JP2020021736A - Hybrid energy storage device including supporting filament - Google Patents

Abstract

To provide an electrode that suppresses breakage due to structural stress due to large body expansion during lithiation.SOLUTION: An electrode includes a conductive substrate, and an output enhancing material that is disposed on the conductive substrate, and includes carbon, an intercalation material that is interspersed with the carbon and that reversibly adsorbs charge carriers within a bulk of the intercalation material, and a plurality of surface effect dominant sites for intercalating the charge carrier into the intercalation material.SELECTED DRAWING: Figure 1A

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application is a continuation-in-part of U.S. Non Provisional Patent Application No. 13 / 779,409, filed February 27, 2013,
A continuation-in-part of U.S. Non Provisional Patent Application No. 13 / 725,969, filed December 21, 2012;
US Provisional Patent Application No. 61 / 667,876, filed July 3, 2012,
US Provisional Patent Application No. 61 / 677,317, filed July 30, 2012,
Claim the benefits and priority of U.S. Provisional Patent Application No. 61 / 806,819, filed March 29, 2013 and U.S. Provisional Patent Application No. 61 / 752,437, filed January 14, 2013.
This application is further subject to U.S. Non-Provisional Patent Application No. 13/77, all filed on March 26, 2013.
9,472, 13 / 779,522 and 13 / 779,571.

The disclosures of all U.S. provisional and non-provisional patent applications mentioned above are incorporated herein by reference.

The present invention relates to the field of energy storage devices, including but not limited to batteries, capacitors and fuel cells.

Rechargeable lithium-ion batteries are important electrical energy storage devices for power supplies in portable electronics, power tools, and future electric vehicles. Improving intrinsic energy capacity, charge / discharge rate, and cycle operating life is important for wider applications.

In lithium ion batteries that are currently commercially available, using a graphite or other carbonaceous material as an anode (negative electrode), the anode of 372 mAh / g by forming fully LiC ₆ compound intercalated Has a theoretical capacity limit. On the other hand, silicon forms 4,2 by forming a fully intercalated alloy Li _4.4 Si.
It has a considerably high theoretical specific capacity (specific output) of 00 mAh / g. However, ~ 300-400
The large volume expansion of lithiated Si, which can be as high as 10%, results in large structural stresses, which in the past have always led to breakage and mechanical failure, which has severely limited the life of Si anodes in the past.

In some embodiments, the power storage device comprises a vertically aligned carbon nanofiber (VACNFs) coaxially coated with an amorphous silicon layer.
Incorporating an array of ibers has a hybrid core shell NW (nanowire) in a high performance lithium ion anode. Vertically aligned CNFs have multiwalled carbon nanotubes (MWCNTs), which are optionally DC-biased plasma chemical vapor deposited (PECVD).
(r deposition) process to grow on Cu substrate. Carbon nanofibers (CNFs) grown in this way can have a different internal shape of the lottery than common MWCNTs and conventional hollow structures of solid carbon nanofibers. One of the distinguishing characteristics is that
These CNFs are optionally composed of a series of bamboo-like nodes along a generally hollow central channel. This microstructure is believed to be due to the stack of conical graphite cups described elsewhere herein. At longer scales, these PECVD grown CNFs are generally uniformly aligned perpendicular to the substrate surface and are well separated from each other. CNFs have no or little entanglement and therefore have a VA
A brush-like structure called a CNF array is formed. The diameter of the individual CNFs is selected to provide the desired mechanical strength, which allows the VACNF array to be robust and maintain integrity over Si deposition and wet electrochemical inspections.

Various embodiments of the present invention have support filament types other than VACNFs. These support filaments can include, for example, nanowires, carbon sheets, or other structures described herein. Other embodiments do not have any supporting filaments,
Use a binder instead.

Various embodiments of the present invention include a conductive substrate and a plurality of vertically aligned carbon nanofibers grown on the conductive substrate, the carbon nanofibers comprising a plurality of multi-walled carbon nanotubes. And an energy storage system comprising the carbon nanofiber and an electrolyte comprising one or more charge carriers.

Various embodiments of the present invention include a conductive substrate, carbon nanofibers grown on the conductive substrate, and a layer of intercalation material disposed on the plurality of vertically aligned carbon nanofibers. About 1 per gram of intercalation material
And a layer of said intercalation material configured to have a lithium ion storage capacity of between 500 and 4,000 mAh.

Various embodiments of the present invention include a conductive substrate, carbon nanofibers grown on the conductive substrate, and an intercalation material disposed on the plurality of vertically aligned carbon nanofibers. An energy storage system comprising a layer and a layer of the intercalation material configured such that the ion storage capacity of the intercalation material is approximately the same at 1 C and 3 C charge rates.

Various embodiments of the present invention include a method of producing an energy storage device, the method comprising the steps of providing a substrate and growing a carbon nanofiber on the substrate, the method comprising: A fiber having a laminated cone structure, the growing step, and an application step of applying an intercalation material to the carbon nanofiber, wherein the intercalation material is configured to intercalate a charge carrier; Coating step.

Various embodiments of the present invention include an electrolyte including one or more charge carriers, a conductive substrate, a plurality of vertically aligned support filaments attached to the substrate, and disposed on each support filament. An intercalation material, wherein the intercalation material is configured to reversibly adsorb charge carrier components within a bulk of the intercalation material; and A binder comprising nanoparticles of, wherein each of the nanoparticles is configured to create a surface effect dominant site capable of adsorbing the charge carrier member to the nanoparticle surface by a Faraday reaction. Includes an energy storage system.

Various embodiments of the present invention include an electrolyte including one or more charge carriers, a conductive substrate, a plurality of vertically aligned support filaments attached to the substrate, and disposed on each support filament. An intercalation material, wherein the intercalation material is configured to reversibly adsorb charge carrier components within a bulk of the intercalation material; and A binder comprising a surface effect dominant site, wherein the surface effect dominant site comprises a binder configured to catalyze the charge carriers to intercalate into the intercalation material. , Energy storage systems.

Various embodiments of the present invention provide an electrolyte including one or more charge carriers, a conductive substrate, and an intercalation material, wherein the charge carrier components are contained within a bulk of the intercalation material. A resorbable adsorbent, the intercalation material, and a binder disposed on the intercalation material and including a plurality of nanoparticles, the nanoparticles comprising a member of the charge carrier. And a binder configured to create a surface effect dominant site that can be adsorbed to a nanoparticle surface by a Faraday reaction.

Various embodiments of the present invention comprise a cathode and an anode separated from the cathode by an electrolyte comprising one or more charge carriers, the anode intercalating the charge carriers and transferring electrons. An intercalation material configured to provide the charge carrier at a first reaction potential; and a plurality of nanoparticles including a surface effect dominant site capable of providing electrons to the charge carrier at a second reaction potential; An energy storage system, wherein the absolute value of the difference between the first reaction potential and the second reaction potential is less than 2.4V.

Various embodiments of the present invention are potential gradient establishing means for establishing a potential gradient at an anode of a charge storage device, wherein the anode has an electrolyte, a plurality of surface effect dominant sites, an intercalation material, and a substrate. The potential gradient establishing means, the means for receiving charge carriers in the electrolyte at one surface effect dominant site, the means for receiving electrons in the charge carriers from the surface effect dominant site, and the charge carrier in the intercalation material. Means for receiving.

Various embodiments of the present invention include a method of producing an energy storage device, the method comprising providing a conductive substrate; growing a support filament on the substrate; Applying to the support filament, wherein the intercalation material is configured to intercalate charge carriers; and the plurality of surface effects predominantly in close proximity to the intercalation material. Applying a site.

Various embodiments of the present invention include a method for producing an anode, the method comprising the steps of providing a conductive substrate and mixing a bonding material, a surface effect dominant site, and an intercalation material. Wherein the surface effect dominant site is configured to receive electrons from a charge carrier at a first reaction potential, and the intercalation material receives charge carriers at or receives electrons from a charge carrier at a second reaction potential. The mixing step and the step of applying a bonding material, a surface effect dominant site and an intercalation material to the substrate.

Various embodiments of the present invention include a method of producing an energy storage device, the method comprising providing a conductive substrate; providing a support filament on the substrate; Applying to the support filament, wherein the intercalation material is configured to intercalate charge carriers, the application step, and adding a surface effect dominant site to the support filament. Have.

Various embodiments of the invention include a method of charging a charge storage device, the method comprising:
A potential establishing step of establishing a potential between a cathode and an anode of the charge storage device, wherein the charge storage device includes an electrolyte; Receiving charge carriers; transferring electrons at the anode to the first charge carriers; receiving a second charge carrier at the electrolyte with an intercalation material at the anode; Transferring electrons to the second charge carrier.

Various embodiments of the invention include a method of charging a charge storage device, the method comprising:
Establishing a potential gradient at an anode of the charge storage device, said anode comprising an electrolyte, a plurality of nanoparticles having surface effect dominant sites, an intercalation material, and a substrate. Receiving a first charge carrier in the electrolyte at one of the surface effect dominant sites; and
Transferring an electron to a charge carrier; receiving a second charge carrier with an intercalation material at the anode; and transferring an electron from the intercalation material to the second charge carrier.

Various embodiments of the present invention include a conductive substrate and a carbon nanofiber or other support filament coupled to the conductive substrate, wherein the carbon nanofibers extend along a length of the carbon nanofiber. An energy storage system comprising the carbon nanofiber having a plurality of exposed nanoscale edges and an intercalation material configured to form a shell over at least a portion of the carbon nanofiber.

Various embodiments of the present invention include an energy storage system, such as a battery or an electrode,
The energy storage system includes a conductive substrate and a carbon nanofiber or other support filament coupled to the conductive substrate, wherein the carbon nanofiber comprises a plurality of carbon nanofibers along a length of the carbon nanofiber. The carbon nanofiber having a cup-like structure, and an intercalation material configured to form a shell over at least a portion of the carbon nanofiber.

Various embodiments of the present invention are configured to form a conductive substrate, a carbon nanofiber or other support filament coupled to the conductive substrate, and a shell over at least a portion of the carbon nanofiber. An intercalation material, wherein the intercalation material is disposed in a vane-like structure along a length of the carbon nanofiber.

Various embodiments of the present invention include a conductive substrate, a carbon nanofiber coupled to the conductive substrate, and an intercalation material configured to form a shell over at least a portion of the carbon nanofiber. An energy storage system comprising: the intercalation material configured to prevent the intercalation material from separating from the carbon nanofibers due to expansion of the intercalation material.

A preferred embodiment of the present invention includes a method of producing an energy storage device, the method comprising: providing a conductive substrate; and adding carbon nanofibers to the conductive substrate. Each of the carbon nanofibers has a plurality of exposed nanoscale edges along the length of the carbon nanofiber, the step of applying the carbon nanofiber, and applying an intercalation material to the carbon nanofiber A coating step, wherein the intercalation material is configured to cause charge carrier intercalation.

A preferred embodiment of the present invention includes a method of producing an energy storage device, the method comprising: providing a conductive substrate; and adding carbon nanofibers to the conductive substrate. Each of the carbon nanofibers has a plurality of cup-shaped structures along the length of the carbon nanofiber, the carbon nanofiber adding step, and a coating step of applying an intercalation material to the carbon nanofiber. Said intercalating material having an application step configured to cause intercalation of charge carriers.

A preferred embodiment of the present invention includes a method of producing an energy storage device, the method comprising: providing a conductive substrate; adding carbon nanofibers to the conductive substrate; A coating step of applying an intercalation material to the carbon nanofibers, wherein the intercalation material causes charge carrier intercalation, and the intercalation material extends along a length of the carbon nanofibers. And disposing them in a blade-like structure.

