Anode For Potassium-ion Batteries Research Articles

Needle coke anodes for potassium-ion batteries: Storage mechanism and interfacial evolution in soft carbon

Needle coke has attracted much attention as soft carbon anode material for potassium-ion batteries (PIBs) owing to its high crystallinity and conductivity. However, limited research has been conducted on the storage mechanism and the functional and structural evolution of the solid electrolyte interphase (SEI) in ester and ether based electrolytes. This work investigates the potassium ion storage mechanisms of soft carbon anodes in three electrolytes: KPF6 EC/DEC, KPF6 DME, and KFSI DME, and reveals that K+ stored in the KPF6 EC/DEC electrolyte could be through an “adsorption-intercalation” mechanism. Whereas K+ stored in the DME-based electrolytes is believed to undergo a “co-intercalation/adsorption-intercalation” process. Interfacial analyses indicate that the SEI formed in the EC/DEC electrolyte inhibits co-intercalation of potassium ion and solvent, which preserves sufficient space to accommodate potassium ion. Conversely, the [K-DME]+ solvation co-intercalation in DME-based electrolytes compromises the structural integrity, and results in a persistent capacity decline. This work offers novel insights into potassium ion storage in ester and ether-based electrolytes, and provides theoretical support for the fabrication of high-performance soft carbon anodes.

Molecular structure regulation of FCCs enabling N/S co-doped hollow amorphous carbon with enlarged interlayer spacing and rich defects for superior potassium storage

Constructing high-performance and low-cost carbon anodes for potassium-ion batteries (PIBs) is highly desirable but faces great challenges. In this study, we present a novel approach to fabricating N/S co-doped hollow amorphous carbon (LNSHAC) for superior potassium storage through a template-assisted molecular structure regulation strategy. By tailoring a 3D crosslinked aromatics precursor from fluid catalytic cracking slurry (FCCs), the LNSHAC features a N/S co-doped hollow structure with enlarged interlayer spacing of up to 0.405 nm and rich defects. Such unique microstructure offers fast transport channels for K-ion intercalation/deintercalation and provides more active sites, leading to boosted reaction kinetics and potassium storage capacity. Consequently, the LNSHAC electrode delivers an impressive reversible capacity (466.2 mAh g−1 at 0.1 A/g), excellent rate capability (336.3 mAh g−1 at 2 A/g), and superior cyclic performance (256.9 mAh g−1 after 5000 cycles at 5 A/g with admirable retention of 76.9 %), standing out among the reported carbon-based anodes. When KFeHCF is employed as the cathode, the LNSHAC-based K-ion full cell exhibits a high reversible capacity of 176.6 mAh g−1 at 0.1 A/g and excellent cyclic stability over 200 cycles. This work will inspire the development and application of advanced carbon-based materials for potassium electrochemical energy storage.

GeV4S8: a Novel Bimetallic Sulfide for Robust and Fast Potassium Storage.

Potassium-ion batteries (PIBs) have attracted much attention due to their low production cost and abundant resources. Germanium is a promising alloying-type anode with a high theoretical capacity for PIBs, yet suffering significant volume expansion and sluggish potassium-ion transport kinetics. Herein, a rational strategy is formulated to disperse Ge atoms into transition metal V-S sulfide frameworks to form a loosely packed and metallic GeV4S8 medium. The theoretical prediction shows that GeV4S8 is conducive to the adsorption and diffusion of K+. The V-S frameworks provide fast ion/electron diffusion channels and also help to buffer the volume expansion during K+ insertion. In situ and ex situ characterizations manifest that KGe alloy clusters are constrained and dispersed by potassiated VS2 topological structure during discharging, and revert to the original GeV4S8 after charging. Consequently, as a novel anode for PIBs, GeV4S8 provides a high specific capacity of ≈400mAhg-1 at 0.5C, maintaining 160mAhg-1 even at 12.5C and ≈80% capacity after 1000 cycles at 5C, superior to most of the state-of-the-art anode materials. The proposed strategy of combining alloy and intercalation dual-functional units is expected to open up a new way for high-capacity and high-rate anode for PIBs.

