Method of making hard-carbon composite material

Abstract

A method is described to make a metal-containing non-amorphous hard-carbon composite material that is synthesized from furan-ring containing compounds. The metals described in the process include lithium and transition metals, including transition metal oxides like lithium titanates. The non-amorphous hard-carbon component of the metal-containing non-amorphous hard-carbon composite material is characterized by a d.sub.002 peak—in the X-ray diffraction patterns—that corresponds to an interlayer spacing of >3.6 Å, along with a prominent D-band peak in the Raman spectra. These metal-containing hard-carbon composites are used for constructing electrodes for Li-ion batteries and Li-ion capacitors.

Claims

1. A method of producing a lithium-containing non-amorphous hard-carbon composite from a furan-ring containing compound, comprising: a. mixing an insoluble lithium compound and an acidic catalyst with a furan-ring containing compound to form a mixture, wherein the furan-ring compound is a 5 membered ring with 4 carbon atoms and 1 oxygen atom; b. soaking the mixture at room temperature and further heating the mixture between 25° C. and 200° C. to form a solid-polymer/lithium-containing composite; and c. heating the solid-polymer/lithium-containing composite between 200° C. to 1100° C. under an inert atmosphere, to carbonize the solid-polymer/lithium-containing composite and make the lithium-containing non-amorphous hard carbon.

2. The method of claim 1, wherein the furan-ring containing compound is at least one of a furfuryl alcohol, furfuraldehyde, 5-hydroxymethylfurfural, 5-methylfurfural, 2-acetylfuran and polyfurfuryl alcohol.

3. The method of claim 1, wherein the catalyst is at least one of an organic acid with a pKa value equal to or greater than that of oxalic acid, either directly or in a solution with deionized water.

4. The method of claim 1, wherein the insoluble lithium compound is a titanium containing compound, wherein the titanium containing compound is a lithium titanate.

5. The method of claim 1, wherein the lithium-containing non-amorphous hard carbon is used for constructing electrodes for Li-ion batteries and Li-ion capacitors.

6. The method of claim 1, wherein the acidic catalyst is a nitric acid solution.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1: X-ray diffraction (XRD) plot of intensity versus 2θ (from 10° to 70°) for graphite, activated carbon and hard carbon.

(2) FIG. 2: Thermal gravimetric analysis (TGA) of a room-temperature polymerized furfuryl alcohol resin (from 100° C. to 900° C., @ 10° C./min)

(3) FIG. 3: XRD plots of hard carbons from Examples 1 through 7.

(4) FIG. 4 (a): Raman spectrographs of hard carbons from Examples 1 and 5; 4(b) from Examples 2-4, 6 and 7.

(5) FIG. 5: N.sub.2 isotherms (from BET measurement) for hard carbons from Examples 1 through 8.

(6) FIG. 6: (a) Cyclic voltammogram of hard carbon from Example 1, 1st and 10th cycle; (b) Capacity versus # cycle for hard carbon from Example 1, at different C-rates, up to 100 C.

(7) FIG. 7: (a) Typical charge/discharge cycle at 10 Amp/gm for a Li-ion capacitor configuration using the hard carbon of Example 1; 7 (b) Cycle life for the same configuration over 1000 cycles.

(8) FIG. 8: Capacity versus number of cycles for hard carbon from Example 5 at different C-rates, up to 100 C.

(9) FIG. 9: XRD plot of hard carbon from Example 7, showing hard carbon and metallic Si.

DETAILED DESCRIPTION

(10) Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application, the preferred methods and materials are now described. All publications mentioned herein are incorporated herein by reference to disclose and describe the methods and/or materials in connection with which the publications are cited.

(11) The process described in this disclosure is a room-temperature (22-25° C.) polymerization of furan-ring containing liquid precursor materials, followed by heating to complete polymerization and cross linking—without any special refluxing or vacuum distillation set-ups. Polymerization is catalyzed by using catalysts that dissolve in the precursor liquid. One category of catalysts is a group of weak organic acids like oxalic acid, maleic acid, tartaric acid, benzoic acid, citric acid, formic acid and similar compounds. These organic acids are characterized by having acid dissociation constants (pKa) values that are greater than that of oxalic acid (which has a pKa value of 1.23). We have used these organic acids in powder form (i.e. dissolving in the furan-ring compounds) or first dissolving them in DI-water, and then mixing with the furan-ring compounds. The furan-ring compounds included in this group are furfuryl alcohol, furfuraldehyde, 5-hydroxymethylfurfural, 5-methylfurfural, and poly furfuryl alcohol (PFA) resins. The ratio of catalyst to precursor furan ring containing liquid is generally between 5 wt. % and 12 wt. %—depending on the specific type of catalyst (if only oxalic acid is used, then the wt. % is closer to the lower end, while use of weaker catalysts requires the higher end of the wt. %).

(12) In one embodiment, 440 gm of furfuryl alcohol (#W249106, from Sigma Aldrich, St. Louis, Mo.) was mixed with 44 gm of a combination of organic acid catalysts (oxalic acid, maleic acid and tartaric acid, in a 1:1:1 molar ratio). Once the catalysts are dissolved, the mixture is allowed to soak at room temperature, under air. The objective here is to polymerize the precursors in such a way that it promotes the formation of a non-graphitizable carbon, i.e. encourages the formation of only micro-graphitic crystalline domains which is characterized by a high I.sub.D/I.sub.G ratio (from Raman spectroscopy). At the same time, the polymerization (and subsequent carbonization process) should also ensure that an amorphous carbon does not form—as indicated by the absence of a d.sub.002 peak in an XRD measurement (d.sub.002 peaks of >3.6 Å are indicators of the presence of hard carbons—which are neither graphite nor amorphous carbon).

