Anode For KIBs Research Articles

Fluorine Doping Modulating Pore Structure and Adsorption Capability of Carbon Matrix Boosting Potassium Storage Performance of Red Phosphorus Anode

AbstractThe application of alloying‐typed red phosphorus (red P) anode in potassium‐ion batteries (KIBs) with ultra‐high theoretical capacity is hindered by the limited capacity and fast capacity decay due to poor electronic conductivity and huge volume change. Herein, a facile and efficient strategy of fluorine (F) doping is innovatively developed to modulate the pore structure of carbon matrix (F‐CNS) to encapsulate red P with enhanced potassium storage capability. Theoretical calculations reveal that F doping induces additional defects within the carbon layer, which facilitates P4 molecules embedding into the F‐doping‐induced micropores, enhances the adsorption ability toward K atoms and P4 molecules, and improves electrochemical kinetics assisted with more charge transfer obtained from the electron density difference, thus enabling robust potassium storage capability for such unique Red P@F‐CNS anode. Accordingly, the Red P@F‐CNS anode demonstrates outstanding cycling stability (90% capacity retention after 800 cycles at 2A g−1), and the potassium‐ion full cell (Red P@F‐CNS//KFeHCF) exhibits exceptional long‐term cycling performance (129 mAh g−1 after 2500 cycles at 5 A g−1 with only 0.014% decay per cycle). In situ characterizations confirm the superior structural integrity of the carbon‐based matrix. This study offers a rational design principle for engineering high‐performance carbon‐supported alloying‐typed anodes for KIBs.

Electrospun MOF-derived N-doped mesoporous carbon fibers embedded with ultrafine vanadium oxide as an ultralong cycling stability for potassium ion storage

Potassium-ion batteries (KIBs) are promising options for large-scale energy storage because of their low cost and low redox potential. The use of anodes with porous structures is an attractive strategy to improve the electrochemical properties of KIBs. However, the development of KIB anodes has been hindered by their low capacity and difficulty in synthesizing porous structures. Herein, ultrafine vanadium oxide nanoparticles embedded in porous N-doped carbon nanofibers (VO@PNCNFs) using electrospinning and one-step heat treatment are reported. The uniform growth of vanadium oxide crystals is facilitated by the porous structure of the carbon nanofiber. The numerous pores play a crucial role in the transfer of electrons and ions and provide structural stability to the N-doped carbon matrix. As a result, the VO@PNCNF electrode demonstrates a high reversible capacity (∼205 mA h g−1 at 1.0 A g−1), good cycle stability over 3000 cycles, and excellent rate performance (95 mA h g−1 at 3.0 A g−1).

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.

Conductive Metal-Organic Framework with Superior Redox Activity as a Stable High-Capacity Anode for High-Temperature K-Ion Batteries.

High-temperature rechargeable batteries are essential for energy storage in elevated-temperature situations. Due to the resource abundance of potassium, high-temperature K-ion batteries are drawing increasing research interest. However, raising the working temperature would aggravate the chemical and mechanical instability of the KIB anode, resulting in very fast capacity fading, especially when high capacity is pursued. Here, we demonstrated that a porous conductive metal-organic framework (MOF), which is constructed by N-rich aromatic molecules and CuO4 units via π-d conjugation, could provide multiple accessible redox-active sites and promised robust structure stability for efficient potassium storage at high temperatures. Even working at 60 °C, this MOF anode could deliver high initial capacity (455 mAh g-1), impressive rate, and extraordinary cyclability (96.7% capacity retention for 1600 cycles), which is much better than those of reported high-temperature KIB anodes. The mechanistic study revealed that C═N groups and CuO4 units contributed abundant redox-active sites; the synergistic effect of π-d conjugated character and reticular porous architecture facilitated the K+/e- transport and ensured an insoluble electrode with small volume deformation, thus achieving stable high-capacity potassium storage.

