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Synthesis of three-dimensionally interconnected sulfur-rich polymers for cathode materials of high-rate lithium-sulfur batteries.

Kim H, Lee J, Ahn H, Kim O, Park MJ - Nat Commun (2015)

Bottom Line: Porous trithiocyanuric acid crystals are synthesized for use as a soft template, where the ring-opening polymerization of elemental sulfur takes place along the thiol surfaces to create three-dimensionally interconnected sulfur-rich phases.Our lithium-sulfur cells display discharge capacity of 945 mAh g(-1) after 100 cycles at 0.2 C with high-capacity retention of 92%, as well as lifetimes of 450 cycles.Particularly, the organized amine groups in the crystals increase Li(+)-ion transfer rate, affording a rate performance of 1210, mAh g(-1) at 0.1 C and 730 mAh g(-1) at 5 C.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang 790-784, Korea.

ABSTRACT
Elemental sulfur is one of the most attractive cathode active materials in lithium batteries because of its high theoretical specific capacity. Despite the positive aspect, lithium-sulfur batteries have suffered from severe capacity fading and limited rate capability. Here we report facile large-scale synthesis of a class of organosulfur compounds that could open a new chapter in designing cathode materials to advance lithium-sulfur battery technologies. Porous trithiocyanuric acid crystals are synthesized for use as a soft template, where the ring-opening polymerization of elemental sulfur takes place along the thiol surfaces to create three-dimensionally interconnected sulfur-rich phases. Our lithium-sulfur cells display discharge capacity of 945 mAh g(-1) after 100 cycles at 0.2 C with high-capacity retention of 92%, as well as lifetimes of 450 cycles. Particularly, the organized amine groups in the crystals increase Li(+)-ion transfer rate, affording a rate performance of 1210, mAh g(-1) at 0.1 C and 730 mAh g(-1) at 5 C.

No MeSH data available.


Related in: MedlinePlus

Vulcanized TTCAs having different morphologies.(a,b) SEM and OM images of TTCA-I and TTCA-II co-crystals prepared by varying crystallization solvents, described as rectangular tubes and sliced plates, respectively. (c,d) SEM and OM images of the TTCA-I and TTCA-II after the removal of solvents at 160 °C, presenting the appearance of interconnected polydisperse pores. (e,f) SEM and OM images of the S-TTCA-I and S-TTCA-II synthesized at 245 °C using the porous TTCAs as a soft template. The SEM images confirm the restoration of smooth surfaces and disappearance of most of the pores after the vulcanization.
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f2: Vulcanized TTCAs having different morphologies.(a,b) SEM and OM images of TTCA-I and TTCA-II co-crystals prepared by varying crystallization solvents, described as rectangular tubes and sliced plates, respectively. (c,d) SEM and OM images of the TTCA-I and TTCA-II after the removal of solvents at 160 °C, presenting the appearance of interconnected polydisperse pores. (e,f) SEM and OM images of the S-TTCA-I and S-TTCA-II synthesized at 245 °C using the porous TTCAs as a soft template. The SEM images confirm the restoration of smooth surfaces and disappearance of most of the pores after the vulcanization.

Mentions: By using two different solvents, that is, dimethylformamide (DMF)/water (1:1 vol) co-solvent and acetone, two types of TTCA co-crystals with different morphologies, rectangular tubes and splice plates, respectively, were obtained. Hereafter, the co-crystals are referred to as TTCA-I (DMF/water) and TTCA-II (acetone). As examined by scanning electron microscopy (SEM) and optical microscopy (OM), the TTCA-I crystals are ∼50 × 20 μm and hundreds of microns in length, and have a rectangular hole (Fig. 2a), while the TTCA-II crystals are ∼1 × 1 mm rhombi with a thickness of 150 μm (Fig. 2b). Removal of solvent from TTCA-I and TTCA-II at 160 °C resulted in the appearance of intriguing rough surfaces, as shown in Fig. 2c,d, which include the formation of interconnected polydisperse pores in the range of a few tens of nanometres to a few microns throughout the crystals. The evolution of porous morphologies can be readily perceived from the changes in transparency of the crystals, as can be seen from OM images. The amounts of solvents in TTCA-I and TTCA-II were determined by thermogravimetric analysis (TGA) to be 30 wt% and 14 wt%, respectively (Supplementary Fig. 1), implying that the surface area of the heat-treated TTCA-I and TTCA-II are fundamentally different. Nevertheless, both crystals are still described as having the same morphologies, including the unperturbed rectangular hole of TTCA-I.