Pre-bonded hybrid carbon materials with stable structure as anode for potassium-ion batteries

Pre-bonded hybrid carbon materials with stable structure as anode for potassium-ion batteries

Nanopore design of sulfur doped hollow carbon nanospheres for superior potassium-ion battery anodes

Nanopore design of sulfur doped hollow carbon nanospheres for superior potassium-ion battery anodes

Unlocking the potential of ultra-thin two-dimensional antimony materials: Selective growth and carbon coating for efficient potassium-ion storage

Antimony-based anodes have attracted wide attention in potassium-ion batteries due to their high theoretical specific capacities (∼660 mA h g−1) and suitable voltage platforms. However, severe capacity fading caused by huge volume change and limited ion transportation hinders their practical applications. Recently, strategies for controlling the morphologies of Sb-based materials to improve the electrochemical performances have been proposed. Among these, the two-dimensional Sb (2D-Sb) materials present excellent properties due to shorted ion immigration paths and enhanced ion diffusion. Nevertheless, the synthetic methods are usually tedious, and even the mechanism of these strategies remains elusive, especially how to obtain large-scale 2D-Sb materials. Herein, a novel strategy to synthesize 2D-Sb material using a straightforward solvothermal method without the requirement of a complex nanostructure design is provided. This method leverages the selective adsorption of aldehyde groups in furfural to induce crystal growth, while concurrently reducing and coating a nitrogen-doped carbon layer. Compared to the reported methods, it is simpler, more efficient, and conducive to the production of composite nanosheets with uniform thickness (3–4 nm). The 2D-Sb@NC nanosheet anode delivers an extremely high capacity of 504.5 mA h g−1 at current densities of 100 mA g−1 and remains stable for more than 200 cycles. Through characterizations and molecular dynamic simulations, how potassium storage kinetics between 2D Sb-based materials and bulk Sb-based materials are explored, and detailed explanations are provided. These findings offer novel insights into the development of durable 2D alloy-based anodes for next-generation potassium-ion batteries.

A red phosphorus/mesoporous carbon anode for potassium-ion storage

Red phosphorus/mesoporous carbon (RP/CMK-3) composite was fabricated by a facile ultrasonic treatment and freeze-drying approach. As the anode for potassium-ion batteries, RP/CMK-3 with the weight ratio of 2:1 between RP and CMK-3 exhibits high capacities of 192.8 mAh g−1 at 200 mA g−1 and 232.7 mAh/g after 100 cycles at 50 mA g−1. Such a good K+ storage behavior can be attributed to small-size RP particles combined with CMK-3 through P-C bonds, which not only provide a feasible conductive network but also suppress the volume change of RP during repeated potassiation/de-potassiation processes.

Encapsulation of CoS2 nanoparticles in bamboo-like carbon nanotubes as advanced potassium-ion batteries anodes

Transition metal sulfides (TMSs) have been widely investigated as anode materials for potassium ion batteries (PIBs) due to their high theoretical capacity. However, the intense volume change of TMSs in the process of charge/discharge will lead to the destruction of material structure and the decrease of potassium storage performance. Herein, CoS2/CNTs composites are prepared by carbonization and in-situ vulcanization, and the CoS2 nanoparticles are encapsulated in bamboo-like carbon nanotubes. The unique structure can buffer the volume change during charge/discharge, which is responsible for the strong structural stability and remarkable electrochemical storage performance of the composite. When assembled as PIBs half-cell, the CoS2/CNT-600 composite exhibits excellent rate performance (303.7 mAh g−1 at 2000 mA g−1) and favorable cycling stability (325.7mAh g−1 at 100 mA g−1 after 500 cycles). In addition, the successful assembly of the full cell validates the practical application prospects of CoS2/CNT-600 electrodes.

3D Micro‐Flower Structured BiFeO3 Constructing High Energy Efficiency/Stability Potassium Ion Batteries Over Wide Temperature Range

AbstractThe fatty K+ ion calls for suitable host materials to meet the requirement for high safety and long‐term stability of potassium‐ion batteries (PIBs) to rival lithium‐ion batteries, thus anode materials possessing high capacity, high stability, and well‐defined plateaus involving favorable working voltage (≈0.5 V) have always been desired. Here, a 3D BiFeO3 with micro‐flower structure (BFO‐MF) constructed by nanosheets is proposed as an anode for PIBs. Density functional theory calculations evidence that the intrinsically favorable affinity and diffusion for K+ ion render fast electrochemical kinetics and attenuated voltage‐hysteresis, and electrochemical measurements indicate that the stable 3D structure of BFO‐MF enables to achieve impressive performances including a high capacity of 606 mAh g−1, flat plateaus at ≈0.5 V, stable performances for 5000 cycles at 500 mA g−1, and 500 cycles at 100 mA g−1 upon −20 °C. In situ and ex situ characterizations definitely elucidate the conversion and alloy/dealloy mechanism. The satisfying features of BFO‐MF anode ensure full‐cells to achieve excellent cyclic performances, and a high energy efficiency retention rate of ≈98.2% for the cathode, with energy density/power density output up to 177.1 Wh kg−1/2152.8 W kg−1, respectively. This work can provide new insights for developing advanced anodes for PIBs.

