Potassium-ion Storage Research Articles

Carbon-Encapsulated Bimetallic Fe-W-Based Selenides with Abundant Heterogeneous Conductive Network for Superior Potassium Ion Storage.

Potassium-ion batteries (KIBs) are one of the most promising alternatives to lithium-ion batteries (LIBs) due to their high ion mobility, abundant resources, and low cost. However, the problems of low capacity and poor cycling stability of KIBs remain unsolved; therefore, it is crucial to explore alternative electrode materials suitable for reversible insertion and extraction of K+. Herein, carbon-encapsulated Fe3Se4/WSe2 microsphere material assembled from nanosheets with abundant heterogeneous interfaces and expanded interlayer spacing (denoted as FWSC) is designed as an anode material for superior potassium ion storage. The microspheres assembled from nanosheets, the outer carbon coating, and the expanded layer spacing can expose more active sites and improve the electronic conductivity and structural stability of the material. The abundant heterogeneous conductive network not only improves the conductivity of the material but also enhances the reversibility of the electrochemical reaction. As a result, the FWSC exhibits outstanding cycling stability, excellent rate performance (the capacity retention is 53% when the current density is from 0.5 to 1.0 A g-1), and stable long-term cycle performance (a capacity of 209 mAh g-1 at 1.0 A g-1 over 1000 cycles).

Enhancing the potassium-ion storage performance of potassium manganese oxide cathode by single-element doping strategies

Layered manganese-based oxides are considered as ideal cathode materials for potassium-ion batteries (PIBs) due to their ease of synthesis and relatively large interlayer spacing. Nevertheless, the Jahn-Teller effect of Mn3+ and the irreversible phase transitions in high-voltage regions of layered manganese-based oxide leads to slow diffusion kinetics of potassium ions and severe capacity fading. Herein, a series of single-element doped manganese-based oxide cathodes K0.5Mn0.98X0.02O2 (X = Fe, Mg, Cu, Ti and Zn) are designed and investigated. The results demonstrate that trace doping with these elements stabilizes the layered structure of KMnO2 cathode materials, improves the diffusion coefficient of K+, and effectively suppresses the P3-O3-P3 phase transition in high-voltage regions. Among the doping-samples, the K0.5Mn0.98Fe0.02O2 exhibits outstanding reversible specific capacity of 127 mAh g−1 at a current density of 20 mA g−1. Meanwhile, K0.5Mn0.98Ti0.02O2 demonstrates exceptional cycling stability and rate capability, retaining 83.8 % of its initial capacity after 300 cycles at 200 mA g−1, and maintaining a high specific capacity close to 40 mAh g−1 even at 1000 mA g−1. This study validates the feasibility of trace element doping in enhancing the electrochemical performance of layered Mn-based cathode materials for PIBs.

Composition-optimized NiGa-LDH on MOF-derived and cobalt-nanoparticles-embedded carbon flakes for enhanced potassium-ion storage

Layered double hydroxides (LDHs), renowned for their distinct nanostructures, efficient ion channels, and high specific capacitance, are promising electrode materials for supercapacitors (SCs). However, commercial applications remain limited due to constraints in the rate capabilities and cycling. The synergistic effects of the composites can be leveraged by pairing LDHs with carbon materials to enhance the conductivity for better SC characteristics. Herein, flaky Zeolitic Imidazolate Framework(ZIF)-67 is deposited on carbon cloth and calcined to produce the MOF-derived composite of carbon nanosheet-embedded nano-cobalt particles (CPEC) on the surface of the carbon cloth. Afterward, NiGa-LDH with a controllable Ni to Ga ratio is synthesized on the CPEC to form a flower-like hierarchical nanostructure NiGa-LDH/CPEC@CC. Co nanoparticles act as nucleation sites for cohesive formation within the carbon cloth framework. Ni2Ga1-LDH/CPEC@CC has the best properties, such as a specific capacitance of 729.6F g−1 at 1 mA cm−2 and 97.3 % capacitance retention at 2 mA cm−2. The asymmetric supercapacitor (ASC) consisting of Ni2Ga1-LDH/CPEC@CC//AC has an excellent energy density of 83.96 Wh kg−1 with a power density of 80 W kg−1. Density-functional theory (DFT) calculations of Ni2Ga1-LDH/CPEC@CC affirm a potassium ion adsorption energy of −2.127 eV and density of state (DOS) near the Fermi level. The study imparts theoretical and technical knowledge about the design of complex nanostructures from MOF precursors.

