Free-Standing Nitrogen-Doped Cup-Stacked Carbon Nanotube Mats for Potassium-Ion Battery Anodes

Zhao, Xinxin; Tang, Yifan; Ni, Chaolun; Wang, Jiangwei; Star, Alexander; Xu, Yunhua

doi:10.1021/acsaem.8b00182

Cited by 90 publications

(43 citation statements)

References 32 publications

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“…Coulombic efficiency values above 55% have been obtained for heteroatom‐free carbon anodes such as graphite and soft/hard carbons . However, 51.4% actually compares favorably to prior‐reported cycle 1 CEs for heteroatom‐doped carbon KIB anodes, which are in the range of 14–50% (Table S1, Supporting Information) . A reversible capacity of 581 mAh g −1 is to our knowledge the highest reported for a K–carbon system, and is more than double the known capacity of graphite with K (270 mAh g −1 ) .…”

Section: Methodssupporting

confidence: 51%

“…The electrodes were prepared by coating the slurry of active material (SHCS), carbon black, and polyvinylidene difluoride binder (8:1:1 in weight ratio) on copper foil, with a mass loading of 2.5 mg cm −2 . This mass loading is on the high side of the typical range (0.7–3 mg cm −2 ) for prior studies on KIB anode carbons (as listed in Table S1, Supporting Information) . The electrolyte was 0.8 M potassium hexafluorophosphate in 1:1 (volume ratio) ethylene carbonate: diethyl carbonate.…”

Section: Methodsmentioning

confidence: 99%

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Sulfur‐Grafted Hollow Carbon Spheres for Potassium‐Ion Battery Anodes

et al. 2019

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Sulfur‐rich carbons are minimally explored for potassium‐ion batteries (KIBs). Here, a large amount of S (38 wt%) is chemically incorporated into a carbon host, creating sulfur‐grafted hollow carbon spheres (SHCS) for KIB anodes. The SHCS architecture provides a combination of nanoscale (≈40 nm) diffusion distances and CS chemical bonding to minimize cycling capacity decay and Coulombic efficiency (CE) loss. The SHCS exhibit a reversible capacity of 581 mAh g−1 (at 0.025 A g−1), which is the highest reversible capacity reported for any carbon‐based KIB anode. Electrochemical analysis of S‐free carbon spheres baseline demonstrates that both the carbon matrix and the sulfur species are highly electrochemically active. SHCS also show excellent rate capability, achieving 202, 160, and 110 mAh g−1 at 1.5, 3, and 5 A g−1, respectively. The electrode maintains 93% of the capacity from the 5th to 1000th cycle at 3 A g−1, with steady‐state CE being near 100%. Raman analysis indicates reversible breakage of CS and SS bonds upon potassiation to 0.01 V versus K/K+. The galvanostatic intermittent titration technique (GITT) analysis provides voltage‐dependent K+ diffusion coefficients that range from 10−10 to 10−12 cm2 s−1 upon potassiation and depotassiation, with approximately five times higher coefficient for the former.

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Section: Methodssupporting

confidence: 51%

Section: Methodsmentioning

confidence: 99%

Sulfur‐Grafted Hollow Carbon Spheres for Potassium‐Ion Battery Anodes

et al. 2019

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“…When GNC800 is charged to 2.0 V, the C/K ratio becomes 9.8, which implies that a significant amount of potassium ions remains inside the carbon matrix . Considering the lowest possible C/K ratio is 8 for graphite corresponding to the formation of stage I KC 8 , the much lower C/K ratio of GNC800 discharged to 0.001 V could originate from the irreversible intercalation of potassium ions, which could be the reason why almost all the carbonaceous anodes face low Coulombic efficiencies within tens of cycles . The EDS mappings of carbon and potassium elements demonstrate that there is no phase separation indicating the intercalation mechanism.…”

Section: Resultsmentioning

confidence: 99%

Graphitic Nanocarbon with Engineered Defects for High‐Performance Potassium‐Ion Battery Anodes