Chemically bonded MXene/SnSe2 composite with special structural transformation as a high-performance anode for lithium and potassium ions battery

Sn-C bonding coupled MXene/SnSe2 composite with SnSe2 nanosheets vertically coating on the MXene surface was prepared successfully by the solvothermal method, in which MXene matrix etched separately by HF and LiF/HCl was used to explore the improving effect on the electrochemical performance of SnSe2. It is found that MXene etched by HF acid shows more obvious accordion-like structure with larger layer spacing, and its composite with SnSe2 demonstrates better lithium and potassium storage properties. When employed as potassium-ion batteries (PIBs) anode, MXene/SnSe2 electrode can deliver a reversible capacity of 222.8 mAh·g−1 till 300 cycles at the current density of 200 mA·g−1. As an anode for lithium-ion batteries (LIBs), MXene/SnSe2 could provide high reversible capacity (515.6 mAh·g−1 after 300 cycles at 200 mA·g−1) and rate capacity (1015.1 mAh·g−1 at 500 mA·g−1 and 496.2 mAh·g−1 at 5000 mA·g−1). Even at 2000 mA·g−1, the capacity of MXene/SnSe2 can be maintained at 322.6 mAh·g−1 after 500 cycles. Further analysis by ex-situ SEM finds that the MXene/SnSe2 electrode undergoes structural reconstruction at the high current density of 2000 mA·g−1. In the first few cycles, SnSe2 nanosheets are changed into a network structure and then in-situ pulverized into many small nanoparticles, all which immerged on MXene surface and between layers. Although MXene/SnSe2 electrode experiences structural transformation, it retains apparent layered structure. This provides a fast channel for electrons and ions migration, resulting in higher Li+ diffusion rate and diffusion-controlled storage capacity. It is believed that the work could be acted as a reference for design composite with MXene and used for anode as well as other materials.

Efficient Polytelluride Anchoring for Ultralong-Life Potassium Storage: Combined Physical Barrier and Chemisorption in Nanogrid-in-Nanofiber

HighlightsThe hierarchical nanogrid-in-nanofiber-structured dual-type carbon-confined CoTe2 nanodots (CoTe2@NC@NSPCNFs) were synthesized via facile templates and an electrospinning approach.Hierarchical nanogrid-in-nanofiber structure effectively suppresses the volume change of CoTe2 and the shuttle of potassium polytelluride (K-pTex) through robust physical restraint and strong chemisorption.CoTe2@NC@NSPCNFs hybrid achieves ultralong lifespan potassium-storage performance over 3500 cycles, and the deep mechanisms underlying the evolution, dissolution, and shuttle of K-pTex have been clearly revealed.

Interfacial tuning of the graphite anode for potassium ion intercalation in a wide temperature range

An electrolyte design strategy is proposed for graphite anode in potassium-ion batteries working in a wide temperature range.

Ginger-derived hierarchical porous carbon as an anode material for potassium-ion batteries and capacitors

Carbonaceous materials are ideal as an anode for potassium-ion batteries (KIBs) because of their low cost, tunable physiochemical properties, and excellent reversible intercalation of potassium-ions (K+).

Highly crystalline graphite nanofibers as an anode for high-performance potassium-ion batteries

Graphite nanofibres with high crystallinity and low defect levels for potassium-ion batteries with high initial Coulombic efficiency and long cycling stability are reported in this study.

SAXS unveils porous anodes for potassium-ion batteries: dynamic evolution of pore structures in Fe@Fe2O3/PCNFs composite nanofibers.

