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Development of alternative cathode materials is of highly desirable for sustainable and cost-efficient lithium-ion batteries (LIBs) in energy storage fields. In this study, for the first time, we report tunable nitrogen-doped graphene with active functional groups for cathode utilization of LIBs. When employed as cathode materials, the functionaliz...
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... superior cathode performance of NGNS was further confirmed at an operated voltage range of 2.5−4.5 V. As shown in SI Figure S5a, the charge−discharge profiles of GNS, NGNS- I, and NGNS-II in the fifth cycle were similar to that of the samples tested at the voltage range of 1.5−4.5 V. Importantly, all the samples reveal good cycling performance in SI Figure S5b. By contrast, NGNS-II shows better performance than the other two cathode materials, which is similar to the results in Figure 3c. ...
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... superior cathode performance of NGNS was further confirmed at an operated voltage range of 2.5−4.5 V. As shown in SI Figure S5a, the charge−discharge profiles of GNS, NGNS- I, and NGNS-II in the fifth cycle were similar to that of the samples tested at the voltage range of 1.5−4.5 V. Importantly, all the samples reveal good cycling performance in SI Figure S5b. By contrast, NGNS-II shows better performance than the other two cathode materials, which is similar to the results in Figure 3c. ...
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... can be illustrated in Figure 5, the improved rate capability and cycling performance of the cathode materials are due to several factors: (1) the heterodoped N atoms enhance the reactivity and electrical conductivity of graphene because of the larger electronegativity of N (3.04) than C (2.55), which facilitates fast electron transfer; 45 (2) the introduction of N atoms cause more edges as well as open and flexible vacancy defects for efficient lithium storage sites; (3) the pyrrolic-N possesses high binding energy with Li, increasing the Li storage capacity; (4) the pyridinic-N and pyrrolic-N formed at the edges and vacancy sites can facilitate the perpendicular diffusion of Li + , and shorten Li + diffusion distances, significantly leading to the excellent rate capability. 46 In addition to above- mentioned reasons, the energy storage mechanism for N-rich cathode materials is another key factor according to previous reports. ...
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... can be illustrated in Figure 5, the improved rate capability and cycling performance of the cathode materials are due to several factors: (1) the heterodoped N atoms enhance the reactivity and electrical conductivity of graphene because of the larger electronegativity of N (3.04) than C (2.55), which facilitates fast electron transfer; 45 (2) the introduction of N atoms cause more edges as well as open and flexible vacancy defects for efficient lithium storage sites; (3) the pyrrolic-N possesses high binding energy with Li, increasing the Li storage capacity; (4) the pyridinic-N and pyrrolic-N formed at the edges and vacancy sites can facilitate the perpendicular diffusion of Li + , and shorten Li + diffusion distances, significantly leading to the excellent rate capability. 46 In addition to above- mentioned reasons, the energy storage mechanism for N-rich cathode materials is another key factor according to previous reports. 47,48 NGNS shows high energy storage performance through the reversible redox reaction accompanied by the association/disassociation of Li + or electrolyte anions (PF 6 − ): ...
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... superior cathode performance of NGNS was further confirmed at an operated voltage range of 2.5−4.5 V. As shown in SI Figure S5a, the charge−discharge profiles of GNS, NGNS- I, and NGNS-II in the fifth cycle were similar to that of the samples tested at the voltage range of 1.5−4.5 V. Importantly, all the samples reveal good cycling performance in SI Figure S5b. By contrast, NGNS-II shows better performance than the other two cathode materials, which is similar to the results in Figure 3c. As expected, the cathode materials deliver lower reversible capacities than that shown in Figure 3c. However, NGNS-II still delivers high reversible capacity of 147 mAh g −1 ...
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... superior cathode performance of NGNS was further confirmed at an operated voltage range of 2.5−4.5 V. As shown in SI Figure S5a, the charge−discharge profiles of GNS, NGNS- I, and NGNS-II in the fifth cycle were similar to that of the samples tested at the voltage range of 1.5−4.5 V. Importantly, all the samples reveal good cycling performance in SI Figure S5b. By contrast, NGNS-II shows better performance than the other two cathode materials, which is similar to the results in Figure 3c. As expected, the cathode materials deliver lower reversible capacities than that shown in Figure 3c. However, NGNS-II still delivers high reversible capacity of 147 mAh g −1 ...
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... 13 Due to these intriguing physicochemical properties, graphene and graphene-containing compounds have found success as both anode and cathode materials in LIBs. 14,15 Beyond graphene, other 2D materials like silicene, hexagonal boron nitrides (h-BN), borophene, silicon carbides, transition metal dichalcogenides (TMDs), and MXenes have attracted attention for LIB applications. 16−23 Among these, TMDs have particularly enthralled battery researchers. ...
