CN102044659B - Electrode including ring stopper - Google Patents

Abstract

An electrode comprising an annular stopper includes a structure configured to prevent an interlayer from separating from the electrode and/or a structure configured to create a region on the electrode having a smaller concentration of sandwiched material. The electrode includes a support wire on which an interlayer is disposed. The support filaments may optionally have nanoscale dimensions.

Description

Electrode including ring stopper

Cross References to Related Applications

This application claims the benefit of and priority to U.S. Provisional Patent Application No. 61/254,090, filed October 22, 2009, entitled "Electrodes Including CollarStop"; and filed February 25, 2009, entitled A continuation-in-part of U.S. Patent Application No. 12/392,525 for "High Capacity Electrodes," which claims U.S. Provisional Patent Application 61/067,018 filed February 25, 2008 and filed in June 2008 Priority and benefit to U.S. Provisional Patent Application 61/130,679 filed on 2nd. All of the aforementioned provisional and non-provisional patent applications are hereby incorporated by reference.

technical field

The invention belongs to the technical field of electrodes.

Contents of the invention

Various embodiments of the invention include an electrode comprising: a substrate; a support filament coupled to the substrate; an interlayer comprising a donor acceptor material configured to receive electrical The reactants of the chemical reaction (for example, ions, electrons, charge donors and/or charge acceptors), the donor acceptor material is arranged along the length direction of the support filament; and the interlayer region close to the substrate and relatively far away from the substrate The sandwich region of the bottom, which includes a lesser amount of donor acceptor material.

Various embodiments of the invention include a method of producing an electrode comprising: receiving a substrate; growing a first region of a support filament coupled to the substrate; growing an end of the support filament remote from the substrate in the first region of the support filament an annular stop configured to reduce the amount of donor-receptor material reaching the first region; a second region of support filaments grown from the annular stop, the second region of the annular stop having a ratio of a small diameter; and applying the donor acceptor material to the support filament such that a greater thickness of the donor acceptor material is deposited in the second region of the support filament relative to the first region of the support filament.

Various embodiments of the invention include a battery comprising a first electrode and a second electrode comprising: a substrate; a support wire coupled to the substrate; a reactant configured to receive an electrochemical reaction and means for creating a sandwich region close to the substrate comprising a lower amount of donor-receptor material relative to a region of the sandwich farther from the substrate.

Description of drawings

Figure 1 shows a support cap electrode design according to various embodiments of the invention.

Figure 2 shows a support ring electrode design according to various embodiments of the invention.

Figure 3 shows a ring stopper electrode design according to various embodiments of the invention.

Figure 4 shows a support cap and support ring electrode design according to various embodiments of the invention.

Figure 5 shows a support cap and ring stopper electrode design according to various embodiments of the invention.

Figure 6 shows a support ring and ring stopper electrode design according to various embodiments of the invention.

7A, 7B and 7C illustrate electrodes including intercalation materials according to various embodiments of the invention.

Figure 8 illustrates a method of creating electrode extensions according to various embodiments of the invention.

9A, 9B illustrate measured charge capacity versus intercalation material thickness according to various embodiments of the invention.

Figure 10 shows battery cycle life versus sandwich material thickness according to various embodiments of the invention.

Figure 11 shows a battery according to various embodiments of the invention.

12A and 12B illustrate carbon nanofibers grown on copper substrates according to various embodiments of the invention.

13A and 13B illustrate carbon nanofibers grown on a copper substrate coated with an intercalation material according to various embodiments of the invention.

Figure 14 shows a cross-sectional view of an electrode without interlayer 750 used to collect the data for Figures 9A, 9B, and 10, according to various embodiments of the invention.

detailed description

FIG. 1 shows an electrode comprising a support wire 110 . The support wire 110 includes a support cap 150 . Support cap 150 is optionally an extension of support wire 110 and has a support cap width 157 that is approximately 1%, 2.5%, 10%, 25%, 40%, or up to 60% greater than support wire diameter 112 . Support wire height 114 includes support cap height 155 . In some embodiments, support cap height 155 is at least 250 nanometers, 500 nanometers, 2000 nanometers, or 5000 nanometers. In other embodiments, the support cap height 155 is at least 1, 5, 20, 30, or 50 percent of the wire height 114 . The support cap width 157 can be at least 1, 5, 15, 40 or 75 percent of the starting point separation distance 126 . The starting point is the location on the seed layer 122 where the growth of supportive filaments begins. The cross-sectional shape of the support cap 150 (shown in FIG. 1 ) may be rectangular, triangular, square, circular or rhombus. Other shapes are also possible. Support cap 150 may be configured to prevent interlayer 750 ( FIG. 7 ) from sliding off the unattached end of support wire 110 .

The supporting filament 110 may be carbon nanotubes (CNTs), carbon nanofibers (CNFs) or nanowires (NWs), or other nanoscale structures. The material comprising CNTs is typically carbon and may include other materials such as metals, semiconductors and insulators that are input in the feed gas during the growth of the CNTs. Additionally, CNTs can be single-walled or multi-walled. The material comprising CNFs is typically carbon and may include other materials such as metals, semiconductors and insulators that are input in the feed gas during the growth of the CNFs. CNTs are generally described as having a diameter of at least 2 nm, 5 nm, 10 nm, 30 nm, or 50 nm. CNFs are generally described as having a diameter of at least 30 nm, 50 nm, 150 nm, 250 nm, 500 nm, or 750 nm. Nanowires (NWs) may comprise metals such as gold, copper or tin, or semiconductors such as silicon, germanium, Inp, GaN, GaP, ZnO, or oxides such as _MnO2 , indium tin oxide, ZnO, _SnO2 , Fe ₂ O ₃ , In ₂ O ₃ or Ga ₂ O ₃ . Other materials are also possible.