Crystallinity degree of MoSe 2 influencing its potassium-ion storage performance

Crystallinity degree of MoSe ₂ influencing its potassium-ion storage performance

Tuning the electrochemical performance of a biphenylene coated metal as the anode for K+-ion batteries

The researchers employed density functional theory (DFT) computations to assess suitability of BP-biphenylene (b-BP) monolayers for application in potassium-ion battery systems. In their evaluations, the researchers considered various factors, like adsorption energy (Ead) of the b-BP monolayer with adsorbed potassium adatoms, in addition to diffusion energy barrier (Ebar) and storage capacity and of potassium ions on this surface. The results indicated that the b-BP monolayer has significantly higher potassium-ion storage capacities, reaching 1026 mAh/g, compared to typical graphite anodes and other carbon materials. The Ebar for potassium ions on the b-BP monolayer was determined to be 0.22 eV. Furthermore, anticipated open-circuit voltage (OCV) values for this material were found to lie within acceptable range of 0.25–1.2 V, making it suitable for use as an anode. These research findings underscore the potential of the b-BP monolayer as an appropriate anode material for potassium-ion battery (KIBs) applications.

A versatile opened hollow carbon sphere with highly loaded antimony alloy for ultra-stable potassium-ion storage

Carbon materials meet the stringent practical requirements for anodes for potassium-ion batteries (PIBs) due to their abundance and chemical stability. The major issue of carbon-based anodes is the low specific capacity and poor cyclic stability. Equally importantly, scalable synthesis approaches for electrodes are highly desired for the future application in large-scale energy storage systems. Herein, we developed a novel composite of Sb encapsulated in N/P co-doped opened hollow carbon spheres (N/POHCs) with high Sb loading through a simple carbonization and subsequent impregnation process. Beneficial from the virtue of abundant pyridinic-N−P bonding and opened hollow spherical structure advantages, N/POHCs exhibit much lower diffusion barrier than that of pure carbon, prominent Sb carrier capability, as well as the extraordinary resistance to volume expansion. The resulting Sb@N/POHCs composite delivers a high specific capacity of 533.3 mAh g−1 at 0.1 A g−1 with an initial Coulombic efficiency of 83 %, and can maintain a specific capacity of 345 mAh g−1 at 1 A g−1 after 4000 cycles. This work provides rational structure design with universal carrier capability of active materials to achieve high-capacity and long cycle life anode for advanced PIBs accompanied by the potential for large-scale production.

Coupling of graphitic microcrystalline and available functional groups in hard carbon unlocking deep and fast potassium-ion storage

Coupling of graphitic microcrystalline and available functional groups in hard carbon unlocking deep and fast potassium-ion storage

Scalable Ambient Synthesis of Metal–Organic Frameworks and Their Derivative Nanoporous Carbon for Superior Potassium Ion Storage

Scalable Ambient Synthesis of Metal–Organic Frameworks and Their Derivative Nanoporous Carbon for Superior Potassium Ion Storage

Uniform carbon coating and solid electrolyte interphase synergistically enhanced exceptional anodic K‐ion storage properties of stable KTiOPO4 single crystals

