Electrochemical capacitors, also known as supercapacitors (SCs), have lately played an important role in energy storage and conversion systems due to their specific characteristics such as high strength, durability, and environmental friendliness. A wide range of materials is used as electrodes for SC applications because the electrochemical efficiency is primarily determined by the electrode materials used. Carbonaceous materials with unique surface, chemical, electrochemical, and electronic characteristics have become attractive for energy storage research, but they cannot meet the rising need for high specific energy and specific power. Besides, heteroatom-doped carbon materials have shown pseudocapacitance characteristics and improved specific energy, specific power, and conductivity. This makes them more adaptable in SC application. Among different heteroatom doping of carbon, S-doped carbon has gained considerable attention in SC applications due to its unpaired electrons and easily polarizable nature. S-doped carbon materials-based SCs have demonstrated enhanced surface wettability, improved conductivity, and induced pseudocapacitance effect, thereby delivering improved specific energy and specific power. Many reports on S-doped carbon for SC applications have been published, but there is no specific Review on the preparation of S-doped carbon for SC applications. This Review focuses on recent developments in the field of SC electrodes made from S-doped carbon materials. Herein, the preparation methods and applications of S-doped carbon for SCs were summarized following a brief discussion of different electrochemical characterization techniques of SCs. Finally, the challenges of S-doped carbon materials and their potential prospects were discussed to give crucial insights into the favorable factors for future innovations of SC electrodes. This Review aims to provide insight for further research on the preparation of S-doped carbon for electrochemical energy storage applications.

Preparation of Sulfur-doped Carbon for Supercapacitor Applications: A Review

S-doped carbon materials: Synthesis, properties and applications

Among anode materials for potassium‐ion batteries (PIBs), carbon‐based materials attract extensive attention due to their abundant material resources, low cost, high surface capacity, and excellent electrical conductivity. However, carbon‐based materials always display a low initial coulombic efficiency (ICE), which greatly hinders the full utilization of the battery capacity and energy density. Moreover, the slow dynamic process and the large volume expansion during intercalation result in poor cyclic stability. In this work, a sulfonic acid modified porous N‐doped carbon (SA‐NC) is prepared as an anode for PIBs. This SA‐NC material provides abundant migration channels and active potassium storage sites with K+ adsorption energy as low as −1.752 eV, which promote rapidly reversible surface adsorption/desorption capacitance storage of K+, and improve the potassium storage performance and the ICE of the electrode simultaneously. The material exhibits outstanding performance with high reversible initial charging specific capacity (793 mAh g–1 at 0.05 A g–1 current density, 90% capacity retention after 80 cycles), high initial coulomb efficiency (68.21% at 0.1 A g–1), and long‐time hyper‐stable cycling stability (288 mAh g–1 after 2000 cycles at 2 A g–1), which show outstanding performance in all aspects and is at the leading level in carbon anode materials.

Modification of Porous N‐Doped Carbon with Sulfonic Acid toward High‐ICE/Capacity Anode Material for Potassium‐Ion Batteries

Design and synthesis of carbon-based nanomaterials for electrochemical energy storage

We fabricated sulfur and nitrogen codoped cyanoethyl cellulose-derived carbons (SNCCs) with state-of-the-art electrochemical performance for potassium ion battery (PIB) and potassium ion capacitor (PIC) anodes. At 0.2, 0.5, 1, 2, 5, and 10 A g−1, the SNCC shows reversible capacities of 369, 328, 249, 208, 150, and 121 mA h g−1, respectively. Due to a high packing density of 1.01 g cm−3, the volumetric capacities are also uniquely favorable, being 373, 331, 251, 210, 151, and 122 mA h cm−3 at these currents, respectively. SNCC also shows promising initial Coulombic efficiency of 69.0% and extended cycling stability with 99.8% capacity retention after 1000 cycles. As proof of principle, an SNCC-based PIC is fabricated and tested, achieving 94.3 Wh kg−1 at 237.5 W kg−1 and sustaining over 6000 cycles at 30 A g−1 with 84.5% retention. The internal structure of S and N codoped SNCC is based on highly dilated and defective graphene sheets arranged into nanometer-scale walls. Using a baseline S-free carbon for comparison (termed NCC), the role of S doping and the resultant dilated structure was elucidated. According to galvanostatic intermittent titration technique and electrochemical impedance spectroscopy analyses, as well as COMSOL simulations, this structure promotes rapid solid-state diffusion of potassium ions and a solid electrolyte interphase that is stable during cycling. X-ray diffraction was used to probe the ion storage mechanisms in SNCC, establishing the role of reversible potassium intercalation and the presence of KC36, KC24, and KC8 phases at low voltages. 