FIG. 2 shows an electrode comprising a support wire 110 including a support ring 210 . Support ring 210 is optionally an extension of support wire 110 having a diameter that is at least 1%, 2.5%, 10%, 25%, 40%, or 60% greater than support wire diameter 112 . In some embodiments, support ring height 214 is at least 100, 250, 500, 2000, or 5000 nanometers, possibly greater, and may be as small as 50 nanometers, possibly less. In some embodiments, support ring height 214 is at least 1, 5, 15, 40, or 75 percent of support wire height 114 . Support ring width 212 may be at least 1%, 5%, 15%, 40%, or 75% of origin separation distance 126 . The shape of the support ring 210 may be rectangular, square, circular, triangular, circular, diamond, curved, and the like. Other shapes are also possible. The support ring base distance 216 is optionally at least half the support wire height 114 . It is possible for the ring base distance 216 to be 10%, 30%, or 75% of the support wire height 114 . The base distance 216 may extend from the starting point 120 by at least 500, 1000, 2500, 5000, or 12500 nanometers. Additionally, it is possible for the base distance 216 to end up within a few microns of the wire extension tip 152 .

FIG. 3 shows an electrode comprising a support wire 110 including an annular stopper 310 . Annular stop 310 is a region of support wire 110 characterized by a diameter that is greater than the diameter of other regions of support wire 110 . In some embodiments, the diameter of the annular stopper 310 is at least 1, 2.5, 10, 25 percent greater than the diameter of the support wire 110 (e.g., support wire diameter 112) in one or more other regions of the support wire 110 , 40 or 60. The diameter of the ring stops 310 and the ring stop spacing 312 are controlled to create the backbone 350 . This backbone 350 will result in a region of reduced donor acceptor material (DAM). A region of reduced DAM is a region where there is a reduced amount of entrapped material relative to other regions of the support filament, but not necessarily completely free of entrapped material. For example, in various embodiments, the DAM region may comprise less than 75, 50, 25, 10, or 5 percent (weight per unit area of support filament 110 ) of entrapped material relative to other regions of support filament 110 . (For purposes of this description, an intercalation material is defined as a material that supplies or accepts electrical charge to complete the external circuit of the electrode. An intercalation material is configured to exchange charge carriers, charge donors, and/or charge acceptors with the surrounding electrolyte. body. The inclusion material is optionally permeable to these substances). Ring stop spacing 312 may be close to zero, or at least 10, 50, 75, or 95 percent of the distance between starting points 126 . The annular stopper 310 can grow anywhere along the length of the support wire 110, for example, in some embodiments, the annular stopper 310 can be placed at 10000, 5000, 2000, 1000, 750, 250, 100, within 25 or 5 nanometers.

The method of creating ring stop 310 is generally similar to the method of creating support ring 210 or support cap 150 . Methods of controlling the diameter of the support ring 210, the support cap 150, and/or the annular stopper 310 may include varying the temperature of the feed gas, the substrate, or the reaction chamber (or a combination of the three), or varying the flow rates of the various feed gases . For example, varying the composition of the feed gas during growth of support filament 110 can also control these diameters. Another method of controlling the diameter of the support wire 110, annular stopper 310, support ring 210, and/or support cap 150 is to apply a static or dynamic electric field, apply a static or dynamic magnetic field, or apply a combination of electric and magnetic fields. Other methods of controlling these diameters will be readily apparent to those of ordinary skill in the art.

Ring stopper 310, support ring 210 and support cap 150 are optionally the same material as support wire 110, but other materials and their ratios may be used depending on the particular process being implemented. For example, different feedstock gases can be used at different processing times, such as using acetylene, ethylene or ethanol instead of methane (in the case of CNT/CNF growth). Additionally, different process gases can be used at different times. For example, argon may be replaced with a process gas such as ammonia, nitrogen or hydrogen. Different gas mixtures can be used depending on the desired effect. Those skilled in the art of CNT/CNF growth will appreciate that other feed and process gases may be used.

Annular stop thickness 314 will typically be less than several microns, but can be 1, 5, 10, 26, 50, or 75 percent of support wire height 114 . In some embodiments, annular stopper thickness 314 is less than 40, 20, 5, 2, or 0.25 percent of support wire height 114 . Depending on the growth rate of the support filament 110, the cross-section of the annular stopper 310 as shown in the plane of FIG. 3 may be oval, rhombus, or square. Other cross-sectional shapes are possible. Support cap 150 and support ring 210 and ring stop 310 optionally have these shapes and dimensions.

Ring stop diameter 316 is controlled by the process method chosen to create ring stop 310 . For example, during growth of annular stopper 310 , the temperature of the reaction chamber may be varied to speed up or slow down the reaction creating support filament 110 , thereby creating regions of support filament 110 that are larger in diameter than other regions of support filament 110 . For example, support wire 110 may include narrower diameter regions separated by annular stops 310 having a relatively larger diameter. Alternatively, the support wire may include a region between the substrate 124 and the annular stopper 310 with a relatively larger diameter (the annular stopper 310 may be smaller than or close to the same diameter of this region), and a region away from the substrate 124. regions with smaller diameters. The support wire diameter 112 is defined as the smallest diameter along the support wire.

