Anode For Potassium-ion Batteries Research Articles

Synthesis of monodisperse hollow carbon spheres and their electrochemical performance as anodes in potassium-ion batteries

Synthesis of monodisperse hollow carbon spheres and their electrochemical performance as anodes in potassium-ion batteries

Fe2O3 nanoparticles anchored on N-doped pinecone-based porous carbon as potential anode for potassium-ion battery

Fe2O3/carbon composites have received widespread attention as a potential anode material for lithium/sodium ion battery owing to its rich reserves, wide distribution, and environmental friendliness. However, studies on potassium-ion battery (PIB) have rarely been reported. Besides, majority carbon-based matrices are mainly focused on the utilization of synthetic carbons, which have a high cost and complicated synthesis process. In contrast, biomass-based carbon is inexpensive, environment-friendly, and abundant in terms of its precursor resources, making it a promising matrix. In this work, the dispersal of Fe2O3 nanoparticles on a N-doped pinecone-based porous carbon matrix (Fe2O3/NPC) was proposed as a simple and effective approach for improving the electrochemical performance of the Fe2O3 anode in potassium-ion battery. Fe2O3/NPC was prepared using a hydrothermal method, and the morphology of Fe2O3 was optimized by varying the reaction temperature. Compared with Fe2O3, NPC and Fe2O3/NPC prepared at different temperature, the Fe2O3/NPC-150 electrode exhibited an improved discharge capacity of 178.7 mAh·g−1 after 100 cycles at 50 mA·g−1 with good rate performance and the high capacity retention rate of 91.6% after 500 cycles. The improved electrochemical performance is attributed to the synergistic effect of small Fe2O3 nanoparticles and N-doped pinecone-based porous carbon. This strategy provides a simple, mild and low cost method for preparing iron based anode materials for potassium-ion battery, and also provides some guidances for large-scale industrial production.

Dual‑carbon confined Sb2Se3 nanorods for potassium ion batteries anode with improved capacity and cycling stability

Sb2Se3 is regarded as a promising conversion-alloying type anode material for potassium ion batteries (PIBs) owing to its high theoretical specific capacity. However, the low electric conductivity and large volume change during the charge/discharge process hinder its practical applications. Herein, we proposed a novel ‘dual carbon coating’ strategy to construct carbon confined Sb2Se3 nanorods for high performance PIBs anode. Owing to the enhanced electric conductivity resulted from the inner carbon and the strengthened mechanical stability from the outer graphene layer, the confined Sb2Se3 exhibit outstanding electrochemical potassium ion storage performances with a specific capacity of 482.1 mAh g−1 after 50 cycles at a current density of 0.1 A g−1. Even at a high current density of 1 A g−1 after 500 cycles, it still maintains a specific capacity of 283.7 mAh g−1. These results outperform the pure Sb2Se3 and those traditional ‘single carbon’ coated Sb2Se3 from both specific capacity and cycling stability. This ‘dual carbon coating’ method could also be applied to other conversion or alloying type anode materials of PIBs with high theoretical capacities and large volume variation during the repeated charge/discharge process.

Tunable Interfacial Electric Field‐Mediated Cobalt‐Doped FeSe/Fe3Se4 Heterostructure for High‐Efficiency Potassium Storage

The interfacial electric field (IEF) in the heterostructure can accelerate electron transport and ion migration, thereby enhancing the electrochemical performance of potassium‐ion batteries (PIBs). Nevertheless, the quantification and modulation of the IEF for high‐efficiency PIB anodes currently remains a blank slate. Herein, we achieve for the first time the quantification and tuning of IEF via amorphous carbon‐coated undifferentiated cobalt‐doped FeSe/Fe3Se4 heterostructure (denoted UN‐CoFe4Se5/C) for efficient potassium storage. Co doping can increase the IEF in FeSe/Fe3Se4, thereby improving the electron transport, promoting the potassium adsorption capacity, and lowering the diffusion barrier. As expected, the IEF magnitude in UN‐CoFe4Se5/C is experimentally quantified as 62.84 mV, which is 3.65 times larger than that of amorphous carbon‐coated FeSe/Fe3Se4 heterostructure (Fe4Se5/C). Benefiting from the strong IEF, UN‐CoFe4Se5/C as a PIB anode exhibits superior rate capability (145.8 mAh g−1 at 10.0 A g−1) and long cycle lifespan (capacity retention of 95.1% over 3000 cycles at 1.0 A g−1). Furthermore, this undifferentiated doping strategy can universally regulate the IEF magnitude in CoSe2/Co9Se8 and FeS2/Fe7S8 heterostructures. This work can provide fundamental insights into the design of advanced PIB electrodes.

