Abstract
The present invention relates to an electrode material comprising at least one sulfur-limonene sulfide component or a composite of the sulfur-limonene sulfide component with a first conductive component; electrodes, in particular cathodes, containing the electrode material; half-cells, cells, and batteries containing the electrodes; and processes for obtaining the electrode material, the electrode, the half-cell, the cell, and the battery comprising electrode material and/or electrodes of the present invention.
Claims
1. (canceled)
2. An electrode comprising: an electrode material, the electrode material comprising at least one of: a sulfur-limonene sulfide component and a composite of the sulfur-limonene sulfide component with a first conductive component, and wherein the electrode material is applied to a current collector.
3. (canceled)
4. The electrode according to claim 2, wherein the electrode material comprises at least one of: sulfur-limonene polysulfide (SLP), and a polymeric sulfur-limonene disulfide structure.
5. The electrode according to claim 4, wherein the polymeric sulfur-limonene disulfide structure is at least one of: a lithium-sulfur-limonene disulfide structure, and elemental sulfur-limonene disulfide structure.
6. The electrode according to claim 4, wherein the composite of the sulfur-limonene sulfide component with the first conductive component comprises SLP with the first conductive component having a SLP content by weight selected from the ranges of: from 50 to 95%, from 65 to 80%, from 70 to 75%, and from 72 to 73%; wherein the SLP content by weight is based on overall weight of the composite of the SLP with the first conductive component.
7. The electrode according to claim 4, wherein the composite of the sulfur-limonene sulfide component with the first conductive component has a content of a polymeric sulfur limonene disulfide structure by weight selected from the ranges of: from 50 to 95%, from 65 to 80%, from 70 to 75%, and from 72 to 73%, wherein the content by weight is based on overall weight of the composite of the polymeric sulfur-limonene disulfide structure with the first conductive component.
8. The electrode according to claim 2, wherein the first conductive component is at least one of: conductive carbon, porous metal oxide, porous metal sulfide, porous metal hydroxides, and conductive polymer.
9. The electrode according to claim 2, wherein the electrode material comprises at least one of: least one binder, and at least one second conductive component.
10. The electrode according to claim 9, comprising at least one second conductive component and at least one binder, in a weight ratio of 80 to 90 of the electrode material 1 to 10 of the second conductive component: 5 to 15 of the at least one binder.
11. The electrode according to claim 2, wherein the electrode is a free-standing electrode consisting of a composite of the sulfur-limonene sulfide component with the first conductive component.
12. (canceled)
13. (canceled)
14. A battery comprising at least one electrode according to claim 2.
15. A process for preparing a composite of a sulfur-limonene polysulfide (SLP) with a first conductive component, comprising the following process steps: providing a sulfur-limonene polysulfide (SLP) and a first conductive component, contacting the sulfur-limonene polysulfide (SLP) with the first conductive component at an elevated temperature from 100° C. to 200° C. for 3 to 5 hours, and obtaining the composite of the sulfur-limonene polysulfide (SLP) with the first conductive component.
16. A process for preparing an electrode material, comprising the following steps: providing at least one of a sulfur-limonene sulfide component, and a composite of the sulfur-limonene sulfide component with a first conductive component, and further providing at least one of a second conductive material and a binder, contacting the sulfur-limonene sulfide component, or the composite of the sulfur-limonene sulfide component, with the first conductive component, with at least one of the second conductive material and the binder, a weight ratio of (80 to 90):(1 to 10):(5 to 15), and obtaining the electrode material.
17. A process for preparing the battery according to claim 14, comprising the following process steps: providing an electrode according to claim 2, a second electrode, a separator, and, optionally at least one additive selected from the group consisting of, an electrolytic solvent, a salt, and an electrolyte, and assembling them to provide a battery.
18. The process according to claim 17, wherein subsequent to the step of assembling the battery is subjected to an activation process.
19. (canceled)
20. (canceled)
21. The electrode of claim 2, wherein the electrode is a free-standing sulfur-limonene polysulfide-electrode consisting of a composite of a sulfur-limonene sulfide component with a first conductive component, wherein the first conductive component is a free-standing first conductive component comprised of at least one of: carbon sheets, graphene sheets, carbonized polymer sheet, CNT papers, carbonized cellulose films, carbonized paper, and carbonized porous cellulose paper.