https://onlinelibrary.wiley.com/doi/pdfdirect/10.1002/cey2.233

Sulfur and nitrogen codoped cyanoethyl cellulose‐derived carbon with superior gravimetric and volumetric capacity for potassium ion storage

Interconnected carbon nanocapsules with high N/S co-doping as stable and high-capacity potassium-ion battery anode

Foam-like porous carbons with ultrahigh surface area from petroleum pitch and their supercapacitive performance

The pollution from acid treatment process in the preparation process of hierarchical porous carbons is a substantial challenge for industrial application of supercapacitors (SCs), which necessitates the development of green alternative technologies. In this work, S-doped hierarchical porous carbons (S-HPCs) are prepared from cheap coal tar pitch by a less harmful in situ KHCO3 activation strategy. The sample obtained at 800°C (S-HPC800 ) possesses 3D framework structure with hierarchical pores, large specific surface area (1485 m2 g-1 ) and O, S-containing functional groups. Due to these synergistic characteristics, SHPC800 as supercapacitor electrode exhibits high specific capacitance of 246 F g-1 at 0.1 A g-1 with a capacitance retention of 68.3% at 40 A g-1 and excellent cycle stability with 96.7% capacitance retention after 10, 000 charge-discharge cycles. This work provides an environmentally friendly approach to prepare advanced carbon-based electrode materials from industrial by-products for energy storage devices.

/pdf/construction-of-s-doped-hierarchical-porous-carbons-by-acid-1ffq27en44.pdf

Construction of S-doped hierarchical porous carbons by acid-free treatment strategy for supercapacitors

Mn-modification, as a method of material element modification, has a vital efficacy on the structure of materials, providing abundant active sites for the loading of metal nanoparticles. Herein, highly dispersed PtNi nanoparticles deposited on Mn-modified graphitic carbon nitride (g-C3N4) was synergistically constructed by a facile and valid impregnation reduction method. Interestingly, among all the tested samples, the obtained Pt0.6Ni0.4/(MnOx)2-C3N4 display perfect catalytic activity towards decomposition of hydrous hydrazine to produce hydrogen in alkaline solution, with the value of turnover frequency (TOF) is 2749 h−1 at 323 K. Simultaneously, the as-synthetic catalyst remains outstanding hydrogen selectivity and stability after five recycles. This work proposes a novel strategy for structural modification catalysts to enhance the catalytic performance for dehydrogenation of hydrous hydrazine. 

Mn‐Modified Graphitic Carbon Nitride‐Supported Bimetallic PtNi Nanoparticles for Hydrogen Generation from Hydrous Hydrazine

A composite polymer electrolyte with ionic liquid grafted-LAP exhibits high conductivity and mechanical strength, contributing to dendrite-free all-solid-state lithium metal batteries.

/pdf/composite-polymer-electrolytes-with-ionic-liquid-grafted-2e1u9u3j.pdf

Biyu Jin

Papers

Interconnected carbon nanocapsules with high N/S co-doping as stable and high-capacity potassium-ion battery anode

Foam-like porous carbons with ultrahigh surface area from petroleum pitch and their supercapacitive performance

Construction of S-doped hierarchical porous carbons by acid-free treatment strategy for supercapacitors

Mn‐Modified Graphitic Carbon Nitride‐Supported Bimetallic PtNi Nanoparticles for Hydrogen Generation from Hydrous Hydrazine

Composite polymer electrolytes with ionic liquid grafted-Laponite for dendrite-free all-solid-state lithium metal batteries