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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.


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Battery performance of Li–S cells.(a) Representative galvanostatic discharge/charge voltage profiles of the Li/S-TTCA-I cell, cycled between 1.7 and 2.7 V at 0.2 C at room temperature. The discharge/charge voltage profiles of the Li/S-C cell obtained at the first cycle are also shown as dashed lines. (b) The discharge/charge capacities and Coulombic efficiencies of the Li/S-TTCA-I and Li/S-TTCA-II cells, compared with those of conventional Li/S–C cells. (c) Photographs displaying the dissolution of polysulfide intermediates into electrolyte during discharge at 0.2 C for the Li/S–C beaker cell, contrary to the colourless electrolytes of the Li/S-TTCA cells.
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f5: Battery performance of Li–S cells.(a) Representative galvanostatic discharge/charge voltage profiles of the Li/S-TTCA-I cell, cycled between 1.7 and 2.7 V at 0.2 C at room temperature. The discharge/charge voltage profiles of the Li/S-C cell obtained at the first cycle are also shown as dashed lines. (b) The discharge/charge capacities and Coulombic efficiencies of the Li/S-TTCA-I and Li/S-TTCA-II cells, compared with those of conventional Li/S–C cells. (c) Photographs displaying the dissolution of polysulfide intermediates into electrolyte during discharge at 0.2 C for the Li/S–C beaker cell, contrary to the colourless electrolytes of the Li/S-TTCA cells.

Mentions: Sulfur cathodes were fabricated by integrating S-TTCA-I (or S-TTCA-II), Super P carbon and polyvinylidene (PVDF) binder. Conventional sulfur cathodes composed of elemental sulfur, Super P carbon and PVDF (40 wt% of sulfur) were used as controls. After assembling coin cells containing a Li-metal anode, liquid electrolyte and the sulfur cathode, discharge/charge cycle properties of the cells at room temperature were examined. Figure 5a shows representative galvanostatic discharge/charge voltage profiles of the Li/S-TTCA-I cell, cycled between 1.7 and 2.7 V at 0.2 C (1 C=1,675 mA g−1). Only one distinct plateau at 2.06 V (vs. Li/Li+) was seen during the first discharge process for the Li/S-TTCA-I cell, in contrast to two plateaus for the Li/S–C cell at 2.35 and 2.10 V (dashed lines). This denotes that most of the sulfur in the S-TTCA-I electrode is bound to TTCA frameworks by forming disulfide bonds. After the first discharge/charge cycle, two stable discharge plateaus appeared at 2.33 and 2.06 V, ascribed to the appearance of S8 after electrochemical scission and regeneration of disulfide bonds with cycling. Overall, the discharge/charge voltage profiles of the Li/S-TTCA-II cell are similar to those of the Li/S-TTCA-I cell in their absence of the ring-opening plateau at 2.33 V during the first discharge cycle (see Supplementary Fig. 5).


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)

Battery performance of Li–S cells.(a) Representative galvanostatic discharge/charge voltage profiles of the Li/S-TTCA-I cell, cycled between 1.7 and 2.7 V at 0.2 C at room temperature. The discharge/charge voltage profiles of the Li/S-C cell obtained at the first cycle are also shown as dashed lines. (b) The discharge/charge capacities and Coulombic efficiencies of the Li/S-TTCA-I and Li/S-TTCA-II cells, compared with those of conventional Li/S–C cells. (c) Photographs displaying the dissolution of polysulfide intermediates into electrolyte during discharge at 0.2 C for the Li/S–C beaker cell, contrary to the colourless electrolytes of the Li/S-TTCA cells.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f5: Battery performance of Li–S cells.(a) Representative galvanostatic discharge/charge voltage profiles of the Li/S-TTCA-I cell, cycled between 1.7 and 2.7 V at 0.2 C at room temperature. The discharge/charge voltage profiles of the Li/S-C cell obtained at the first cycle are also shown as dashed lines. (b) The discharge/charge capacities and Coulombic efficiencies of the Li/S-TTCA-I and Li/S-TTCA-II cells, compared with those of conventional Li/S–C cells. (c) Photographs displaying the dissolution of polysulfide intermediates into electrolyte during discharge at 0.2 C for the Li/S–C beaker cell, contrary to the colourless electrolytes of the Li/S-TTCA cells.
Mentions: Sulfur cathodes were fabricated by integrating S-TTCA-I (or S-TTCA-II), Super P carbon and polyvinylidene (PVDF) binder. Conventional sulfur cathodes composed of elemental sulfur, Super P carbon and PVDF (40 wt% of sulfur) were used as controls. After assembling coin cells containing a Li-metal anode, liquid electrolyte and the sulfur cathode, discharge/charge cycle properties of the cells at room temperature were examined. Figure 5a shows representative galvanostatic discharge/charge voltage profiles of the Li/S-TTCA-I cell, cycled between 1.7 and 2.7 V at 0.2 C (1 C=1,675 mA g−1). Only one distinct plateau at 2.06 V (vs. Li/Li+) was seen during the first discharge process for the Li/S-TTCA-I cell, in contrast to two plateaus for the Li/S–C cell at 2.35 and 2.10 V (dashed lines). This denotes that most of the sulfur in the S-TTCA-I electrode is bound to TTCA frameworks by forming disulfide bonds. After the first discharge/charge cycle, two stable discharge plateaus appeared at 2.33 and 2.06 V, ascribed to the appearance of S8 after electrochemical scission and regeneration of disulfide bonds with cycling. Overall, the discharge/charge voltage profiles of the Li/S-TTCA-II cell are similar to those of the Li/S-TTCA-I cell in their absence of the ring-opening plateau at 2.33 V during the first discharge cycle (see Supplementary Fig. 5).

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