(13) To achieve this objective, the mixture is soaked at room temperature until a pasty solid (held its shape when inverted) is obtained—signifying progress of the polymerization reaction. The weight of the mixture was tracked, along with rate of weight loss which decreased over time, until it approached zero, at which point the pasty solid was formed. Thermogravimetric analysis (TGA) of this material is shown in FIG. 2, for a heating rate of 10° C./min from 100° C. to 900° C. Referring to the d(W)/dt versus temperature curve, one can see changes below 200° C., and again a sharp peak between 350° C. and 400° C. The reactions below 200° C. are related to the polymerization reaction, and inform our choice of 200° C. as the end of the polymerization heat treatment. The pasty solid formed after room temperature soaking was subjected to additional heat treatments at intermediate temperatures—up to 200° C., all under air, for 24 hours. The hard polymer solid that forms at this stage is then carbonized. From FIG. 2, we see that the d(W)/dt curve flattens out after 800° C., which is then picked as a suitable temperature for carbonization.

(14) To encourage the formation of HC from the precursors described in this embodiment, regions of micro-crystalline graphitic order need to form in the solid. According to the prevalent theories, this can be achieved by using the carbonization heat treatment to create the appropriate porosity (from the departing volatile organic compounds), followed by high temperature heat treatment that aligns the material to form larger micro-crystalline regions. The initial polymerization reaction is also important in this scheme, as it provides the basic structure for the carbonization and final heat treatment process. To that end, the initial polymerization reaction which forms the solid, needs to have in a higher level of graphitic order than a typical soft activated carbon, so as to facilitate the structural adjustments during the subsequent heat treatment steps.

(15) To ensure that a HC is formed, the carbonization heat treatment is performed at a slow heating rate, and must be held at the final carbonizing temperature of 800° C. for several hours. We have followed this up with a final higher temperature calcination treatment at 1000° C. Heating rates are generally less than 5° C./min, ideally 2° C./min and lower through the 350° C. to 400° C. range to ensure that the reaction shown in the TGA data of FIG. 2 is complete. Faster rates to 800° C. can be used, but must be accompanied by an initial soak between 350° C. to 400° C. Carbonization is performed under an inert atmosphere. The final calcination step at 1000° C. is also performed under an inert atmosphere.

(16) For the embodiment described above, room temperature polymerization was followed by heating at several intermediate temperatures between 60° C. and 120° C., followed by a treatment at 200° C., all under air, to form the hard polymer solid. Carbonization was carried out at 800° C. for 4 hours, under nitrogen. No high temperature calcination was used. XRD measurements of the embodiment were made on a Malvern Panalytical Empyrean X-ray instrument, with Cu K.sub.α radiation, operating at 35 kV, 30 mA. The XRD pattern shows a strong d.sub.002 peak at 23.65°, corresponding to a d-spacing of 3.76 Å. BET measurements were made on a Quantachrome NovaTouch LX2 instrument using N.sub.2 as the adsorbent gas. BET multi-point surface area and pore volumes (using the NLDFT model for slit pores in the carbon—as derived by Quantachrome Instrument's TouchWin™ version 1.21 software) were obtained to be 89.8 m.sup.2/gm and 0.0644 cc/gm, respectively (shown in Table 2).

(17) In a variation of the above embodiment, 150 ml of furfuryl alcohol was mixed with 14.7 gm of a combination of organic acids (oxalic acid+maleic acid+tartaric acid, in 1:1:1 molar ratios) and the mixture was allowed to soak at room temperature until a pasty solid formed (coinciding with the rate of weight loss approaching zero). At this point the material was heated at 120° C. and 200° C., under air to complete the polymerization process. Carbonization was performed by first heating at 360° C. followed by 4 hours at 800° C. and 30 mins at 1000° C. The density of this material was measured to be 1.41 gm/cc, BET surface area was 3.89 m.sup.2/gm, and the pore volume was 0.0047 cc/gm (NLDFT model with slit pores). By changing the polymerization and carbonization conditions, the characteristics of the final HC can be changed to dramatically reduce the SSA from ˜90 m.sup.2/gm to 3.9 m.sup.2/gm, while maintaining similar XRD characteristics. These data are shown in Table 2.

(18) TABLE-US-00002 TABLE 2 BET data BET Pore SSA volume XRD data Precursors Polymerization Carbonization (m.sup.2/gm) (cc/gm) 2θ (°) d.sub.002 (Å) Furfuryl Room temp. + 4 hours/800° C. .sup.  89.9 0.0644 23.65 3.76 alcohol + intermediate organic temp + acids 120° C. + 200° C. Furfuryl Room temp. + 4 hr./360° C. 3.89 0.0047 23.9 3.71 alcohol + 120° C. + 200° C. 4 hr./800° C. organic 0.5 hr./1000° C.  acids

(19) The two embodiments discussed produce HCs from a furfuryl alcohol/organic acid catalyst mixture. This differs from our earlier disclosure (U.S. Pat. No. 9,458,021) to make high surface area activated carbons from furfuryl alcohol/organic acid mixtures in the following ways: (i) the activated carbon version needs the addition of a conductive carbon powder like carbon black to the starting mixture—which the HC process does not; and (ii) the heat treatments used to carbonize are different. Specifically, the HCs need much slower carbonization steps, with higher temperatures (800-1000° C.) than the activated carbons.

(20) Besides furfuryl alcohol, other furan-ring containing chemicals like poly furfuryl alcohol (PFA) resins can also be used as precursor materials. Specifically, we have used commercially available FUROLITE, from TransFuran Chemicals in Geel, Belgium. We have evaluated the polymerization of this PFA using the following acid catalysts: oxalic acid, tartaric acid, maleic acid, citric acid, formic acid and a 1.5M nitric acid solution. PFA is a slower polymerizing material than furfuryl alcohol, can be polymerized with stronger acidic catalysts like nitric acid. We have also evaluated the organic acids dissolved in water, instead of in their dry powder form. This was done to better mix the catalyst with the PFA, since the PFA is a viscous liquid (the version we used had a viscosity ˜2100 cP). Any excess water (e.g. in the case of oxalic acid that has a low solubility in water) was naturally removed during the subsequent heating steps. In all cases, we have successfully polymerized the PFA by using between 5 and 12% (by wt.) of the catalyst, and soaking at room temperature for 24 hours before heating at temperatures between 60° C. and 200° C., under air.

