films may be bonded to a current 

collector via an intermediate layer of conductive adhesive 

known to those skilled in the art. 

In one implementation, a product obtained from process 

100 may be mixed with a processing aid to obtain a slurry-like 

composition used by those skilled in the art to coat an elec 

trode film onto a collector (i.e. a coating process). The slurry 

may be then deposited on one or both sides of a current 

collector. After a drying operation, a film or films of active 

electrode material may be formed on the current collector. 

The current collector with the films may be calendared one or 

more times to densify the films and to improve adhesion of the 

films to the current collector. 

In one implementation, a product obtained from process 

100 may be mixed with a processing aid to obtain a paste-like 

material. The paste-like material may be then be extruded, 

formed into a film, and deposited on one or both sides of a 

current collector. After a drying operation, a film or films of 

active electrode material may be formed on the current col 

lector. The current collector with the dried films may be 

calendared one or more times to densify the films and to 

improve adhesion of the films to the current collector. 

In yet another implementation, in a product obtained 

through the process 100 the binder particles may include 

thermoplastic or thermoset particles. A product obtained 

through the process 100 that includes thermoplastic or ther 

moset particles may be used to make an electrode film. Such 

a film may then be bonded to a current collector, such as a foil 

made from aluminum or another conductor. The films may be 

bonded to a current collector in a heated calendar apparatus. The current collector may be pretreated prior to bonding to 

enhance its adhesion properties. Pretreatment of the current 

collector may include mechanical roughing, chemical pitting, 

and/or use of a Surface activation treatment, Such as corona 

discharge, active plasma, ultraviolet, laser, or high frequency 

treatment methods known to a person in the art. 

Other methods of forming the active electrode material 

films with or without additives and attaching the films to the 

current collector may also be used. 

FIG. 2, including sub-part FIGS. 2A and 2B, illustrates, in 

a high level manner, respective cross-sectional views of an 

electrode assembly 200 which may be used in an ultracapaci 

tor or a double layer capacitor. In FIG. 2A, the components of 

the assembly 200 are arranged in the following order: a first 

current collector 205, a first active electrode film 210, a 

porous separator 220, a second active electrode film 230, and 

a second current collector 235. In some implementations, a 

conductive adhesive layer (not shown) may be disposed on 

current collector 205 prior to bonding of the electrode film 

5 

10 

15 

25 

30 

35 

40 

45 

50 

55 

60 

65 

10 

210 (or likewise on collector 235 relative to film 230). In FIG. 

2B, a double layer of films 210 and 210A are shown relative 

to collector 205, and a double layer 230, 230A relative to 

collector 235. In this way, a double-layer capacitor may be 

formed, i.e., with each current collector having a carbon film 

attached to both sides. A further porous separator 220A may then also be included, particularly for a jellyroll application, 

the porous separator 220A either attached to or otherwise 

disposed adjacent the top film 210A, as shown, or to or 

adjacent the bottom film 230A (not shown). The films 210 and 

230 (and 210A and 230A, if used) may be made using par ticles of active electrode material obtained through the pro 

cess 100 described in relation to FIG.1. An exemplary double 

layer capacitor using the electrode assembly 200 may further 

include an electrolyte and a container, for example, a sealed 

can, that holds the electrolyte. The assembly 200 may be 

disposed within the container (can) and immersed in the 

electrolyte. In many implementations, the current collectors 

205 and 235 may be made from aluminum foil, the porous 

separator 220 may be made from one or more ceramics, 

paper, polymers, polymer fibers, glass fibers, and the electro 

lytic solution may include in Some examples, 1.5 M tetram 

ethylammonium tetrafluroborate in organic solutions, such as 

PC or Acetronitrile solvent. Alternative electrolyte examples are set forth below. 

Following are several non-limiting examples of aqueous 

electrolytes which may be used in double-layer capacitors or 

ultracapacitors hereof: 1-molar Sodium sulphate, NaSO; 

1-molar Sodium perchlorate, NaClO. 1-molar Potassium 

hydroxide, KOH: 1-molar Potassium chloride, KCl: 1-molar 

Perchloric acid, HClO. 1-molar Sulfuric acid, HSO. 1-mo 

lar Magnesium chloride, MgCl, and, Mixed aqueous 1-mo 

lar MgCl/HO/Ethanol. Some non-limitative nonaqueous aprotic electrolyte solvents which can be used in capacitors 

include: 