4 illustrates a CNF array having a plurality of CNFs grown on a substrate, according to various embodiments of the invention. 4 illustrates a CNF array having a plurality of CNFs grown on a substrate, according to various embodiments of the invention. FIG. 3 illustrates a plurality of vertically aligned CNFs in different states, according to various embodiments of the invention. FIG. 3 illustrates a plurality of vertically aligned CNFs in different states, according to various embodiments of the invention. FIG. 3 illustrates a plurality of vertically aligned CNFs in different states, according to various embodiments of the invention. 4 illustrates details of a CNF, according to various embodiments of the invention. 4 illustrates details of a CNF, according to various embodiments of the invention. 4 illustrates details of a CNF, according to various embodiments of the invention. FIG. 4 shows a schematic diagram of a laminated cone structure of CNF, according to various embodiments of the present invention. FIG. 5A shows the electrochemical properties of CNF having a length of ３3 μm (up to 3 μm), according to various embodiments of the present invention. FIG. 5B shows the electrochemical properties of CNF having a length of ３3 μm (up to 3 μm), according to various embodiments of the present invention. FIG. 5C shows the electrochemical properties of CNF having a length of ３3 μm (up to 3 μm), according to various embodiments of the present invention. 4 shows scanning electron microscope images of CNF having a length of 3 μm, according to various embodiments of the present invention. 4 shows scanning electron microscope images of CNF having a length of 3 μm, according to various embodiments of the present invention. 4 shows scanning electron microscope images of CNF having a length of 3 μm, according to various embodiments of the present invention. FIG. 7A shows results obtained using CNF with a Si layer as a lithium ion battery anode (negative electrode), according to various embodiments of the present invention. FIG. 7B illustrates results obtained using CNF with a Si layer as a lithium ion battery anode, according to various embodiments of the present invention. FIG. 7C illustrates results obtained using CNF with a Si layer as a lithium ion battery anode, according to various embodiments of the present invention. 4 illustrates how the capacity of a CNF array varies with the charge rate, according to various embodiments of the present invention. 4 shows Raman spectra of a CNF array according to various embodiments of the present invention. FIG. 10A shows variation in Li ⁺ intercalation and desorption (extraction) capacity, and variation in Coulombic efficiency over 15 charge and discharge cycles, according to various embodiments of the present invention. FIG. 10B shows variation in Li ⁺ intercalation and desorption (extraction) capacity, and variation in Coulombic efficiency over 15 charge / discharge cycles, according to various embodiments of the present invention. FIG. 10C shows variation in Li ⁺ intercalation and desorption (extraction) capacity, and variation in Coulombic efficiency over 15 charge and discharge cycles, according to various embodiments of the present invention. 4 shows scanning electron microscope images of freshly prepared CNF arrays, according to various embodiments of the present invention. 4 shows scanning electron microscope images of freshly prepared CNF arrays, according to various embodiments of the present invention. 4 shows scanning electron microscope images of freshly prepared CNF arrays, according to various embodiments of the present invention. 1 shows a cross-sectional view of a nanofiber / silicon complex containing more than one CNF. 4 illustrates an array of carbon nanofibers including 10 μm long fibers, according to various embodiments of the invention. 4 illustrates a method for producing a CNF array and / or CNF, according to various embodiments of the invention. 3 illustrates a CNF containing a power enhancing material, according to various embodiments of the invention. FIG. 144B shows a detail of the power enhancing material shown in FIG. 144A, according to various embodiments of the invention. FIG. 14B illustrates details of the alternative power enhancing material shown in FIG. 14A, according to various embodiments of the present invention. 4 illustrates an electrode surface containing a non-aligned CNF coated with a power enhancing material and an intercalation material, according to various embodiments of the invention. FIG. 2 illustrates an electrode surface containing a power enhancing material, a non-aligned CNF, and a free intercalation material, according to various embodiments of the invention. 4 illustrates an electrode surface containing an intercalation material and a power enhancement material without CNF, according to various embodiments of the invention. FIG. 4 illustrates an electrode surface having a surface effect dominant site closely spaced near a CNF, according to various embodiments of the invention. FIG. 4 illustrates an electrode surface having surface effect dominant sites closely spaced near a free intercalation material, according to various embodiments of the invention. FIG. 4 illustrates an electrode surface having surface effect dominant sites closely spaced near a free intercalation material, according to various embodiments of the invention. 4 illustrates a method of making an electrode surface according to various embodiments of the invention. 4 illustrates a method of operating a charge storage device according to various embodiments of the invention.

1A and 1B illustrate a CNF array 100 having a plurality of CNFs 110 grown on a conductive substrate 105, according to various embodiments of the present invention. In FIG. 1A, CNF array 1
00 shows a state in which Li has been desorbed (discharged), and FIG. 1A shows a state in which Li has been inserted (charged) in the CNF array 100. The CNFs 110 in these and other embodiments detailed herein are optionally vertically aligned. CNF 110 is grown on a Cu substrate 105 using a DC-biased plasma enhanced chemical vapor deposition (PECVD) process. As described above, CNFs 110 grown in this manner have a unique morphology, which has a stacked cup or cone or stack of conical graphite structures resembling a spiral. This results in very fine structures that facilitate lithium intercalation. This structure may be referred to elsewhere herein as a "stacked cone." On a larger length scale, the CNFs 110 are typically uniformly aligned orthogonal to the substrate and well separated from each other. The diameter of the individual CNFs is selected to achieve the desired mechanical strength, which makes the CNF array 100 robust and maintains integrity during Si deposition and wet electrochemical cycling. Optionally, using a seed layer to form the substrate 105
The CNF 110 is grown thereon. In use, the CNF array 100 is placed in contact with an electrolyte 125, which may be solid or liquid, or a combination of solid and liquid, and one or more charge carriers such as lithium ions. Can be included. In this CNF 110, a part of the electrolyte 125 is CNF1.
10 and / or a gap between the CNFs 110 with the substrate 1
05 is prepared.

The nominal diameter of the individual CNFs 110 shown in FIGS. 1A and 1B is between 100 and 200 nm, but can also be between 75 and 300 nm or other values. CNF 110 is optionally tapered along its length. CNF110 produced using the techniques described herein
Has excellent conductivity (σ = 〜2.5 × 10 ⁵ S / m) along the axis, and the substrate 105
Form a strong ohmic contact to Due to the open space between CNFs 110, each CNF
The silicon layer 115 is deposited on the NF 110 to form a coaxial shell that has a lump at the tip of the CNF 110 and gradually becomes thinner. According to this design, the silicon layer 1
15 is electrically connected to the CNF 110, and can be kept completely active during a charge / discharge cycle. The expansion that occurs when lithium is alloyed into the silicon layer 115 can be easily accommodated in a radial direction, for example, a direction orthogonal to the length dimension of the CNF 110. The charge / discharge capacity and cycle stability of the non-Si coated CNF 110 and the Si coated CNF 110 can be compared. By adding the silicon layer 115, C / 2
At a rate of 3938 mAh / g _Si , a remarkable Li ⁺ insertion (charging) capacity was obtained,
In addition, 1944 mAh / g _Si was maintained after 110 cycles. This charge / discharge rate and corresponding capacity is significantly higher than conventional architectures using Si nanowires or Si-C nanostructures. 1A and 1B are perspective views.

In various embodiments, 0.01 to 0.5, 1.0, 1.5, 2.5, 3.0, 4.0, 1,
A nominal Si thickness of up to 0, 20, or 25 μm (or greater) can be deposited on a 3 μm long CNF to form a CNF array 100 as shown in FIGS. 1A and 1B. Similarly, in various embodiments, 0.01 to 0.5, 1.0, 1.5, 2.5,
A nominal Si thickness of up to 3.0, 4.0, 10, 20, or 25 μm (or greater) can be deposited on a 10 μm long CNF to form the CNF array 100.
In some embodiments, the nominal thickness of Si is between 0.01 μm and the average distance between CNFs 110.

Using the CNF array 100, lithium ion storage can be performed at a rate of C / 2 at 4,000.
It is possible to obtain a mass-specific capacity (specific discharge amount) that reaches up to 0 mAh / g. This capacity is significantly higher than that obtained with Si nanowires alone or other Si nanostructured carbon hybrids at the same power rate. This improved performance is due to the fully activated Si shell, which is due to the effective charge collection by CNF 110 and the short Li ⁺ path length in this hybrid architecture. Good cycle stability has been demonstrated over 110 cycles. In various embodiments, the storage capacity of lithium ion storage in CNF array 100 is -750, 1500, 2000, 2500, per gram of Si.
3000, 3500 or 4000 mAh or any range between these values. As used herein, the term "nominal thickness" (e.g., Si
) Is the amount of Si that produces a flat layer of the access Si on the substrate 105. For example, a nominal Si thickness of 1.0 μm, if deposited directly on the substrate 105, would have a Si thickness of 1.0 μm.
This is the amount of Si to be a μm layer. The nominal thickness is reported because the nominal thickness can be easily measured by weight using methods known in the art. The nominal thickness of 1.0 μm results in a thinner Si layer 115 on the CNF 110 because Si is distributed over a larger area of the surface of the CNF 110.

2A-2C illustrate a CNF array 100 having an average fiber length of ３3 μm, according to various embodiments of the present invention. 2A-2C are layered electron microscope (SEM) images. FIG. 2A shows a plurality of CNFs 110 without a silicon layer 115 and aligned vertically. FIG. 2B
Shows a plurality of CNFs 110 having a silicon layer 115 and aligned vertically. FIG. 2C shows a plurality of vertically aligned CNFs 110 in a detached (discharged) state after undergoing 100 charge and discharge cycles. The CNFs 110 are aligned substantially uniformly in the vertical direction with respect to the Cu substrate 105, and are randomly distributed and firmly mounted on the substrate surface. The sample used in this study had a 1.11 × 10 ⁹ CNF corresponding to an average nearest neighbor distance of ３３０330 nm.
It has an average areal density of s / cm ² (counted from the SEM top image). C in FIG.
The average length of NF110 is 〜3.0 μm with more than 90% (> 90%) of CNF in the 2.5-3.5 μm length range. Diameters range from ８０80 nm to 240 nm, with an average of １４147 nm. The inverted teardrop-shaped Ni catalyst at the tip 120
110, which closes the lid of the hollow channel at the center of the CNF,
Promotes CNF110 growth during the CVD process. The size of the Ni catalyst nanoparticles is
The diameter of F110 was specified. CNF110 longer than 10 μm were also used in some of the studies described below.

In some embodiments, the average nearest neighbor distance is between 200-450 nm, 275-
It can vary between 385 nm, between 300 and 360 nm, and so on. Further, the average length of the CNF 110 is between ２〜2-20, between 20-40, between 40-60, between 60-80, 80-1
Between 00, 100-120, 120-250 (μm) or more. Standard carbon nanofibers with lengths as long as millimeters are conventionally known. In various embodiments, the average diameter is between ５０50-125, between 100-200,
It can vary between 125 and 175 (nm) or in other ranges.

