Anode Material For Potassium-ion Batteries Research Articles

Theoretical prediction of metallic R12-graphene as a promising anode material for potassium-ion batteries with high ion mobility, high capacity, and excellent electrolyte wettability

Although graphene has excellent electrical and mechanical properties, the giant delocalized π-electron system makes it chemically inert. Here, we propose an idea to design two-dimensional (2D) carbon allotropes via incorporating multiple rings in sp2-hybridized carbon networks, which can break the π-bonding network and enhance the surface reactivity. By assembling molecule of cyclobut(a)acenaphthylene, we predict a monolayer 2D carbon material, named as R12-graphene, which is composed of quadrilateral, pentagonal, hexagonal, and dodecagonal carbon rings. It shows great stability in energetic, dynamic, thermodynamic, and mechanical aspects. It exhibits high-performance as an anode material for potassium-ion batteries (PIBs), including an intrinsic metallic behavior, a high theoretical capacity (632 mA h g−1), a low K diffusion barrier (0.33 eV), and a low average open-circuit voltage (0.5 V). The presence of electrolytes can provide better K ion adsorption and diffusion capability compared to that in vacuum. Furthermore, R12-graphene has excellent wettability toward some commonly used electrolytes, which is beneficial for improving the charge/discharge rate for PIBs.

Sustainable Polyvinyl Chloride-Derived Soft Carbon Anodes for Potassium-Ion Storage: Electrochemical Behaviors and Mechanism.

Soft carbon is a promising anode material for potassium-ion batteries due to its favorable properties such as low cost, high conductivity, stable capacity, and low potential platform. Polyvinyl chloride, as a white pollutant, is a soft carbon precursor that can be carbonized at varying temperatures to produce soft carbons with controllable defect and crystal structures. This work investigates the effect of carbonization temperature on the crystalline structures of the obtained soft carbons. In situ Raman spectroscopy was used to elucidate the adsorption-intercalation charge storage mechanism of potassium ions in soft carbons. Soft carbons prepared at the temperature of 800 °C have a defect-rich, short-range ordered structure, which provides optimal intercalation and adsorption sites for potassium ions, resulting in a satisfactory capacity of 302 mAh g-1 . This work presents new possibilities for designing soft carbon materials from recycling plastics for potassium-ion batteries.

Bismuth Telluride Nanoplates Hierarchically Confined by Graphene and N-Doped C as Conversion-Alloying Anode Materials for Potassium-Ion Batteries.

Potassium-ion batteries (PIBs) have broad application prospects in the field of electric energy storage systems because of its abundant K reserves, and similar "rocking chair" operating principle as lithium-ion batteries (LIBs). Aiming to the large volume expansion and sluggish dynamic behavior of anode materials for storing large sized K-ion, bismuth telluride (Bi2 Te3 ) nanoplates hierarchically encapsulated by reduced graphene oxide (rGO), and nitrogen-doped carbon (NC) are constructed as anodes for PIBs. The resultant Bi2 Te3 @rGO@NC architecture features robust chemical bond of Bi─O─C, tightly physicochemical confinement effect, typical conductor property, and enhanced K-ion adsorption ability, thereby producing superior electrochemical kinetics and outstanding morphological and structural stability. It is visually elucidated via high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) that conversion-alloying dual-mechanism plays a significant role in K-ion storage, allowing 12 K-ion transport per formular unit employing Bi as redox site. Thus, the high first reversible specific capacity of 322.70mAhg-1 at 50mAg-1 , great rate capability and cyclic stability can be achieved for Bi2 Te3 @rGO@NC. This work lays the foundation for an in-depth understanding of conversion-alloying mechanism in potassium-ion storage.

Two-Dimensional Molecular Brush-Based Ultrahigh Edge-Nitrogen-Doped Carbon Nanosheets for Ultrafast Potassium-Ion Storage

Heteroatom doping, especially nitrogen doping, has been regarded as an efficient strategy to break through the capacity limitation of carbonaceous anode materials in potassium-ion batteries (PIBs). Constructing edge-nitrogen-rich carbon skeleton with highly exposed active sites and efficient charge transfer is critical for the high performance of nitrogen-doped carbonaceous anode materials. Herein, a kind of ultrahigh edge-nitrogen (up to 16.2 at%) doped carbon nanosheets (ENCNS) has been developed by an efficient assembly of high-nitrogen-ratio melamine (MA) with polyacrylic acid grafted graphene oxide (GO-g-PAA) molecular brushes. The assembled PAA/MA structure facilitates the formation of an edge-nitrogen-rich carbon skeleton during heat treatment, while the highly conductive graphene backbone with a 2D nanomorphology enables shortened ion diffusion pathways and numerous exposed active surfaces. As a result, the ENCNS demonstrate excellent rate performance (up to 144 mAh g−1 at 10 A g−1) and good cycle stability (136 and 100 mAh g−1 after 400 cycles at 5 and 10 A g−1, respectively).