AbstractSearching for low‐cost, high‐capacity, high‐power, high‐stability, high‐tap‐density, and inherently safe materials for developing cheap, safe, and high‐performance batteries has always been a research hotspot. Herein, an inherently safe, low‐cost, and low‐strain KTiOPO4 (KTOP) submicron single crystals with a uniform thin layer carbon coating are developed using a ball‐mill assisted solid‐state method. Uniform solid electrolyte interphase, carbon coating, and inherently stable structure synergistically help compact KTOP submicron single crystals achieve an exceptional anodic K‐ion storage performance. The carbon‐coated KTOP single crystals obtained under the carbonization temperature of 400°C (KTOP‐C‐400) can deliver an exceptional potassium ion storage performance of 253.3, 224.0, 175.5, and 131.1 mA h g−1 at the current density of 100, 200, 500, and 1000 mA g−1, respectively, in the electrolyte of 5 M potassium bis(fluorosulfonyl)imide (KFSI) in DIGLYME electrolytes. Even after being cycled at 1000 mA g−1 for 1000 cycles, the capacity was maintained at 182.5 mA h g−1 with a coulombic efficiency of 99.9%.

Synergistic Triple-Action morphological composite Anode: Integrating lattice Softening, Interfacial electric Fields, and dual confinement for superior Potassium-Ion battery performance

Synergistic effects could significantly improve slow redox kinetics and structural pulverization of electrodes in potassium ion batteries (PIBs); however, the performance of single synergistic designs is limited. Multi-synergistic composite, shaped by a blend of factors, substantially boosts performance, yielding outcomes that surpass single synergistic coupling design. Herein, we develop a Bi2Se3/Sb2Se3@NC@G electrode that integrates three key features for enhanced potassium-ion storage: p-n junctions enhance electron transfer through internal electric fields, dual confinement prevents K2Se dissolution into the electrolyte, and lattice softening in the Bi-Sb alloy relieves stress during potassium ion insertion/extraction. These multi-synergistic effects enable the heterostructure to exhibit superior electrochemical performance in potassium-ion batteries.The Bi2Se3/Sb2Se3@NC@G electrode demonstrates notable capacity of 640 mA h g-1 at current density of 50 mA g-1, achieving 95.5 % of its theoretical capacity, maintain stable capacity of 310 mA h g−1 after 5000 cycles at current density of 0.5 A/g with 0.002 % per cycle degradation, and exhibits the fastest rate capability up to 10 A/g (172 mA h g−1). Furthermore, potassium ion hybrid capacitor (PIHC) can achieve a high energy density of 118 Wh kg−1 and a power density of 5200 W kg−1, and full cell shows an attractive energy density of 97 Wh kg-1 and a stable performance after 250 cycling number under 1 A g-1. This study proposes an effective strategy that employs multiple synergistic coupling designs to maximize potassium-ion storage capacity, achieving a breakthrough in extending battery lifecycle.

Polypyrrole-encapsulated TiSe2 with excellent electrochemical performance for potassium-ion storage

TiSe2 as a potential electrode for potassium-ion batteries, has garnered significant attention owing to its stable ion storage property. Nevertheless, the inadequate electronic conductivity of TiSe2 impedes its practical implementation. In this investigation, we adopt a polymerization method to fabricate TiSe2@PPy, which boasts enhanced conductivity and exceptional performance. Once coated with polypyrrole, the TiSe2@PPy composites demonstrate the optimum electrochemical performance, providing a charge capacity of 67.4 mAh g−1 at 1 C with a capacity retention of 68.4 % after 170 cycles. The PPy coating enhances the conductivity of TiSe2 and enables potassium-ion batteries to exhibit outstanding electrochemical performance. Ex-situ Raman and FTIR tests are utilized to comprehend the electrochemical reaction between K+ and the TiSe2@PPy electrode during cycling. Overall, this work introduces a PPy coating on TiSe2, which presents a novel concept for the development.