22. The electrode of claim 2, wherein the electrode is for a lithium sulfur battery.
23. The electrode according to claim 10, wherein the at least one second conductive component and at least one binder are present in a weight ratio of 85 of the electrode material: 5 of the second conductive component: 10 of the at least one binder.
24. The process of claim 15, wherein the step of contacting the sulfur-limonene polysulfide (SLP) with the first conductive component at an elevated temperature from 100° C. to 200° C. comprises contacting the sulfur-limonene polysulfide (SLP) with the first conductive component at an elevated temperature from 120° C. to 180° C.
25. The process of claim 16, wherein the step of contacting the sulfur-limonene sulfide component, or the composite of the sulfur-limonene sulfide component with the first conductive component, with at least one of the second conductive material and the binder, in a weight ratio of (80 to 90):(1 to 10):(5 to 15), comprises contacting the sulfur-limonene sulfide component, or the composite of the sulfur-limonene sulfide component with the first conductive component, with at least one of the second conductive material and the binder, in a weight ratio of 85:5:10
26. The process of claim 17, wherein the second electrode is a lithium electrode.
Description
[0133] The present invention is further explained by way of the following examples and the accompanying figures.
[0134] The Figures show:
[0135] FIG. 1 Chemical synthesis of sulfur-limonene polysulfide (SLP).
[0136] FIG. 2a The .sup.1H NMR spectra of D-limonene and sulfur-limonene polysulfide (SLP).
[0137] FIG. 2b The X-ray diffraction patterns of commercial sulfur powder and sulfur-limonene polysulfide (SLP).
[0138] FIG. 3 Raman spectrum (a) and IR spectrum (b) of produced sulfur-limonene polysulfide (SLP).
[0139] FIG. 4 Preparation of a composite of the sulfur-limonene polysulfide (SLP) with carbon black as first conductive component.
[0140] FIG. 5 Preparation of a composite of the sulfur-limonene polysulfide (SLP) with carbon nanotube as first conductive component.
[0141] FIG. 6a Preparation of a composite of the sulfur-limonene polysulfide (SLP) with porous carbon as first conductive component by melt infiltration to obtain SLP which is nano-confined in the porous carbon.
[0142] FIG. 6b BET surface area decrease after successful infiltration of SLP within CS.
[0143] FIG. 7 Preparation of a composite of the sulfur-limonene polysulfide (SLP) with graphene as first conductive component.
[0144] FIG. 8 Preparation of a composite of the sulfur-limonene polysulfide (SLP) with porous carbon sheets as first conductive component by melt-infiltration to form a free-standing flexible carbon paper-SLP electrode.
[0145] FIG. 9 SEM images of (a) carbonized cellulose film and (b) carbonized cellulose film with loading of sulfur-limonene polysulfide (SLP).
[0146] FIG. 10 Electrochemical performance of Li—S batteries based on sulfur-limonene polysulfide (SLP) electrodes.
[0147] FIG. 11 Electrochemical performance of Li—S batteries based on sulfur-limonene polysulfide (SLP) electrodes.
[0148] FIG. 12 The change of discharge/charge voltage profiles of a carbon paper-based sulfur-limonene polysulfide (SLP) cathode at a rate of C/2 over 100 cycles.
[0149] FIG. 13 Long-term cycle stability and coulombic efficiency of a free-standing carbon paper-SLP electrode.
[0150] FIG. 14 Electrochemical performance of Li—S batteries based on sulfur-limonene polysulfide (SLP) electrodes (CS-SLP and CB-SLP) and conventional electrodes based on sulfur with carbon spheres (CS-S).
[0151] FIG. 15 Ex-situ XRD (a) and STEM (b j) studies of phase change and nanostructure evolution of sulfur-limonene polysulfide (SLP) during first cycle.
[0152] FIG. 16 A schematic illustration of the irreversible conditioning (activation) of sulfur-limonene polysulfide (SLP) and the subsequent reversible redox reaction of sulfur-limonene disulfide.