Ring stop spacing 312 is controlled by starting point spacing 126 and ring stop diameter 316 . The dimensions of the ring stop 310 are selected such that a reduced DAM attachment occurs between the ring stop 310 and the substrate 124 relative to the area of the support wire 110 remote from the substrate 124 . A single support wire 110 may include more than one annular stopper 310 and/or more than one support ring 210 .

In the illustrated embodiment, the backbone 350 is a region that will have substantially no DAM material or a reduced amount of DAM material relative to the portion of the support wire 110 above the annular stop 310 (away from the substrate 124 ). This will be accomplished by proper selection of the ring stop diameter 316 and the ring stop spacing 312 . For example, ring stop spacing 312 and ring stop diameter 316 may be selected such that a particular ring stop 310 just contacts its closest adjacent ring stop, effectively creating ring stop spacing 312 equal to zero. Alternatively, annular stop spacing 312 may be greater than zero. The ring stop 310 forms a barrier that reduces the amount of DAM reaching the region of the support wire 110 between the ring stop 310 and the substrate 124 relative to the rest of the support wire 110 .

FIG. 4 shows various embodiments of the present invention in which a support wire 110 has a support cap 150 and a support ring 210 but does not have an annular stopper 310 .

FIG. 5 shows various embodiments of the invention in which the support wire 110 has the support cap 150 and the ring stopper 310 but does not have the support ring 210 .

FIG. 6 shows various embodiments of the invention in which a support wire 110 has a support ring 210 and an annular stop 310 , but without a support cap 150 . 4-6 illustrate any combination of support cap 150 , support ring 210 and ring stopper 310 that may be included on support wire 110 . These combinations may include one, two, three or more of these elements. A single support wire 110 may include more than one annular stopper 310 and/or more than one support ring 210 . The position of the support ring 210 and the annular stopper 310 can be varied up or down the length of the support wire 110 relative to the positions shown in the figures. Annular stop 310 and support ring 210 are generally cylindrically symmetrical about the longitudinal axis of support wire 110 .

FIG. 7A shows a sandwich 750 comprising a DAM, an annular stopper 310 , a support cap 150 and a support ring 210 . This illustration graphically represents the basic function on the ring stopper 310, e.g., the interlayer 750 is deposited/grown substantially on the upper portion of the support wire 110 between the support cap 150 and the ring stopper 310, and not (or less) Deposits/grows on the area below the annular stopper 310, thereby creating a DAM-reduced region 720 with relatively little or substantially no entrapped material. By proper selection of the ring stop diameter 316 and the ring stop spacing 312 , a mask is created such that minimal (or less) trapped material reaches the substrate 124 .

The DAM reduction region 720 is an area on the support filament 110 that prevents deposition of the interlayer 750 . Typically, the DAM reduced region 720 is adjacent to the seed layer 122 .

FIG. 7A also shows the use of support cap 150 and support ring 210 . Both the support cap 150 and the support ring 210 are characterized by a diameter that is greater than the diameter 112 of the rest of the support wire 110 . In some embodiments, the interlayer will separate from the diameter of the support wire 110 provided that the interlayer 750 expands during operation of the electrode. In some embodiments, as long as the diameter of the support ring width 212 and/or support cap width 157 is greater than the inner diameter of the expanded insert material, the sandwich 750 will be mechanically constrained to the support wire 110, thereby ensuring that the insert material will not Separated from support wire 110.

Ring stop 310 and support ring 210 are optionally similar in size and/or shape. One difference between the ring stopper 310 and the support ring 210 is that the support ring 210 is arranged at a position on the support wire 110 (or is otherwise configured) such that its support sandwich 750 is attached to the support wire 110 . For example, the support ring 210 is configured to prevent the interlayer 750 from sliding off the unattached ends of the support wires 110 . Instead, the ring stop 310 is arranged (or otherwise configured) at a position on the support wire 110 such that it creates an additional gap relative to the support wire 110 in the region of the support wire 110 between the ring stop 310 and the substrate 124. Some have reduced interlayer 750 area. To a lesser extent, support ring 210 may also create a slightly reduced area of interlayer 750 .

Free intercalation material 710 is material that is not stopped by annular stopper 310 during deposition/growth of interlayer 750 . The source of material for the deposition/growth of the interlayer 750 is generally viewed as coming from above the support filament 110 (above the page), as shown in Figures 7A-7C.

An alternate embodiment of support wire 110 is shown in FIG. 7C . These embodiments include examples with more than one support ring and tapered support wires. The various instances of support wire 110 shown in Figures 7B and 7C are generally not on the same electrode. An electrode typically includes one type of support wire 110, support ring 210, support cap 150, and ring stopper 310, since all support wires are produced together. The variants shown here are for example purposes only. The thickness of the interlayer 750 shown in FIGS. 7A-7C is also for illustrative purposes only. In typical embodiments, interlayer 750 is substantially thicker than support wire 110 . As the charged species is absorbed and released, the thickness of the interlayer 750 will also change. It should also be noted that the thickness of the interlayer 750 described herein is for the case where no charging species is absorbed or released by the interlayer 750 .

FIG. 8 shows a method for manufacturing a support wire with an interlayer 750 . The first step 801 is to receive a substrate 124 . Substrate 124 is optionally copper in the case of an anode, or aluminum in the case of a cathode. The substrate can be other materials depending on the desired application. For example, stainless steel or graphite can be used as the substrate. Other materials may be specified by those skilled in the art of battery design, depending on the desired application.