In this work, we report the results of density functional theory (DFT) calculations on a van der Waals (VdW) heterostructure formed by vertically stacking single-layers of tungsten disulfide and graphene (WS2/graphene) for use as an anode material in lithium-ion batteries (LIBs). The electronic properties of the heterostructure reveal that the graphene layer improves the electronic conductivity of this hybrid system. Phonon calculations demonstrate that the WS2/graphene heterostructure is dynamically stable. Charge transfer from Li to the WS2/graphene heterostructure further enhances its metallic character. Moreover, the Li binding energy in this heterostructure is higher than that of the Li metal’s cohesive energy, significantly reducing the possibility of Li-dendrite formation in this WS2/graphene electrode. Ab initio molecular dynamics (AIMD) simulations of the lithiated WS2/graphene heterostructure show the system’s thermal stability. Additionally, we explore the effect of heteroatom doping (boron (B) and nitrogen (N)) on the graphene layer of the heterostructure and its impact on Li-adsorption ability. The results suggest that B-doping strengthens the Li-adsorption energy. Notably, the calculated open-circuit voltage (OCV) and Li-diffusion energy barrier further support the potential of this heterostructure as a promising anode material for LIBs.
... 13 As a result of the intriguing physicochemical properties, graphene and several graphene containing compounds have been successfully utilized as both anode and cathode materials in LIBs. 14,15 Besides graphene, efforts have been made to fabricate LIBs from other 2D materials like silicene, hexagonal boron nitrides (h-BN), borophene, silicon carbides, transition-metal dichalcogenides (TMDs), and MXenes. [16][17][18][19][20][21][22][23] Among these 2D materials the TMDs attracted battery researchers as many of them can be synthesized from their bulk phase by several methods such as exfoliation, chemical vapor deposition and super critical assisted methods. ...
In this work, we report the results of density functional theory (DFT) calculations on van der Waals (VdW) heterostructure formed by vertically stacking single-layers of tungsten disulfide and graphene (WS2/graphene) for employing them in Lithium-ion batteries (LIBs) as an anode material. The electronic properties of the heterostructure reveal that the graphene layer helps to improve the electronic conductivity of this hybrid system. Indeed, the charge transfer from Li to WS2/graphene heterostructure further improves their metallic character. Moreover, the Li binding energy in this heterostructure was higher than that of Li-metal's cohesive energy, which indicates the possibility of Li-dendrite formation in this WS2/graphene electrode is low. In addition, the effect of heteroatoms like boron (B) and nitrogen (N) doping on the graphene layer of the heterostructure on Li-adsorption ability is also explored here. The results suggest that B-doping improves the Li-adsorption energy. Interestingly, the computed open-circuit voltage (OCV) and Li-diffusion energy barrier also favor that this heterostructure can act as a promising anode material for LIBs.
... 13 As a result of the intriguing physicochemical properties, graphene and several graphene containing compounds have been successfully utilized as both anode and cathode materials in LIBs. 14,15 Besides graphene, efforts have been made to fabricate LIBs from other 2D materials like silicene, hexagonal boron nitrides (h-BN), borophene, silicon carbides, transition-metal dichalcogenides (TMDs), and MXenes. [16][17][18][19][20][21][22][23] Among these 2D materials the TMDs attracted battery researchers as many of them can be synthesized from their bulk phase by several methods such as exfoliation, chemical vapor deposition and super critical assisted methods. ...
Herein, we report the results of density functional theory (DFT) calculations on van der Waals (VdW) heterostructure formed by vertically stacking single-layers of tungsten disulfide and graphene (WS2/graphene) for employing them in Lithium-ion batteries (LIBs) as an anode material. The electronic properties of the heterostructure reveal that the graphene layer helps to improve the electronic conductivity of this hybrid system. Indeed, the charge transfer from Li to WS2/graphene heterostructure further improves their metallic character. Moreover, the Li binding energy in this heterostructure was higher than that of Li-metal's cohesive energy, which indicates the possibility of Li-dendrite formation in this WS2/graphene electrode is low. The effect of heteroatoms such B and N doping on graphene layer of the heterostructure on Li-adsorption ability also explored here. The results revealed that B-doping improves the Li-adsorption energy. Interestingly, the calculated open-circuit voltage (OCV) and Li-diffusion barrier also favor that this heterostructure can act as a potential candidate for LIB anode applications.