The amorphous Si layer 115 was deposited on the CNF array 100 by magnetron sputtering. The open configuration of the brush-like CNF array 100 allows Si to settle deep into the array and create a conformal structure between the CNFs 110. This results in an interesting tapered core shell resembling a cotton swab if a thick Si coating at the CNF tip is formed followed by a gradually thinning coaxial Si shell around the lower portion of the CNF. During the sputtering, the amount of Si deposited was determined by a quartz crystal microbalance method (QCM: qu
It is characterized by the nominal thickness of the Si film on a flat surface using artz crystal microbalance. The Li ⁺ insertion / desorption capacity was normalized to the total Si mass derived from the nominal thickness.
At a nominal thickness of 0.50 μm, the Si-coated CNF 110 is well separated from each other and the open core shell C
An NF array structure (shown in FIG. 2B) was formed. According to this structure, the electrolyte is free of Si
The entire surface of the layer 115 could be reached. In the illustrated embodiment, the average tip diameter is
In comparison with the average diameter of CNF110 before applying No. 15, which is 〜147 nm,
nm. The average radial Si thickness at tip 120 was estimated to be 〜155 nm. This value is clearly less than 0,0 because most Si extends along the entire length of the CNF.
Much smaller than the nominal Si thickness of 50 μm. In an alternative embodiment, 10-1000;
Other radial Si thicknesses in the range of 20-500, 50-250, 100-200 (nm), or other ranges are also seen. As described in detail elsewhere herein, CNF11
A zero cone results in a microstructure added to the Si layer 115. The laminated cone structure is optionally a result of a spiral growth pattern, and is a laminated cone structure when viewed in cross section.

The transmission electron microscope (TEM) images in FIGS. 3A-3C further show Si-coated CNF11.
0 shows structural details. An Si layer 115 having a thickness of ３390 nm is formed on a C layer having a diameter of ２１０210 nm.
Fabricated directly on tip 120 in NF110. The largest part of the swab-shaped Si layer 115 had a diameter of about 430 nm that appeared near the end of the tip 120. Coaxial S around CNF110
The i-layer 115 exhibits a feather-like texture having a modulation contrast, and is clearly different from the uniform Si deposition portion above the tip (see FIG. 3A). This condition is likely to be the result of the laminated cone microstructure of PECVD grown CNF110. From the literature, it is known that such a CNF 110 includes a cup-shaped graphite structure that is non-uniformly laminated along the central axis of the CNF 110. The use of such variations in the diameter of CNF 110 is disclosed in commonly owned US patent application Ser. No. 12/904, filed Oct. 13, 2010.
, 113.

The laminated cone structure along the length of each CNF is comprised of 1-5, 5-15, more than 10 cup-shaped graphite layers, as indicated by the dashed lines in FIG. 3B. At these exposed edges, lithium can penetrate between the graphite layers. On a molecular scale, the cup-like structure has cones of graphene and / or graphite sheets with which lithium can interact. The cup edge is a nanoscale edge and can have the properties of a graphene edge, with properties like those between graphene sheets between graphite layers. The cup edge provides a seam in the vertically aligned carbon nanofiber through which lithium ions can move. The novel microstructure of VACNF is CN
This results in a stack of exposed graphite edges, e.g., cup edges, along the length of the F sidewall. These nanoscale edges are similar to those commonly found in graphene / graphite sheets and ribbons. These exposed cup edges are the result of varying silicon nucleation rates and therefore
Produces a texture of a modulated silicone shell. These exposed edges are further integrated with VACNF core and Si
It forms a good interface with the shell, facilitating rapid electron transfer in this hybrid structure. Two different structures in the Si shell can be controlled by varying the growth process of VACNF. The region of VACNF with the cup structure becomes a feather-like Si shell, and the region of VACNF without the cup structure has a Si structure similar to that seen at the tip of VACNF. The VACNF is optionally configured to have one or more regions along the length of the VACNF as well as at the tip that do not have a cup laminate structure. In an alternative embodiment, a cup laminate structure with graphite / graphene or graphite edges exposed on carbon nanofibers is provided, but not vertically aligned and / or even attached directly to the substrate. Although the use of "cup-laminated" graphite microstructures is described in detail elsewhere herein, another method for making exposed nanoscale edges of graphite sheets is to use an acid to dissociate carbon nanotubes ( There is something to unzip. The exposed nanoscale edge thus produced is also expected to have the advantage of controlling and / or fixing the Si shell, and may be provided in some embodiments. For example, the edges of graphite nanoscale ribbons can be used to influence the growth of Si shells around these ribbons.

The term "nanofiber" as used herein is meant to have a structure having at least two dimensions on the nanoscale (less than 1 micrometer). These nanofibers include, for example, wires, tubes and ribbons, and are nanoscale in thickness and width,
The length may or may not be nanoscale. The term "nanofiber" is meant to exclude graphene sheets that are nanoscale in thickness, but both length and width are also nanoscale. In various embodiments, the support filaments described herein are nanofibers.

The resolution and contrast of FIGS. 3B and 3C are limited because the electron beam must penetrate several hundred nanometers thick CNF or Si-CNF hybrid, but the structural properties are High resolution TEM observations using smaller CNFs are consistent. This unique structure produced a group of broken graphite edge clusters along the CNF sidewalls, thereby altering the nucleation rate during Si deposition,
Therefore, the density of the Si layer 115 on the side wall of the CNF 110 was modulated. The modulation density results in a super-large surface area Si structure as shown by box 310 (100 nm square) in FIG. 3A. The feathered Si structure of the Si layer 115 provides an excellent lithium ion interface, resulting in extremely high Li capacity and CNF.
Resulting in rapid electron transfer to In FIG. 3A, the dark area at tip 120 is CNF
Nickel catalyst for growth. Other catalysts can be used.

3B and 3C are images recorded before (FIG. 3B) and after (FIG. 3C) the lithium intercalation / desorption cycle. The sample in FIG. 3C is in a lithium desorbed (discharged) state, as taken from the electrochemical cell. The dashed line in FIG.
This is for visually providing guidance for the laminated cone graphite layer in the CNF 110. The long dashed line in FIG. 3C represents the sidewall surface of CNF 110.

As described elsewhere herein, the laminated cone structure of CNF 110 is significantly different from commonly used carbon nanotubes (CNTs) or graphite. The laminated cone structure provides improved Li ⁺ insertion without the addition of a Si layer 115 when compared to standard carbon nanotubes or nanowires. For example, the laminated cone graphite structure of CNF 110 allows for Li ⁺ intercalation through the sidewalls of CNF 110 (not just at the edges) into the graphite layer. The Li ⁺ migration path through the wall of each CNF 110 is very short (D is ２290 nm in some embodiments) and long from the open end in commonly used seamless carbon nanotubes (CNTs) It is completely different from a route. FIG. 4 schematically shows a laminated cone structure of CNF. In this particular embodiment, the average values of the parameters are as follows: CNF radius r _CNF = 74 nm, CNF wall thickness t
_w = up to 50 nm, the graphite cone angle theta = 10 °, and graphite cone length _D = t w / _sinθ =
290 nm.

5A-5C show the electrochemical properties of CNF 110 having a length of ３3 μm. This characteristic shows the phenomenon described with reference to FIG. FIG. 5A shows a cyclic voltammogram (CV) of a potential from 1.5 V to 0.001 V for a Li / Li ⁺ reference electrode at scan rates of 0.1, 0.5, and 1.0 mV / s. Lithium disks were used as counter electrodes. Data was obtained from the second cycle and normalized to the exposed geometric surface area. FIG. 5B shows the constant current charge / discharge profiles (change curves) at power rates of C / 0.5, C1, and C / 2, with current densities of 647 and 323 and 162 mA / g (normalized to estimated carbon mass, respectively). Values), or 71.0, 35.5 and 17.8 μA / cm ² (values normalized to geometric surface area). FIG. 5C shows intercalation capacity and desorption capacity (left vertical axis) and Coulomb efficiency (right vertical axis) with respect to the number of cycles at a C / 1 charge / discharge rate. (C / 1 discharge rate = 1 hour, C / 2 discharge rate = 120 minutes, 2C = C /
0.5 = 30 minutes, etc. )

Generally, the open circuit potential (OCP) of the uncoated CNF110 anode
The newly assembled half-cell (half-cell) shows ~ 2.5 with respect to the Li / Li ⁺ reference electrode.
It was from 0V to 3.00V. A CV measured between 0.001 V and 1.5 V indicates that Li ⁺ intercalation begins when the electrode potential is less than 1.20 V. The first cycle from OCP to 0.001 V is a necessary protective layer due to the deposition of solvents, salts and impurities, i.e. solid electrolyte interphase (SEI)
And thus resulted in large cathodic currents. Subsequent CVs showed a smaller but more stable current. The cathode current associated with Li ⁺ intercalation rose slowly as the electrode potential was swept negative until a sharp cathode peak appeared at 0.18V. When reversing the electrode potential to the positive side after reaching the lower limit of 0.001 V, lithium desorption was observed over the entire range up to 1.50 V, indicating a continuous anode current and a broad peak at 1.06 V. .

The CV characteristics of the CNF array 100 are based on gradual intercalation into graphite and CNT.
Is somewhat different from the slow Li ⁺ diffusion characteristics into the hollow channel of Lithium ion insertion into the CNF 110 can occur by intercalation from the sidewalls to the graphite layers due to its unique structure. TEM image of FIG. 3C, the graphite stack in CNF110 inner lamination cone, possibly due to the large volume changes occurring with Li ⁺ intercalation, Li ⁺ intercalation - state is somewhat split into desorption cycle Is shown.
Some residues and nanoparticles are observed as white objects inside and outside of CNF110. These show penetration from the sidewall into the interior of the CNF.

The constant current charge / discharge profile in FIG. 5B indicates that the power rate is from C / 2 to C / 0.5 (
When increasing to C / 0.5 (also referred to as “2C”), it indicates that the Li ⁺ storage capacity decreases. To facilitate comparisons between power rates (especially power rates higher than C / 1), we have chosen a fraction of C / 0.5 over the most commonly used "2C" in the literature. Notation is used herein. The Li ⁺ intercalation and desorption volumes were normalized to the estimated mass of CNF110 (1.1 × 10 ⁴ g / cm ² ), which estimated mass was the following average parameter: length (3.0 μm) , Density (1.1 × 10 ⁹ CNF / cm ² ), outer diameter (1
47 nm), and a hollow vertical alignment C with a hollow inner diameter (49 nm, 〜 outer diameter)
Calculated based on NF structure. The density of the solid graphite wall of CNF110 is the same as that of graphite (2.2
g / cm ³ ). For normal C / 2, the intercalation capacity is 430
mAhg ⁻¹ , the desorption capacity is 390 mAhg ⁻¹ , and both are 372 mAh in graphite.
Although slightly higher than the theoretical hg ^-1 value, this indicates that SEI formation and CNF1
It is likely due to reversible Li ⁺ insertion into the hollow compartment inside 10. The desorption capacity was found to be higher than 90% of the intercalation value at all power rates, and both the intercalation and desorption capacities were from power rates C / 2 to C /
A decrease of ９9% when increasing to 1 and a 〜20% decrease when increasing from C / 1 to C / 0.5.

During charge and discharge cycle operation, intercalation capacity, with decreases slightly from 410MAhg ^-1 after 20 cycles at C / 1 to 370MAhg ^-1, desorption capacity, between 375MAhg ^-1 and 355MAhg ^-1 It was found that the value was maintained. The overall Coulomb efficiency (ie, the ratio of desorption capacity to intercalation capacity) is
Except for the first two cycles, it was ９４94% due to SEI formation on the CNF110 surface. It is known that SEI films allow lithium ion diffusion, but are easily formed on carbonaceous anodes during the initial cycle, which results in electrical isolation and increased series resistance. The TEM image (see FIG. 3C) and the SEM image (see FIG. 6A) show that a non-uniform thin film was deposited on the CNF 110 surface during the charge / discharge cycle. In some embodiments, the SEI is C
Acts as a sheath that increases the mechanical strength of NF110 and prevents CNF from collapsing into fine bundles due to the cohesive capillary forces of the solvent observed in studies with other polymer coatings.