An optional second step 803 is to clean the substrate. The purpose of cleaning 803 the substrate is to prepare the substrate for subsequent deposition and growth of materials in subsequent process steps. This means removing any organics, oxides and other contaminants present on the current collector. Methods for cleaning substrates can range from physical (such as using grinding to remove thin layers of material that have been exposed to contaminants), chemical (using solvents such as acetone, isopropanol, TCE, or methanol) and/or chemical etching. etch (citric acid soak/rinse, which dissolves part of the actual substrate in the case of copper), or any combination of physical and chemical methods to prepare the surface for subsequent process steps.

The third step 805 is optional seed layer deposition. Seed layer deposition 805 is a process step that creates a base layer or seed layer 122 for supporting filament 110 growth. This process step can be achieved by vapor phase (physical or chemical) deposition/growth, liquid phase deposition/growth or solid phase deposition/growth or any combination thereof.

Physical vapor deposition techniques (where the material to be deposited is transported in the gas phase from the source to the substrate) can include: thermal evaporation, electron beam evaporation, DC sputtering, DC magnetron sputtering, RF sputtering, pulsed laser deposition, cathodic arc deposition etc. It is also possible to use reactive physical vapor deposition and a method that incorporates itself into the layer as it grows by injecting a "contaminating gas" into the chamber during the growth process.

Chemical vapor deposition techniques (in which chemical precursors are delivered to a surface in the gas phase and subsequently undergo chemical reactions at the surface) can include low pressure chemical vapor deposition, plasma enhanced chemical vapor deposition, atmospheric pressure chemical vapor deposition, metalorganic chemical vapor deposition phase deposition, hot wire chemical vapor deposition, very high frequency plasma enhanced chemical vapor deposition, microwave plasma enhanced chemical vapor deposition, etc.

Liquid deposition techniques for creating seed layer 122 may include plating, electroplating, or chemical solution deposition, among others. Solid phase deposition techniques may include focused ion beam deposition. Another possibility for deposition is a solution containing a liquid and suspending particles of appropriate size, which is sprayed on the current collector, and then the substrate is subsequently "cured" such that the carrier solution is removed while the particles are left intact on the substrate surface.

Any combination of the above process steps may be used to create a suitable seed layer 122 for creating an initiation point for supporting filament 110 growth.

The fourth step 815 in the process is to create a starting point. This step depends on the method chosen for creating the seed layer 122 . For example, the starting point separation distance 126 may be determined by the thickness and material selected for the seed layer deposition 805 . For example, a seed layer of 3000 angstrom nickel/300 angstrom chrome will produce a specific number of onsets per square centimeter. If the thickness of nickel is reduced to 2000 angstroms, the number of starting points per square centimeter will be different from that of 3000 angstroms thick nickel. If another material is chosen, such as iron, instead of nickel, the resulting starting point per square centimeter will also be different. Step 815 is optionally part of step 805 .

Solid phase deposition techniques can allow control of the onset point per square centimeter. This could be focused ion beam deposition, where the onset point/ ^cm2 is directly controlled by where the focused ion beam deposits its material, or nanoparticle suspension, where the onset point/ ^cm2 is controlled by the nanoparticles contained in a given suspension volume number to control. The number of starting sites can also be controlled by the size of the focused ion beam deposition spot or the size of the nanoparticles in solution, etc.

An inception point is typically created when the reactants making the electrode reach a suitable reaction temperature with a suitable feed gas flow, and the feed gas begins to catalyze the seed layer 122 . The starting point has thus been created and the growth of the supporting filament 110 has begun.

The fifth step 820 is to grow supportive filaments 110 . There are numerous growth processes available for growth support filaments 110 . For example, chemical vapor deposition, thermal chemical vapor deposition, vapor-liquid-solid growth (a type of CVD), and plasma-enhanced chemical vapor deposition are by which carbon nanotubes (CNTs), carbon nanofibers (CNF) and nanowire (NW) growth processes. Those skilled in the art of filament growth will recognize that there are other growth methods available.

Examples of feedstock gases that can be used to grow CNTs/CNFs are carbon monoxide, methane, ethane, ethylene, acetylene, and the like. It is also possible to use other hydrocarbon or inorganic compounds for the growth process.

Of interest is the plasma-enhanced chemical vapor deposition (CVD) method, which allows the creation of vertically aligned support filaments 110 since the growth of support filaments 110 is aligned with the electric field of the plasma. Under certain process conditions, thermal CVD can also produce vertically aligned support filaments 110 . In addition, water-assisted CVD enables vertically aligned support filaments with very high aspect ratios (length/diameter approximately equal to 1,000,000), allowing the creation of very tall support filaments.

It has also been shown that appropriately altered bacteria and viruses have grown as nanowire structures. Such techniques can be used to create support wire 110 .

With proper choice of materials, several techniques can be used together at one time. For example, bacteria/viruses can be used to grow CNTs/CNFs/NWs with an applied electric field to produce vertically aligned support filaments. Another method to support the growth of the filament 110 is to apply electric and/or magnetic field during VLS growth to control the trajectory of the growing CNT/CNF/NW, which controls the three-dimensional shape of the support filament 110. Another technique is to start the growth of CNT/CNF/NW support filament 110 with reactants operating in PECVD mode; after a specified time, the reactants can be switched to thermal CVD mode; and then again after a specified time, the reactants Switch back to PECVD mode. Those skilled in the art of CNT/CNF/NW growth will understand that there are other possible combinations that allow proper growth control of the support filaments 110 .