(21) In one embodiment, the PFA (FUROLITE, from TransFuran Chemicals) was polymerized using 10 wt. % of formic acid by heating the mixture up to 200° C. The polymerized PFA was then carbonized under two different conditions: (a) 2 hours at 800° C. (under an inert atmosphere); and (b) 4 hours at 800° C., (under an inert atmosphere); followed by 30 mins at 1000° C. (also under an inert atmosphere). BET measurements were done to evaluate the surface area and pore sizes as a function of the difference in processing conditions. BET multi-point surface area, pore volume and pore sizes obtained (Quantachrome Instruments) for the two carbons described above are shown in Table 2. Additionally, the bulk density of the carbonized materials was measured and the results are also included in Table 3.

(22) TABLE-US-00003 TABLE 3 BET Pore volume Pore width Bulk surface area (cc/gm) (nm) Density (m.sup.2/gm) (NLDFT) (NLDFT) (gm/cc) (a) PFA polymer 34.33 0.0352 1.18 1.12 with faster carbonization (b) PFA polymer 11.13 0.0065 1.18 1.43 with slower carbonization

(23) As can be seen from the table above, the carbonization process has a significant effect on the development of surface area and pore volume, although the size of the pores (as measured by nitrogen adsorbents) remains the same. Also, the density of the carbon with the slower carbonization process was measured to be significantly larger than the other. Consequently, changing processing conditions like the carbonization treatment can be used to determine the density, surface area and pore volume of the final hard carbon produced by the method described in this disclosure. This has implications with respect to end-use applications—specifically for fast-charging LIB devices versus high-capacity devices. As we have indicated earlier, fast charging devices would benefit from a larger surface area anode carbon material, since this facilitates the Li ion intercalation process at the expense of a larger 1st cycle irreversible capacity loss due to a larger SEI formation. Smaller surface area carbons, on the other hand, have a much lower 1st cycle loss (irreversible) due to a smaller SEI. In either case, the method described here can be tuned to produce hard carbons with a range of surface areas.

(24) The methods described by Nishi et al. (U.S. Pat. No. 4,959,281), Imoto et al. (U.S. Pat. Nos. 5,643,426, 56,716,732) and Azuma et al. (U.S. Pat. No. 5,093,216), also utilize furfuryl alcohol but there are significant differences between the instant disclosure and the methods described in the aforementioned patents. Specifically: The most important distinction is that our method described here first polymerizes the furfuryl alcohol into a party solid at room temperature. This is critical, since it affects the nature of the materials formed by all the subsequent heating steps. The processes described in the other patents do not soak at room temperature. The other methods use some form of heating of liquid furfuryl alcohol—which undergoes an exothermic reaction during polymerization and can be dangerous in large scale industrial settings. With a benign room temperature process, no risk of thermal runaway exists. Our method does not require a vacuum distillation step (as described in U.S. Pat. No. 4,959,281). Our method uses only weak solid acids (organic acids), unlike the methods described in U.S. Pat. No. 5,093,216, which uses H.sub.3PO.sub.4 (a toxic and hazardous substance). Our method does not need to reflux-heat the initial furfuryl-alcohol precursor (U.S. Pat. No. 5,093,216 describes reflux heating of the furfuryl-resin water mixture to maintain the pH). Our method involves a long room temperature soak, until a solid is obtained (keeping the manufacturing processes simple). Our method does not require the addition of phosphorous to achieve a d.sub.002 spacing greater than that of graphite (U.S. Pat. Nos. 5,093,216 and 4,959,281 require the presence of phosphorous). The instant method does not use heating under a constant low pressure (˜20 KPa), as described in U.S. Pat. No. 5,716,732.

(25) In another embodiment, the furan-ring containing compound is an acetylfuran. The catalysts used for this precursor include tetrachlorosilane, dichlorosilane, trichlorosilane or dichlorodimethylsilane. In one particular embodiment, 100 ml of acetylfuran (Sigma Aldrich) was mixed with 25 ml of dichlorodimethylsilane (Sigma Aldrich). The mixture was then soaked at room temperature until a pasty solid was obtained. This was heated at 40° C., 87° C., 127° C. and 200° C. under air to complete the polymerization. Carbonization was performed by first soaking the polymerized solid at 360° C. for 4 hours under nitrogen, followed by 4 hours at 800° C. This embodiment is further described in detail in Example 5, below.

(26) We have earlier disclosed methods to make high surface area activated carbons by polymerizing acetylfuran using dichlorodimethylsilane as a catalyst (U.S. Pat. No. 9,458,021). In that case, the polymerized solid was carbonized for 1 hr. at 600° C., with a heating rate close to 10° C./min. In the instant case, we carbonize by first soaking at 360° C. for 4 hours before holding at 800° C. for an additional 4 hours. This is followed by a high temperature calcination treatment and results in the formation of HC with clear d.sub.002 peaks in the XRD pattern and low surface area of ˜100 m.sup.2/gm. PIXE (proton induced x-ray emission) measurements of the Si content of these HCs resulted in 0.24 wt. %. This Si was allowed to remain in the HC as there is not expected to be any deleterious effect in the performance of a LIB anode with embedded Si in the carbon (unlike the Si in the C/Si composites described earlier, the Si in this material is not capable of intercalating Li as it exists as a siloxane in the carbon—U.S. Pat. No. 9,458,021).