Design of multifunctional graphene oxide-modified nanofiber film with heterostructure (ZnS-CoS@GO@CNFs) for long-term stable potassium ion storage

When transition metal sulfides are used as high-theoretical-capacity anodes for potassium ion batteries (PIBs), their low conductivity and large volume expansion resulted in inferior rate performance and cyclic stability. In this study, multifunctional graphene oxide (GO) was employed to control the diameter and distribution of nanoparticles within composite fibers, which improved their conductivity and tensile deformation. In addition, a three-dimensional conductive carbon network composed of heterostructures and GO (ZnS-CoS@GO@CNFs) accelerated the kinetics and stabilized potassium ion storage. As the anode material of PIBs, the composite provided an excellent rate performance of 210 mA h g−1 at 3 A g−1, and after 2800 cycles under a large current of 2 A g−1, the capacity retention rate was 97.7% (171 mA h g−1). Furthermore, when the nanofiber film was used as a self-supporting anode, it maintained a stable capacity output (302 mA h g−1 after 100 cycles at 0.1 A g−1). A foldable pouch cell was assembled using a potassium ion hybrid super-capacitor, and it was found to operate safely and normally under multiangle repeated bending and final recovery; further, it provided a high energy density (134 W h kg−1) and power density (5815 W kg−1). The excellent electrochemical properties determined here further reveal the application prospects of multifunctional GO composite fiber film.

Low-Strain KVPO4F@C as Hyperstable Anode for Potassium-Ion Batteries

Potassium-ion batteries with carbon-based materials and alloy materials as anodes possess pronounced potassium storage and cycling abilities, yet they suffer from harsh synthetic processes, low initial Coulombic efficiency, and limited structure stability. Herein, we first put forward potassium vanadium fluorophosphate (KVPO4F) as a highly stable anode material for potassium-ion batteries (PIBs). KVPO4F@C composite is successfully synthesized through hydrothermal method followed by a low-temperature roasting process. An amorphous carbon film is homogeneously wrapped on the surface of the KVPO4F particles to improve electronic conductivity. As the anode for PIBs, the KVPO4F@C presents a super-high discharge capacity of 242.32 mAh g−1 and a superior cycle stability over 120 cycles at 100 mA·g−1 with 93.1% capacity retention. Additionally, it maintains 92.9% of its initial capacity of 100 mA·g−1 at 1000 mA·g−1 after cycling 2100 times, which indicates an excellent long cycling performance. The in situ X-ray Diffraction and ex situ Transmission Electron Microscopy tests prove the minimal volume variation and stable structure of KVPO4F@C. The designed KVPO4F@C provides facilitative electronic conductivity and stable structure, successfully innovating an ultra-stable and high-performance anode material for potassium-ion batteries and other energy storage application fields.

A Novel Hexaazatriphenylene Carboxylate with Compatible Binder as Anode for High‐Performance Organic Potassium‐Ion Batteries

AbstractOrganic electrode materials have attracted tremendous attention for potassium‐ion batteries (PIBs). Whereas, high‐performance anodes are scarcely reported. Herein, a novel hexaazatriphenylene potassium carboxylate (HAT‐COOK) is proposed as anode materials for PIBs. The rich CN/CO bonds guarantee the high theoretical capacity. It is also demonstrated HAT‐COOK is more compatible with the water‐soluble binders than the hydrophobic fluoride binders, forming homogenous electrode film, maintaining structural integrity, and achieving stable cycling and excellent rate performance. With the compatible binder, each HAT‐COOK molecule can involve 6‐electron transfer, yielding a high reversible discharge capacity of 288 mAh g−1 at 50 mA g−1, excellent rate performance (105 mAh g−1 at 5000 mA g−1), and good cycling stability (143 mAh g−1 after 500 cycles at 500 mA g−1). These results highlight the importance of the delicate molecular design of organic molecules as well as the optimization of binders to achieve high‐performance PIBs.