The height 114 of the support filament 110 is generally determined by the duration of the growth process. The temperature of the reactants, the feed gas used, and the combination and strength of the applied electric and magnetic fields (or their absence) can affect the rate and amount of filament growth.

The diameter 112 of the support filament 110 is typically determined by the thickness of the seed layer 122 or the size of the nanoparticles contained in the suspension if the nanoparticle suspension method is selected for creating the seed layer 122, or if focused ion beam deposition is selected for To create the seed layer 122, the diameter 112 of the support filament 110 is determined by the size of the ion beam. The temperature of the reactants, the feed gas used, and the combination and strength of the applied electric and magnetic fields (or their absence) can also affect the diameter of the support filament 110 .

During the growing step 820 of the support wire 110, it is possible to implement a sub-step 820a in which the annular stopper 310 is grown. This can be accomplished by varying the temperature of the reactants, the feedstock gases used and their relative compositions and flow rates, and the direction and strength of the applied electric and magnetic fields (or their absence). The duration of the change implicitly determines the ring stop thickness 314 and the ring stop diameter 316 . The ring stop spacing is controlled by the duration of the above parameter change to the ready state (and the duration of the change itself), as well as by the starting point separation distance 126 . Sub-step 820a may be repeated.

During the growth step 820 of the support filament 110, a sub-step 820b may be implemented in which the support ring 210 is grown; if step 820b occurs, this will occur after step 820a. Sub-step 820b is accomplished by varying the temperature of the reactants, varying the feedstock gases used and their relative compositions, and varying the combination and strength of the applied electric and magnetic fields (or their absence). The diameter, thickness and height of the support ring 210 are largely controlled by changes in the above parameters.

During the growth step 820 of the support filament 110, a sub-step 820c may be implemented in which the support cap 150 is grown; if step 820c occurs, this will occur after step 820b. This can be achieved by changing the temperature of the reactants, changing the feed gas used and its relative composition, and changing the combination, direction and strength of the applied electric and magnetic fields (or their absence). The diameter, thickness and height of the support cap 150 are optionally controlled by changes in the above parameters.

Any of the three steps 820a, 820b, and 820c may be implemented regardless of the presence or absence of the other steps 820a, 820b, and 820c. For example, step 820a may be performed without performing step 820b or step 820c. Alternatively, steps 820a and 820c may be performed instead of step 820b, or it may be decided to perform step 820b instead of steps 820a or 820c. Alternatively, it may be decided not to implement any of the sub-steps 820a, 820b, and 820c, thereby creating a support wire 110 with minimal diameter change along its length.

The sixth step 825 is to create the DAM reduced area 720 , note that the DAM reduced area 720 corresponds to the backbone 350 . (The reason for the difference between elements 350 and 370 is that the DAM reduced region 720 is created during the deposition of the interlayer 750, while the backbone 350 is co-defined with the shape of the support filament 110. When the interlayer 750 is added, the backbone 350 will become the DAM reduced region 720 In particular, the backbone 350 is a portion of the support filament 110, while the DAM-reduced region 720 refers to the region in which the intervening material 750 is reduced or absent). DAM region creation process step 825 can be accomplished by several methods including, but not limited to, using ring stopper 310 . Examples of such methods include controlling the aspect ratio of the support filaments 110 during growth and directional deposition of sandwiched material, such as evaporation or ion beam deposition. Additional methods include electrodeposition and electroless deposition at the bottom layer to isolate the backbone 350 . It is possible to perform sputtering/photolithography of the mask layer to open the support filament 110 to the growth/deposition of the interlayer 750, or alternatively, the growth parameters of the support filament 110 can be modified to achieve a beneficial aspect ratio (such as a tree structure) . This can be done by varying the composition of the feedstock and process gases used during growth. Another possible approach is to create a DAM-reduced region 720 to perform deposition and directed etch-back (eg reactive ion etching) of the intercalation material so that the support filament 110 is not covered by the interlayer 750 . The creation of the DAM reduced region 729 depends on the method and structure chosen for CNT/CNF/NW growth, and the method and structure chosen for interlayer deposition. For example, after the interlayer 750 has been deposited, it may be possible to create the DAM reduced region 720, for example via a suitable directional etch such as reactive ion etching or inductively coupled plasma etching.

An eighth process step 830 is to deposit/grow an interlayer 750 . (Note that DAM refers to a material that supplies or accepts ions during battery charge and discharge, where interlayer 750 includes DAM and other layers that may provide adhesion, or may provide layers that increase absorption, or may improve conductivity. Layers of Other purposes are possible. These additional layers can be above or below the deposited DAM).

Growth of the interlayer 750 can be achieved by vapor phase (physical or chemical) deposition/growth, liquid phase deposition/growth or solid phase deposition/growth or any combination thereof.

Physical vapor deposition techniques (where the material to be deposited is transported in the gas phase from the source to the substrate) can include: thermal evaporation, electron beam evaporation, DC sputtering, DC magnetron sputtering, RF sputtering, pulsed laser deposition, cathodic arc deposition etc. It is also possible to use reactive physical vapor deposition and a method that incorporates itself into the layer as it grows by injecting a "contaminating gas" into the chamber during the growth process.