(27) HC composites with Si can also be derived from the methods described here. Specifically, in one embodiment, a mixture of oxalic acid (2.5 gm) and maleic acid (5 gm) was added to 100 gm of PFA, along with 8.7 gm of metallic Si powder (<325 mesh, Sigma Aldrich, St. Louis, Mo.). In a variation of this embodiment, the same ratio of organic acids was first dissolved in de-ionized (DI) water before being added to the PFA. In both cases a pasty solid was formed after soaking at room temperature for 24 hours. Further processing was then performed by heating the solid at temperatures between 60° C. and 200° C. to complete the polymerization reaction. The polymerized solid was then carbonized and calcinated as described in the previous embodiments. The final silicon content was measured by PIXE methods to be 12 wt. %. A similar HC/Si composite can be synthesized using furfuryl alcohol instead of PFA. The method described above differs substantially from other methods to make HC/Si composites in that it is simpler (does not involve CVD of Si or C) and involves mixing a solid Si powder with a liquid furan-ring compound (rather than mixing Si and C solids—which will not result in the same level of homogeneous mixing as can be obtained when one of the components is a liquid).

(28) Another material we have used as a source for Si is an aluminosilicate clay mineral, Halloysite. It is a naturally occurring clay mineral with the chemical formula Al.sub.2Si.sub.2O.sub.5(OH).sub.4.nH.sub.2O. It has a nano-tube structure, with a wall thickness of ˜10 aluminosilicate sheets and is ˜10 to 50 nm in diameter. TGA studies of Halloysite show the main weight loss appearing between 450° C. and 700° C., with the peak at 471° C. related to the removal of the structural water. Beyond 700° C., weight loss is negligible up to 1050° C., although a small endothermic peak is seen at 1002° C., associated with the nucleation of mullite [Boordeepong, S., et al., 2011]. The total weight lost when Halloysite is heated up to 1000° C. is ˜15 wt. %. It also has interesting electrochemical properties as has been recently evaluated as an electrolyte-filler in solid-state Li-sulfur battery applications (Lin, Y., et al., 2017). Also, it has been used to make porous carbon micro-particles from furfuryl alcohol—for use as LIB anode materials (Subramaniyam, C. M. et al. 2017). Here, the Halloysite is first etched to remove the alumina, and after several washing steps, the resulting porous tubular silica is mixed with furfuryl alcohol and polymerized. After carbonization, the remaining porous tubular silica is etched away to create porous carbon micro-particles with a BET surface area of 329 m.sup.2/gm. The basic idea here was to use the Halloysite as a template to create a carbon structure that mimics the nano-tubular structure of the Halloysite. We consider a very different approach in our method, by incorporating the Halloysite directly into the HC, without etching it away. Also in our case, the furan-ring precursor compounds are polymerized using organic acid catalysts at room temperature to ensure the formation of a bulk hard carbon with low specific surface area values (<100 m.sup.2/gm), rather than a porous carbon micro-particle structure obtained by Subramaniyam, C. M. et al.

(29) In one embodiment of the invention, 246 gm of PFA (Furolite™ from TransFuran Chemicals, Geel, Belgium) was mixed with 21 gm of a mixture of oxalic acid, maleic acid and tartaric acid, in 1:1:1 molar ratios) and 11 gm of as-received Halloysite powder (Dragonite™ from Applied Minerals, Inc., NY). The mixture was soaked at room temperature until a pasty solid was obtained. This solid was heated at intermediate temperatures of 60° C. to 200° C., under air, to complete the polymerization reaction. Next, carbonization was performed by heating under nitrogen at 800° C. for 4 hours. The heating rate from 360° C. to 800° C. was less 3° C./min. BET measurements resulted in a multi-point specific surface area value of 40.1 m.sup.2/gm. The corresponding pore volume was 0.0216 cc/gm (NLDFT model, using slit pores in carbon). The density of this HC was measured to be 1.51 gm/cc.

(30) Other combinations of catalysts have also been used with PFA and Halloysite. Specifically, we have polymerized 139 gm of PFA with 7 gm of Halloysite using 15 gm of tartaric acid in a solution of DI water. Also, we have polymerized 142 gm of PFA with 7 gm of Halloysite using 5 gm of dry oxalic acid powder. Other combinations including citric acid in DI water solution, formic acid and maleic acid have also been used successfully to polymerize the PFA.

(31) Halloysite was also been successfully added to furfuryl alcohol, which as then polymerized using the organic acid combination. In one embodiment, 105 gm of furfuryl alcohol was mixed with 4.3 gm of Halloysite and polymerized using a combination of oxalic acid, maleic acid and tartaric acid. The polymerized solid was carbonized and characterized using XRD, Raman and BET measurements (see example #6, below).

(32) Finally, HCs made with the method described in this disclosure have also been embedded with transition-metal containing material, such as, but not limited to, Li.sub.4Ti.sub.5O.sub.12 powder (LTO). LTO is a promising anode material for LIB s targeting the electric vehicle market due to its high potential ˜1.55 V (vs. Li/Li+), and its excellent cycle life due to its negligible volume change during charge/discharge cycles. In one embodiment, we have added 23 gm of LTO (MSE Supplies, Tucson Ariz.) to 143 gm of PFA and polymerized this with 3.5 gm of oxalic acid and 7 gm of maleic acid. The LTO had a d50 particle size of 0.8-1.6 micrometers. Polymerization was done by soaking at room temperature, followed by heating at intermediate temperatures between 60° C. and 200° C. The polymerized solid was then carbonized by heating at 800° C. for 4 hours under nitrogen. In another embodiment, 105 gm of furfuryl alcohol was mixed with 17 gm of LTO and polymerized using 4 gm of oxalic acid and 6 gm of maleic acid. In yet another embodiment, we used citric acid in a DI water solution as the catalyst. In another embodiment, oxalic acid in a DI water solution was used as the catalyst to polymerize a mixture of PFA and LTO. Besides transition-metal compounds like LTO (described above), transition metals can also be embedded by themselves in the HCs using this method.