KTi2(PO4)3 nanoparticles wrapped in 3D RGO as enhanced electrode for potassium-ion batteries

Potassium-ion batteries (KIBs) have drawn great attention because of the abundant resources and low cost of potassium. Nevertheless, large size K+ slows the reaction kinetics of the ion and increases volume expansion of the host material, thus hindering its practical application. Herein, we construct nanocomposite of KTi2(PO4)3 nanoparticles and rGO (KTP-rGO) as electrode for KIBs by solvothermal-annealing process. In this nanocomposite, KTP nanoparticles (about 400 nm) effectively were wrapped in 3D rGO. The synergistic effects of 3D conductive carbon networks and active KTP nanoparticle improve electronic conductivity, alleviate the volume varies, and provide a wider diffusion channel to accelerate ion transport. Therefore, the KTP-rGO displays impressive reversible capacity of 66 mAh g−1 at 2 C after 150 cycles, superior rate of 28 mAh g−1 at 20 C, and good cycling ability. The strategy can offer new sights for the design and preparation of composite anode for KIBs.

Investigation on bare ZnO nanotubes and nanosheet as electrode materials for potassium-ion batteries: A DFT search

Within this work, the possibility of using (5,0), (6,0), (7,0), (8,0), and (9,0) zigzag ZnO nano-tubes and a ZnO nano-sheet (ZnONS) was investigated in potassium-ion batteries (KIBs) through the B3LYP-gCP-D3/6-31G* scheme. The cell voltage, ion diffusion coefficient, the maximum energy barrier for the migration of K+ and the adhesion energies of K+ and K of (5,0) nano-tube were 0.93 V, 5.31 × 10−8 cm2/s, –33.4 kcal/mol, respectively. The results showed that the impact of the dispersion term (D3) on the K and K+ adhesion energies was more than that of the gCP (basis set superposition error). A reduction in the curvature of the ZnONS dramatically weakened the interaction of the K atom, whereas it had a slight impact on the interaction of K+. Therefore, a decrease in the curvature of the ZnONS increased the cell voltage to 1.21 V. We can use ZnO nano-structures as a promising anode for KIBs.

Efficient resource utilization achieves simple synthesis of Fe3Se4@CNF for robust potassium-ion storage

Metal selenides with excellent storage capacities have attracted extensive attention in the field of potassium ion batteries (KIBs). As a typical metal selenide, Fe3Se4 has also been gradually used in KIBs. However, the synthesis process of metal selenides is usually complicated and requires a lot of selenium powder, which is time-consuming and causes the waste of resources. In this paper, an internal selenization strategy with an approximate stoichiometric ratio (1.3:1) of Se:Fe is proposed to synthesize Fe3Se4 composites, resulting in the efficient use of selenium powder to synthesize selenide. Most of Fe3Se4 particles are embedded in carbon fibers to obtain Fe3Se4@carbon nanofibers (Fe3Se4@CNFs). As anodes for KIBs, Fe3Se4@CNFs show improved electrochemical performances for K+ storage when compared with Fe@CNF-Se0.1–400 (external selenide products) with more particles on the surface. Fe3Se4@CNF show a reversible capacity of 278 mA h g−1 after 150 cycles at a current density of 0.1 A g−1 in KIBs. The enhanced capacities and stability of Fe3Se4@CNF can be attributed to the technique of internal selenization, which controls Fe3Se4 nanoparticles to better distribute in CNF. This study provides a new idea for the efficient synthesis of selenides and sulfides, and extends the application of selenides and sulfides.

A dual-carbon structured molybdenum selenide composites controlled via interface engineering and chemical bonding to attain high initial coulombic efficiency and rate capability of potassium-ion batteries