[0153] FIG. 17a Cycling performance and coulombic efficiency of CS-S cathode (for the purpose of comparison) at a rate of C/2 using as electrolyte 0.5 M LiTFSI with LiNO.sub.3.
[0154] FIG. 17b The initial discharge/charge voltage profile of CB-S cathode at C/10 in the electrolyte comprising 0.5 M LiTFSI without LiNO.sub.3.
[0155] FIG. 18 Discharge/charge voltage profiles of CS-SLP cathode at various C-rates from C/10 to 5C are shown in (a). Long-term cycle stability and coulombic efficiency of produced CS-SLP electrode with mass loading of 3.4 mg.sub.SLP/cm.sup.2 over 250 cycles at C/2 are shown in (b).
[0156] FIG. 19 The initial two discharge/charge voltage profiles of free-standing carbon paper-based SLP cathode at C/10 are shown.
[0157] FIG. 20 Free-standing carbon paper-based SLP electrodes: cycling performance at a rate of C/2 using different mass loadings from 2.4 to 7.0 mg.sub.SLP/cm.sup.2 over 100 cycles.
[0158] FIG. 21 HAADF-STEM micrograph of (a) fresh SLP and EDS elemental (b) C-K, (c) S-K and (d) their overlapped maps.
[0159] FIG. 22 Overlapped C-K (FIG. 15i) and S-K (FIG. 15j) EDS elemental maps corresponding to HAADF-STEM image of charged SLP in FIG. 15h.
EXAMPLE 1
Synthesis and Preparation of a Battery of the Present Invention
[0160] 1.1 Synthesis of sulfur-limonene polysulfide (SLP): FIG. 1 shows the chemical synthesis of sulfur-limonene polysulfide (SLP) and its characterizations, in particular of a one-pot synthesis of sulfide-limonene polysulfide (SLP) using D-limonene and sulfur as raw materials (inset photos are showing the low-cost and abundant of raw materials, and the large-scale of this chemical synthesis).
[0161] Sulfur (5-50 grams) was added to a beaker or glass vial equipped with a stir bar and heated to 175° C. in an oil bath. Under vigorous stirring, the sulfur was observed to melt and change from a yellow liquid to a dark orange liquid over several minutes. Then, the limonene (5-50 grams) was added into molten sulfur slowly and the two-phase mixture was stirred vigorously for another 4 hours forming dark red material. After above reaction, the dark red material was transferred to vacuum oven for drying under vacuum at 100° C. for 12 hours to form final product of SLP. In this one-pot reaction, the mass ratio between sulfur and limonene is one to one.
[0162] Heating elemental sulfur (eight-membered ring: S.sub.8) to 175° C. results in S.sub.8 ring opening and subsequent polymerization to form linear and polymeric sulfur chains of high molecular weight. Then, D-limonene was oxidized by polymeric sulfur forming SLP with long S—S chains. The by-products of this reaction including p-cymene, thiol and sulfide were volatilized during reaction and vacuum drying, leaving a red wax or rubber-like material depending on its sulfur content. Owing to this simple synthesis route, SLP can be produced from these inexpensive and abundant starting materials on a large scale (FIG. 1 refer to 10-100 g in lab experiments). The .sup.1H NMR spectrum between D-limonene and SLP in FIG. 2a indicates oxidation of limonene via emergence of aromatic signals and therefore reveal the successful synthesis of the sulfur-limonene polysulfide (SLP). Clear evidence of the above reaction is also provided by XRD studies (FIG. 2b) revealing an amorphous SLP phase and absence of any crystalline sulfur phase. The broad and strong peak at 475 cm.sup.−1 in the Raman spectrum in FIG. 3 (a) can be explained by the symmetric and asymmetric stretching modes of the S—S bond. The IR spectrum in FIG. 3 (b) confirms the emergence of aromatic rings, as well as the appearance of C—S and S—S bonds. Combustion analysis indicates an elemental composition of 4.9% H, 36.1% C, and 59% S, corresponding to two limonene units (C.sub.20) owning twelve sulfur atoms (S.sub.12).