CoSe2 nanocrystals embedded in one-dimensional mesoporous carbon nanofibers as advanced anode for potassium-ion storage

High-performance potassium-ion batteries have received great attention for electrochemical energy storage owing to their low redox potential, abundant natural resources and excellent safety. As an advanced negative material, CoSe2 has been widely investigated for potassium-ion batteries. Unfortunately, the pure CoSe2 anode suffers from the fast capacity decay and sluggish kinetics, preventing its practical application. Herein, we introduce a novel strategy to fabricate the CoSe2 nanoparticles embedded in one-dimensional mesoporous carbon nanofibers (denoted as 1D-CoSe2@CNFs) with superior high-rate property and good cycle stability for the first time. In this designed material, the conductive carbon nanofibers are loaded with CoSe2 particles. The obtained 1D-CoSe2@CNFs anode shows a specific capacity of 706.3 mAh/g at 0.1 A/g and presents a high capacity retention ratio of around 96.3 % at 5 A/g over 400 cycles. Therefore, this fabricated 1D-CoSe2@CNFs nanocomposite can be employed as a novel negative electrode for potassium-ion storage.

Ultrahigh nitrogen-doped carbon derived from g-C3N4 assisted by citric acid for superior potassium-ion storage

Nitrogen-doped carbon is regarded as a promising anode for potassium ion batteries (PIBs) because nitrogen atoms can regulate the structures of carbon and generate abundant active sites. How to improve the nitrogen content in carbon through simple and effective methods remains to be further addressed. In this paper, a carbon material (60NC) with ultrahigh nitrogen content (16 %) was prepared from graphite phase carbon nitride (g-C3N4) by a convenient freeze-drying and high-temperature pyrolysis method, assisted by citric acid. When used as an anode for PIBs, 60NC exhibited a superior reversible capacity of 318.1 mAh g−1 after 200 cycles at 0.1 A g−1. Even at the high current density of 1A g−1, 60NC maintained a specific capacity of 261.8 mAh g−1 after 1000 cycles. The excellent electrochemical performance of 60NC mainly stems from its abundant K+ storage active sites caused by nitrogen doping, large layer spacing, and hierarchical porous structure.

Defect-engineered TiNOx catalyst targeted to activate rate-determining step for highly efficient K-SeS2 batteries

SeS2 material is attracting intensive attention in the potassium ion storage system due to its high theoretic capacity and compensated physicochemical properties. However, the actual capacity (usually below 400 mAh g−1) in practical studies is far below its theoretical value. This is mainly due to the notorious “shuttle effect” of soluble intermediates and some unknown sluggish conversion steps involved in the SeS2 cathode. In this work, the whole kinetic reaction mechanism is revealed for the first time by in situ Raman and DFT calculations, and the rate-determining step also is identified as the conversion step from K2S2 to K2S. Based on this insight, we synthesized an electrocatalyst (labeled as TiNOx) to maximize the conversion of the SeS2 cathode. The regulated Fermi level and d-band center of the Ti atoms can greatly enhance the adsorption of dissolvable intermediates and especially can be targeted to accelerate the rate-determining step. Consequently, the resultant K-SeS2@TiNOx battery displays a high capacity of 806.6 mAh g−1, two times that of the raw K-SeS2 battery, and achieves a stable capacity retention after 800 cycles. Moreover, the whole smooth conversion process on SeS2@TiNOx is reasonably explained by in situ monitoring techniques and DFT calculations.

Synthesis of nitrogen-doped amorphous carbon nanotubes from novel cobalt-based MOF precursors for improving potassium-ion storage capability

Amorphous carbon materials with sophisticated morphologies, variable carbon layer structures, abundant defects, and tunable porosities are favorable as anodes for potassium-ion batteries (PIBs). Synthesizing amorphous carbon materials typically involves the pyrolysis of carbonaceous precursors. Nonetheless, there is still a lack of studies focused on achieving multifaceted structural optimizations of amorphous carbon through precursor formulation. Herein, nitrogen-doped amorphous carbon nanotubes (NACNTs) are derived from a novel composite precursor of cobalt-based metal–organic framework (CMOF) and graphitic carbon nitride (g-CN). The addition of g-CN in the precursor optimizes the structure of amorphous carbon such as morphology, interlayer spacing, nitrogen doping, and porosity. As a result, NACNTs demonstrate significantly improved electrochemical performance. The specific capacities of NACNTs after cycling at current densities of 100 mA/g and 1000 mA/g increased by 194 % and 230 %, reaching 346.6 mAh/g and 211.8 mAh/g, respectively. Furthermore, the NACNTs anode is matched with an organic cathode for full-cell evaluation. The full-cell attains a high specific capacity of 106 mAh/gcathode at a current density of 100 mA/g, retaining 90.5 % of the specific capacity of the cathode half-cell. This study provides a valuable reference for multifaceted structural optimization of amorphous carbon to improve potassium-ion storage capability.