Molybdenum selenide (MoSe2) is considered representative anode material for Potassium-ion batteries (PIBs) by reason of its adjustable forbidden bandwidth and large interlayer spacing allowing the intercalation/deintercalation of large-sized K+. However, its inferior electronic conductivity, substantial volume variation, and aggregation make it difficult to achieve satisfactory cycling performance and rate capability. Herein, we reported a novel composite with MoSe2 nanosheets grown vertically on the surface of N-doped hollow porous carbon bowls and wrapped by ultrathin/wrinkled reduced graphene oxide layers (G-MoSe2/NHPCB) as the anode material for PIBs. The strong chemical bonds between MoSe2 and carbon materials (including C-Mo, C-O-Mo, and C-N-Mo bonds) were profitable for the charge-transfer kinetics and structural durability. The NHPCB substrate, with a large specific surface area, could significantly prohibit the aggregation of MoSe2 nanosheets and shorten the transmission path for electrons and ions. Meanwhile, the ultrathin/wrinkled graphene layers could effectively strengthen the composite structure stability and reinforce the overall conductivity. Benefitting from the distinctive structure, when evaluated as a K-ion half-cell anode, the G-MoSe2/NHPCB electrode exhibited a high discharge capacity of 601.59 mA h g−1 and initial coulombic efficiency (ICE) of 83.4% at 0.1 A/g, exceptional rate capability (261.3 mA h g−1 at 5.0 A/g) and long-term cycling stability (304.3 mA h g−1 at 1.0 A/g after 500 cycles and 214.9 mA h g−1 at 2.0 A/g after 1000 cycles). The electrochemical reaction mechanism and kinetic analysis were investigated using in-situ and ex-situ methods and first-principles calculation. This work demonstrates the advantages of G-MoSe2/NHPCB as KIBs anode materials and provides innovative thinking for the rational design of high-performance transition metal selenides with unique structures.

Flexible carbon film with local enlarged interlayer spacing for ultrafast and highly durable potassium storage

Carbon materials have drawn much attention as a rigid electrode for the reversible intercalation of K+ along with a high surface adsorption capacity for potassium-ion batteries (KIBs). However, it is a challenge to prepare flexible carbon film for freestanding KIBs anodes, which could promote the free transfer of electrolyte and allow sufficient interlayer spacing to relieve the tension generated by K+-intercalation. Herein, a flexible carbon film constructed by honeycomb-like porous nanofibers with local enlarged interlayer spacing is synthesized by an electrospinning method together with a metal-organic frameworks (MOFs)-derived strategy. The flexible carbon film improves the electrical conductivity of freestanding electrode, and the interconnected porous structure with local enlarged interlayer spacing facilitates the transfer of electrolyte to active sites fluently and relieves the K+-intercalation induced tension, which synergistically boosts the reaction kinetics and K+-storage capacity. The freestanding flexible carbon film delivers excellent potassium storage performance of 386.1 mAh g−1 at 0.1 A g−1 after 500 cycles and 190.1 mAh g−1 at 5 A g−1 after 2400 cycles. Moreover, density functional theory (DFT) calculation confirms the advantage of edge-N atoms at graphene defect in adsorbing the K+ with limited volume expansion, which could provide extra capacity beyond K+-intercalated contribution for KIBs.

Advancements and Prospects of Graphite Anode for Potassium-Ion Batteries.

Potassium-ion batteries (KIBs) have recently attracted considerable attention owing to their resource abundance, low cost and environmental friendliness. Graphite as a mature commercial anode material for lithium-ion batteries, has been proved as a promising anode candidate for KIBs by reversible forming potassium-graphite intercalation compounds. However, large volume expansion and sluggish K+ kinetics caused by the incompatibility between large radius of K+ and the small interlayer spacing of graphite, result in the poor cycle stability and rate performances, hindering its practical application. Extensive research efforts have focused on improving the potassium storage performance of graphite anodes. This review provides an overview of recent advances in addressing these challenges and optimizing the electrochemical performance of graphite anodes for KIBs. Various strategies to improve the electrochemical performance of graphite and graphitic carbon anodes, such as microcrystalline regulation, heteroatom doping, morphological adjustment, and coating modification, are discussed, while the critical issues and challenges associated with graphite anodes and the prospects for their advancement in KIBs are highlighted. The review offers valuable guidelines for rational structural design and promotes the commercial development of high-performance graphite anode materials for KIBs.