Tunable Interfacial Electric Field-Mediated Cobalt-Doped FeSe/Fe3Se4 Heterostructure for High-Efficiency Potassium Storage.

The interfacial electric field (IEF) in the heterostructure can accelerate electron transport and ion migration, thereby enhancing the electrochemical performance of potassium-ion batteries (PIBs). Nevertheless, the quantification and modulation of the IEF for high-efficiency PIB anodes currently remains a blank slate. Herein, we achieve for the first time the quantification and tuning of IEF via amorphous carbon-coated undifferentiated cobalt-doped FeSe/Fe3Se4 heterostructure (denoted UN-CoFe4Se5/C) for efficient potassium storage. Co doping can increase the IEF in FeSe/Fe3Se4, thereby improving the electron transport, promoting the potassium adsorption capacity, and lowering the diffusion barrier. As expected, the IEF magnitude in UN-CoFe4Se5/C is experimentally quantified as 62.84 mV, which is 3.65 times larger than that of amorphous carbon-coated FeSe/Fe3Se4 heterostructure (Fe4Se5/C). Benefiting from the strong IEF, UN-CoFe4Se5/C as a PIB anode exhibits superior rate capability (145.8 mAh g-1 at 10.0 A g-1) and long cycle lifespan (capacity retention of 95.1% over 3000 cycles at 1.0 A g-1). Furthermore, this undifferentiated doping strategy can universally regulate the IEF magnitude in CoSe2/Co9Se8 and FeS2/Fe7S8 heterostructures. This work can provide fundamental insights into the design of advanced PIB electrodes.

Topological Defect-regulated Porous Carbon Anodes with fast Interfacial and Bulk Kinetics for High-rate and High-energy-density Potassium-ion Batteries.

Carbonaceous materials are regarded as one of the most promising anodes for potassium-ion batteries (PIBs), but their rate capabilities have been largely limited by the slow solid-state potassium diffusion kinetics inside anode and sluggish interfacial potassium ion transfer process. Herein, high-rate and high-capacity PIBs have been demonstrated by facile topological defect-regulation of the microstructure of carbon anodes. The carbon lattice of the as-obtained porous carbon nanosheets with abundant topological defects (TDPCNSs) holds high potassium adsorption energy yet low potassium migration barrier, thereby enabling efficient storage and diffusion of potassium inside graphitic layers. Moreover, the topological defects can induce preferential decomposition of anions, leading to the formation of high potassium ion conductive solid electrolyte interphase (SEI) film with decreased potassium ion de-solvation and transfer barrier. Additionally, the dominant sp2-hybridized carbon conjugated skeleton of TDPCNSs enables high electrical conductivity (39.4 S cm-1) and relatively low potassium storage potential. As a result, the as-constructed TDPCNSs anode demonstrates high potassium storage capacity (504mA h g-1 at 0.1 A g-1), remarkable rate capability (118mA h g-1 at 40 A g-1) as well as long-term cycling stability. This article is protected by copyright. All rights reserved.

Heterostructures Assembled from Bi2O2CO3 and MXene for Boosted Potassium-Ion Storage by Arousing the Built-in Electric Field.

Bismuth-based materials have been recognized as the appealing anodes for potassium-ion batteries (PIBs) due to their high theoretical capacity. However, the kinetics sluggishness and capacity decline induced by the structure distortion predominately retard their further development. Here, a heterostructure of polyaniline intercalated Bi2O2CO3/MXene (BOC-PA/MXene) hybrids is reported via simple self-assembly strategy. The ingenious design of heterointerface-rich architecture motivates significantly the interior self-built-in electric field (IEF) and high-density electron flow, thus accelerating the charge transfer and boosting ion diffusion. As a result, the hybrids realize a high reversible specific capacity, satisfying rate capability as well as long-term cycling stability. The in/ex situ characterizations further elucidate the stepwise intercalation-conversion-alloying reaction mechanism of BOC-PA/MXene. More encouragingly, the full cell investigation further highlights its competitive merits for practical application in further PIBs. The present work not only opensthewayto thedesignof other electrodes with an appropriate working mechanism but also offers inspiration for built-in electric-field engineering toward high-performance energy storage devices.