Zhang

Ming

Zhao

et al. 2019

Adv Funct Materials

243

182

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The application of graphite anodes in potassium-ion batteries (KIB) is limited by the large variation in lattice volume and the low diffusion coefficient of potassium ions during (de)potassiation. This study demonstrates nitrogendoped, defect-rich graphitic nanocarbons (GNCs) as high-performance KIB anodes. The GNCs with controllable defect densities are synthesized by annealing an ethylenediaminetetraacetic acid nickel coordination compound. The GNCs show better performance than the previously reported thin-walled graphitic carbonaceous materials such as carbon nanocages and nanotubes. In particular, the GNC prepared at 600 °C shows a stabilized capacity of 280 mAh g −1 at 50 mA g −1 , robust rate capability, and long cycling life due to its high-nitrogen-doping, short-range-ordered, defect-rich graphitic structure. A high capacity of 189 mAh g −1 with a long cycle life over 200 cycles is demonstrated at a current density of 200 mA g −1 . Further, it is confirmed that the potassium ion storage mechanism of GNCs is different from that of graphite using multiple characterization methods. Specifically, the GNCs with numerous defects provide more active sites for the potassiation process, which results in a final discharge product with short-range order. This study opens a new pathway for designing graphitic carbonaceous materials for KIB anodes.

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“…In addition, PIBs have some other merits, such as high potassiation potential [0.2 V versus K/K + , higher than lithiation potential (0.1 V versus Li/Li + )], high ion mobility and ion conductivity, and possible use of aluminum foil as current collector to reduce the weight of full cells thus improving energy density . Moreover, electrochemically intercalation of K + into graphitic materials is demonstrated feasible, thereby enabling direct transformation of the existing manufacturing techniques from LIBs to PIBs . These favorable advantages have made PIBs one of the most promising energy storage systems .…”

Section: Introductionmentioning

confidence: 99%

Oxygen/Fluorine Dual‐Doped Porous Carbon Nanopolyhedra Enabled Ultrafast and Highly Stable Potassium Storage

Wang

et al. 2019

Adv Funct Materials

135

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Carbon-based materials are promising anodes for potassium-ion batteries (PIBs). However, due to the significant volume expansion and structural instability, it is still a challenge to achieve a high capacity, high rate and long cycle life for carbonaceous anodes. Herein, oxygen/ fluorine dual-doped porous carbon nanopolyhedra (OFPCN) is reported for the first time as a novel anode for PIBs, which exhibits a high reversible capacity of 481 mA h g −1 at 0.05 A g −1 and excellent performance of 218 mA h g −1 after 2000 cycles at 1 A g −1 with 92% capacity retention. Even after 5000 robust cycles at 10 A g −1 with charging/discharging time of around 40 s, an unprecedented capacity of 111 mA h g −1 is still maintained. Such ultrafast potassium storage and unprecedented cycling stability have been seldom reported in PIBs. Quantitative kinetics analysis reveals that both diffusion and capacitance processes are involved in the potassium storage mechanism. Density functional theory calculations demon strate that the O/F dual-doped porous carbon promotes the K-adsorption ability and can absorb multiple K atoms with slight structural distortion, which accounts for the high specific capacity, outstanding rate capability, and excellent cycling stability of the OFPCN anode.

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Free-Standing Nitrogen-Doped Cup-Stacked Carbon Nanotube Mats for Potassium-Ion Battery Anodes

Cited by 90 publications

References 32 publications

Sulfur‐Grafted Hollow Carbon Spheres for Potassium‐Ion Battery Anodes

Sulfur‐Grafted Hollow Carbon Spheres for Potassium‐Ion Battery Anodes

Graphitic Nanocarbon with Engineered Defects for High‐Performance Potassium‐Ion Battery Anodes

Oxygen/Fluorine Dual‐Doped Porous Carbon Nanopolyhedra Enabled Ultrafast and Highly Stable Potassium Storage

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