(33) EXAMPLE 1: In this embodiment, 150 ml of furfuryl alcohol (#W249106, from Sigma Aldrich, St. Louis, Mo.) was mixed with 15 gms of organic acids—comprising a mixture of oxalic acid (#75688, from Sigma Aldrich St. Louis, Mo.), maleic acid (#M0375, from Sigma Aldrich St. Louis, Mo.), and L-(+)-tartaric acid (#T109, from Sigma Aldrich St. Louis, Mo.), in weight ratios of 1:1.29:1.66, respectively. The mixture was stirred using an overhead stirrer operating at 100 rpm, for 1.5 hours and then set aside at room temperature (22° C.). During room temperature aging, measurements of the weight of the mixture were periodically made to track the weight loss behavior. As the rate of weight loss approached zero, the mixture formed a pasty solid. At that point, the material was placed in a 120° C. oven, under air. Weight loss was again monitored, and once the rate approached zero, the oven temperature was raised to 200° C. Once again, after the rate of weight loss approached zero, a hard polymerized solid was formed. This material was then carbonized at 800° C., by holding it at temperature for 2 hours under nitrogen. This was performed in a standard quartz tube (50 mm diameter) furnace, using a heating rate of 5° C./min. Finally, a high temperature heat treatment was performed at 1000° C. for 30 minutes to produce the hard carbon.

(34) The hard carbon produced with this method was then characterized using X-ray diffraction (XRD) and Raman spectroscopy. XRD plots were obtained using Cu K.sub.α radiation (operating at 35 kV and 30 mA), in a continuous scan mode. FIG. 3 shows the XRD plot of intensity versus 2theta (from 10° to 70°) for this material (labeled as ‘Example 1’). A d.sub.002 peak is seen at 22.79°, corresponding to 3.90 Å spacing. However, the asymmetrical shape of the d.sub.002 peak suggests more micro-crystalline regions with d.sub.002 spacings greater than this value too (>4 Å—left leg of Example 1's d.sub.002 peak). A smaller peak is also seen at 43.79°. Furthermore, from the measurement of the d.sub.002 peak—full width at half maximum (FWHM)—the size of the individual crystalline domains can be estimated using the Scherrer equation (=K.Math.λ/β.Math.cos θ), where K is a dimensionless shape factor (typically ˜0.9); λ, is the X-ray wavelength; β is the (FWHM) minus the instrumental line broadening, and θ is the Bragg angle. FWHM for the d.sub.002 peak is 7.960°, which results in a micro-crystalline dimension of 1.06 nm. This XRD pattern is—with the d.sub.002 peak around 23° (2θ values) distinguishes this carbon from both amorphous high SSA activated carbons and graphite.

(35) Raman spectroscopy measurements are shown in FIG. 4(a) and were recorded with an inVia Raman Microscope (Renishaw PLC, Gloucestershire, UK) using an excitation wavelength of 785 nm at 100 mW laser power. The ratio of the intensities for the D-band and G-band peaks is best described by using a ratio of the deconvoluted areas under the respective peaks. This was measured to be 1.78, compared to a ratio of 0.113 obtained for graphite (Tianchan, J., et al., 2017).

(36) BET surface area measurements were also made on this carbon using N.sub.2 adsorption at 77K. A QUADRASORB Evo™ Gas Sorption Surface Area and Pore Size Analyzer was used for textural characterization. Before adsorption measurements were made, samples were outgassed at 250° C. for at least 20 hours. The N.sub.2 isotherm (adsorption) is shown in FIG. 5. Multi-point BET surface area was measured to be 110 m.sup.2/gm and pore volume was calculated to be 0.083 cc/gm (using NLDFT theory, assuming slit pores in the carbon). Finally, the tap-density (powder form) of this material was measured to be 1.25 gm/cc.

(37) TABLE-US-00004 TABLE 4 BET data XRD data Raman data Pore (002) d.sub.002 FWHM D G SSA Volume Example Description 2θ (°) (Å) (°) (cm.sup.−1) (cm.sup.−1) I.sub.D/I.sub.G (m.sup.2/gm) (cc/gm) #1 Furfuryl alcohol + 22.79 3.90 7.960  1303*  1599* 1.62 110 0.083 organic acid #2 Furfuryl alcohol + 23.97 3.71 7.488 1352 1604 1.75 2.02 0.0022 organic acid #3 Furfuryl alcohol + 23.58 3.77 7.92 1347 1595 2.15 6.76 0.0043 Furfural + organic acid #4 Poly furfuryl 23.45 3.79 8.010 1337 1603 1.85 6.71 0.0071 alcohol + formic acid #5 Acetylfuran + 23.94 3.71 6.941  1314*  1625* 1.54 105 0.053 dichlorodimethyl silane #6 Furfuryl alcohol + 23.70 3.75 7.799 1351 1598 1.98 20.7 0.019 organic acids + Halloysite #7 PFA + 23.45 3.79 6.323 1341 1603 1.5 277 0.127 Si powder #8 Furfuryl alcohol + — — — — — — 131 0.080 organic acids + LTO *Measured with 785 nm laser (all others with 532 nm laser).