1.2 Preparation of Carbon-SLP Composites:
[0163] In terms of ion-S, preferably Li—S, batteries, SLP offers excellent universality as to the combination with various carbon phases including commercial carbon black, porous carbons, free-standing flexible carbon films or graphene sheets. Here, commercial carbon black (CB), porous carbon sphere (CS) and free-standing carbon paper carbonized by cellulose films were selected as examples to study electrochemical performances of cathodes with and without SLP-nanoconfinement (FIGS. 4, 5, 6a, 7 and 8). Appropriate amounts of sulfur-limonene polysulfide (SLP) and a first conductive carbon, preferably selective conductive carbon powders, were mixed at 160° C. in the vial for 4 hours. The final amounts of sulfur-limonene polysulfide (SLP) content in composites was calculated from the mass increase of the conductive carbon before and after preparation. Commercial carbon black (Alfa Aesar, carbon black, Super P, metals basis, >99%, Germany) and porous carbon spheres were used. The amounts of sulfur-limonene polysulfide (SLP) contents in carbon black and carbon sphere were 75% and 72%, respectively.
[0164] FIG. 4 shows the preparation of a composite of the sulfur-limonene polysulfide (SLP) with carbon black as first conductive component. Schematic of preparing SLP-carbon composites including commercial carbon black (CB): SEM images show the examples of the carbon black (middle) and carbon black/sulfur-limonene polysulfide (CB-SLP) composite (right). In a typical synthesis, appropriate amounts of SLP and carbon black powders were mixed at 160° C. in the vial for 4 hours. The final SLP content in composites was calculated from the mass increase of the conductive carbon before and after preparation.
[0165] FIG. 5 shows the preparation of a composite of the sulfur-limonene polysulfide (SLP) with carbon nanotube as first conductive component. Schematic of preparing SLP-carbon composites including carbon nanotube (CNT): SEM images show the examples of the CNT (middle) and CNT/sulfur-limonene polysulfide (CNT-SLP) composite (right). In a typical synthesis, appropriate amounts of SLP and carbon nanotube powders were mixed at 160° C. in the vial for 4 hours. The final SLP content in composites was calculated from the mass increase of the conductive carbon before and after preparation.
[0166] FIG. 6a shows a schematic of preparing SLP-carbon composites including highly porous carbon hosts as first conductive component by simple molten mixing/infiltration. Furthermore, the Figure is showing a high universality of SLP in various carbon hosts by a simple approach. SEM images show the examples of the carbon spheres before and after SLP infiltration. EDS elemental mapping results show the success SLP infiltration of SLP in porous carbon spheres. In a typical synthesis, appropriate amounts of SLP and selective conductive carbon powders were mixed at 160° C. in the vial for 4 hours. The final SLP content in the composites was calculated from the mass increase of the conductive carbon before and after preparation. Porous carbon spheres were used.
[0167] Large decrease of BET surface area after infiltration (FIG. 6b) further indicated successful infiltration of SLP within CS. To be flexible electrodes, SLP was also easily loaded through molten infiltration/soak within porous carbon films forming free-standing electrodes (FIG. 8).
[0168] FIG. 7 shows the preparation of a composite of the sulfur-limonene polysulfide (SLP) with graphene as first conductive component. Schematic of preparing SLP-carbon composites including graphene: SEM images show the examples of the graphene (middle) and graphene/sulfur-limonene polysulfide (graphene-SLP) composite (right). In a typical synthesis, appropriate amounts of SLP and graphene powders were mixed at 160° C. in the vial for 4 hours. The final SLP content in composites was calculated from the mass increase of the conductive carbon before and after preparation.
1.3 Preparation of Free-Standing Sulfur-Limonene Polysulfide (SLP) Electrodes:
[0169] The free-standing carbon paper used as first conductive component was generated by carbonization of porous cellulose paper at 600° C. for 4 hours with the heating rate of 1° C./min. Then, the carbon paper soaked molten SLP at 160° C., and the mass of SLP on the carbon paper was measured before and after the soak.