Chemical vapor deposition techniques (in which chemical precursors are delivered to a surface in the gas phase and subsequently undergo chemical reactions at the surface) can include low pressure chemical vapor deposition, plasma enhanced chemical vapor deposition, atmospheric pressure chemical vapor deposition, metalorganic chemical vapor deposition phase deposition, hot wire chemical vapor deposition, very high frequency plasma enhanced chemical vapor deposition, microwave plasma enhanced chemical vapor deposition, etc.

Note that at any deposition stage, more than one material can be deposited simultaneously. For example, two (or more) different types of metals, such as tin (Sn) and gold (Au), can be deposited/grown simultaneously; two (or more) different types of semiconductors, such as silicon, can be deposited/grown (Si) and germanium (Ge); two (or more) different types of oxides can be grown/deposited, such as lithium iron phosphate (LiFePO ₄ ) and lithium nickel cobalt manganese oxide (Li(NiCoMn)O ₂ ) . In addition, it is possible to mix material types, such as metal and semiconductor, or semiconductor and oxide, or metal and oxide, or metal, semiconductor and oxide. Examples include silicon (Si) and lithium (Li) co-deposition, silicon (Si) and LiO ₂ (or SiO ₂ ) co-deposition, and silicon (Si), lithium (Li) and LiO ₂ (or SiO ₂ ) co-deposition. It may also be desirable to co-deposit insulating materials such as silicon dioxide (SiO ₂ ) or silicon nitride (Si ₃ N ₄ ). In addition, co-deposition of carbon (C) may also be desired.

Interlayer 750 is optionally created by a liquid phase process, such as electroless deposition or electroplating. It is also possible to create interlayers by coating support wires with an intercalation material such as silicon (Si) or tin (Sn) suspended in a binder solvent matrix. After proper processing, the solvent is driven out of the matrix, leaving only the binder and intercalation material, thereby creating an electrode comprising support wire 110 and intercalation material. This technique can also be applied to cathodes. The interlayer may comprise aerogel. When the interlayer 750 is produced according to a liquid process, the DAM reduced region 720 can optionally be produced by including a material in the backbone 350 that repels the liquid. For example, if water is used, a hydrophobic substance may be included in the region of the backbone 350 . These substances may be incorporated into the support filament 110 or coated on the surface of the support filament 110 .

In some embodiments, the conductivity of interlayer 750 is controlled by appropriate selection of deposition and growth techniques. For example, in the case of sputtering, using heavily p+ or n+ doped silicon versus undoped silicon will create a relatively conductive bulk silicon interlayer (for example, highly doped silicon is 10'sohm-cm, while pure silicon is 10000'sohm-cm). In the case of CVD silicon deposition using silane, the addition of phosphine or arsine may optionally be used to increase the conductivity of the deposited/grown silicon. In various embodiments, dopants include boron (B), gallium (Ga), arsenic (As), phosphorus (P), antimony (Sb), indium (In), thallium (Th), and/or bismuth ( Bi). Other dopants are possible.

In some embodiments, the interlayer 750 can be added by depositing a metal such as, but not limited to, gold (Au), tin (Sn), silver (Ag), lithium (Li), or aluminum (Al) while depositing/growing silicon. conductivity. In some embodiments, the conductivity of interlayer 750 is controlled via ion implantation. These methods are also possible using other materials selected for interlayer 750, such as germanium (Ge). In various embodiments, the resulting interlayer 750 has a resistivity of less than 1 ohm-cm, less than 10 ohm-cm, less than 500 ohm-cm, less than 2000 ohm-cm, or less than 12000 ohm-cm. In other embodiments, the resistivity is greater than 12000 ohm-cm.

In some embodiments, step 830 includes post-processing the deposited interlayer 750 . This post-processing can change the crystal structure of the interlayer 750 . For example, in some embodiments, amorphous silicon is deposited as interlayer 750 , and subsequent process steps appropriately anneal the amorphous silicon, thereby creating a layer and/or surface of polysilicon on interlayer 750 . The resulting structure may include a polysilicon layer on the outer surface and an amorphous silicon layer between the polysilicon layer and the support wire 110 . Both silicon layers are considered part of interlayer 750 . This annealing process can be accomplished by using a high power laser or some other rapid high temperature heat source. A post-annealing method after this deposition can optionally be applied to the cathode and/or anode material.

In some embodiments, the deposited interlayer 750 is passivated. In the case of silicon, passivation can be achieved by annealing as discussed elsewhere herein, or by depositing oxide, nitride and/or carbide layers of approximately less than 5, 10, 40, 100 or 250 nanometers . This oxide, carbide or nitride layer is considered part of the interlayer 750 and may be produced as part of the growing support filament step 820 . Oxide or nitride can be grown or deposited by heat treatment methods as well as standard CVD and PECVD techniques. Surface passivation can optionally be achieved by growing carbides on the surface of the interlayer 750, for example. This growth can be achieved by performing a seed layer deposition step 805 , a create starting point step 815 , and a growing support filament step 820 in which carbides, oxides and/nitrides are grown. In some embodiments, the CNT/CNF/NW height grown on the interlayer 750 is a few microns at most, and typically less than 250 nm.

Due to the shape of the support wire 110 , annular stopper 310 , support ring 210 and support cap 150 , different amounts of trapped material are deposited at different locations along the length of the support wire 110 . The deposition/growth method used to create interlayer 750 optionally relies on surface reactions for initiating and continuing the growth process. If the flux of reactants to the surface of support filament 110 is reduced, the deposition/growth rate of interlayer 750 will be correspondingly reduced.