6A-6C illustrate CNF 110 having a length of 3 μm, according to various embodiments of the present invention.
3 shows a scanning electron microscope image of the sample. FIG. 6A shows delithiated (discharged) CNF110 after an intercalation / desorption cycle. FIG. 6B shows CNF 110 including Si layer 115 in a delithiated state after 100 cycles. FIG. 6C shows the CNF 110 including the Si layer 115 in the lithiated state after 100 cycles. These images are perspective views as viewed from an angle of 45 °.

7A-7C show CNF 11 with Si layer 115 as lithium ion battery anode.
The results obtained using 0 are shown. These results were observed using a nominal Si thickness of 0.50 μm. FIG. 7A shows the scan rates at 0.10, 0.50 and 1.0 mVs ⁻¹ .
Figure 4 shows a cyclic voltammogram between 1.5 V and 0.05 V for Li / Li ⁺ . Measurements were taken after the sample underwent 150 charge / discharge cycles and represent data for the second cycle at each scan rate. FIG. 7B shows a constant current charge / discharge profile at a power rate of C / 0.5, C / 1 and C / 2 over 120 cycles of the sample. All profiles were taken from the second cycle at each rate. FIG. 7C shows the insertion capacity and desorption capacity (the left vertical axis) versus the number of charge / discharge cycles, and two CNF arrays 10.
The Coulomb efficiency (right vertical axis) of 0 (used as an electrode) is shown. The first CNF array 100 was first conditioned with one cycle at the C / 10 rate, one cycle at the C / 5 rate, and two cycles at the C / 2 rate. Thereafter, the remaining 96 cycles were tested at the C / 2 insertion rate and C / 5 desorption rate. Filled squares and blank squares indicate insertion capacity and desorption capacity, respectively. The second electrode was first conditioned in two cycles at C / 10, C / 5, C / 2, C / 1, C / 0.5 and C / 0.2 rates, respectively. This was followed by a test at the C / 1 rate for the next 88 cycles. The Coulomb efficiencies of both electrodes are indicated by filled diamonds (first electrode) and blank diamonds (second electrode), with 99% of the majority overlapping.

The CV in FIG. 7A shows features very similar to Si nanowires. Compared to the uncoated CNF array 110, both the Li ⁺ insertion cathode waveform and the Li ⁺ desorption anode waveform shift to lower values (below ~ 0.5V and 0.7V, respectively). The peak current density increases 10 to 30 times after application of the Si layer 115, and is directly proportional to the scan rate. Clearly, alloying Li ⁺ insertion into Si is much faster than intercalation into uncoated CNF limited by slow diffusion of Li ⁺ between graphite layers.
A cathode peak at に お け る 0.28 V was not observed in studies on pure Si nanowires. The three anode peaks representing the conversion of the Li-Si alloy to amorphous Si are 10
Similar to in Si nanowires despite a shift to a potential lower by 0-200 mV.

The constant current charge / discharge profile of the CNF array including the Si layer 115 shown in FIG. 7B has two salient features: (1) a high Li ⁺ insertion (charge) of 3000 mAh (g _si ) ⁻¹
And desorption (discharge) capacity is obtained even after 120 cycles at a C / 2 rate, and (2) its L
The feature is that the i ⁺ capacity is approximately the same at power rates of C / 2, C / 1 and C / 0.5. In other words, the capacity of the CNF array 100 operating as an electrode has a rate of C / 2.
Does not decrease when increasing from to C / 1 and C / 0.5. For these charging rates, in the above embodiment, the capacity was almost independent of the charging rate. C including Si layer 115
The total Li ⁺ storage capacity of the NF array 100 is １1 of the CNF array 100 without the Si layer 115.
It was 0 times. This occurs even when the lower potential limit for the discharge cycle increases from 0.001V to 0.050V. As a result, it can be seen that the amount of Li ⁺ intercalation to the CNF core was extremely small. The specific capacity (specific spring rate) is the nominal thickness measured and 2.
Calculated by dividing only the mass of Si calculated from the bulk (bulk) density of 33 gcm- ³ . In this method, the specific capacity of the Si layer 115 was selected as an appropriate metric to compare with the theoretical value of bulk Si. For a 3.0 μm long CNF 110 with a 0.456 μm Si layer 115 deposited, the mass density of the Si layer 115 is the mass density of the CNF 110 (〜1.1).
× 10 ⁻⁴ gcm ⁻² ), which was １1.06 × 10 ⁻⁴ gcm ⁻² . FIG. 7B
The corresponding Coulomb efficiency in is higher than 99% at all three power rates,
It is significantly higher than the Coulombic efficiency of CNF 110 without layer 115.

FIG. 8 illustrates how the capacity of the CNF array 100 changes with the charge rate according to various embodiments of the present invention. Data is shown for several cycles. FIG. 8 shows the average specific discharge capacity over several cycles at the same current rate versus the charge rate (C rate) required to obtain a full capacity (C / h, eg, full capacity / hour) at a set time. CNF array 10
0 is first C / 8, C / 4, C / 2, C / 1, C / 0.8, C / 0.4, and C / 0.16.
Adjusted symmetrically in two cycles at each of the rates, and then tested at a symmetric rate of C / 1 for the next 88 cycles. This was repeated from 101 cycles to 200 cycles. At the beginning of cycle 201, the electrodes are C / 4, C / 3, C / 2, C / 1
, C / 0.75, C / 0.66, C / 0.50, C / 0.33, C / 0.25, C / 0.20,
And symmetrically adjusted in 5 cycles at each C / 0.15 rate, after which the next 4
The test was performed at a symmetric rate of C / 1 for 5 cycles. This was repeated from 301 cycles to 400 cycles and from 401 cycles to 500 cycles. The change in capacity is slight (<16%) while changing the C-rate by a factor of 32. The electrode after 100 cycles showed increased capacity when changing the C rate from 3C to 8C. Thus, a faster charge rate was obtained with improved capacity. High capacity (> 2,700 mAh / g) was obtained at high and low rates (C / 4 and 8C). Capacity at rates higher than 3C increases as the C rate increases. It is known that a decrease in specific capacity according to the number of cycles is a factor that can be corrected.

Both CV and charge-discharge measurements have shown that the insertion of Li ⁺ into the Si layer 115 is rapid and highly reversible, a requirement for high performance lithium ion battery anodes. Is what is done. This further implies that different test conditions, namely (1) a slow asymmetric test at C / 2 rate for insertion and C / 5 rate for desorption, and (2)
) Demonstrated in two long cycle tests on two identical samples in a rapid symmetric test at C / 1 for both insertion and removal (see FIG. 7C). Both data sets showed Coulomb efficiencies higher than 98% (> 98%) over long cycle runs except during the initial conditioning cycle (4 cycles before and 12 cycles after changing low rates). In slow asymmetric tests, insertion volume was decreased only 8.3% in 3341MAhg ^-1 at 100 th cycle from 3643MAhg ^-1 of the fifth cycle. C / 1 charge - even discharge rate are also intercalation capacity was reduced only 11% in 2752MAhg ^-1 at 100 th cycle from 3096MAhg ^-1 at 13 th cycle. The difference in Li ⁺ capacity between these two data sets was mainly due to initial tuning parameters and small inter-sample variability. This is the first 2 in FIG. 7C at C / 10 and C / 5 rates.
, Indicated by similar values of insertion-desorption capacity during the three conditioning cycles. Faster rates (C / 0.5 for ninth and tenth cycles and C / 0.2 for eleventh and twelfth cycles in sample # 2) are detrimental to capacity and cause irreversible degradation I understood that. However, the electrodes remained stable after longer cycle runs. As shown in FIG. 7B, the charge-discharge profiles are C / 2, C / 1 and C / 0.
It was almost the same at a rate of 0.5 and was measured on sample # 1 after 120 cycles. This exceeds a four-fold charge rate variation.

The specific capacity of the Si layer 115 in the range of 3000 to 3650 mAhg ^-1 matches the highest value of the amorphous Si anode described in the literature. It is worth noting that the CNF array 11
The Si shell at 0 is active for Li ⁺ insertion, almost 90% over 120 cycles
This was not obtained except for the ultra-thin flat Si film as far as we could know. Specific capacities disclosed herein range from は 2500 mAhg ⁻¹ at C / 2 rates at similar power rates, に お け る at C / 1 rates of Si nanowires (NW).
2200 mAhg ^-1 and randomly oriented carbon nanofiber-Si core-shell NW
Significantly higher than those reported using other nanostructured Si materials, including ８００800 mAhg ⁻¹ at C / 1. Clearly, the coaxial core-shell NW structure in the well-separated CNF 110 as included in various embodiments of the present invention provides improved charge-discharge rates, full Li ⁺ storage capacity of Si, And a long cycle life.

As shown in FIG. 7C, an unusually high insertion capacity (〜4500 mAhg ⁻¹ ) was always observed in the initial cycle, which was 20-30% higher than in subsequent cycles. In contrast, the desorption values were relatively stable throughout the cycle. Excess insertion capacity can be attributed to three irreversible reactions: (1) thin SEI (surface electrolyte phase: surface electr).
olyte interphase) layer (several tens of nanometers), (2) SiO _x existing on Si surface
Of Li (SiO _x + _{2 ×} Li → Si + xLi ₂ O) to (3) the lower capacity of the starting crystalline Si coating with a higher theoretical capacity (〜4200 mAhg ⁻¹ ) (<380)
0 mAhg ^-1 ). The TEM image (FIG. 3C) and the SEM image (FIG. 6B) show that the uneven SEI
It was shown that it could be deposited on the surface of the i-layer. When the CNF array 110 undergoes significant body expansion and contraction that occurs during a charge-discharge cycle, the elastic SEI
0 can help fix to the surface. The striking differences between the SEM images in FIGS. 6B and 6C indicate a large expansion of the Si layer 115 in the lithiated (charged) versus non-lithiated state. (However, some swelling may be due to oxidation of Li by air when the electrochemical cell is armed for imaging.) SEI generation during the initial charge-discharge cycle makes this difference FIG. 3A. Note that it is found in the Si layer 115 between FIG.
In FIG. 3B, Si interacts with the electrolyte to fill the gap between the feathered structures.
Produces EI. This interaction can include mixing, chemical reaction, charge binding, encapsulation, and the like. The Si layer 115 therefore looks more uniform in FIG. 3B. However, the Si layer 115
Have in this case an inter-layer of Si (feathered structure) and SEI. Each of these alternating layers can be on the order of 20-30 nanometers. The SEI layer is an ion permeable material, which is the product of the interaction between the electrolyte and the Si layer 115 (or other electrode material).

The crystalline and amorphous structure of the Si shell was revealed by Raman spectroscopy. As shown in FIG. 9, the initial CNF array 100 including the Si layer 115 has a thickness of 350 to
Multiple width broadband overlapping in the range of 550 cm ^-1, and showed sharper band of 480 cm ^-1 corresponding to the nanocrystalline Si. After the charge-discharge test, the sharp peak disappeared while the broadband merged with the single peak at 470 cm ^-1 . Bare CNF 110 does not show any features in this range. The crystalline Si peak is only ４０40 cm ⁻¹ from that measured on a single crystal Si (100) wafer and 〜20-30 cm from other microcrystalline Si materials.
Downshifted by ^-1 . This shift is probably due to much smaller crystal size and larger irregularities. The original Si layer 115 is the feathered TEM in FIG. 3A.
It appears to be composed of nanocrystals embedded in an amorphous matrix associated with the image. After the initial cycle, the Si nanocrystals were examined by TEM images after cycle operation inspection (FIGS. 3B and 3C).
) Was converted to amorphous Si. However, the Si layer 115 apparently did not slide along the length of the CNF, in contrast to the large longitudinal expansion (up to 100%) in pure SiNW. This indicates that in some embodiments, the expansion of silicon is primarily radial, rather than longitudinal, with respect to the carbon nanofiber.
In some embodiments, expansion occurs between the Si feathered structures. For example, inflation in one blade occurs in the direction of the upper and lower most adjacent blades, bridging the gap between the blades. In each case, the swelling stratifies to reduce the delamination of silicon dramatically. The Si layer 115 was thus securely fixed to the CNF 110 for 120 cycles. The volume change of the Si shell during Li ⁺ insertion was dominated by radial expansion and the CNF-Si interface remained intact.

