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

Abstract

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 KC 36 , KC 24, and KC 8 phases at low voltages.

Rational construction of loosely packed nickel nanoparticulates with residual HCOO ligands derived from a Ni-MOF for high-efficiency electrocatalytic overall water splitting

“…2c): C-C, CO and HCOO in three samples. [48][49][50] Notably, the presence of HCOO might be attributed to part of the residual organic ligand aer calcination treatment. According to the quantitative analysis by XPS measurements (Table S1 †), the original HCOO content in the Ni-MOF@NF precursor is ca.…”

Integrated Design from Microstructural Engineering to Binder Optimization Enabling a Practical Carbon Anode with Ultrahigh ICE and Efficient Potassium Storage

“…Correspondingly, the anodic peak around 0.5 V can be related to the K + deintercalation process. Furthermore, another pair of weak peaks (0.7/1.0 V) is mainly owing to the reversible K + adsorption at edges and defects . After the first cycle, the curves almost overlap except for the irreversible peak disappearance, indicating the good stability of PC- x electrodes.…”

Rationally Tailoring Superstructured Hexahedron Composed of Defective Graphitic Nanosheets and Macropores: Realizing Durable and Fast Potassium Storage

“…Through the calculation process in Figure S8 (Supporting Information), it is found that R ‐values increase from 1.70 to 1.98 with increasing carbonization temperature ( Figure 3 a ), which means an enhanced graphitic structure, agreeing well with the observation of HRTEM images. Through Raman spectra in Figure 3b , two obvious peaks at 1353 and 1596 cm −1 are observed, indexing to D‐band and G‐band of carbon matrix, [ 25 , 26 ] respectively. The integrated peak intensity ( I D / I G ) ratio can intuitively unveil the degree of structure defects, and as a result DGN‐900 has a medium I D / I G value (1.04) in comparison with DGN‐800 (1.09) and DGN‐1000 (1.01), demonstrating its suitable defects and graphitic domain units.…”