(38) This HC was also tested for electrochemical performance First, it was ball milled to reduce the size to an average of 20 microns for electrode making. Next, a 3-electrode set up was used with a Li/Li+ reference electrode and a Li counter electrode, along with a 1M LiFP.sub.6 EC:DMC electrolyte. Cyclic voltammetry results are shown in FIG. 6 (a), for the 1.sup.st and 10.sup.th cycle, along with capacity versus charge/discharge cycles at different charging rates (‘C’ rates) FIG. 6(b). The 1st cycle in FIG. 6 (a) shows a reaction around 0.6 V believed to be associated with the formation of the SEI layer. From FIG. 6 (b), a large 1st cycle irreversible loss can be seen (from a 1.sup.st cycle capacity of 1194 mAh/gm). This is attributable to the relatively large surface area measured with this HC (110 m.sup.2/gm). However, it is also seen from FIG. 6(b), that the capacity values hold up well as the charging rate is increased—even up to 100 C, implying good fast-charging behavior on the part of this HC. Finally, Li-ion capacitor performance was also evaluated from this 3-electrode set up (along with a counter electrode of commercial activated carbon). The HC electrode characteristics are 1-1.5 mg/cm.sup.2 (mass loading), 40-60 micron thickness and a 1:1 mass ratio for the HC and activated carbon electrode. A typical charge/discharge curve for a charging current of 10 Ampere/gm is shown in FIG. 7 (a), along with long term cycling behavior (2.2V to 3.8V) over 1000 cycles in FIG. 7 (b). This HC was also tested against Na/Na+ reference electrodes for Na-ion battery and capacitor applications. Once again, the large 1.sup.st cycle loss (from 480 mAh/gm) is attributed to the SSA of this HC. These data are also shown in FIG. 6 (b).

(39) In this example we have synthesized a non-amorphous hard carbon with a d.sub.002 spacing of >3.6 Å (in the XRD plot)—from furfuryl alcohol by polymerizing it with organic acids and using carbonizing heat treatments. Additionally, Raman spectra obtained from this carbon are characteristic of non-graphitic carbons. The HC made with this method is suitable for constructing anodes for Li-ion and Na-ion batteries and capacitors.

(40) EXAMPLE 2: In another embodiment, 150 ml of furfuryl alcohol was mixed with 15 gm of oxalic, maleic and tartaric acid (in 1:1:1 molar ratios). The mixture was allowed to soak at room temperature to begin the polymerization process—similar to Example 1. When the rate of weight loss approached zero, the mixture had formed a pasty solid. It was then heated in an oven at 60° C., under air, for 24 hours. This was followed by heating at 120° C. under air for 24 hours, and for an additional 24 hours at 200° C., to form a hard polymerized solid. This material was then carbonized at 800° C. under nitrogen for 4 hours. A heating rate of ˜1.5° C./min was used. Finally, a calcination treatment at 1000° C. was performed for 30 mins.

(41) The XRD plot of this HC is shown in FIG. 3. A d.sub.002 peak is seen at 23.97°, corresponding to 3.71 Å spacing. As with Example 1, the asymmetrical shape of the d.sub.002 peak suggests more micro-crystalline regions with d.sub.002 spacings greater than this value too. The FWHM for this peak is measured to be 7.488°. Raman spectroscopic measurements of this material were obtained with a Renishaw inVia Raman microscope (with a 532 nm laser source). Plots are shown in FIG. 4(b). Once again a pronounced D-band peak can be seen—indicating the presence of a non-graphitic hard carbon structure. The ratio of the intensities for the D-band and G-band peaks was calculated based on the area of the two deconvoluted peaks to be 1.75.

(42) N.sub.2 adsorption isotherms were measured on a Quantachrome NovaTouch LX2 instrument, and are shown in FIG. 5 (adsorption only). Specific surface area and pore volumes (NLDFT, slit pores) were also obtained (data shown in Table 4). The surface area measured for this HC was 2.018 m.sup.2/gm, along with a pore volume of 0.0022 cc/gm.

(43) The main difference between this HC and that from Example 1 is the dramatic difference in surface area (˜110 m.sup.2/gm versus ˜2 m.sup.2/gm). This is attributed to the change in processing conditions, specifically the additional heating step at 60° C. during polymerization, the longer carbonizing and slower heating rate—in the case of Example 2. Changes in the XRD characteristics are also observed with the additional heat treatments of Example 2 resulting in a smaller d.sub.002 spacing, and a sharper peak (smaller FWHM).

(44) Given the low SSA values for Example 2, LIB anodes made for this HC would then be expected to result in a much smaller 1st cycle irreversible capacity loss, due to a smaller SEI layer formation associated with the much smaller surface area of this HC. Clearly, control of the heat treatment parameters—after initial room temperature polymerization—will control the final properties of these HCs—in particular the specific surface area obtained from these different heat treatments.

(45) EXAMPLE 3: In a further embodiment, 115 gm of furfuryl alcohol was mixed with a total of 11.5 gm of oxalic, maleic and tartaric acid (in 1:1:1 molar ratios). Next, 11 gm of furfural (#185914, from Sigma Aldrich, St. Louis, Mo.) was stirred into the mixture. This was allowed to polymerize by soaking at room temperature till it formed a pasty solid. This was then heated at intermediate temperatures between 60° C., and 200° C., all under air, to form a hard polymerized solid. Next, the polymerized solid was carbonized by heating it up to 800° C. for 4 hours under an inert atmosphere (nitrogen was used).

(46) The carbon formed from this process was also evaluated using the same tools as before (XRD, Raman and BET). The XRD plot is shown in FIG. 3, with the d.sub.002 peak at 23.58°, corresponding to a spacing of 3.77 Å, indicating the presence of a hard carbon. The FWHM of this peak was measured to be 7.92°. Raman spectra (FIG. 4(a)) also show a large d-band peak, indicating the presence of non-graphitized hard carbon. The ratio of the intensities of the D and G peaks (deconvoluted areas under the peak) was calculated to be 2.15. The N.sub.2 isotherm (adsorption) from the BET testing is shown in FIG. 5. The SSA calculated for this HC was 6.76 m.sup.2/gm, along with a pore volume of 0.0042 cc/gm (NLDFT, slit pores). This example shows a combination of two furan-ring containing compounds—furfuryl alcohol and furfural—that was synthesized with an XRD d.sub.002 peak of >3.6 Å and a large D-band peak—indicating the presence of a non-amorphous, non-graphitic hard carbon. This HC example also had a very low specific surface area—suitable for high energy Li-ion and Na-ion batteries and capacitors.