In various embodiments of the present invention, CNFs 11 having different lengths and silicon shell thicknesses
Has zero. One factor that can be controlled when creating CNF 110 is that each CNF 11
This is the open space between zeros, that is, the average distance between CNFs in the CNF array 100. This open space allows the Si layer 115 to expand radially when charged, thus providing stability in some embodiments. The optimal electrode structure is the length of CNF110 and SiF
Because it depends on both the thickness of layer 115, it may be desirable to use a longer CNF 110 and a thicker Si layer 115 in order to obtain a higher total Li ⁺ storage capacity. A longer CNF 110 correlates to a larger storage capacity. FIG.
A-10C were filled 15 times using three samples of long 10 μm long CNF 110 with Si layers 115 deposited at nominal thicknesses of 0.50, 1.5 and 4.0 μm, respectively.
3 shows variations in Li ⁺ insertion-desorption capacity and Coulomb efficiency over discharge cycles.
After adjusting at the C / 10 rate for the first cycle and at the C / 5 rate for the second cycle, in subsequent cycles, the asymmetric rate (insertion) is similar to that of sample # 1 in FIG. 7C. C / 2 for elimination and C / 5) for elimination. With this procedure,
Nearly 100% Coulomb efficiency and minimal degradation over the entire cycle were obtained. Nominal thickness was measured in situ with a quartz crystal microbalance during sputtering.

High specific capacities, such as 3597 mAhg ^-1 and 3416 mAhg ^-1 , have a length of 3.0 μm.
having a 0.5 μm thick Si layer 115 on a CNF 110 having a thickness of m (see FIG. 7C)
Very similar to the above, Si layers 115 having thicknesses of 0.5 μm and 1.5 μm were obtained. This capacity was kept almost constant over 15 cycles. However, the nominal Si thickness is 4.0μ.
The m electrode exhibited a significantly lower specific capacity of only 2221 mAhg ^-1 . This indicates that due to expansion, the Si layers 115 begin to contact each other from adjacent CNFs 110, limiting further expansion of the Si layers and limiting Li diffusion between CNFs. As a result, only a portion of the silicon coating exhibited activity for lithium insertion. Therefore, the cycle stability was worse than the sample with the thinner Si layer 115.

The same amount of Si (nominal thickness 500 nm) on a CNF array 100 with a 10 μm long CNF 110 has a 3 μm long CNF 1 even though the carbon mass is three times greater.
10 (3643mAhg ^-1 / see Fig. 7C) and substantially the same amount of Li ⁺ storage capacity (3597M
Ahg ^-1 / see FIG. 6A). This is a very strong proof that the involvement of CNF110 is negligible in calculating Li ⁺ storage. Little Li ⁺ ions were intercalated into CNF 110 in the Si-coated samples, which would contribute to structural stability during multiple charge-discharge cycles.

The variation in Li ⁺ storage specific capacity in the three samples correlated deeply with their structure as revealed by the SEM images shown in FIGS. 11A-11C show scanning electron microscope images of a freshly prepared CNF array 100 (based on a CNF 110 of 10 μm length). The Si layer 115 was measured in-situ using a quartz crystal microbalance during deposition (1)
Produced using nominal Si thicknesses of 0.5 μm, (2) 1.5 μm, and (3) 4.0 μm. All images are perspective views from a 45 ° angle. At a nominal Si thickness of 0.5 μm, the average tip diameter is ３８388 nm for a 10 μm long CNF and a 3.0 μm long CNF1
It was found to be significantly smaller than the average diameter of ４５457 nm at 10. Si
Layer 115 spread more evenly along the thinner but 10 μm long CNF 110.

Note that growing a 10 μm long CNF 110 took approximately six times 120 minutes to grow a 3 μm long CNF 110. Some nickel catalysts,
Etch slowly with NH ₃ during the long PECVD process, which results in Ni
A continuous reduction in the size of the nanoparticles results and a tapered tip 120 (shown in FIG. 12)
Became. CNF110 length variation further increased with longer CNF110. Together, these factors reduced the shadow effect of the tip 120. As a result, even with a nominal Si thickness of 1.5 μm, the CNFs 110 covered by the Si layer 115 are well separated from each other. 10 μm
An SEM image of 1.5 μm Si in the CNV array 110 (FIG. 11B) shows a 3.0 μm CN
Very similar to the SEM image of 0.50 μm Si in V array 110 (FIG. 2B). However, as the nominal Si thickness increased to 4.0 μm, the Si layers 115 clearly merged together, filling most of the space between the CNFs 110 (see FIG. 11C). This reduces the free space required to allow body expansion of Si layer 115. As a result, the Li ⁺ storage specific capacity was significantly reduced.

11A and 11B each include approximately the same number of CNFs 110, but have tips 120 that appear much less in FIG. 11B. This is because the Si layer 115 can form a nanofiber / silicon complex that includes a single CNF 110 (cross-section shown in FIG. 1A). Or Si
Layer 115 can form a nanofiber / silicon complex that includes two, three or more CNFs 110 under a single cover of silicon. This occurs when two or more CNFs 110 coalesce during the Si layer 115 deposition process. Nanofiber / silicon complex is 1
The structure includes a continuous Si layer 115 covering one or more CNFs 110. Two CNFs
A cross section of the nanofiber / silicon complex containing 110 is shown in FIG. 11D. In various embodiments, at least 1%, 5% or 10% of the nanofiber / silicon complex comprises more than one CNF110.

In various embodiments, CNF arrays 100 having nominal Si thicknesses of 0.50 and 1.5 μm have comparable mass-specific capacities of 3208 ± 343 and 3212 ± 234 mAhg ⁻¹ , respectively. A sample with a nominal Si thickness of 4.0 μm has a significantly lower capacity 2
072 ± 298 mAhg ⁻¹ . Thinner Si coatings show sufficient activity and amorphous S
The maximum Li insertion capacity provided by i is obtained. On the other hand, the area-specific capacity increases in proportion to the Si thickness, from 0.373 ± 0.040 mAhcm ^{−2 at} 0.50 μm Si to 1.5 μm Si.
At 1.12 ± 0.08 mAhcm ⁻² at a nominal Si thickness of 4.0 μm, but falls from the linear curve to 1.93 ± 0.28 mAhcm ⁻² . At a nominal silicon thickness of 4.0 micrometers, only a portion of the excess silicon in the thick Si coating effectively participates in Li storage. A thickness of 4.0 μm is greater than the average distance between CNFs 110. This electrochemical result shows that the space between the CNFs 110 is almost completely filled,
It is consistent with the structure shown in the EM image.

In various embodiments of the present invention, the structure of the CNF array 100 has a length of ３０30-40,
It has a Si layer with a radial thickness of に 対 す る 200-300 nm for a CNF 110 having a diameter on the order of ５０50 nm, or a length on the order of 〜50 nm (or more or a combination thereof). In some embodiments, the CNF arrays 100 are grown on conductive foils having a thickness in the range of -10 microns (up to 10 microns), -10-20 microns, -10-50 microns, or more. Let it. In various embodiments, Si (equivalent to a nominal thickness of 1.5 μm on a flat surface) is coated with a 10 μm long CN.
Deposited on F110 to form CNF array 100. This is achieved while maintaining the open vertical core-shell nanowire structures with the individual CNFs 110 well separated from each other, thereby allowing lithium ions to penetrate between the CNFs 110 of the CNF array 100. This unique hybrid architecture allows the Si layer 115 to freely expand / contract radially during Li ⁺ insertion and desorption. High performance Li storage with a mass-specific capacity of 3000-3650 mAhg ^-1 was also obtained at C / 1 rate. This capacitance is equivalent to the Si layer 11
5 is comparable to the maximum expected for the same mass of amorphous Si showing sufficient activity. This 3D nanostructure architecture allows for bulk and efficient electrical connection of the Si material while maintaining a short Li ⁺ insertion-desorption path. As a result, high capacities near the theoretical limit are possible over 120 charge-discharge cycles. Rate goes from C / 10 to C / 0.5 (or 2C) 2
Even if it is increased by a factor of 0, there is almost no change in capacitance. High capacity and extraordinary cycling stability at greatly improved charging and power rates make this new structure a choice anode material for high performance lithium ion batteries. Same core - shell concept, the Si shell _TiO 2, LiC
It can be applied to a cathode material by exchanging with oO ₂ , LiNiO ₂ , LiMn ₂ O ₄ , LiFePO ₄ , Li ₂ O, Li ₂ O _{2 and the} like.

FIG. 13 illustrates a method of producing the CNF array 100 and / or CNF 110 described herein. In a substrate preparing step 1310, the substrate 105 is prepared. Substrate 105 is optionally suitable for growing CNF 110. The substrate 105 can include various materials, for example, Cu. Substrate 105 is optionally a conductive foil having a thickness as described elsewhere herein. In an optional nucleation site preparation step 1320, CN
A nucleation site for F110 growth is prepared on the substrate 105. Various nucleation materials, such as Ni particles, are known in the art. The nucleation sites are optionally provided at a density that produces an average distance between the CNFs 110 as taught elsewhere herein. The nucleation site preparation step 1320 is an embodiment in which nucleation is not required to grow the CNF 110 or similar structure, or performing the attachment of the CNF 110 to the substrate 105 using a binder somewhere after growth. The form is optional.

In a CNF growth step 1330, CNF 110 is grown on substrate 105 or, in some embodiments, separated from substrate 105. CNF 110 is optionally grown to create a laminated cone structure taught elsewhere herein, or to create a structure with exposed graphite edges along its length, or to create a similar variable structure. I do. CNF 110 can be grown to any of the lengths taught elsewhere herein. Growth is optionally described in “A high-performance li” in Klankowski et al. J. Mater. Chem, 2013, 1, 1055.
thium-ion battery anode based on the core-shell heterostructureof silicon-coated
Performed using the PECVD process taught or cited in "Vertically aligned carbon nanofibers."

In a Si layer application step 1340, an intercalation material such as a Si layer 115 is applied on the grown CNF 110. In some embodiments, the Si layer application step 1340 is performed after attaching the CNF 110 to the substrate 105. The material to be applied should have a nominal thickness of tens or hundreds of nanometers of S in any of the nominal thickness taught elsewhere herein.
This produces an i-layer 115 thickness. In some embodiments, the Si layer applying step 1340 comprises:
Growing the intercalation material into a structure that follows the exposed edges along the length of the CNF 110. For example, when the CNF 110 has a cup-like structure as described herein, the Si layer applying step 1340 includes growing a wing-like structure, for example, as shown in FIG. 3A.

In an optional PEM application step 1345, a power enhancer (PEM)
ement material) is added to the CNF array 100 or the CNF 110. In some embodiments, the PEM application step 1345 is performed after attaching the CNF 110 to the substrate 105. The PEM generally includes a binder and a surface effect dominant site, as described elsewhere herein. In an optional conditioning step 1350, the CNF array 100 created using steps 1310-1340 is conditioned using one or more lithium intercalation cycles.