Lignite-based hard carbon for high-performance potassium-ion battery anode

Lignite-based hard carbon for high-performance potassium-ion battery anode

Resolving the tradeoff between energy storage capacity and charge transfer kinetics of sulfur-doped carbon anodes for potassium ion batteries by pre-oxidation-anchored sulfurization

Sulfur-heteroatom doping is an effective approach to improve the capacity of carbon anodes for potassium-ion batteries due to the reversible K+-sulfur reaction. However, the random sulfur doping induces unresolved tradeoff between capacity and kinetics, which results from the fundamental difficulty in controllable sulfur incorporation using traditional approaches where breaking robust carbon-containing bonds is necessary. Herein, a pre-oxidation-anchored sulfurization approach is proposed to realize site-controlled and content-adjustable sulfur doping, demonstrating the optimum sulfur content of 9.8 at.% in sulfur-doped hollow carbon sphere (S-HCS). Intentional pre-oxidation introduces easy-to-break C-O/C-O-C bond-included oxygen-containing functional groups serving as anchoring sites for substitution with sulfur atoms. Consequently, S-HCS-9.8 % achieves superior performance for K+ storage (406.1 mA h g–1 at 0.1 A g–1, 112.6 mA h g–1 at 5 A g–1 and 170 mA h g–1 after 2,000 cycles at 2 A g–1). The enhanced electrochemical performances are attributed to the largest interlayer spacing and highest disorder degree resulting from the thiophene-sulfur-dominated configuration at high sulfur content, which realizes high structure reversibility and stable solid-electrolyte-interface layer. This work provides new insights and guiding principles for the development of heteroatom-doped carbon anodes for next-generation high-performance energy storage applications.

Ultrathin carbon nanosheets with carbon composite structure of amorphous carbon and pseudo-graphite domains for high-capacity, stable and fast potassium storage

Although great progress has been made in carbon anodes for potassium-ion batteries, the development of advanced carbon anodes with fast reaction kinetics and high cycle stability is still a great challenge due to the large radius of K+ (0.138 nm). In this work, novel ultrathin carbon nanosheets (UCNs) fabricated by vapor-induced bubbling strategy are reported to address current challenge. The results show that the UCNs are composed of 3D interconnected 30 nm-thick sheet units with well-developed hierarchical micro-/meso-/macro-pores, which can not only increase the contact area between electrode/electrolyte, but also effectively buffer the volume expansion caused by the (de)potassiation. In addition, UCNs have a carbon composite structure of intertwined pseudo-graphite domains and amorphous carbon domains, providing abundant storage active sites and fast transport channels for K+. Specifically, the UCN-1300 delivers a K+ storage capacity of ≈350 mAh g−1 at a current density of 0.05 A g−1. Moreover, it presents excellent cycle stability, maintaining a capacity of 120 mAh g−1 after 5000 cycles at a current density of 5 A g−1, with a capacity retention rate of more than 99%. In prior reports, carbon anodes demonstrating such a high K+ storage capacity and outstanding cycle stability are rarely obtained.

Mn-doped FeNCN as advance anode for potassium ion batteries

The development of anode materials with advanced structures to facilitate rapid charge transport and enhance potassium storage performance is urgently needed to propel the advancement of potassium ion batteries (PIBs). Transition metal carbodiimides have emerged as promising PIB electrode materials, but achieving high capacity and long-lasting cycling stability remains a challenging task. Here, Mn-doped FeNCN was synthesized by a one-step high-temperature solid-state reaction. Mn doping expands the lattice and boosts ionic conductivity, enabling favorable potassium ion storage and enhanced charging/discharging rates. In addition, density functional theory (DFT) calculations also prove that Mn-doped FeNCN facilitates the enhancement of potassium ions adsorption and promotes electron transfer. As a result, optimized Mn-FeNCN delivers high reversible capacity (402.6 mAh/g at 100 mA g−1) as PIBs anode. Even at high current density of 1000 mA g−1, it still delivers the reverse capacity of 301 mAh/g. This work provides a promising strategy to improve electrochemical performance of the transition metal carbodiimides