By way of example, and with reference to FIGS. 7A-7C , if the annular stopper spacing 312 is 0, substantially no or only a minimal amount of reactant will reach the surface of the support wire 110 below the annular stopper 310, which produces A DAM-reduced region 720 is provided, which has relatively little interlayer 750 compared to the rest of the support wire 110.

Another way to ensure deposition/growth of different amounts of interlayer 750 along the length of support filament 110 relies on a larger aspect ratio of support filament height 114 to starting point separation 126 . The aspect ratio may be of the order of approximately 5:1, 10:1, 100:1, 1000:1, 10000:1 or as high as 1000000:1, possibly greater. Since a larger aspect ratio means that the lateral surfaces of the support filaments have an imperceptibly smaller solid angle as the reactants move toward the substrate 124, the amount of growth along the support filaments is correspondingly reduced, resulting in little or no DAM reduced region 720 of interlayer 750 . Creating the DAM-reduced region 720 in this manner does not require the annular stop 310 .

At step 840, electrode fabrication may be completed. Electrodes are optionally included in the battery.

Figures 9A and 9B show the measured capacity of an anode created using the process described herein, where the support filaments 110 are carbon nanofibers and the interlayer 750 is silicon. FIG. 9A shows the capacity of the electrodes as the thickness of the interlayer 750 increases. In Figure 9B, line 910 shows the calculated capacity of graphite coating only, while line 920 shows the experimental results using a mixture of amorphous and polycrystalline silicon. Measurements were performed in a half-cell setup. Figure 9B shows a 5 to 7 fold improvement in charge storage capacity compared to a pure graphite based anode. The amount of improvement depends on the thickness and material type of interlayer 750 .

Figure 10 shows the cycle life of cells using anodes created using the process described herein as a function of interlayer temperature and thickness compared to industry standard electrodes. The support filaments 110 are carbon nanofibers and the interlayer 750 is silicon. Measurements can be performed at two different temperatures in a full-cell setup and cycling performed at a C/2 rate. The data show significantly enhanced cycle life at elevated temperatures relative to the prior art.

FIG. 11 shows a battery 1100 according to various embodiments of the invention. Battery 1100 includes a first electrode 1110 such as shown in FIGS. 1-8 herein, and a second electrode 1120 . The second electrode 1120 may or may not include the features shown in FIGS. 1-8 . The battery 1100 also includes a conductor (not shown) configured to couple the first electrode 1110 and the second electrode 1120 in a circuit configured to provide electrical power to a load. Those of ordinary skill in the art will understand how these conductors can be configured. Battery 1100 is typically a rechargeable battery. The first electrode can be configured to operate as an anode or a cathode.

Figure 12A is a diagram of an electrode in which the height 114 of the support wire 110 is 3.5 microns. Figure 12B is a diagram of an electrode in which the height 114 of the support wire 110 is 17.5 microns. The support filaments in Figures 12A and 12B do not include intercalated material.

FIG. 13A is a diagram of an electrode in which the height 114 of the support wire 110 is 3.5 microns and 0.25 microns of silicon is deposited as the interlayer 750 . The data indicated that the 3.5 micron support wire 110 coated with the 0.25 micron interlayer 750 (silicon) had a very low cycle life (<10 cycles).

FIG. 13B is a diagram of an electrode where the height 114 of the support wire 110 is 17.5 microns and 0.25 microns of silicon is deposited as the interlayer 750 . The data indicates that the 17.5 micron support wire 110 coated with the 0.25 micron interlayer 750 (silicon) has very good cycle life (>30 cycles, <20% capacity fade). Various embodiments of the present invention include support filaments 110 having a height 114 of at least 17.5 microns (17.5 x 10 ⁻⁶ meters) and having interlayers 750 of at least 0.1, 0.25, 0.35, 0.5, or 0.75 microns.

Figure 14 is a cross-section of an electrode with a support filament height 114 of 10 microns and no interlayer present. This electrode design (with linearly measured interlayer material deposition thicknesses of 0.5 microns, 1.5 microns, and 4.0 microns) was tested and produced the data presented in FIGS. 9A , 9B and 10 . The results indicate enhanced capacity and improved cycle life at elevated temperatures (300 cycles at 60 degrees Celsius, 40% capacity fade, C/2 rate). Various embodiments of the invention include a support filament 110 having a height 114 of at least 10 microns (10.0×10 ⁻⁶ meters) and an interlayer 750 of at least 0.1, 0.25, 0.35, 0.5, or 0.75 microns.

Several embodiments are specifically shown and/or described herein. It will be understood, however, that modifications and variations are covered by the above teaching and are within the scope of protection without departing from the spirit and scope of the appended claims. For example, the electrodes described herein may be used in devices other than batteries.

The embodiments described here are examples of the present invention. As these embodiments of the invention have been described with reference to examples, various modifications and adaptations of the methods and/or specific structures described may become apparent to those skilled in the art. All such modifications, adaptations or variations that rely on the teachings of the invention and advance the art on those teachings are considered to be within the spirit and scope of the invention. Accordingly, these descriptions and drawings should not be interpreted in a limiting manner, it being understood that the invention is by no means limited to the embodiments shown.