FIG. 14A illustrates a CNF 110 including a power enhancing material 1320 according to various embodiments of the invention.
Is shown. The power enhancing material 1320 may be provided on the intercalation material, for example, the silicon layer 11.
5 as a layer on top. FIG. 14B shows details of the power enhancing material 1320 shown in FIG. 14A, according to various embodiments of the present invention. The power enhancing material 1320 may be
And an optional binder 1440. However, the silicon layer 115 is one example of an intercalation material. It is to be understood that other types of intercalation materials can be substituted for or combined with silicon, even though silicon layer 115 is used as an example described herein. Such alternative or additional intercalation materials include Ag, Al, Bi, C, Se, Sb, Sn and Zn. CNF11 shown in FIG.
0 is a representative one of many CNFs 110 in the CNF array 100.

In some embodiments, surface effect dominant sites 1430 have a nanoparticle surface configured to adsorb charge carriers in a Faraday reaction, for example, to undergo a redox reaction with the charge carriers. The sites are referred to as "surface effect dominant", which means that typically for these nanoparticles, the Faraday reaction between the charge carrier and the nanoparticle surface favors the bulk Faraday reaction. Because they rule. Thus, the charge carriers tend to react more at the surface to the bulk of the nanoparticles. For example, lithium ions tend to adsorb on the surface of the nanoparticles rather than in the bulk of the nanoparticles. These nanoparticles are sometimes referred to as surface redox particles. The Faraday reaction results in a pseudo-capacitor that can accumulate large amounts of loosely-coupled charge and thus produce a high power density. In the pseudo capacitor, electrons are exchanged (for example, emitted). In this case, there is exchange between the charge carrier and the nanoparticles.
Any potential results in the intercalation of charge carriers into the nanoparticles, but this does not constitute a bulk of interaction at the surface effect dominant site 1430 and can degrade some types of nanoparticles. Faraday reactions are reactions in which charge is transferred (eg, released) as a result of an electrochemical reaction.

Nanoparticles containing surface effect dominant sites 1430 can be transition metal oxides, such as TiO2, V
It can be composed of aO2, MnO, MnO2, NiO, tantalum oxide, ruthenium oxide, tin oxide, cobalt oxide, nickel oxide, copper oxide, iron oxide, or the like. These nanoparticles further include metal nitride, carbon, activated carbon, graphene, graphite, titanate (Li ₄ Ti ₅
O ₁₂ ), crystalline silicon, tin, germanium, metal hydride, iron phosphate, polyaniline,
It can be composed of mesophase carbon or the like. It should be understood that mixtures of the above and / or corresponding materials having desirable Faraday properties are also included in the surface effect dominant portion 1430. In various embodiments, the nanoparticles are 1, 2, 3, 5, 8, 13, 21 in diameter.
Or less than 34. The lower limit of nanoparticle size is a function of the molecular size of the constituent materials. Nanoparticles include at least a few molecules. For smaller sizes,
Gives the volume ratio of possible adsorption sites for a larger plane. However, particles having only two molecules had reduced stability. The nanoparticles optionally have a multilayer structure. For example, on a transition metal, for example, Co, Ni, Mn, Ta, Ru, Rb, Ti, Sn, V ₂ O ₂ , FeO, C
It can have a TiO2 layer on a u or Fe core (or any of the other nanoparticle materials mentioned above), or a graphene / graphite layer on some other material core. In some embodiments, different core materials affect the reaction potential of the surface material. The amount of surface effect dominant portion 1430 is optionally selected based on the desired power density and energy density. For example, a higher power density can be obtained by having a higher number of surface effect dominant sites 1430 per amount of intercalation material, or a higher energy density is more per number of surface effect dominant sites 1430 It can be obtained by making the amount of intercalation material. An advantage with some embodiments of the present invention is that both historically high energy and power densities are obtained simultaneously.

Due to the adsorption of charge carriers on the nanoparticle surface, the charge carriers provide a power density as conventionally obtained only with capacitors. This is because charge emission does not depend on the diffusion of charge carriers into the intercalation material. Further, by placing the surface effect dominant portion 1430 very close to the intercalation material,
Charge carriers can migrate from the intercalation material to surface effect dominant sites 1430 (or directly to the electrolyte). As a result, an energy density equal to or greater than that of a conventional battery is obtained. Both the energy density of the battery and the power density of the capacitor are obtained in the same device. During the discharge, the charge carriers in the intercalation material are
30 so that these surface effect dominant sites can be recharged.

In some embodiments, surface effect dominant sites 1430 are located on larger particles. For example, the particle size can be greater than 1, 10, 25, 100 or 250 microns (but generally less than 1 millimeter). Activated carbon, graphite, and graphene are materials that can be particles of these sizes. Further, the activated carbon is included in the power enhancing material 1320 and has a pore size at the surface effect dominant site 1430 similar to the nanoparticle diameter described above. For the purposes of this disclosure, nanoparticles are 1 μm
particles having an average diameter of less than m.

Optional binder 1440 is configured to maintain surface effect dominant site 1430 in proximity to the intercalation material. In some embodiments, the distribution of surface effect dominant sites 1430 is uniform throughout the binder 1440. For example, the nanoparticles including surface effect dominant sites 1430 may be mixed with binder 1440 and then applied to the intercalation material to provide a relatively uniform distribution. Alternatively, the nanoparticles can be applied to the surface of the intercalation material before applying the binder 1440. As a result,
The concentration of surface effect dominant sites 1430 near the intercalation material (the concentration in the binder 1440) can be higher than the region of the binder 1440 distal to the intercalation material. Binder 1440 is optional in embodiments that attach surface effect dominant sites 1430 or related nanoparticles directly to an intercalation material, eg, silicon layer 115.

The binder 1440 is permeable (porous) to the charge carriers of the electrolyte. An example of a suitable material for the binder 1440 is polyvinylidene fluoride (PVDF: po
lyvinylidene fluoride), styrene butadiene rubber, polyacrylic acid (PAA: polyacr)
ylic acid) and carboxymethyl cellulose (CMC). Other binders 1440 include conductive polymers, graphite, graphene, metal nanoparticles, carbon nanotubes, metal nanowires, Super P (conductive carbon black), and the like. Preferably, the material is at a concentration sufficient for the binder 1440 to be conductive, eg, to the permeation limit.

The surface effect dominant portion 1430 is made of an intercalation material (for example, a silicon layer 115).
It is not necessary to use a vertically aligned CNF 110 or any supporting filament to add in the vicinity of the. For example, FIG. 15 illustrates an electrode surface having a non-aligned CNF 110 coated with a power enhancement material 1320 and an intercalation material, according to various embodiments of the present invention. In these embodiments, CNF 110 does not attach directly to substrate 105, but
It is held near the substrate 105 by the binder 1440. In some embodiments, FIG.
The CNF 110 having the cup-shaped structure shown as an example in B is used in a non-attached configuration as shown in FIG. In these embodiments, the cup-like structure comprises a layer of CN, also of silicon underlayer.
Helps prevent delamination from F110. Here, CN is used as an example of the supporting filament.
Although the use of F110 has been shown, other types of support filaments as described herein as optional examples can be used to complement or replace the carbon nanofibers of CNF110.

The embodiment shown in FIG. 15 can be produced, for example, by first growing an unattached CNF 110. These CNFs are coated with a silicon layer 115 (or some other intercalation material), and the coating is such that the intercalation material is
This is performed so as to entirely contact the NF 110. Next, the coated CNF 110 is mixed with the surface effect dominant sites 1430 and the binder 1440. Finally, the resulting mixture is deposited on the substrate 105.

FIG. 16 illustrates a power boost material 1320, a non-aligned CNF 11 according to various embodiments of the invention.
9 shows an electrode surface including zero and free intercalation material 1610. In these embodiments, the intercalation material 1610 need not necessarily be disposed as a coating around the CNF 110. The intercalation material 1610 is not limited to the surface of the CNF 110 and is free in that it is still held near the substrate 105 by the binder 1440.

The embodiment shown in FIG. 16 can be produced, for example, by mixing together the binder 1440, the surface effect dominant site 1430, the intercalation material 1610, and the CNF 110 (in any order). Thereafter, the mixture is applied to the substrate 105. In these embodiments, CNF 110 may be attached or not attached to substrate 105 by means other than binder 1440. Intercalation material 1610 is C
It may be brought into contact with the NF 110 or the substrate 105 and / or not. Similarly, surface effect dominant sites 1430 optionally contact substrate 105, CNF 110 and / or intercalation material 1610. Intercalation material 1610
Optionally has a size of at least 0.1, 0.6, 1, 1.5, 2, 3, 5, 7, 9, 1,
It may include particles, suspensions, clusters and / or droplets of intercalation material at 0, 13, 15, 18, 21, or 29 μm, or any range therebetween.

FIG. 17 illustrates a binder 1440 without a supporting filament, according to various embodiments of the present invention.
, An electrode surface including surface effect dominant sites 1430 and intercalation material 1610. In these embodiments, surface effect dominant sites 1430 and intercalation material 1610 are held in proximity to substrate 105 by binder 1440.

FIG. 18 shows an electrode surface similar to that shown in FIG. However, in the embodiment shown in FIG. 18, the surface effect dominant portion 1430 is concentrated very close to the intercalation material 1610. For example, in some embodiments, at least 2%, 10%, 25%, 50%, 75%, or 80% of the surface effect dominant sites 1430 have intercalation material 1
610 is on the particle. Increased concentrations of surface effect dominant sites 1430 proximate to intercalation material 1610 can be obtained using the methods described elsewhere herein. This results in an increase in the concentration of surface effect dominant sites 1430 on the surface of intercalation material 1610 relative to other volumes within binder 1440.

FIGS. 14C, 19 and 20 show electrode surfaces similar to those shown in FIGS. 14B, 16 and 17, respectively. However, in the embodiments shown in these figures, according to various embodiments of the present invention, the surface effect dominant portion 1430 is located very close to the free intercalation material. In some embodiments, such as the embodiment shown in FIG. 18, at least 2%, 10%, 25%, 50%, 75%, or 80% of the surface effect dominant portions 1430 contact the intercalation material 1610. I do. In some embodiments, surface effect dominant sites 14
A higher concentration of nanoparticles, including 30
Located within 5 nanometers than よ り 15 nanometers. Intercalation 16
The high concentration of surface effect dominant sites 1430 close to 10 properly selects the zeta potential of the nanoparticles and the intercalation material 1610 in solution, causing the nanoparticles to have a double electrostatic potential on the surface of the intercalation material 1610. A layer is formed. The zeta potential is the potential of the interface bilayer at the surface location relative to the point in the bulk liquid away from the surface. The zeta potential is optionally greater than 25 mV (absolute value). In other embodiments, the nanoparticles are treated with an intercalation material 1610 prior to applying the binder 1440.
To adhere to the surface.

The intercalation material 1610 shown in FIGS. 16-20 can be any one or combination (with or without silicon) of the materials described herein for the silicon layer 115. Similarly, the CNFs 110 shown in FIGS. 16-20 can be any one or combination (with or without carbon nanofibers) of the various types of fibers described herein. For example, these CNFs 110 can be branch fibers, multi-wall fibers, wires, aerogels, graphite, carbon, graphene, boron nitride nanotubes, and the like. Surface effect dominant sites 1430 and CNF1 shown in these and other figures.
The number 10 is for illustration only. For example, in practice, the number of surface effect dominant sites 1430 can be significantly increased. Similarly, the amounts and sizes of the illustrated intercalation material 1610 and silicon layer 115 are also illustrative. Alternative embodiments can be more or less in volume and larger or smaller in size. Similarly, PE
The depth of M1420 and the length of CNF 110 may vary from those shown.