The porous structure of composite nanofibers plays a key role in improving their electrochemical performance. However, the dynamic evolution of pore structures and their action during ion intercalation/extraction processes for negative electrodes are not clear. Herein, porous carbon composite nanofibers (Fe@Fe2O3/PCNFs) were prepared as negative electrode materials for potassium-ion batteries. Electrochemical test findings revealed that the composites had good electrochemical characteristics, and the porous structure endowed composite electrodes with pseudo-capacitive behaviors. After 1500 discharge/charge cycles at a current density of 1000 mA g-1, the specific capacity of the potassium-ion batteries was 144.8 mAh g-1. We innovatively used synchrotron small-angle X-ray scattering (SAXS) technique to systematically investigate the kinetic process of potassium formation in composites and showed that the kinetic process of potassium reaction in composites can be divided into four stages, and the pores with smaller average diameter distribution are more sensitive to changes in the reaction process. This work paves a new way to study the deposition kinetics of potassium in porous materials, which facilitates the design of porous structures and realizes the development of alkali metal ion-anode materials with high energies.

A bimetallic sulfide FeCoS4@rGO hybrid as a high-performance anode for potassium-ion batteries.

We synthesized a low metal-to-sulfur atomic ratio (0.5) FeCoS4, exhibiting high reversible specific capacity. Reduced graphene oxide was covered on the surface to improve the cycling stability and rate performance further. Density functional theory calculations show that composite materials can effectively increase the adsorption energy and enhance the diffusion kinetics.

Advances in bismuth-based anodes for potassium-ion batteries

Bi-based materials with low cost, high capacity and suitable operating voltage are promising candidates for potassium-ion battery anodes. Rational optimization strategies are expected to bring them from laboratory to commercial applications.

Anisotropic lens-shaped mesoporous carbon from interfacially perpendicular self-assembly for potassium-ion batteries.

Anisotropic lens-shaped nitrogen-doped carbon (Lens-NMC) with unidirectionally aligned mesopores was achieved via perpendicular block copolymer self-assembly at the polymer interface. Lens-NMC is applied as a potassium-ion battery anode material as a next-generation battery system.

Deciphering Unexplored Reversible Potassium Storage and Small Volume Change in a CaV4O9 Anode with In Situ Transmission Electron Microscopy

AbstractVanadium‐based compounds are explored as promising electrode materials in lithium/sodium‐ion batteries exhibiting superior energy storage properties. However, similar attempts are rarely reported for potassium‐ion batteries (PIBs), in which the fundamental reaction mechanisms remain inexplicit. Herein, porous CaV4O9 nanobelts (NBs) are selected as a PIB anode to systematically investigate potassium storage mechanisms through in situ transmission electron microscopy. In situ measurements track overall electrochemical potassiation reactions of CaV4O9 and identify a polyphase state of V4O7, CaO, and K2O phases after potassiation. Unexpectedly, the potassiated products can be partially converted back to the original CaV4O9 phase with residual VO2 and CaO phases, which is different from the irreversible phase transformations in lithium/sodium storages of CaV4O9. Impressively, the cavities in NBs alternately disappear and appear with (de)potassiation, avoiding the drastic volume change and structural degradation of anodes. The reversible potassium storage and stable cycling are evaluated by electrochemical measurements and in situ X‐ray diffraction analysis. This work provides a paradigm by revisiting the existing anode materials in lithium/sodium‐ion batteries to seek out viable anodes for next‐generation PIBs.

Modulating Co[sbnd]Co bonds average length in Co0.85Se1−xSx to enhance conversion reaction for potassium storage

While alloying transition metal chalcogenides (TMCs) with other chalcogen elements can effectively improve their conductivity and electrochemical properties, the optimal alloying content is still uncertain. In this study, we study the influence of dopant concentration on the chemical bonds in TMC and reveal the associated stepwise conversion reaction mechanism for potassium ion storage. According to density function theory calculations, appropriate S-doping in Co0.85Se (Co0.85Se1−xSx) can reduce the average length of CoCo bonds because of the electronegativity variation, which is thermodynamically favourable to the phase transition reactions. The optimal Se/S ratio (x = 0.12) for the conductivity has been obtained from experimental results. When assembled as an anode in potassium-ion batteries (PIBs), the sample with optimized Se/S ratio exhibits extraordinary electrochemical performance. The rate performance (229.2 mA h g−1 at 10 A g−1) is superior to the state-of-the-art results. When assembled with Prussian blue (PB) as a cathode, the pouch cell exhibits excellent performance, demonstrating its great potential for applications. Moreover, the stepwise K+ storage mechanism caused by the coexistence of S and Se is revealed by in-situ X-ray diffraction and ex-situ transmission electron microscopy techniques. Hence, this work not only provides an effective strategy to enhance the electrochemical performance of transition metal chalcogenides but also reveals the underlying mechanism for the construction of advanced electrode materials.