Synthesis of three-dimensionally interconnected sulfur-rich polymers for cathode materials of high-rate lithium-sulfur batteries.

Kim H, Lee J, Ahn H, Kim O, Park MJ - Nat Commun (2015)

Vulcanized TTCAs having different morphologies.(a,b) SEM and OM images of TTCA-I and TTCA-II co-crystals prepared by varying crystallization solvents, described as rectangular tubes and sliced plates, respectively. (c,d) SEM and OM images of the TTCA-I and TTCA-II after the removal of solvents at 160 °C, presenting the appearance of interconnected polydisperse pores. (e,f) SEM and OM images of the S-TTCA-I and S-TTCA-II synthesized at 245 °C using the porous TTCAs as a soft template. The SEM images confirm the restoration of smooth surfaces and disappearance of most of the pores after the vulcanization.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4490390&req=5

f2: Vulcanized TTCAs having different morphologies.(a,b) SEM and OM images of TTCA-I and TTCA-II co-crystals prepared by varying crystallization solvents, described as rectangular tubes and sliced plates, respectively. (c,d) SEM and OM images of the TTCA-I and TTCA-II after the removal of solvents at 160 °C, presenting the appearance of interconnected polydisperse pores. (e,f) SEM and OM images of the S-TTCA-I and S-TTCA-II synthesized at 245 °C using the porous TTCAs as a soft template. The SEM images confirm the restoration of smooth surfaces and disappearance of most of the pores after the vulcanization.
Mentions: By using two different solvents, that is, dimethylformamide (DMF)/water (1:1 vol) co-solvent and acetone, two types of TTCA co-crystals with different morphologies, rectangular tubes and splice plates, respectively, were obtained. Hereafter, the co-crystals are referred to as TTCA-I (DMF/water) and TTCA-II (acetone). As examined by scanning electron microscopy (SEM) and optical microscopy (OM), the TTCA-I crystals are ∼50 × 20 μm and hundreds of microns in length, and have a rectangular hole (Fig. 2a), while the TTCA-II crystals are ∼1 × 1 mm rhombi with a thickness of 150 μm (Fig. 2b). Removal of solvent from TTCA-I and TTCA-II at 160 °C resulted in the appearance of intriguing rough surfaces, as shown in Fig. 2c,d, which include the formation of interconnected polydisperse pores in the range of a few tens of nanometres to a few microns throughout the crystals. The evolution of porous morphologies can be readily perceived from the changes in transparency of the crystals, as can be seen from OM images. The amounts of solvents in TTCA-I and TTCA-II were determined by thermogravimetric analysis (TGA) to be 30 wt% and 14 wt%, respectively (Supplementary Fig. 1), implying that the surface area of the heat-treated TTCA-I and TTCA-II are fundamentally different. Nevertheless, both crystals are still described as having the same morphologies, including the unperturbed rectangular hole of TTCA-I.

Bottom Line: Porous trithiocyanuric acid crystals are synthesized for use as a soft template, where the ring-opening polymerization of elemental sulfur takes place along the thiol surfaces to create three-dimensionally interconnected sulfur-rich phases.Our lithium-sulfur cells display discharge capacity of 945 mAh g(-1) after 100 cycles at 0.2 C with high-capacity retention of 92%, as well as lifetimes of 450 cycles.Particularly, the organized amine groups in the crystals increase Li(+)-ion transfer rate, affording a rate performance of 1210, mAh g(-1) at 0.1 C and 730 mAh g(-1) at 5 C.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang 790-784, Korea.

ABSTRACT
Elemental sulfur is one of the most attractive cathode active materials in lithium batteries because of its high theoretical specific capacity. Despite the positive aspect, lithium-sulfur batteries have suffered from severe capacity fading and limited rate capability. Here we report facile large-scale synthesis of a class of organosulfur compounds that could open a new chapter in designing cathode materials to advance lithium-sulfur battery technologies. Porous trithiocyanuric acid crystals are synthesized for use as a soft template, where the ring-opening polymerization of elemental sulfur takes place along the thiol surfaces to create three-dimensionally interconnected sulfur-rich phases. Our lithium-sulfur cells display discharge capacity of 945 mAh g(-1) after 100 cycles at 0.2 C with high-capacity retention of 92%, as well as lifetimes of 450 cycles. Particularly, the organized amine groups in the crystals increase Li(+)-ion transfer rate, affording a rate performance of 1210, mAh g(-1) at 0.1 C and 730 mAh g(-1) at 5 C.

No MeSH data available.


Related in: MedlinePlus