In various embodiments, the amount of nanoparticles comprising surface effect dominant sites 1430 is at least 0.1 of the intercalation material 1610 or the monolayer of nanoparticles at the surface of silicon layer 115 (measured in the discharge state). , 0.5, 0.7, 0.9, 1.1, 1.3, 1.5,
It can be chosen to be 2, 3, 5, 10, 25, 50, or 100 (or any range between these values) times. As used herein, the term 0.1 monolayer indicates 10%.
X The monolayer is 10 monolayers. In various embodiments, the surface effect dominant portion 1430
The amount of nanoparticles comprising (measured in the discharged state) the nanoparticles at the surface of the intercalation material 1610 is at least 1, 5, 10, 20, 50, 100, 250, or 500 (or any of these values). The combination is selected to be a nanometer layer. Other coating densities or additions, measured in monolayers, are also possible. Nanoparticle (surface effect dominant site 143
When the coverage reaches 1.0 monolayer, the nanoparticles can form a layer between the intercalation material 1610 and the charge carrier of the electrolyte traveling through the binder 1440. For example, in some embodiments, the electrolyte includes lithium as a charge carrier. The lithium can migrate through the binder 1440 and cause a Faraday reaction with the surface effect dominant site 1430, in which electrons are released from one of the surface effect dominant sites 1430 to lithium. The electrons are transferred (eg, emitted) from the substrate 105 to the nanoparticles via the intercalation material 1610. Since the nanoparticles form a barrier at this stage of the charging process, only a limited amount of charge carriers reach the intercalation material 1610. The reaction at the surface effect dominant site 1430 causes charging to dominate. In some embodiments, charging is rapid because no charge carrier intercalation into the intercalation material 1610 is required before a Faraday reaction with the charge carrier occurs. The presence of surface effect dominant sites 1430 greatly increases the surface area where the initial Faraday reaction occurs before intercalation occurs. Surface effect dominant part 1
430 acts as a catalyst for charge carrier intercalation into intercalation material 1610. The charge carriers can be intercalated in a form received at surface effect dominant sites 1430, or in other forms such as metal oxides. When intercalated, such as a metal oxide, the oxygen of the oxide is circulated back to the surface effect dominant site 1430 following the intercalation.

In some embodiments, because the nanoparticles form an imperfect barrier, some charge carriers may be charged at this stage of charging (eg, the initial stage of charging a power storage device including the electrodes described herein). ) Still reaches the intercalation material 1610. In some embodiments, the intercalation material, for example, silicon, expands when charge carrier intercalation occurs, thus also increasing the surface area of the intercalation material 1610. This reduces the surface coverage of the nanoparticles on the surface of the intercalation material 1610 and reduces the effectiveness of the nanoparticles in forming a barrier to charge carriers. Thus, as charge progresses, more charge carriers reach the intercalation material 1610 per unit time. This optionally persists until the charge in the intercalation material 1610 becomes dominant. The reduction in surface coverage increases the average ratio of surface effect dominant sites 1430 for each nanoparticle exposed to the electrolyte. As used herein, the term "surface coverage" refers to the seed density at a surface and can be measured as the number (or fractional form), thickness, or concentration of monolayers.

In some embodiments, power storage at the surface effect dominant site 1430 is performed at a potential that results in a Faraday surface reaction, but no intercalation of charge carriers into the nanoparticles that include the surface effect dominant site 1430. This prevents nanoparticle degradation due to repeated intercalation and deintercalation of charge carriers, and allows for longer cycle life. At the same electrode, power is stored in the intercalation material 1610 via a Faraday reaction that occurs at a higher potential, optionally at a potential that causes the intercalation of charge carriers into the nanoparticles having surface effect dominant sites 1430. It is desirable. This can occur in some embodiments of the present invention because there is a potential drop between the substrate 105 and the electrolyte 125.

In a particular embodiment where lithium is the charge carrier, the surface effect dominant site 1430 is
It is located on the iO ₂ nanoparticles and the intercalation material 1610 is mainly silicon. It should be understood that the specific voltage in other embodiments depends on the species contained in the surface effect dominant portion 1430 and the intercalation material 1610, as well as the reactions that occur during charging. In various embodiments, the potential difference between the surface effect dominant portion 1430 and the substrate 105 is at least 0.001, 0.2, 0.3, 0.4, 0.5, 0.6, 0.8, 1.
0, 1.3, 1.7, 2.0, 2.2, or 2.4 V, or any range of potential differences between these values. As used herein, the term “potential” refers to the absolute value of the electrostatic potential (eg, |
x |).

FIG. 21 illustrates a method of assembling an electrode surface according to various embodiments of the present invention. The assembled electrode surface can be used, for example, as an anode in a battery, capacitor, or hybrid device. The method shown in FIG. 21 is optionally used to produce the various electrodes described elsewhere herein.

In a substrate preparing step 2110, a conductive substrate is prepared. Substrate preparation step 2110
Is similar to the substrate preparation step 1310. In a substrate preparation step 2110, optionally, a substrate 105 suitable for growing CNF 110 or other support filaments is provided.
As described herein, the substrate 105 can include various materials, for example, Cu, Au, Sn, and the like. Substrate 105 optionally includes nucleation sites as described elsewhere herein.

In an optional CNF preparation step 2120, CNF 110 (or other support filaments as described herein) is prepared. The CNF preparation step 2120 is described in FIGS.
Embodiments producing electrodes without supporting filaments as shown at 0 are optional. In some embodiments, CNF 110 is prepared by growing CNF 110 on substrate 105. In some embodiments, CNF 110 is prepared by adding CNF 110 to a mixture that is subsequently applied to substrate 105. In some embodiments,
The CNF 110 is produced separately from the substrate 105 and is attached to the substrate 105 later.

In an intercalation material preparation step 2130, an intercalation material 1610 is prepared. Intercalation material 1610 is first applied to CNF 110. In various embodiments, the intercalation material 1610 is applied using vapor deposition as a colloidal suspension, paste, or the like in a solvent.

In a surface effect dominant site (SEDS) preparation step, a surface effect dominant site 1430 is prepared. As described elsewhere herein, surface effect dominant sites 1430 can be deposited on nanoparticles or larger structures such as graphite, graphene, or activated carbon. The surface effect dominant portion 1430 includes a binder 1440,
Alternatively, as a suspension in a solvent, it is prepared using sputter deposition, electron deposition, vapor deposition, or using a spray or the like. In some embodiments, the intercalation material 16
A zeta potential of 10 is selected such that the surface effect dominant site 1430 is concentrated on the surface of the intercalation material 1610.

In an application step 2150, an intercalation material 1610, surface effect dominant sites 1430 and optional CNF 110 are applied to the substrate 105. These materials can be applied in various orders and combinations. For example, the intercalation material 1610 may be CN
F110 (which may be pre-attached to substrate 105) and then surface effect dominant portion 1430 can be applied to the top surface of intercalation material 1610. Alternatively, free CNF 110, intercalation material 1610 is first mixed and then surface effect dominant sites 1430 and binder 1140 are added alone or in combination. Based on the teachings herein, one of ordinary skill in the art will appreciate that, in different embodiments, the components can be mixed or added in any order or combination. Further, these components can be mixed before or after application to the substrate 105. Steps 2110-2150 can be performed in any order. After the application step 2150, an optional adjustment step 1350 is performed.

In some embodiments, the method shown in FIG. 21 comprises mixing the intercalation material 1610 and surface effect dominant sites 1430 as a well dispersed suspension in a solvent. This dispersion is optionally applied to CNF110. Thereafter, the solvent of the dispersion is evaporated from the mixture, resulting in a powder or coating on the CNF 110. Binder 1440 can be added to the suspension before or after application of CNF 110. In some embodiments, the application of the surface effect dominant portion 1430 comprises the intercalation material 1
This is done by changing the material being sputtered onto the substrate 105 in the final step of depositing 610. In these embodiments, for example, TiO ₂ can be added to the sputtering mixture after depositing almost all of the intercalation material 1610. This results in a sputtered layer of TiO ₂ as surface effect dominant sites 1430 on the top surface of intercalation material 1610.

FIG. 22 illustrates a method of operating a charge storage device according to various embodiments of the present invention. This method can be used, for example, when charging a charge storage device. In some embodiments, the method includes attaching to the charging device via wires to the anode and cathode of the charge storage device. The charge storage device applies a potential to the anode and the cathode, creating a potential gradient between the two. The steps shown in FIG. 22 may optionally occur simultaneously, for example, they may occur simultaneously or with overlap time with one another.

In a potential establishing step 2210, a potential is established at the charge storage device. This potential exists between the anode and cathode of the charge storage device. Such a potential creates a potential gradient between the substrate 105 and the electrolyte 125 in the charge storage device. This potential gradient can create a potential difference between the location of the surface effect dominant portion 1430 and the intercalation material 1610. In various embodiments, this potential difference is at least 0.001, 0.2
, 0.3, 0.4, 0.5, 0.8, 1.0, 1.3, 1.7, 2.0, or 2.4 V, or any range of potential differences between these values. .

In a lithium receiving step 2220, charge carriers, which in one possible embodiment are lithium, are received at one surface effect dominant site 1430. This charge carrier is optionally received via a binder 1440.

In the charge transfer step 2230, electrons are transferred (eg, emitted) from the surface effect dominant site 1430 to the charge carriers received in the lithium receiving step 2220.
This transition involves sharing an electron between the surface effect dominant site 1430 and the charge carrier. Electrons are transferred by the Faraday reaction and are generally guided from the substrate 105. This transition occurs when the charge carrier is at the surface of the surface effect dominant site 1430 and occurs at the potential there. The reaction potential of the electron transfer depends, for example, on the reaction potential of the charge carrier and the reaction potential of the surface effect dominant site 1430. The reaction potential may depend on both the surface effect dominant site 1430 and the intercalating material 1610 in its vicinity. As used herein, the term "reaction potential" is used to mean the potential at which the reaction occurs at an appropriate rate. The reaction potential in the reaction can be explained, for example, by a peak in a cyclic voltammogram. In other embodiments, Li ⁺ + e ⁻ → Li or 2Li ⁺ + MO + 2e ⁻ → Li ₂ O + M generated in an electrochemical cell.
(Where M is any transition metal described herein) is the reaction potential in these reactions. The reaction potential can greatly depend on the environment in which the reaction takes place. For example, the second reaction mentioned above may have a lower reaction potential in the presence of TiO ₂ nanoparticles having a diameter in the range of 2 to 10 nm. Similarly, the reaction potential may be affected by the energy required for intercalation, the close proximity of the surface effect dominant sites 1430 and the intercalation material 1610.

In a lithium intercalation step 2240, charge carriers, which in one possible embodiment are lithium, are intercalated into the intercalation material 1610. This step involves the transfer of charge carriers into the bulk of the intercalation material 1610. Charge carriers may be received at the intercalation material 1610 as the same species as received at the surface effect dominant site 1430 in the lithium receiving step 2220, or alternatively, as a species generated at the surface effect dominant site 1430. For example, charge carriers can be received at the intercalation material 1610 as oxides of species (eg, Li ₂ O, etc.) received at the surface effect dominant sites 1430.

In the electron transfer step 2250, electrons transfer from the intercalation material 1610 to charge carriers in the lithium intercalation step 2240. The electron
It is transferred by the Faraday reaction and is generally guided from the substrate 105. This transition occurs when the charge carriers are within the intercalation material 1610 and occurs at the local potential. The reaction potential of the electron transfer depends on the reaction potential of the charge carrier and the intercalation material 1.
610. The reaction potential may depend on both the intercalation material 1610 and the nearby surface effect dominant site 1430. The surface effect dominant portion 1430 can act as a catalyst in transferring lithium from the electrolyte 125 to the intercalation material 1610. As discussed elsewhere herein, this transition can occur via the intermediate oxide such as Li 2 _O. The work function of the electron transfer in this step can be different from the work function of the electron transfer in the electron transfer step 2230.
For example, in various embodiments, the work function is at least 0.001, 0.3, 0.4,
0.5, 0.8, 1.0, 1.3, 1.7, 2.0, or 2.4 V, or any range of potential differences between these values. In some embodiments, it is thermodynamically desirable to intercalate lithium into the intercalation material 1610 rather than into the bulk of the nanoparticles that include the surface effect dominant sites 1430. However, the presence of surface effect dominant sites 1430 can catalyze the intercalation of charge carriers into intercalation material 1610.