[0170] FIG. 8 shows the preparation of a composite of the sulfur-limonene polysulfide (SLP) component with porous carbon sheets as first conductive component through melt-infiltration to form a free-standing carbon paper-SLP electrode. Schematic for fabricating free-standing electrodes using sulfur-limonene polysulfide and porous carbon sheets through melt-infiltration. Digital photos show the example of the produced free-standing electrodes using carbonized cellulose sheets.
[0171] FIG. 9 shows SEM images of (a) carbonized cellulose film and (b) carbonized cellulose film with loading of sulfur-limonene polysulfide (SLP).
1.4 Cathode Preparation:
[0172] Powder of the composite SLP with carbon was mixed with carbon black as a second conductive component (Alfa Aesar, carbon black, super P, metals basis, >99%, Germany) and Carboxymethyl cellulose (MTI, CMC binder, USA) as binder at the weight ratio of 85:5:10 in water with several drops of ethanol to adjust the wetting properties to form a thin slurry. Then the slurry was cast on a battery grade A1 foil via doctor-blade technique. After drying the cathode sheets at 60° C. for 12 h under vacuum, circular samples with a diameter of 1.0 cm were punched for electrochemical tests in CR2032 coin cells.
1.5 Coin Cell Assembly:
[0173] The free-standing SLP cathodes prepared according to section 1.4 were directly used for cell-assembly. Coin cells were assembled with a 0.5M lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt solution in distilled dimethoxyethane (DME):1,3-dioxolane (DIOX) (1:1, v:v) with and without 1 wt % of LiNO.sub.3 (Alfa Aesar, anhydrous, 99.99%, USA) additive as electrolyte. Celgard2400 (Celgard, USA) was used as a separator and pure Li foil anode as a counter electrode in half-cells. The cells were equilibrated for 24 h before operation.
EXAMPLE 2
[0174] Performance of batteries of the present invention
2.1 Electrochemical Measurements:
[0175] The coin-cells of section 1.5 assembled inside an Ar glovebox (<0.2 ppm of H.sub.2O, <0.6 ppm of O.sub.2, Mbraun, Unilab, Germany) were charged and discharged over a voltage range of 1.6-2.8 V versus Li/Li+ for the electrochemical test under room temperature by using Arbin battery test system (Arbin Instruments, USA) and Neware system (Shenzhen, China). The cells were active at small C-rates and then the cycle durability test was continued at C/2. The specific capacities were calculated based on the mass of sulfur in SLP.
2.2 Materials Characterization
[0176] Powder X-ray diffraction (Rigaku D/max-2550V) using Cu-Kα radiation was employed to identify the crystalline phase of the nanocomposite. SEM micrographs have been collected on a field-emission LEO microscope (Zeiss, Germany) at a working distance of 3-6 mm and an accelerating voltage of 2-3 kV. HAADF-STEM imaging combined with EDX measurements were carried out at 60 kV with an advanced analytical TEM/STEM (JEOL ARM200F, JEOL Co. Ltd.), equipped with a cold field-emission gun and a DCOR probe Cs-corrector (CEOS Co. Ltd.). EDX spectra and elemental maps were obtained by using a 100 mm.sup.2 JEOL Centurio SDD-EDX detector and the Thermo Noran System 7 EDX system (Thermo Fisher Scientific Inc.). The free-standing SLP electrodes according to section 1.3 without any binder and carbon black cycled at C/10 were used for XRD and TEM studies.
2.3 Results
[0177] In order to evaluate the electrochemical performance of SLP-based cathodes, cells were measured in both 0.5M LiTFSI electrolytes (note that it is referred to the inexpensive low-concentration electrolytes) without and with LiNO.sub.3 additive (FIGS. 14 and 11). Both SLP with carbon black (CB-SLP) and SLP with carbon spheres (CS-SLP) show high discharge capacities of ˜790 and 880 mAh g.sup.−1 at C/2, respectively, and this with unprecedented cycling stability in both electrolytes. No significant degradation (less than 3-5%) is observed even after 200 cycles as demonstrated in FIGS. 14 and 11. In addition, by passivating the Li metal anode using the LiNO.sub.3 additive, the coulombic efficiency (CE) is stable and close to 100% in both CB-SLP and CS-SLP cells (FIG. 11). FIG. 10 displays the rate capability of the CS-SLP cathode for different (dis)charge rates. At C/10 the cell exhibits a capacity as high as ˜1160 mAh g.sup.−1. Even at 5C, a capacity of 510 mAh g.sup.−1 remains. These high capacities remain essentially unchanged when returned to low current densities, with very good rate capability, excellent capacity retention, and a very high CE (>99.5%) for all currents used (FIG. 10). The details of discharge and charge curves using the CS-SLP composite electrodes at different C rates are evident from FIG. 18(a). For the purpose of demonstrating the application potential, additional cycling tests were conducted using CS-SLP cathodes with higher mass loadings (˜3.4 mg.sub.SLP/cm.sup.2). As depicted in FIG. 18(b), the cell showed a discharge capacity of ˜810 mAh g.sup.−1 at C/2, and excellent cycling performance in 250 cycles with no capacity degradation.