... The asymmetry spin density and atomic charge density occurs in the Ndoped Graphene for the neighboring nitrogen atoms [34]. The N-doped Graphene can be used in batteries, sensors and ultracapacitors [35][36][37][38]. The temperature dependence of thermal conductivity in N-doped graphene is less than that of pure graphene and this sensitivity decreases as the impurity concentration increases [39]. ...
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... While, it is pertinent to note that earlier reports have also similarly demonstrated that Li anchoring on nitrogen doped graphene is less favourable as compared to its anchoring on the boron counterpart, [74,75] binding energy of a minimum of À 0.64 eV (of nearly À 14.75 kcal/mol) for single Li atom to be anchored on single nitrogen doped graphene makes this doping thermodynamically stable and viable for various applications. [76][77][78][79] In case of B-doped systems, Li intercalation lies just above the ring containing the doped atom (viz., boron). The maximum binding energy obtained (i. ...
The most successful electrochemical conversion of ammonia from dinitrogen molecule reported to date is through a Li mediated mechanism. In the framework of the above fact and that Li anchored graphene is an experimentally feasible system, the present work is a computational experiment to identify the potential of Li anchored graphene as a catalyst for N2 to NH3 conversion as a function of (a) minimum number of Li atoms needed for anchoring on graphene sheets and (b) the role of chemical modification of graphene surfaces. The studies bring forth an understanding that Li anchored graphene sheets are potential catalysts for ammonia conversion with preferential adsorption of N2 through end‐on configuration on Li atoms anchored on doped and pristine graphene surfaces. This mode of adsorption being characteristic of Nitrogen Reduction Reaction (NRR) through enzymatic pathway, examination of the same followed by analysis of electronic properties demonstrates that tri‐Li atoms (Tri Atom Catalysts, TACs) are more efficient as catalysts for NRR as compared to two Li atoms (Di Atom Catalysts, DACs). Either way, the rate determining step was found to be *NH2→*NH3 step (mixed pathway) with ΔGmax=1.02 eV and *NH2−*NH3→*NH2 step (enzymatic pathway) with ΔGmax=1.11 eV for 1B doped TAC and DAC on graphene sheet, respectively. Consequently, this work identifies the viability of Li anchored graphene based 2‐D sheets as hetero‐atom catalyst for NRR.
... Generally, the D band corresponds to the mode of the sp 2 -rings of the disordered graphene layer that is related to various defects (such as hybridization caused by heteroatom doping and structural defects originated from oxidation/reduction treatment). 33 The G band peak has arisen from sp 2 hybridization of well-ordered carbon atoms in the plane hexagonal lattice structure. 34 Hence, the intensity ratio of D band vs G band (I D /I G ) is usually applied to assess the disorder and defect degree of carbon materials. ...
Fe2O3 has been widely investigated as an anode material for its high theoretical capacity and natural abundance, but the low conductivity, large volume variation, and slow kinetics seriously hinder its commercialization. Here, we propose the in situ growth of ultra-fine Maghemite (γ-Fe2O3) NPs on the 3D rGO aerogel with abundant pores by a facile freeze-drying process followed by thermal annealing, which is confirmed by X-ray diffraction and high-resolution-tunneling electron microscopy. This novel 3D porous structure ensures fast electron and ion diffusion within the electrode, which effectively mitigates the volume expansion of Fe2O3 during cycling. Benefiting from these advantages, an excellent cycling performance of 668 mAh g-1 at 0.5 A g-1 over 100 cycles as well as outstanding rate performance are achieved. These results provide a promising approach of advanced anode materials for lithium-ion batteries.
... It should be emphasized that although graphene exhibits an extraordinary capacity as anode in LiBs [91][92][93], as cathode the values are much lower. However, the value that we obtained on graphene is in agreement with the value found for multi-layer graphene [94]. The results indicated the superior capacity performance of the electrode after being coated with vanadium sesquioxide films. ...
... In recent years, red phosphorus has gained wide attention for LIBs, but its low electrical conductivity and large volume expansion have hampered large-scale applications. Therefore, Jiao et al. [88] designed red phosphorous/crumpled N-doped graphene (P/CNG) nanocomposites with excellent rate performance and high capacity density as anode Xiong group's [90] described an easy hydrothermal method for the synthesis of functionalised N-doped graphene nanosheets (Fig. 11a). The as-prepared N-doped graphene was employed as a cathode in LIBs and delivered remarkable rate potential, promising reversible capacity, and long-life cycling stability owing to its unique active oxygenic functional groups, high nitrogen doping, and 3D porous morphology. ...
