Boosting the Potassium-Ion Storage Performance in Soft Carbon Anodes by the Synergistic Effect of Optimized Molten Salt Medium and N/S Dual-Doping

Abstract

Soft carbon is attracting tremendous attention as a promising anode material for potassium-ion batteries (PIBs) because of its graphitizable structure and adjustable interlayer distance. Herein, nitrogen/sulfur dual-doped porous soft carbon nanosheets (NSC) have been prepared with coal tar pitch as carbon precursors in an appropriate molten salt medium. The molten salt medium and N/S dual-doping are responsible for the formation of nanosheet-like morphology, abundant microporous channels with a high surface area of 436 m2 g–1, expanded interlamellar spacing of 0.378 nm, and enormous defect-induced active sites. These structural features are crucial for boosting potassium-ion storage performance, endowing the NSC to deliver a high potassiation storage capacity of 359 mAh g–1 at 100 mA g–1 and 115 mAh g–1 at 5.0 A g–1, and retaining 92.4% capacity retention at 1.0 A g–1 after 1000 cycles. More importantly, the pre-intercalation of K atom from the molten salts helps improve the initial Coulombic efficiency to 50%, which outperforms those of the recently reported carbon anode materials with large surface areas. The density functional theory calculations further illuminate that the N/S dual-doping can facilitate the adsorption of K-ion in carbon materials and decrease the ion diffusion energy barrier during the solid-state charge migration.

Tempura-like carbon/carbon composite as advanced anode materials for K-ion batteries

“…And the comparison of rate and long cycling performances with previous reporting also demonstrates that the G@PSC electrodes have superiority of electrochemical performances, superior to most carbon materials in the aspects of reversible capacity and stability (Fig. 3, Table S2) [32,33,36,[39][40][41][42][43]53].…”

“…Among multitudinous candidates, pitch, the low-cost petrochemical byproduct, is considered as suitable coating carbon source for conventional graphite due to crosslinking, flexible, and compatible structure characteristics [45,46]. In addition, it is also a competitively applicable carbon source to prepare carbonaceous anodes in LIBs, Na-ion batteries (NIBs), and KIBs, differing from complicated preparation of the majority of reported carbon materials from organic polymer precursors [47][48][49][50][51][52][53].…”

Unraveling the Voltage Failure Mechanism in Metal Sulfide Anodes for Sodium Storage and Improving Their Long Cycle Life by Sulfur‐Doped Carbon Protection

“…[13a,24] The additional C 1s spectra in Co 1−x S/s-C and s-C can be divided to two obvious peaks close located at 284.6 and 285.2 eV, corresponding to the CC/CC and CS bonds, respectively ( Figure S9c, Supporting Information), indicating the presence of the polar carbon-sulfur bonds on the surface of the carbon matrix. [25] The electrochemical performance of the prepared samples was studied in half-cells with a voltage range of 0.005-3 V. Figure 4a displays the representative cyclic voltammogram (CV) curves of the Co 1−x S/s-C anode with initial four cycles to reveal the sodiation/desodiation reaction mechanism. It can be seen that there is one main reduction peak at about 0.70 V in the initial cathodic scan, and the peak is evolved into three distinct peaks at 1.36, 0.94, and 0.54 V in the subsequent cycles.…”

Prospects of Electrode Materials and Electrolytes for Practical Potassium‐Based Batteries

“…Except for graphite, various carbonaceous materials (soft carbon, [162,[165][166][167][168][169][170][171][172][173] hard carbon, [74,[174][175][176][177][178][179][180][181][182][183][184][185][186][187][188] heteroatomic doped carbon, [189][190][191][192][193][194][195][196][197][198][199][200][201][202][203][204][205][206][207] graphitic carbon [164,[208][209][210][211]…”