Claims (45)

1. An electrode comprising: Substrate; a support wire coupled to the substrate; an interlayer comprising a donor-acceptor material configured to receive reactants of an electrochemical reaction, the donor-acceptor material disposed along the length of the support filament, the interlayer having a thickness less than the length of the support filament; a region of the interlayer closer to the substrate comprising a lesser amount of donor acceptor material relative to a region of the interlayer further away from the substrate; and An annular stop disposed along the length of the support wire, the annular stop configured to create a sandwich region comprising a lesser amount of the donor-receptor material. 2. The electrode according to claim 1, wherein the support filament comprises carbon nanotubes or carbon nanofibers, or nanowires. 3. The electrode of claim 1, wherein the interlayer comprises silicon, tin or germanium. 4. The electrode of claim 1 , wherein the amount of intercalated material in interlayer regions containing lesser amounts of donor acceptors includes less in regions away from the substrate in terms of weight per unit area of the support wire. at 75% of the donor acceptor material. 5. The electrode of claim 1 , wherein the amount of intercalation material in interlayer regions containing lesser amounts of donor acceptors comprises less than 50% of the donor acceptor material. 6. The electrode of claim 1, further comprising a support ring configured to prevent separation of the interlayer from the support wire. 7. The electrode of claim 1, further comprising a support cap configured to prevent separation of the interlayer from the support wire. 8. The electrode of claim 1, wherein the interlayer is p+ or n+ doped. 9. The electrode of claim 1, further comprising a seed layer disposed between the substrate and the support filament, the seed layer configured to couple the support filament to the substrate. 10. The electrode of claim 1, wherein the support wire comprises more than one support ring. 11. The electrode of claim 1, further comprising a carbide layer, an oxide layer, or a nitride layer on the surface of the interlayer. 12. The electrode of claim 1, wherein the interlayer comprises metal. 13. The electrode of claim 1, wherein the surface of the interlayer is passivated. 14. The electrode of claim 1, wherein the support filament comprises carbon nanotubes or carbon nanofibers. 15. The electrode of claim 1, further comprising a support ring configured to support attachment of the interlayer to the support wire. 16. The electrode of claim 12, wherein the metal is selected to increase the conductivity of the interlayer. 17. The electrode of claim 15, wherein the support ring is configured to create regions along the support wire with varying amounts of interlayer. 18. The electrode of claim 15, wherein the support ring has a conical or triangular cross-section. 19. The electrode of claim 15, wherein the support ring has a conical shape. 20. The electrode of claim 1, wherein the interlayer comprises a metal and an oxide. 21. The electrode of claim 1, further comprising a support ring disposed along the length of the support wire, the support ring being characterized by a diameter greater than that of other portions of the support wire. 22. The electrode of claim 1, wherein the support filaments comprise multi-walled carbon nanotubes. 23. A method of producing an electrode, the method comprising: receiving substrate; a first region of growth support filaments coupled to the substrate; growing an annular stop at an end of the first region of the support wire remote from the substrate, the annular stop configured to reduce the amount of donor acceptor material reaching the first region; growing a second region of the support filament from the annular stop, the second region of support filament having a smaller diameter than the annular stop; and A donor acceptor material is applied to the support filament such that a greater thickness of the donor acceptor material is deposited in the second region of the support filament than in the first region of the support filament. 24. The method of claim 23, wherein the annular stopper is grown by changing growth conditions such that the diameter of the support wire increases. 25. The method of claim 23, wherein the donor acceptor material comprises silicon, tin or germanium, and the support filaments comprise carbon nanotubes, carbon nanofibers and nanowires. 26. The method of claim 23, further comprising a growth support cap configured to prevent the donor acceptor material from slipping off the unattached ends of the support filaments. 27. The method of claim 23, further comprising a growth support ring configured to prevent the donor acceptor material from slipping off the unattached ends of the support filaments. 28. The method of claim 23, further comprising applying a seed layer to the substrate, the seed layer configured to grow supporting filaments. 29. The method of claim 23, further comprising adding an oxide, carbide, or nitride layer to the surface of the donor acceptor material. 30. The method of claim 23, further comprising adding an n+ or p+ doped material to the donor acceptor material. 31. The method of claim 23, further comprising adding a metal to the donor acceptor material. 32. The method of claim 23, further comprising heating the donor acceptor material after applying the donor acceptor material to the support filament, so as to change the crystal structure of the donor acceptor material . 33. The method of claim 23, further comprising passivating the donor acceptor material after applying the donor acceptor material to the support filament. 34. The method of claim 23, wherein the support filaments comprise multi-walled carbon nanotubes. 35. A battery comprising: the first electrode; and a second electrode, including: substrate, a support wire coupled to the substrate, an interlayer configured to receive reactants for an electrochemical reaction, the interlayer disposed on the support filament and having a deposited thickness less than or equal to 4 microns, and an annular stop disposed along the length of the support wire, the annular stop configured to create a sandwich that is proximal to the substrate and includes a lesser amount of donor-receptor material relative to a region remote from the substrate area. 36. The cell of claim 35, wherein the second electrode is configured to operate as an anode. 37. The cell of claim 35, further comprising means for preventing said interlayer from slipping off said support wire. 38. The battery of claim 35, further comprising means for increasing the conductivity of the interlayer. 39. The battery of claim 35, wherein the support filaments comprise multi-walled carbon nanotubes. 40. The battery of claim 35, wherein the interlayer comprises a metal and an oxide. 41. The cell of claim 35, wherein the interlayer comprises silicon. 42. The cell of claim 35, wherein the interlayer comprises silicon, metal and oxide. 43. The cell of claim 35, wherein the annular stopper is configured to create regions of different interlayer thicknesses along the support wire. 44. The cell of claim 35, wherein the annular stop is configured to support attachment of the interlayer to the support wire. 45. The battery of claim 35, wherein the support filaments comprise multi-walled carbon nanotubes.