[0178] In order to avoid the use of binders and heavy metal foil current collectors, free-standing SLP-based electrodes with demonstrated mass loadings in the range from 2.4 to 7.0 mg.sub.SLP cm.sup.−2 were explored by low-cost carbonized natural biomass sheets through a simple carbonization. The produced cathodes show 1st discharge and charge capacities of up to ˜1454 and ˜1494 mAh g.sup.−1s at C/10 (FIG. 19), respectively, characterized by a very high 1st CE of ˜98% and a small voltage hysteresis of ˜0.15V. In turn, the 2nd cycle shows a discharge capacity of ˜1447 mAh g.sup.−1, indicating absence of a significant irreversible capacity between the initial two cycles. Then, the cell was continuously cycled for 100 times at C/2 (FIG. 12). Neither visible changes nor perceptible polarization occurs, and only minimal fading is observed in all the discharge and charge curves within 100 cycles. FIG. 13 shows longer-term cycling stability data of free-standing sheets with a mass loading of ˜3.0 mg cm.sup.2. Such cell provides a high (initial) discharge capacity of 956 mAh g.sup.−1 at C/2, and retains a capacity of 932 mAh g.sup.−1 at 300th cycle, with a capacity retention of ˜98%, a fading rate as low as 0.008% per cycle and an average CE of 99.9% over 300 cycles, demonstrating a good efficiency and kinetics of the battery. The cells produced by mass loadings up to ˜7.0 mg of SLP per cm.sup.2 still show good discharge capacities and cycle stabilities (FIG. 20). Overall, without any further surface protection, all SLP-based composites with and without nanoconfinement exhibit good cycling stability as a consequence of the internal protection mechanism. As a comparison, elemental sulfur-based composites show under the same experimental conditions very poor cycling capacity retention (FIGS. 14, 17a and 17b). In particular, FIG. 17 (a) shows, compared to SLP-based cathodes, that elemental S-based cells using composites of sulfur and carbon sphere or carbon black offers very poor cycling capacity retention (below 20%) in 200 cycles in both electrolytes and unstable CE (lower than 80% in initial 50 cycles) (FIG. 14 and FIG. 17a), and first over-charging problem in 0.5M LiTFSI (FIG. 17b), respectively, which is known to be due to serious polysulfide dissolution and subsequent shuttle effects. The electrolyte can diffuse into the pores, dissolve the sulfur species, and then diffuse out of the cathode.
[0179] The underlying reason for the stable capacity was further explored by examining the phase change and nanostructure evolution on cycling. Particularly revealing are XRD studies on fresh free-standing SLP electrodes, fully discharged SLP and fully charged SLP after the first cycle (see FIG. 15a). FIG. 15a displays the amorphous phase of the original SLP polymer. After 1st discharge, the emergence of a polymeric lithium sulfur-limonene disulfide structure of a new crystalline phase, namely lithium sulfide (Li.sub.2S), coexisting with an amorphous material is indicated. This observation is in agreement with lithiation causing cleavage of the S—S bonds in SLP and conversion into Li.sub.2S. Then, after charging the cell back, XRD clearly indicates the formation of elemental sulfur (S.sub.8) at the expense of the disappearing Li.sub.2S phase thereof forming a polymeric elemental sulfur-limonene disulfide structure containing (S.sub.8). Evidently, the SLP exhibits an irreversible phase conversion after the first cycle forming two phases including a polymeric elemental sulfur-limonene disulfide structure containing Sg.
