Dual sulfur-doped sites boost potassium storage in carbon nanosheets derived from low-cost sulfonate

Sulfur-Doped Carbon for Potassium-Ion Battery Anode: Insight into the Doping and Potassium Storage Mechanism of Sulfur

“…Theoretical computations have determined that the large-sized sulfur doping would distort the carbon framework, then be responsible for the asymmetry of the charge density and the generation of additional active sites. , Driven by the potential prospects, tremendous efforts have been devoted to design high-performance sulfur-doped carbon (SC) anodes. To date, numerous SC, such as sulfur-grafted hollow carbon spheres and sulfur-rich graphene nanoboxes, have been successfully synthesized and applied to PIB anodes, but they are rarely focused on elucidating the sulfur doping mechanism and the role of sulfur in potassium storage. − …”

Long-Cycling and High-Rate Potassium Storage Enabled by Sulfur-Doped Carbon Derived from Disposable Chopsticks

“…The highest reversible capacity and ICE of SCC2 could be attributed to the fact that appropriate sulfur doping not only increased the interplane distance and active adsorption sites to achieve higher capacity but also reduced the oxygen content, causing less irreversible reactions during the first cycle. 22 Moreover, no significant capacity loss is observed during the 2nd to 100th cycle for all of the studied anodes, indicating excellent electrochemical reversibility owing to the disordered hierarchical porous structure. Figure 3e displays the cycling performance of CC and SCCx at 0.05 A g −1 , and an obviously higher capacity of 401.91 mAh g −1 was demonstrated by SCC2 after 100 cycles compared to the values of 250.60, 283.74, and 302.95 mAh g −1 , respectively, for CC, SCC1, and SCC3.…”

“…The significant enhancement in capacity is mainly due to the fact that the sulfur doping could introduce intrinsic defects and active S–S bonds, providing additional active sites for potassium storage, and the capacity difference of SCC x is because of the diverse doping content and the induced surface area as well as interlayer space. The highest reversible capacity and ICE of SCC2 could be attributed to the fact that appropriate sulfur doping not only increased the interplane distance and active adsorption sites to achieve higher capacity but also reduced the oxygen content, causing less irreversible reactions during the first cycle . Moreover, no significant capacity loss is observed during the 2nd to 100th cycle for all of the studied anodes, indicating excellent electrochemical reversibility owing to the disordered hierarchical porous structure.…”

“…Moreover, the oxygen content decreasing from 4.30 atom % (CC) to 2.13 atom % (SCC2) after sulfur doping might be beneficial for reducing irreversible side reactions during (de)potassiation. 22 For the highresolution C 1s spectrum of SCC2 (Figure 2e), the dominant peak of C−C/C�C at 284.6 eV along with those of C−S/C− O at 285.2 eV, C�O at 286.9 eV, and O−C�O at 290.0 eV can be deconvoluted. The two peaks at 164.1 and 165.3 eV in the S 2p spectrum (Figure 2f) could be attributed to S 2p 3/2 and S 2p 1/2 for the thiophene-type C−S−C covalent bond, and the peak at 167.9 eV is assigned to C−SO x −C for oxidizedtype S in accordance with the O 1s spectrum in Figure S7 of the Supporting Information.…”

“…All of the characteristic peaks of C, O, and S are observed for SCC2 in line with the EDS mapping results, and the surface sulfur content is calculated to be 4.19 atom %, while only C and O are detected in CC, implying again the successful doping of sulfur into carbon. Moreover, the oxygen content decreasing from 4.30 atom % (CC) to 2.13 atom % (SCC2) after sulfur doping might be beneficial for reducing irreversible side reactions during (de)­potassiation . For the high-resolution C 1s spectrum of SCC2 (Figure e), the dominant peak of C–C/CC at 284.6 eV along with those of C–S/C–O at 285.2 eV, CO at 286.9 eV, and O–CO at 290.0 eV can be deconvoluted.…”