Tellurium@nitrogen-doped hierarchical porous carbon nanofibers for potassium-ion storage

Tellurium@nitrogen-doped hierarchical porous carbon nanofibers (Te@N-doped HPCNFs) were fabricated by the electrospinning and high-temperature carbonization to obtain the N-doped HPCNFs host and the subsequent melt-diffusion process for Te loading. As a freestanding electrode for potassium-ion (K+) storage, Te@N-doped HPCNFs exhibit the capacities of 215.3 mAh/g after 650 cycles at 0.1 A/g and 127.2 mAh/g even at 2.0 A/g. Such an excellent cycling stability and high-rate performance can be attributed to small-molecule tellurium confined in N-doped HPCNFs through Te-C bonding and the introduction of nitrogen heteroatom which inhibit the volume change and dissolution of potassium polytellurides during repeated cycling.

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).

Fast and robust potassium storage enabled by controllable hierarchical CoTe2/MoS2@C nanorods with semi-coherent heterogeneous interfaces

Constructing heterostructures in a controllable manner stands as a pivotal strategy for enhancing the potassium-ion storage capabilities of transition metal tellurides. However, the challenge lies in achieving a favorable morphology while simultaneously regulating the heterogeneous interface. This study employs a straightforward one-step hydrothermal method to grow few-layer MoS2 nanosheets on CoTe2 nanorods, thereby fabricating a controllable hierarchical structure with a dense three-dimensional (3D) network of MoS2 nanosheets and abundant semi-coherent heterojunction interfaces with CoTe2. The CoTe2/MoS2 heterostructure exhibits abundant semi-coherent interfaces, at which a built-in electric field is formed that facilitates the migration of electrons and ions. A hierarchical structure of CoTe2/MoS2@C was further formed by carbon coating, that applies a dual constraint on CoTe2 to effectively alleviate its volume expansion during charge and discharge processes. Employed as the anode of potassium-ion batteries, the hierarchical structure of CoTe2/MoS2@C demonstrates a significant improvement in high-rate capacity, achieving a high specific capacity of 144.0 mAh g−1 at 5.0 A g−1. The material also enables excellent long-term cycling stability with a capacity decay of only 0.016 % per cycle up to 1800 cycles at 1.0 A g−1.

Design and optimization of carbon materials as anodes for advanced potassium-ion storage

Design and optimization of carbon materials as anodes for advanced potassium-ion storage

Interlayer expansion and conductive networking of MoS2 nanoroses mediated by bio-derived carbon for enhanced potassium-ion storage

Potassium-ion batteries (PIBs) represent a promising battery technology for energy storage applications. Nevertheless, the progress of PIBs is still hindered by the lack of electrode materials that allow rapid and repeatable accommodation of the large K+ ions. Herein, a composite anode material containing interlayered-expanded MoS2 (55.6% larger) nanoroses in carbon nanonets (MoS2/C@CNs) is designed with the assistance of biomass bagasse, of which the dual carbon sources convert into interlayer and skeleton carbon, respectively. The unique structure facilitates electron/ion transport in the entire electrode and offers excellent structural stability, leading to much improved electrochemical performance compared to simple MoS2/C composite and pure MoS2. Furthermore, the role of electrolyte salts (potassium hexafluorophosphate and potassium bis(fluorosulfonyl)imide) and the electrolyte concentration on the interfacial properties in PIBs have been explored. The results indicate that the low-concentration potassium bis(fluorosulfonyl)imide electrolyte helps to produce optimized organic-inorganic solid electrolyte interface films, contributing to a capacity retention of 90% after 1,000 cycles at 2 A g-1.