C4S Nanosheet: A Potential Anode Material for Potassium-Ion Batteries

Potassium ion batteries (KIBs) have received increasing popularity owing to their distinct advantages. We discover a hitherto unknown C4S nanosheet, a novel carbon-based material with carbon and sulfur consisting of pentagons and hexagons rings. The proposed C4S nanosheet is highly stable dynamically, thermodynamically, mechanically, and chemically, according to first-principles calculations. Moreover, the graphene-like C4S nanosheet is a prospective KIBs anode material, which has a metallic band structure, a relatively low diffusion barrier (0.07 eV), a large capacity (1340 mA h g−1), and an acceptable average voltage (0.44 V). Finally, we demonstrate good cycling stability of the C4S nanosheet. Our findings indicate that the proposed C4S nanosheet is a potentially favorable KIBs anode material.

Pseudohexagonal Nb2O5 Anodes for Fast-Charging Potassium-Ion Batteries

High-rate batteries will play a vital role in future energy storage systems, yet while good progress is being made in the development of high-rate lithium-ion batteries, there is less progress with post-lithium-ion chemistry. In this study, we demonstrate that pseudohexagonal Nb2O5(TT-Nb2O5) can offer a high specific capacity (179 mAh g-1 ∼ 0.3C), good lifetime, and an excellent rate performance (72 mAh g-1 at ∼15C) in potassium-ion batteries (KIBs), when it is composited with a highly conductive carbon framework; this is the first reported investigation of TT-Nb2O5 for KIBs. Specifically, multiwalled carbon nanotubes are strongly tethered to Nb2O5 via glucose-derived carbon (Nb2O5@CNT) by a one-step hydrothermal method, which results in highly conductive and porous needle-like structures. This work therefore offers a route for the scalable production of a viable KIB anode material and hence improves the feasibility of fast-charging KIBs for future applications.

Research on carbon-based and metal-based negative electrode materials via DFT calculation for high potassium storage performance: a review

The key R&D concern in the domain of new energy in recent years has been the large-scale development of electrochemical energy storage. However, the steep increase in pricing has constrained the further expansion of lithium-ion batteries, primarily due to the ongoing depletion of their scarce lithium supplies. A potential candidate material at the moment is the potassium-ion battery (KIB), which has an anode made of carbon and/or an alloy and rich reserves, offering an excellent theoretical capacity and ideal working voltage. More significant advancements are still required to achieve long life and high energy density, despite the fact that some significant breakthroughs have been reported. The most recent findings from research on carbon-based [graphite, hard carbon (HC), and nanoporous carbon] and alloy-based (mainly including Sb, Sn, P, and its compounds) anodes for KIBs are compiled in this document. Numerous simulations at the atomic level based on particular chemical interactions, phase transitions, ion/electron transport dynamics, and conduction band spin utilizing density functional theory (DFT) calculations have been conducted to thoroughly investigate the storage mechanism of K+ on various electrode materials. Moreover, this paper examined contemporary structural modification techniques used in carbon- and alloy-based anode electrode materials and applied DFT calculations to confirm the advancement of its thorough tests. To promote the manufacturing of rechargeable KIBs, the challenges and potential of KIBs were also explored in future research.

A robust conductive covalent organic framework for ultra-stable potassium storage

A conductive and redox-active COF (Ni-TTF) have been synthesized and applied as an promising anode for KIBs, exhibiting remarkable stability with no capacity loss after 2500 cycles at 2C, making it one of the best organic anode materials for KIBs.

S/N-co-doped graphite nanosheets exfoliated via three-roll milling for high-performance sodium/potassium ion batteries

Due to its larger ionic radius, further studies are needed before graphite can be used as an anode for sodium/potassium-ion batteries (SIBs/KIBs). It is believed that doping and increasing the layer spacing can improve the Na+/K+ storage. Herein, S/N co-doped graphite nanosheets (GNS) with an enlarged interlayer spacing of 0.39 nm were prepared via exfoliation with three-roll milling (TRM) combined with thiourea heated at different temperatures. This method generates abundant defects and active sites for GNS, as well as facilitates rapid access and transport of electrolytes and electrons/ions. The electrochemical results show that the S/N-doped GNS exfoliated 15 times and heated at 600 °C (SNGNS15-600) with thiourea as the electrode delivers a discharge capacity of 94 mAh g–1 over 6000 cycles at 10 A g–1 with an enhanced rate capability and stable performance for application in SIBs. Calculations using density functional theory show that the increased interlayer spacing by TRM and S, N co-doping enhances the adsorption energies of Na+ on graphite, thus improving the Na+ storage. As the anode for KIBs, the SNGNS15-600 electrode has a capacity of 142 mAh g–1 after 5000 cycles at 0.5 A g–1. This study provides an essential theoretical basis for the effective exfoliation of layered graphite-based materials and their applications in energy storage.