[0180] To get a more detailed structural insight, imaging and analytical scanning transmission electron microscopy (STEM) measurements on fresh SLP, fully discharged SLP and fully charged SLP during the first cycle (FIG. 15b-j) were performed. The bright-field (BF)- and high-angle annular dark-field (HAADF)-STEM images exhibit significant changes when comparing fresh and cycled SLP. Fresh SLP (FIG. 15b, e) appears as dense and single phase material without any visible pores. However, after first lithiation, appearance of nanoparticles embedded in the polymer matrix (FIG. 15c, f) is observed. After the first charge process, this nanostructure stays invariant (FIG. 15d, g) in cycled SLP instead of returning to a single phase. The STEM results corroborate the XRD results in FIG. 15a, demonstrating that these new phases are Li.sub.2S (discharge) and Sg (charge). Evidently the first lithiation cracks the poly-sulfur chain of SLP and forms electroactive Li.sub.2S nanoparticles which are uniformly embedded in a nonporous polymeric lithium-sulfur-limonene-disulfide matrix (FIG. 15c, f). The following charging and discharging processes switch the composition of the nanoparticles from Li.sub.2S to Sg in a reversible manner (FIG. 15d, g). This reversibility is enabled by the embedding effect that maintains the nanostructure without binder and impedes access of electrolyte which would cause dissolution of sulfur species. In conjunction with transforming Li.sub.2S to Sg, the Li—S groups of the organic backbone are also reversibly delithiated as can be seen from the unvaried capacity (compare initial two cycles in FIG. 19). Energy-dispersive X-ray spectroscopy (EDS) mapping conducted in STEM mode showed the carbon and sulfur distribution within fresh SLP and cycled SLP (after 1st cycle). In the virgin SLP, carbon and sulfur are uniformly distributed (FIG. 21). In FIG. 15h-j and FIG. 22, elemental carbon stays uniformly distributed within the matrix, but the sulfur mapping exhibits rarefied and rich regions, again confirming the proposed mechanism. The sulfur of the rarefied area stems from the polymer matrix. While obviously the connecting original poly-sulfur chain has been cut, the C—S bonds in SLP are stable during phase conversion on charging and discharging. The sulfur of the rich area stems from the formation of Sg after the first charge. Comparing the voltages between the first discharge and 2nd discharge in FIG. 19, it is clear that the differences between them only affect the high voltage range where sulfur richer polysulfides are involved (marked area in FIG. 19). It can—in view of the charges transferred—be concluded that reactions involving the organic matrix including the redox reaction at the C—S-bonds occur in this voltage regime. The similarity of the 2nd discharge curve with conventional Li—S battery characteristics shows the insensitivity of the cell voltage with respect to size issues. This is directly explained by the similar nanoscale of educts and products. Without intending to be bound by theory, the mechanism of lithiation/delithiation, phase changes and nanostructure evolution of SLP giving rise to high capacity and excellent cycle stability, and can be summarized as depicted in the FIG. 16. During the 1st discharge, the —[S.sub.n]— chains of SLP break and tend to locally form Li.sub.2S nanoparticles within the polymeric lithium sulfur-limonene disulfide matrix. This embedded structure is favored by the transport kinetics but is probably also thermodynamically stabilized (interaction of the Li.sub.2S surface with the organic polymeric matrix). This embedding polymeric matrix does not only act as intrinsic binder, but also as a selective protector by allowing Li to exchange but not the solvent to penetrate, hence warranting self-protection. After having formed the embedded structure, the Li.sub.2S nanoparticles are reversibly converted to S.sub.8, concomitantly the C—S—Li groups of the polymeric matrix are reversibly delithiated. As a consequence, all the sulfur atoms are electroactive, as obvious from the voltage-capacity curves. Then, sulfur-limonene disulfide and elemental S.sub.8 separately undergo redox reactions in the following cycles with S.sub.8 and Li.sub.2S staying effectively protected by the nonporous polymeric matrix.