(47) EXAMPLE 4: In yet another embodiment, 100 gm of a poly furfuryl alcohol, (FUROLITE™ from TransFuran Chemicals, Geel, Belgium) was mixed with 10 gm of formic acid. The mixture was then soaked at room temperature for 24 hours before being heated at temperatures between 60° C. and 200° C., under air, to form a solid polymer material. The solid polymer was then carbonized by first heating at 360° C., followed by a 2 hour treatment at 800° C. under an inert atmosphere (nitrogen was used). XRD and Raman data are shown in FIGS. 3 and 4(b), respectively; and the specific values are shown in Table 4. XRD measurements show the d.sub.002 peak at 23.45°, corresponding to a spacing of 3.79 Å. The FWHM is measured to be 8.01°. These data are very similar to the XRD data obtained from Example 3. Raman spectra (with a 532 nm laser) also show a large prominent D-band peak centered at 1337 cm.sup.−1. The ratio of the integrated area under the curves is measured to be 1.85. N.sub.2 isotherms from the BET data are shown in FIG. 5. The specific surface area for this HC was measured to be 6.71 m.sup.2/gm, along with a pore volume of 0.0071 cc/gm (NLDFT, slit pores).

(48) Here we show that PFA can also be used as the precursor material to make a carbon with an XRD d.sub.002 spacing of >3.6 Å and a large Raman D-band peak—indicating the presence of a non-amorphous, non-graphitic hard carbon using the method described in this disclosure. The corresponding BET data also show a very low surface area value of 6.7 m.sup.2/gm, suitable for high energy Li-ion and Na-ion batteries and capacitors.

(49) EXAMPLE 5: In yet another embodiment, 100 ml of 2-Acetylfuran—C.sub.6H.sub.6O.sub.2-(#W316318 from Sigma Aldrich, St. Louis, Mo.) was mixed with 25 ml of dichlorodimethylsilane—C.sub.2H.sub.6Cl.sub.2Si—(#440272 from Sigma Aldrich, St. Louis, Mo.) at room temperature and stirred for 60 minutes. The mixture was then allowed to soak at room temperature under air. Once the rate of weight loss approached zero, the material was heated at 40° C. under air for 24 hours, at 87° C. for 23 hours, at 120° C. for 24 hours, and at 200° C. for 24 hours. Next it was baked at 360° C., under air for 4 hours. Very slow heating rates were used (1.25° C./min, in this case), followed by carbonization at 800° C. for 4 hours, under nitrogen. The carbonized material was then subjected to a high temperature treatment at 950° C., under CO.sub.2 for 100 mins followed by a calcination step at 1025° C. for 60 minutes under nitrogen. XRD, Raman and N.sub.2 isotherm (BET) data are shown in FIGS. 3, 4(a) and 5, respectively. The data are presented in Table 4. This HC was also evaluated for chemical composition using the PIXE (proton-induced x-ray emission) method. No chlorine was found in the HC, although a 0.24 at. % concentration of Si was measured. Raman spectra were gathered with a 785 nm laser (similar to Example 1). Once again, the presence of a d.sub.002 peak in the XRD data, and the presence of a large D-band peak are characteristic of a non-amorphous, non-graphitic hard carbon.

(50) This HC was also used in a 3-electrode set up to evaluate electrochemical performance against Li/Li+ and Na/Na+ reference electrodes (similar to the data presented in Example 1). The methods described in Example 1 were used. The capacity versus charge/discharge cycles plot—for different ‘C’ rates (up to 100 C)—is shown in FIG. 8. These are very similar to the values obtained with Example 1, and show good performance under high charging rates—up to 100 C, although a large 1.sup.st cycle loss is also seen (from 971 mAh/gm for Li/Li.sup.+, and from 420 mAh/gm for Na/Na.sup.+). This irreversible loss can be attributed to the SSA of this HC. As seen from Table 4, the specific surface area values between Example 1 and 5 are similar, but there is some difference in the XRD and Raman data. In this example, we have fabricated a non-amorphous hard carbon from acetylfuran, by polymerizing it with a strong acidic catalyst from the silane group (specifically dimethyldichlorosilane). By controlling the carbonization treatments (temperature, time, heating rate), the properties of this HC can also be changed (similar to the HCs for furfuryl alcohol). This intermediate surface area (˜100 m.sup.2/gm) HC is also suitable for fast charging Li-ion and Na-ion batteries and capacitors.

(51) EXAMPLE 6: In yet another embodiment, we have mixed 105 gm of furfuryl alcohol (# from Sigma Aldrich, St. Louis, Mo.) with 10.5 gm of a mixture of oxalic acid, maleic acid and tartaric acid (in 1:1:1 molar ratios), along with 4.3 gm of Halloysite (Dragonite™ from Applied Minerals, Inc., New York, N.Y.) at room temperature. The Halloysite was first heated under air up to 750° C. to remove its structural water. As discussed earlier, the DTA data show that Halloysite undergoes a weight change (accompanied by an endothermic reaction) between 450° C. and 700° C. Beyond that temperature, further weight loss is negligible. Hence we have chosen 750° C. as the maximum temperature of treatment of the as-received Halloysite. The mixture was allowed to soak at room temperature, and once a pasty solid was formed, it was then heated at intermediate temperatures between 60° C. and 200° C., under air, to form a hard polymer. The polymer material was then carbonized under N.sub.2 at 800° C. for 4 hours. XRD, Raman and N.sub.2 isotherm (BET) data are shown in FIGS. 3, 4(b), and 5, respectively. The data are also presented in Table 4.