Acetonitrile; Gamma-butyrolactone; Dimethoxyethane: N.N.-Dimethylformamide: Hexamethyl-phosphorotriamide: 

Propylene carbonate; Dimethyl carbonate; Tetrahydrofuran: 

2-methyltetra-hydrofuran: Dimethyl sulfoxide; Dimethyl 

sulfite: Sulfolane (tetra-methylenesulfone); Nitromethane: 

and, Dioxolane. Further, some non-limiting examples of elec 

trolyte salts which can be used in the aprotic solvents include: 

Tetraalkylammonium salts (such as: Tetraethylammonium 

tetrafluoroborate, (CHs). NBF, Methyltriethylammonium 

tetrafluoroborate, (CHS)-CHNBF. Tetrabutylammonium 

tetrafluoroborate, (CH), NBF, and, Tetraethylammonium hexafluorophosphate (CH)NPF); Tetraalkylphosphonium 

salts (such as: Tetraethylphosphonium tetrafluoroborate 

(CH), PBF, Tetrapropylphosphonium tetrafluoroborate 

(CH4)PBF. Tetrabutylphosphonium tetrafluoroborate 

(CH), PBF, Tetrahexylphosphonium tetrafluoroborate 

(CH), PBF, Tetraethylphosphonium hexafluorophos 

phate (CHs), PPF, and, Tetraethylphosphonium trifluorom 

ethylsulfonate (CH), PCFSO; and Lithium salts (such as: 

Lithium tetrafluoroborate LiBF Lithium hexafluorophos phate LiPF; Lithium trifluoromethylsulfonate LiCFSO). 

Additionally, some Solvent free ionic liquids which may be 

used include: 1-ethyl-3-methylimidazolium bis(pentafluoro ethylsulfonyl)imide EMIMBeTi; 1-ethyl-3-methylimidazo 

lium bis(trifluoromethylsulfonyl imide EMIMIm; EMIm: 

EMIBeti; EMIMethide; DMPIIm; DMPIBeti; DMPIMe 

thide: BMIIm: BMIBeti; BMIMethide; PMPIm; and, 

BMPIm. Examples for use as Anions include: bis(trifluorom ethylsulfonyl)imide (CFSO)N; bis(perfluoroethylsulfo 

nyl)imide (CFSO)N; and, tris(trifluoromethylsulfonyl) 

methide (CFSO)C. And, examples for use as Cations 

include: EMI: 1-ethyl-3-methylimidazolium; DMPI: 1,2- 

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US 8,591,601 B2 

11 

dimethyl-3-propylimidazolium; BMI: 1-butyl-3-methylimi 

dazolium; PMP: 1-N-propyl-3-methylpyridinium; and, 

BMP: 1-N-butyl-3-methylpyridinium. 

Electrode products that include an active electrode film 

attached to a current collector and/or a porous separator may 

be used in an ultracapacitor or a double layer capacitor and/or 

other electrical energy storage devices. 

In some implementations using a process 100, wherein 

activated carbon with between about 70 and 98 percent 

microporous activated carbon particles and between about 2 

and 30 percent mesoporous activated carbon particles by 

weight or in some cases between about 80 and 98 percent 

microporous activated carbon particles and between about 2 

and 20 percent mesoporous activated carbon particles by 

weight or even between about 85 and 95 percent microporous 

activated carbon particles and between about 5 and 15 percent 

mesoporous activated carbon particles by weight is used, a 

high performance ultracapacitor or double-layer capacitor 

product can be provided. Such a product further may include 

about 10 percent by weight binder, and about 0.5 percent by 

weight conductive particles, such as conductive carbon. 

The inventive methods for making active electrode mate 

rial, films of these materials, electrodes made with the films, 

and double layer capacitors employing the electrodes have 

been described above in considerable detail. This was done 

for illustrative purposes. Neither the specific implementa 

tions of the invention as a whole, nor those of its features, 

limit the general principles underlying the invention. In par 

ticular, the invention is not necessarily limited to the specific 

constituent materials and proportions of constituent materials 

used in making the electrodes. The invention is also not nec 

essarily limited to electrodes used in double layer capacitors, 

but extends to other electrode applications. The specific fea 

tures described herein may be used in Some implementations, 

but not in others, without departure from the spirit and scope 

of the invention as set forth. Many additional modifications 

are intended in the foregoing disclosure, and it will be appre ciated by those of ordinary skill in the art that, in some 

instances, some features of the invention will be employed in 

the absence of other features. The illustrative examples there 

fore do not define the metes and bounds of the invention and 

the legal protection afforded the invention, which function is 

served by the claims and their equivalents. 