Molten-salt-induced interpenetrated meso/macro porous structural hard carbon derived from chitosan for enhanced potassium ions storage

Hard carbon materials are commonly used as anode materials for environmentally friendly potassium-ion energy devices due to excellent development prospects. However, the poor conductivity and unsatisfactory rate performance of hard carbon limit their development. Herein, chitosan was chosen as the carbon precursor to prepare interpenetrated meso/macro-porous structural hard carbon (PC) formed by the template agent NaCl in the molten state at high temperature as the anode for potassium-ion batteries. PC with a high content of pyridinic N, pyrrolic N, and CO bonds can provide a high reversible capacity of 280.1 mAh g−1 at the current density of 0.05 A g−1, and show an improved rate performance of 173.8 mAh g−1 at 1.0 A g−1. Galvanostatic charge/discharge (GCD) curves do not exhibit an obvious plateau, indicating that surface adsorption is dominant in the potassium ions storage mechanism. The high K+ diffusion coefficient indicates that the interconnected meso/macro structure allows potassium ions to diffuse faster in PC. Therefore, using activated carbon (AC) as the cathode and PC as the anode, a potassium-ion hybrid capacitor (PIHC) is fabricated, which can achieve an energy density of 130 Wh kg−1 at the current density of 0.05 A g−1 and an energy density of 62 Wh kg−1 at 1.0 A g−1.

Flower-like CoSe2/N, P-doped carbon microspheres accommodated on carbon nanosheets for high-performance potassium-ion batteries

Transition metal selenides (TMSs) have emerged as promising electrode materials for potassium-ion batteries (PIBs), whereas the large volume expansion and sluggish reaction kinetics have seriously hindered the cycle life and rate performance. Herein, a hierarchical composite of flower-like CoSe2/N, P-doped carbon microspheres accommodated on carbon nanosheets (CoSe2-NPC@CNS) was rationally fabricated as the anode for PIBs through a one-pot hydrothermal and subsequent selenization method. The intimate hybridization of CoSe2/N, P-doped carbon microspheres can effectively alleviate the volume expansion of CoSe2 during charge-discharge cycles, and the ultrathin carbon nanosheets derived from fluid catalytic cracking (FCC) slurry serves as a highly conductive and buffered substrate. By robustly merging them together, the interconnected hierarchical nanoarchitecture with exposed active sites achieves promoted potassium storage capacity, electrochemical reaction kinetics, and structural stability. As a result, the PIBs with CoSe2-NPC@CNS anode deliver high reversible capacities of 320.8 mAh g−1 after 100 cycles at 0.1 A g−1 and 213.9 mAh g−1 after 850 cycles at 1.0 A g−1, excellent rate capability (188.8 mAh g−1 at 5 A g−1), and enhanced pseudo-capacitive contribution rate of 88.7 %. This work offers valuable insight into the rational design and development of hierarchical anode materials with high performance for PIBs and beyond.

Revealing the Charge Storage Mechanism in Porous Carbon to Achieve Efficient K Ion Storage.

Constructing a porous structure is considered an appealing strategy to improve the electrochemical properties of carbon anodes for potassium-ion batteries (PIBs). Nevertheless, the correlation between electrochemical K-storage performance and pore structure has not been well elucidated, which hinders the development of high-performance carbon anodes. Herein, various porous carbons are synthesized with porosity structures ranging from micropores to micro/mesopores and mesopores, and systematic investigations are conducted to establish a relationship between pore characteristics and K-storage performance. It is found that micropores fail to afford accessible active sites for K ion storage, whereas mesopores can provide abundant surface adsorption sites, and the enlarged interlayer spacing facilitates the intercalation process, thus resulting in significantly improved K-storage performances. Consequently, PCa electrode with a prominent mesoporous structure achieves the highest reversible capacity of 421.7 mAh g-1 and an excellent rate capability of 191.8 mAh g-1 at 5C. Furthermore, the assembled potassium-ion hybrid capacitor realizes an impressive energy density of 151.7Wh kg-1 at a power density of 398W kg-1. The proposed work not only deepens the understanding of potassium storage in carbon materials with distinctive porosities but also paves a path toward developing high-performance anodes for PIBs with customized energy storage capabilities.