Designing carbon anodes for advanced potassium-ion batteries: Materials, modifications, and mechanisms

Recently, the limited abundance and uneven geographical distribution of Li resources seriously hamper the growing demand for lithium-based energy storage devices. In this regard, potassium-ion batteries (KIBs) sharing similar “rocking chair” working principles with lithium-ion batteries have started to attract increasing attention due to their high energy density and abundant potassium resources. Carbon material is considered to show great potential for using as high-performance anode in KIBs. However, it is still a challenge to simultaneously achieve satisfactory specific gravimetric and volumetric capacities, high initial Coulombic efficiency, superior rate performance, and excellent cycle stability due to the sluggish reaction kinetics of the large-sized K-ions. Herein, we summarize the latest research achievements of different types of carbon anodes for KIBs, including graphite, graphene, hard carbon, soft carbon, and carbon nanotubes, in which the key factors affecting the electrochemical performance are explored. Importantly, the alternative strategies for addressing the low gravimetric/volumetric capacity and low initial Coulombic efficiency of carbons are thoroughly emphasized. Finally, the critical issues, challenges, and perspectives are proposed to show the development direction of KIBs. We hope this review can provide researchers with new ideas to design high-performance carbon materials and give insightful perspectives to accelerate the application of carbon electrodes for KIBs. The latest research achievements of different types of carbon anodes for KIBs are summarized, including graphite, graphene, hard carbon, soft carbon, and carbon nanotubes, in which the key factors affecting the electrochemical performance are demonstrated. Importantly, the alternative strategies for addressing the low gravimetric/volumetric capacity and low initial Coulombic efficiency of carbons are thoroughly emphasized. Finally, the critical issues, challenges, and perspectives are proposed to show the development direction of KIBs. • The latest progress of carbon materials in potassium ion batteries are presented. • Promising strategies to improve the potassium storage performances are emphasized. • Challenges and prospects for the future development of carbon materials are highlighted.

Mxene Ti3C2 generated TiO2 nanoparticles in situ and uniformly embedded in rGO sheets as high stable anodes for potassium ion batteries

Ti3C2/TiO2/rGO nanosheets were synthesized as anode materials for potassium ion batteries (KIBs) using modified Hummers, freeze drying, and thermal reduction in this paper. Layered Ti3C2 /TiO2/rGO nanosheets were synthesized by in-situ formation of rGO and TiO2 nanoparticles between Ti3C2 layers. As one of the most important members of MXenes family, Ti3C2 exhibits unique electronic characteristics, high specific surface area, strong electrical conductivity and chemically active surface, which can enhance electrode capacity. There are three ways to increase electrode conductivity and capacity: Firstly, rGO is applied as the substrate for the inlaying of TiO2 and Ti3C2 nanoparticles and nanosheets. Secondly, rGO may also buffer electrode volume changes during charging and discharging processes. In addition, the enormous surface area of rGO makes Ti3C2 and TiO2 nanoparticles dispersion well, and Ti3C2 and TiO2 nanoparticles can well separate rGO nanoparticles and prevent them from stacking up again. The synergistic effect of the three can efficiently relieve the stress and provide a rapid transport pathway between electrons and ions. The flake structure of Ti3C2/TiO2/rGO is advantageous to the stability of SEI film, which makes the material maintain good activity during charge and discharge process, and significantly increases its electrochemical performance. Therefore, Ti3C2/TiO2/rGO electrode has a high reversible capacity of 349.2 mAhg−1 after 200 cycles of 100 mAg−1 current, and a high stable capacity of 229.3 mAhg−1 after 500 cycles of 500 mAg−1 current, and has exceptional rate performance. The structure of Ti3C2/TiO2/rGO composite remains stable after 500 cycles, and no agglomeration occurs. The detailed reaction mechanism of Ti3C2/TiO2/rGO electrode as KIBs anode was analyzed by SEM, XRD, Raman, TGA, FT-IR, BET, TEM, XPS, EDS, CV, EX-situ XRD, ex-situ TEM, and so on. Therefore, it can be concluded that the Ti3C2/TiO2/rGO composite is an appropriate anode material for KIBs.