(52) A strong d.sub.002 peak is seen in the XRD data, with a 2theta value of 23.7° corresponding to a d-spacing of 3.75 Å. No other peaks are seen in the XRD, signifying that the original nano-tubular structure of Halloysite (with its typical XRD pattern showing several characteristic peaks) has been altered into an amorphous state by the heating profile (up to 1000° C.). The Raman spectrum also shows a strong D-band peak, indicating a non-graphitic carbon. A BET surface area of ˜20 m.sup.2/gm is obtained and this can be further adjusted by controlling the polymerization and carbonization heating profiles. Finally, X-ray photoelectron spectroscopy (XPS) measurements on this HC showed the presence of Al and Si in the following ratios: Al.sub.2p—with a peak at 74.65 eV, at 1.85 at. %; and Si.sub.2p—with a peak at 103.39 eV at 1.72 at. %. Since all the major characteristics are similar to those discussed in the previous examples, it is expected that this HC will also perform similarly in Li-ion and Na-ion batteries and capacitors.

(53) EXAMPLE 7: In yet another embodiment, a HC/Si composite is synthesized from PFA. Specifically, 100 gm of PFA (FUROLITE™, from Transfuran Chemicals bvba, Geel, Belgium) was mixed with 8.26 gm of −325 mesh metallic silicon powder (#215619, from Sigma Aldrich, St. Louis, Mo.), 5 gm of maleic acid and 2.5 gm of oxalic acid. The mixture was allowed to soak at room temperature until a pasty solid was formed, followed by heat treatment at temperatures between 60° C. and 200° C., under air, to form a hard solid polymer. The polymer was then carbonized at 800° C. for 4 hours under nitrogen, followed by a calcination treatment at 1000° C., also under nitrogen. XRD, Raman and N.sub.2 isotherm (BET) data are shown in FIGS. 9, 4(b), and 5, respectively. The data are also presented in Table 4. Additionally, this HC was tested for Si content using the PIXE method (proton induced X-ray emission). PIXE measurements resulted in a 12.6 wt. % Si content. The XRD pattern in FIG. 9 clearly shows the presence of metallic Si, although the d.sub.002 peak of the HC is also visible at 23.45°, corresponding to a d-spacing of 3.79 Å. The D-band peak in the Raman spectra also confirms the non-graphitic nature of this carbon. The addition of the Si powder results in a BET SSA value of 277 m2/gm. However, the poly furfuryl alcohol is still polymerized and carbonized into a non-amorphous hard carbon with an XRD d.sub.002 spacing of >3.6 Å.

(54) EXAMPLE 8: In this embodiment, 105 gm of furfuryl alcohol (#W from Sigma Aldrich, St. Louis, Mo.) was mixed with 17 gm of L.sub.4Ti.sub.5O.sub.12 (LTO, from MSE Supplies, Tucson, Ariz.), 4 gm of oxalic acid and 6 gm of maleic acid. Mixing was performed using an overhead stirrer to ensure a homogeneous mixture. The mixture was allowed to soak at room temperature till a pasty solid was formed. Next, it was heated at temperatures between 60° C. and 200° C., under air, until a hard solid polymer was formed. Carbonization was done by heating at 800° C. for 4 hours under nitrogen. The N.sub.2 isotherm (BET) data for this carbon is shown in FIG. 5. A specific surface area of 131 m.sup.2/gm was measured for this HC, along with a pore volume of 0.0804 cc/gm. In this example we have shown that a non-amorphous hard carbon with embedded LTO material can be synthesized from furan-ring compounds by polymerizing with an organic acid catalyst—in the presence of the LTO dispersed in the precursor.

(55) In this disclosure, we have described a process to synthesize non-graphitized, hard carbons from furfuryl-functional group containing precursors. The process involves mixing the ingredients and heating them under air, initially, followed by higher temperature heating under an inert atmosphere. This is overall a much simpler process than any previously described method to make hard carbons from furan-based precursors. Furthermore, we have shown that combinations of furan compounds can also be used, including furfuryl alcohol and furfural. Poly furfuryl alcohol resins are also a suitable precursor for this method, as is acetylfuran. We have also synthesized non-amorphous hard carbons with Si and LTO—both good LIB anode materials on their own. Based on results obtained from XRD, we have shown that the d.sub.002 peaks for all these HCs are generally above 3.6 Å, with most of them being >3.7 Å (a feature that is unique to hard carbons, and not activated carbons or graphite). From the Raman spectroscopy results we have shown that in all cases, there is a strong and prominent D-band peak, also signifying the presence of hard carbon. From the BET results we can identify the key processing parameters that affect the final BET surface area of the HCs. These parameters have been identifies as the polymerization and carbonization temperatures, and the heating rates. Finally, we have also shown that the HC synthesized using the methods described here are suitable for LIB and LIC anodes. We have tested two version of the HC with BET surface area of ˜100 m.sup.2/gm and found excellent capacity when high charging currents are used (up to 100 C rates). This indicates good performance by these carbons for fast charging applications, including good cycle life. We have also shown HCs with BET SSA values as low as 2 m.sup.2/gm—synthesized from the same materials—using different processing parameters (specifically heat treatments). These low SSA HCs can overcome the high 1st cycle irreversible loss shown by the HC tested in example 1, and would also be suitable for high energy LIB devices.

(56) Furthermore, we have synthesized HCs with embedded Si (in metallic Si powder form, and in the form of a Si compound—Halloysite). While the BET SSA increased with the HC/Si composite, the Raman and XRD data still indicate good potential for energy storage applications in LIB and LIC devices. Finally, we have also synthesized HCs with embedded LTO, which is also a promising anode material.

(57) This application is not limited to particular methodologies or the specific compositions described herein, and as such, may vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting, since the scope of the present application will be limited only by the appended claims and their equivalents.