If the charge carriers are converted to oxides at the electron transfer step 2230, the electron transfer step 2250 includes the step of causing a transfer of oxygen from the intercalation material 1610 back to the surface effect dominant site 1430. This oxygen is received by the intercalation material 1610 as an oxide of the charge carrier and is released from the charge carrier during intercalation. Oxygen can be used to further perform an electron transfer step 2230 after the transfer back to the surface effect dominant site 1430, ie, the oxygen is recycled.

The description of FIG. 22 above shows that charge carriers are received in a lithium receiving step 2220;
It is also assumed that the charge carriers are two different individual charge carriers (which may be of the same type) in the lithium intercalation step 2240, but in various embodiments, steps 2220, 2230 and 2240 are the same This can be done by charge carriers. For example, in some embodiments, the lithium receiving step 222
0 includes receiving charge carriers at one surface effect dominant site 1430. Subsequent electron transfer step 2230 includes a reaction in which charge carriers react with surface effect dominant sites 1430 to produce intermediate compounds. In some embodiments, the reaction is 2Li ⁺ + MO + 2
e ⁻ → Li ₂ O + M, where M is any of the transition metals described herein and Li ₂ O is the resulting intermediate compound. Lithium intercalation step 2
At 240, an intermediate compound (eg, Li ₂ O) is added to the intercalation material 1610.
One (or both) of Lis intercalated in or in the intermediate compound is Li ₂
The transition from O of O to atoms of an intercalation material (for example, Li _x Si). This transfer results in an MO that is decomposed in the electron transfer step 2230. Note that in this example, the same individual Li atoms are involved in each of steps 2220-2230 and 2240. The electron transfer step 2250 is not required in the method embodiment shown in FIG. In some embodiments, both of the reaction sequence do not contain the reaction sequence and intermediates containing intermediates such as Li 2 _O occurs during a single charging cycle.

Several embodiments have been shown and / or described herein, particularly. However, modifications and variations are encompassed by the above teachings and within the scope of the claims, without departing from the spirit and intended scope of the invention. For example, while the embodiments described above focused on CNFs having a laminated cone structure, the teachings may be applied to other materials having similar or alternative structures. Similarly, while Cu substrate and Li charge carriers have been described herein, other substrates and charge carriers will be apparent to those skilled in the art. The silicon layer 115 forms an intercalation material that is optionally added to silicon, or forms an intercalation material as an alternative to silicon. For example, tin, germanium, carbon, graphite, graphene, silicon, other materials described herein, or combinations thereof, can be used as the intercalation material. Furthermore, aerogels, nanowires, TiO 2 _(titanium oxide), metal wire, carbon wire, or boron nitride nanofibers can be used instead of the carbon nanofibers described herein. The relative concentrations of binder 1440, surface effect dominant sites 1430, intercalation material 1610 and CNF 110, and other elements in the figures can vary widely from those described.

The electrodes taught herein can be provided on a wide range of energy storage devices, including capacitors, batteries and hybrids thereof. These energy storage devices can be used, for example, in lighting systems, portable electronics, load balancing devices, communication devices, backup power supplies, vehicles, and computer devices. The concepts taught herein can often be applied to cathodes as well as anodes.

VACNF growth, silicon deposition, microscopy and spectroscopy features, electrochemical cell assembly,
For details of the charge and discharge inspection, see US Provisional Patent Application No. 61/61, filed July 3, 2012.
667,876.

The embodiments described in the present specification are for describing the present invention. These embodiments of the present invention have been described by way of illustration, and various modifications or adaptations to the methods or particular structures described herein will be apparent to those skilled in the art. All such alterations, adaptations, or modifications that rely on and progress with the teachings of the present invention are deemed to be within the spirit and scope of the present invention. Therefore, it is to be understood that these descriptions and drawings are not limiting and the invention is not limited to only the described embodiments.

Claims (38)

A conductive substrate;
A carbon nanofiber coupled to the conductive substrate, the carbon nanofiber having a plurality of exposed nanoscale edges along a length of the carbon nanofiber,
And an intercalation material configured to form a shell over at least a portion of the carbon nanofiber. 32. The system or method of claim 1, 29, 30, or 31, wherein each of the exposed nanoscale edges comprises an edge of a multiple graphite sheet. 3. The system or method of claim 29, 30, 31, 1 or 2, wherein each of the exposed nanoscale edges is configured to control the growth of the intercalation material. 40. The system or method according to any one of claims 29, 30, 31, 1-2 or 3, wherein each of the exposed nanoscale edges provides a path for the transfer of charge carriers into carbon nanofibers. A system or method configured as follows. 5. The system or method according to any one of claims 29, 30, 31, 1-3 or 4 wherein each of the exposed nanoscale edges comprises multiple graphene edges. A conductive substrate;
A carbon nanofiber connected to the conductive substrate, the carbon nanofiber having a plurality of cup-shaped structures along a length of the carbon nanofiber, and the carbon nanofiber; and a shell over at least a part of the carbon nanofiber. An energy storage system comprising: an intercalation material configured to form. The system or method according to any one of claims 29, 30, 31, 1 to 5 or 6, wherein each of the cup-shaped structures comprises a wall having multiple graphite sheets. 10. The system or method according to any one of claims 29, 30, 31, 1 to 6 or 7, wherein each of the cup-shaped structures is configured to control the growth of the intercalation material. Method. A conductive substrate;
A carbon nanofiber coupled to the conductive substrate; and an intercalation material configured to form a shell over at least a portion of the carbon nanofiber, wherein the wing-like structure extends along a length of the carbon nanofiber. An energy storage system comprising: the intercalation material arranged to: A conductive substrate;
A carbon nanofiber coupled to the conductive substrate, and an intercalation material configured to form a shell over at least a portion of the carbon nanofiber, wherein the expansion of the intercalation material is from the carbon nanofiber. An energy storage system comprising: an intercalation material configured to prevent exfoliation of the intercalation material. 11. The system or method according to any one of claims 29, 30, 31, 1 to 9 or 10, wherein the expansion is a radial expansion of the carbon nanofiber. 12. The system or method according to any one of claims 29, 30, 31, 1 to 10, or 11, wherein the expansion is between parts of an intercalation material disposed on the carbon nanofiber. System or method. 13. The system or method according to any one of claims 1 to 11 or 12, further comprising an electrolyte in contact with the intercalation material and comprising a charge carrier. The system or method according to any one of claims 29, 30, 31, 13,
The system or method wherein the electrolyte is a solid electrolyte. 15. The system or method of claim 29, 30, 31, 13, or 14, wherein the charge carrier comprises lithium. 16. The system or method according to any one of claims 29, 30, 31, 1 to 14 or 15, wherein the carbon nanofibers are a plurality of vertically aligned carbon nanofibers attached to the substrate. A system or method. 17. The system or method according to any one of claims 29, 30, 31, 1 to 15 or 16, wherein the conductive substrate, the carbon nanofiber, and the intercalation material are configured to function as an anode. , System or method. 18. The system or method according to claim 17, further comprising a cathode in contact with said electrolyte. 19. The system or method according to any one of claims 1 to 17 or 18, wherein the carbon nanofibers are directly attached to the conductive substrate. 20. The system or method according to any one of claims 28, 29, 30, 31, 1-18 or 19, wherein the intercalation layer comprises silicon. 21. The system or method according to any one of claims 29, 30, 31, 1 to 19 or 20, wherein the carbon nanofiber comprises a structure of intercalation material on the exposed edge of the carbon nanofiber. A system or method configured to grow. 21. The system or method according to any one of claims 29, 30, 31, 1 to 19 or 20, wherein the carbon nanofibers are indirectly attached to the conductive substrate using a binder. Or method. 23. The system or method according to any one of claims 29, 30, 31, 1, 1-21, or 22, wherein the cup-shaped structure comprises a helix having a cup-shaped cross-section. 24. The system or method according to any one of claims 1 to 22 or 23, wherein the carbon nanofibers and intercalation material are 2752-3650 mAhg- ^1.
At least 8 of the Li ⁺ insertion capacity, and the insertion capacity for 100 charge / discharge cycles
A system or method that produces a 5% retention. 25. The system or method according to any one of claims 29, 30, 31, 1 to 23 or 24, wherein the intercalation material is arranged as a layer having a nominal thickness of 0.1 to 4.0 [mu] m. , System or method. 26. The system or method according to any one of claims 29, 30, 31, 1 to 24 or 25, wherein the carbon nanofibers are 3 to 200 [mu] m long. 27. The system or method according to any one of claims 1 to 25 or 26, further comprising a plurality of nanoparticles attached to the intercalation material, wherein each of the nanoparticles has a charge carrier by a Faraday reaction. A system or method configured to create a surface effect dominant site that can be adsorbed to a surface. 28. The system or method according to any one of claims 29, 30, 31, 1-26 or 27, wherein the carbon nanofiber and the intercalation material have a Li ⁺ insertion capacity that increases the charge rate from 2C to 8C. A system or method that is configured to increase as it increases. A method of producing an energy storage device, comprising:
Providing a conductive substrate;
Adding carbon nanofibers to the conductive substrate, wherein each of the carbon nanofibers has a plurality of exposed nanoscale edges along a length of the carbon nanofibers. And applying the intercalation material to the carbon nanofibers, wherein the intercalation material is configured to cause charge carrier intercalation. A method of producing an energy storage device, comprising:
Providing a conductive substrate;
A step of adding carbon nanofibers to the conductive substrate, wherein each of the carbon nanofibers has a plurality of cup-shaped structures along the length of the carbon nanofibers, And applying the intercalation material to the carbon nanofibers, wherein the intercalation material is configured to cause charge carrier intercalation. A method of producing an energy storage device, comprising:
Providing a conductive substrate;
A step of applying carbon nanofibers to the conductive substrate, and an application step of applying an intercalation material to the carbon nanofibers, wherein the intercalation material causes intercalation of charge carriers, Applying the intercalation material in a vane-like structure along the length of the carbon nanofiber. 32. The method of claim 29, 30 or 31, further comprising the step of contacting the intercalation material and adding an electrolyte comprising a charge carrier. 33. The method according to any one of claims 29 to 31 or 32, wherein the carbon nanofibers are vertically aligned carbon nanofibers attached to the substrate. 34. The method of any one of claims 29-32 or 33, wherein the conductive substrate, the carbon nanofibers, and the intercalation material are configured to function as an anode. 35. The method of any one of claims 29-33 or 34, further comprising a cathode in contact with the electrolyte. 36. The method according to any one of claims 29 to 34 or 35, wherein the carbon nanofibers are attached directly to the conductive substrate. 37. The method according to any one of claims 29 to 35 or 36, further comprising attaching a plurality of nanoparticles to the intercalation material, wherein each nanoparticle has a charge carrier by a Faraday reaction. A method comprising providing a surface effect dominant site that can be adsorbed to a surface. 29. The system or method of any one of claims 1-27 or 28, wherein the intercalation material comprises a first silicon structure at a tip of the carbon nanofiber and a second silicon structure along a length of the carbon nanofiber. A method comprising a silicon structure.