Defective 1T′-ReSe2 nanosheets vertically grown on elastic MXene for fast and stable potassium ion storage

The sluggish reaction kinetics and poor structure stability of transition metal dichalcogenides (TMDs)-based anodes in potassium-ion batteries (KIBs) usually cause limited rate performance and rapid capacity decay, which seriously impede their application. Herein, we report a vacancy engineering strategy for preparing a class of Te-doped 1T’-ReSe2 anchored onto MXene (Te-ReSe2/MXene) as an advanced anode for KIBs with high performance. By taking advantage of the synergistic effects of the defective Te-ReSe2 arrays with expanded interlayers and the elastic MXene nanosheets with self-autoadjustable function, the Te-ReSe2/MXene superstructure exhibits boosted K+ ion storage performance, in terms of high reversible capacity (361.1 mA h g−1 at 0.1 A g−1 over 200 cycles), excellent rate capability (179.3 mA h g−1 at 20 A g−1), ultra-long cycle life (202.8 mA h g−1 at 5 A g−1 over 2000 cycles), and steady operation in flexible full battery, presenting one of the best performances among the TMDs-based anodes reported thus far. The kinetics analysis and theoretical calculations further indicate that satisfactory pseudocapacitive property, high electronic conductivity and outstanding K+ ion adsorption/diffusion capability corroborate the accelerated reaction kinetics. Especially, structural characterizations clearly elaborate that the Te-ReSe2/MXene undergoes reversible evolutions of an initial insertion process followed by a conversion reaction.

Functional group contributions for azo derivatives as anode materials for KIBs: A first-principles study

Due to the large radius of K ions, organic electrodes generally own sufficiently interstitial space and good structural flexibility for potassium-ion batteries (KIBs). Organic compounds containing azo group (NN) are a class of promising anode materials because of their low potential and high reversibility. Herein, we study the electrochemical properties of azo derivatives with different functional groups by using the first-principles method. The results show that during K insertion, these anode materials have small volume expansion ratio of 20%–60% with good cycling performance. The adjunction of functional groups improves the performance of these organic materials as anode for KIBs, and Azobenzene-4,4′-dicarbocylic acid potassium salts (ADAPTS) performs better. This prediction is helpful for the design of azo organic anodes with functional groups.

KOH activated nitrogen and oxygen co-doped tubular carbon clusters as anode material for boosted potassium-ion storage capability

Carbon nanomaterials have become a promising anode material for potassium-ion batteries (KIBs) due to their abundant resources, low cost, and excellent conductivity. However, among carbon materials, the sluggish reaction kinetics and inferior cycle life severely restrict their commercial development as KIBs anodes. It is still a huge challenge to develop carbon materials with various structural advantages and ideal electrochemical properties. Therefore, it is imperative to find a carbon material with heteroatom doping and suitable nanostructure to achieve excellent electrochemical performance. Benefiting from a Na2SO4 template-assisted method and KOH activation process, the KOH activated nitrogen and oxygen co-doped tubular carbon (KNOCTC) material with a porous structure exhibits an impressive reversible capacity of 343 mAh g−1 at 50 mA g−1 and an improved cyclability of 137 mAh g−1 at 2 A g−1 after 3000 cycles with almost no capacity decay. The kinetic analysis indicates that the storage mechanism in KNOCTC is attributed to the pseudocapacitive process during cycling. Furthermore, the new synthesis route of KNOCTC provides a new opportunity to explore carbon-based potassium storage anode materials with high capacity and cycling performance.