Nitrogen-doped carbon with antimony nanoparticles as a stable anode for potassium-ion batteries

Potassium-ion batteries are considered promising alternatives to lithium-ion batteries (LIBs) because they have a lower redox K+/K potential, a lower Stokes radius, abundant raw materials, and economic benefits. However, K has a larger ionic radius than Li, which may limit the diffusion of K ions into electrodes and cause poor electrode rate capability and cycling stability. In this study, N-doped C and Sb (NC@Sb) composites were synthesised using a facile and cost-effective method of carbonisation and ball milling. The NC@Sb composites had an interconnected and highly porous structure, which was formed by the release of gases such as CO, H2O, CO2, and NH3 during carbonisation. Additionally, NC@Sb is a promising anode owing to the synergistic effects of the high specific capacity of Sb and the good cycling stability of NC. In particular, the NC@Sb composite that contained 10 wt% Sb (NC@Sb10) exhibited a high reversible capacity of 264 mAh g−1 after 100 cycles at a specific current of 200 mA g−1. Furthermore, the NC@Sb10 electrode maintained 85% of its initial capacity at a high specific current of 1 A g−1 even after 500 discharge–charge cycles. The excellent electrochemical performance of the NC@Sb composite is mainly attributed to the stable embedding of the Sb nanoparticles in the porous and electrically conductive NC matrix, which can buffer Sb stress and provide a pathway for the penetration of the electrolyte and K ions.

Two-dimensional carbon rich titanium carbide (TiC3) as a high-capacity anode for potassium ion battery

In recent years, two-dimensional (2D) materials, particularly MXenes such as titanium carbide, have gained significant interest for energy storage applications. This study explores the use of potassium-adsorbed TiC3 nanosheets as potential anode materials for potassium ion batteries (KIBs), utilizing first-principles calculations. The investigated electronic, mechanical, and thermal properties of TiC3 demonstrate its suitability as an anode material. The incorporation of potassium into the host material enhances electronic conductivity while maintaining a stable layered structure. Our findings reveal promising adsorption behavior of potassium in TiC3, leading to a high theoretical specific capacity of 958 mAh/g, coupled with a low energy barrier of 0.19 eV for potassium migration, which is indicative of superior electrochemical performance. Moreover, despite the high potassium content, the electrode material shows limited volume expansion of 11.3 %, suggesting good cyclability. Additionally, the equilibrium distance between potassium and TiC3, measured at 3.11 Å, exceeds that of lithium and TiC3 (2.56 Å), potentially augmenting the material’s flexibility. Consequently, TiC3 emerges as a promising candidate for KIB anode materials.

Design of heterostructured hydrangea-like FeS2/MoS2 encapsulated in nitrogen-doped carbon as high-performance anode for potassium-ion capacitors

The means of structural hybridization such as heterojunction construction and carbon-coating engineering for facilitating charge transfer and electron transport are considered viable strategies to address the challenges associated with the low rate capability and poor cycling stability of sulfide-based anodes in potassium-ion batteries (PIBs). Motivated by these concepts, we have successfully prepared a hydrangea-like bimetallic sulfide heterostructure encapsulated in nitrogen-doped carbon (FMS@NC) using a simple solvothermal method, followed by poly-dopamine wrapping and a one-step sulfidation/carbonization process. When served as an anode for PIBs, this FMS@NC demonstrates a high specific capacity (585 mAh g−1 at 0.05 A/g) and long cycling stability. Synergetic effects of mitigated volume expansions and enhanced conductivity that are responsbile for such high performance have been verified to originate from the heterostructured sulfides and the N-doped carbon matrix. Meanwhile, comprehensive characterization reveals existence of an intercalation-conversion hybrid K-ion storage mechanism in this material. Impressively, a K-ion capacitor with the FMS@NC anode and a commercial activated carbon cathode exhibits a superior energy density of up to 192 Wh kg−1, a high power density, and outstanding cycling stability. This study provides constructive guidance for designing high-performance and durable potassium-ion storage anodes for next-generation energy storage devices.