What is claimed is: 

1. A method of making an active electrode material, the 

method comprising: 

providing activated carbon having between about 70 and 

98 percent microporous activated carbon particles of a 

total amount of activated carbon by weight and between 

about 2 and 30 percent mesoporous activated carbon 

particles of the total amount of activated carbon by weight; 

providing binder, and 

mixing the activated carbon and the binder to form an 

active electrode material mixture. 

2. The method of claim 1, wherein the providing activated 

carbon comprises providing activated carbon having between 

about 80 and 98 percent microporous activated carbon par 

ticles of the total amount of activated carbon by weight and 

between about 2 and 20 percent mesoporous activated carbon 

particles of the total amount of activated carbon by weight. 

3. The method of claim 1, wherein the providing activated 

carbon includes providing the total amount of activated car 

bon in amount of between about 80 and about 97 percent of 

the mixture by weight, and wherein the operation of provid 

10 

15 

25 

30 

35 

40 

45 

50 

55 

60 

65 

12 

ing the binder includes providing binder in amount of 

between about 3 and about 20 percent of the mixture by weight. 

4. The method of claim 1, further comprising providing 

conductive particles and mixing the activated carbon and 

binder with the conductive particles to form the mixture. 

5. The method of claim 4, wherein the mixture of activated 

carbon, binder and conductive particles comprises less than 

about 15 percent conductive particles by weight. 

6. The method of claim 5, wherein the mixture of activated 

carbon, binder and conductive particles does not exceed about 

0.5 percent conductive particles by weight. 

7. The method of claim 4, wherein the conductive particles comprise conductive carbon. 

8. The method of claim 7, wherein the conductive particles comprise graphite. 

9. The method of claim 1, wherein providing the binder 

comprises providing an inert binder. 

10. The method of claim 1, wherein the activated carbon 

and binder mixture comprises between about 3 and about 20 

percent binder by weight. 

11. The method of claim 10, wherein the activated carbon 

and binder mixture comprises between about 9 and about 11 

percent binder by weight. 

12. The method of claim 9, wherein the binder comprises polytetrafluoroethylene (PTFE) particles. 

13. The method of claim 1, wherein the mixing comprises 

dry blending the activated carbon and the binder. 

14. The method of claim 1, wherein the mixing is per 

formed without processing additives. 

15. The method of claim 1, wherein the mixing is per formed with processing additives. 

16. The method of claim 1, further comprising forming a 

dry film from the mixture and bonding the dry film to a current 

collector to form an electrode film. 

17. The method of claim 1, wherein the mixing comprises 

milling the activated carbon and the binder. 

18. The method of claim 17, wherein the milling comprises milling using a ball mill, an electromagnetic ball mill, a disk 

mill, a pin mill, a high-energy impact mill, a fluid energy 

impact mill, an opposing nozzle jet mill, a fluidized bed jet 

mill, a hammer mill, a fritz mill, a roll mill, or an impact mill. 

19. A method of making an electrode film, comprising: forming a film of active electrode material comprising 

activated carbon having between about 70 and 98 per 

cent microporous activated carbon particles of a total 

amount of activated carbon by weight and between 

about 2 and 30 percent mesoporous activated carbon 

particles of the total amount of activated carbon by weight; and 

bonding the film to a current collector to form an electrode 

film. 

20. The method of claim 19, further comprising mixing a 

binder with the activated carbon to form a mixture prior to 

forming the film of active electrode material. 

21. The method of claim 20, wherein mixing comprising 

milling the binder and activated carbon. 

22. The method of claim 20, wherein the binder comprises polytetrafluoroethylene (PTFE) particles. 

23. The method of claim 19, wherein the current collector 

comprises a continuous metal foil, metal mesh, or nonwoven 

metal sheet. 

24. The method of claim 19, wherein the method is a 

method of making a capacitor electrode. 

25. The method of claim 19, wherein the method is a 

method of making a double-layer capacitor electrode film. 

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US 8,591,601 B2 

13 

26. The method of claim 19, wherein the method is a 

method of making a battery electrode. 

27. The method of claim 20, whereinforming a film com 

prises forming a dry film comprising dry activated carbon and 

dry binder free from processing solvent residue. 5 k k k k k 

14 

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