In recent years, the demand for high-performance rechargeable lithium batteries has increased significantly, and many efforts have been made to boost the use of advanced electrode materials. Since graphene was first isolated by Novoselov et al., graphene/graphene-based materials have become an active area of research and are considered to be promising high-performance electrode materials. Graphene is a two-dimensional single-atom carbon-packed material that possesses fascinating properties, including a large surface area, remarkable electrical conductivity, extraordinary intrinsic electron mobility, high Young's modulus, superior mechanical strength, optical transmittance, catalytic performance, and stability. Therefore, graphene is considered an attractive material for rechargeable lithium-ion batteries (LIBs), lithium-sulfur batteries (LSBs), and lithium-oxygen batteries (LOBs). In this comprehensive review, we emphasise the recent progress in the controllable synthesis, functionalisation, and role of graphene in rechargeable lithium batteries. Finally, in this review, we aim to address the most promising results, benefits, challenges, critical issues, research directions, and perspectives to explain the developmental directions of graphene for batteries.
... These rGO layers enable to facilitate the electron transfer of the ReS 2 and serve as a cushioning manager against the volume expansion of the ReS 2 in the charge/discharge process, therefore enhancing battery performance. 36 The pristine ReS 2 powder shows spherical-shaped agglomerated nanoparticles ( Figure S2e,f), therefore pointing to the significant influence of the rGO supporter on the geomorphology of ReS 2 . Thus, compared with the aggregated ReS 2 powder, the rGO-supported ReS 2 composites are beneficial to accommodating a larger amount of potassium ions into the modified electrode. ...
Improving the electrochemical kinetics and the intrinsic poor conductivity of transition metal dichalcogenide (TMD) electrodes is meaningful for developing next-generation energy storage systems. As one of the most promising TMD anode materials, ReS2 shows attractive performance in potassium-ion batteries (PIBs). To overcome the poor kinetic ion diffusion and limited cycling stability of the ReS2-based electrode, herein, the interlayer distance expanding strategy was employed, and reduced graphene oxide (rGO) was introduced into ReS2. Few-layered ReS2 nanosheets were grown on the surface of the rGO with expanded interlayer distance. The prepared ReS2 nanosheets show an expanded distance (∼0.77 nm). The synthesized EI-ReS2@rGO composites were used in PIBs as anode materials. The K-ion storage mechanism of the ReS2-based anode was investigated by in situ X-ray diffraction (XRD) technology, which shows the intercalation and conversion types. The EI-ReS2@rGO nanocomposites show high specific capacities of 432.5, 316.5, and 241 mAh g-1 under 0.05, 0.2, and 1.0 A g-1 current densities and exhibit excellent reversibility at 1.0 A g-1. Overall, this strategy, which finely tunes the local chemistry and orbital hybridization for high-performance PIBs, will open up a new field for other materials.
... To substitute for graphite, various anode materials have been explored to improve the electrochemical performance, including transition metal dichalcogenides (TMDs) [6][7][8][9][10], transition metal oxides (TMOs) [11][12][13], titanium-based materials [14,15], carbon nanomaterials [16,17], and their composite materials [18,19]. Alloying-type anodes (Si, Sn, Ge) are Nanomaterials 2022, 12,2008 2 of 15 the other alternative candidates that can replace graphite due to their very high theoretical capacity and relatively higher working potential, beneficial for reducing the risk of dendrite formation. ...
... This phenomenon is commonly observed in the conversion-based anode materials, because during the discharge-charge process of the initial cycles, the SEI layer is not fully formed. This accounts for the low CE and capacity loss during initial cycles, as reported in previous studies [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. The CV result described earlier also accords with this behavior. ...
We explore a phase engineering strategy to improve the electrochemical performance
of transition metal sulfides (TMSs) in anode materials for lithium-ion batteries (LIBs). A one-pot hydrothermal approach has been employed to synthesize MoS2 nanostructures. MoS2 and MoO3 phases can be readily controlled by straightforward calcination in the (200–300) ◦C temperature range. An optimized temperature of 250 ◦C yields a phase-engineered MoO3@MoS2 hybrid, while 200 and 300 ◦C produce single MoS2 and MoO3 phases. When tested in LIBs anode, the optimized MoO3@MoS2 hybrid outperforms the pristine MoS2 and MoO3 counterparts. With above 99% Coulombic efficiency (CE), the hybrid anode retains its capacity of 564 mAh g−1 after 100 cycles, and maintains a capacity of 278 mAh g−1 at 700 mA g−1 current density. These favorable characteristics
are attributed to the formation of MoO3 passivation surface layer on MoS2 and reactive interfaces between the two phases, which facilitate the Li-ion insertion/extraction, successively improving MoO3@MoS2 anode performance.