Electron-repulsion effect of anti-solvent strategy for long-cycle nickel sulfide-containing potassium-ion batteries

Transition metal dichalcogenides experience severe structural degradation when used as anodes in potassium-ion batteries, resulting in undesirable electrochemical behaviors. To tackle this challenge, a novel approach involving "anti-solvent-enhanced local high-concentration electrolytes" was proposed to enhance the electrochemical stability of transition metal dichalcogenides for potassium-ion storage. This improvement is attributed to the facilitation of the aggregation of local solvation structures within the ether-based electrolyte. We demonstrate the effectiveness of this method by utilizing nickel sulfide composite materials. By diluting the ether-based high-concentration electrolyte with 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (HFE) anti-solvent, the nickel sulfide containing anode achieved an ultra-high specific capacity of 382 mAh g−1 after 1500 cycles at 1 A g−1. We found that the HFE anti-solvent, with its high concentration of negatively charged fluorine atoms, exerts a strong electron-repulsion effect on the bis(fluorosulfonyl)imide anions, promoting the aggregation of local solvation structures. It not only lowers the desolvation energy but also exhibits high stability during interactions with the interface, thereby improving and keeping the K-ion’s migration ability. This, in turn, improves the cycling stability of the electrode during the potassiation-depotassiation process. We believe that this new strategy of improving potassium-ion storage performance will drive advancements in related fields.

Boosting Potassium Adsorption and Diffusion Performance of Carbon Anodes for Potassium-Ion Batteries via Topology and Curvature Engineering: From KT-Graphene to KT-CNTs.

We propose a two-dimensional carbon allotrope (named KT-graphene) by incorporating kagome and tetragonal lattices consisting of trigonal, quadrilateral, octagonal, and dodecagonal rings. The introduction of non-hexagonal rings can give rise to the localized electronic states that improve the chemical reactivity toward potassium, making KT-graphene a high-performance anode material for potassium-ion batteries. It shows a high theoretical capacity (892 mAh g-1), a low diffusion barrier (0.33 eV), and a low average open-circuit voltage (0.51 V). The presence of electrolyte solvents is propitious to boost the K-ion adsorption and diffusion capabilities. Moreover, one-dimensional nanotubes (KT-CNTs), rolled up by the KT-graphene sheet, are metallic regardless of the tube diameter. As the curvature increases, KT-CNTs exhibit significantly increased surface activity, which can promote the electron-donating ability of K. Furthermore, the curvature effect greatly enhances the efficiency of K diffusion on the inner surface compared to that on the outer surface.

A synthesis strategy of 3D carbon nanosheet anode with adsorption/intercalation-filling hybrid mechanism for high-performance sodium/potassium-ion batteries

Hard carbons are significant in sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs). However, the structural defects of hard carbons lead to poor rate performance and cycling stability, which need further improvement. The waste cooking oil was used as the precursor to synthesize 3D carbon nanosheets (NWCOC) with amino nitrogen functional groups, multi-layered pores, and expanded interlayer spacing. The excellent electrochemical properties of NWCOC were investigated and it was demonstrated that NWCOC can significantly improve the adsorption of Na+/K+ on hard carbons, substantially enhancing the embedding/de-embedding of Na+/K+, reducing the diffusion distance of ions and electrons, and improving their adaptability to volume changes. In situ XRD and Raman characterization reveal that the Na storage mechanism of NWCOC is mainly based on adsorption/intercalation-filling. Combined with density functional theory, it is shown that the porous structures doped with nitrogen have a greater propensity for ion adsorption, resulting in increased ion capture and storage. As expected, NWCOC650 exhibits high capacities of 489.4 and 388.3 mAh/g in SIBs and PIBs. NWCOC650 displays superior performance in the Na3V2(PO4)3/NWCOC650 full cell, achieving a capacity of 107.84 mAh/g. This work presents a new perspective on the synthesis and mechanisms of high-performance anodes for SIBs and PIBs.