Hierarchical construction of MoSe2 nanoparticles anchored on N-doped porous carbon nanocages with Mo-C bonding for enhanced potassium-ion storage

Molybdenum selenide (MoSe2) is considered as a promising anode material for potassium ion batteries (PIBs) due to its high theoretical capacity and large interlayer spacing. However, the low intrinsic conductivity and large volume expansion impede its practical application. Herein, hierarchical nanostructure of MoSe2 nanoparticles tightly anchored on hollow porous nitrogen-doped carbon nanocages (MoSe2/NCC) is constructed as an anode material for PIBs. Nitrogen-doped carbon nanocages not only improve the conductivity, provide more active sites, and alleviate the volume expansion during K+ insertion and desertion, but also serve as a nucleation substrate for suppressing the agglomeration of MoSe2 nanoparticles. Importantly, the structural stability and electron/ion transfer kinetics are significantly enhanced by strong interfacial coupling between MoSe2 and carbon via the formation of Mo-C bonding. Consequently, MoSe2/NCC electrode exhibits a reversible capacity of 321 mA h g−1 at 0.1 A g−1, excellent cycling stability with a retention of 323 mA h g−1 after 80 cycles, and rate capability of 173 mA h g−1 at 5 A g−1. In addition, the storage mechanism and transfer kinetics of potassium ions during the charging and discharging process are investigated. This work paves the ideas for the design of novel anode materials for high-rate and stable PIBs.

Ultrarapid Nanomanufacturing of High-Quality Bimetallic Anode Library toward Stable Potassium-Ion Storage.

Bimetallic alloy nanomaterials are promising anode materials for potassium-ion batteries (KIBs) due to their high electrochemical performance. The most well-adopted fabrication method for bimetallic alloy nanomaterials is tube furnace annealing (TFA) synthesis, which can hardly satisfy the trade-off among granularity, dispersity and grain coarsening due to mutual constraints. Herein, we report a facile, scalable and ultrafast high-temperature radiation (HTR) method for the fabrication of a library of ultrafine bimetallic alloys with narrow size distribution (≈10-20 nm), uniform dispersion and high loading. The metal-anchor containing heteroatoms (i.e., O and N), ultrarapid heating/cooling rate (≈103 K s-1 ) and super-short heating duration (several seconds) synergistically contribute to the successful synthesis of small-sized alloy anodes. As a proof-of-concept demonstration, the as-prepared BiSb-HTR anode shows ultrahigh stability indicated by negligible degradation after 800 cycles. The in situ X-ray diffraction reveals the K+ storage mechanism of BiSb-HTR. This study can shed light on the new, rapid and scalable nanomanufacturing of high-quality bimetallic alloys toward extended applications of energy storage, energy conversion and electrocatalysis.

Constructing sulfur and oxygen co-doped carbon nanosheets by tailoring poly tannic acid for fast and stable potassium storage

Carbonaceous material with excellent structural stability and low cost has always been deemed focus of pursuer, nevertheless it showed the sluggish dynamics and large volume expansion as the anode materials for potassium-ion batteries (PIBs). Herein, S, O co-doped ultra-thin carbon nanosheets (S/O-CNS) with enlarged interlayer spacing was synthesized through pyrolysis poly tannic acid with a sulfur-assisted carbonization strategy. Under the unique synthesis process, sulfur acts as a dopant and intercalating agent to acquire few-layer carbon nanosheets with large interlayer spacing (0.42 nm), while oxygen was in-situ doped into the carbon lattice and provides sites for sulfur doping. With the synergistic effects of the co-doping effect and heterostructure, S/O-CNS delivers an excellent reversible capacity of 375.6 mA h g−1 at 0.1 A g−1, an impressive rate performance of 159.9 mA h g−1 even at 10 A g−1 as well as outstanding cycle stability of 198.9 mA h g−1 after 700 cycles at 1.0 A g−1. Kinetics analysis indicates that the capacitance-controlled process plays a dominant role in K+ storage. The results prove that the enlarged interlayer spacing and abundant edge defects accelerate the ion diffusion kinetics. This dual-doping strategy provides a way to design high-performance carbonaceous materials for PIBs.

KOH-treated mesocarbon microbeads used as high-rate anode materials for potassium-ion batteries

KOH-treated mesocarbon microbeads used as high-rate anode materials for potassium-ion batteries

Research progress of biomass carbon materials as anode materials for potassium-ion batteries.

Biochar materials have attracted people's attention because of their environmental friendliness, abundant resources, and the use of waste resources for reuse. As a potassium-ion anode material, biomass char materials synthesized by different methods have broad application prospects. However, due to the problems of low initial magnification and limited potassium-storage capacity, it is necessary to improve the electrochemical performance through modifications, such as atomic doping. Atomic doping is an effective way to improve battery conductivity and potassium storage. In this paper, the synthesis method of biochar as an anode material for potassium-ion batteries and the influence of atomic doping on its modification in recent years are reviewed.

ZIF-67-derived Co/CoSe ultrafine nanocrystal Schottky heterojunction decorated hollow carbon nanospheres as new-type anodes for potassium-ion batteries

Metal-organic frameworks (MOFs) have the advantages of controllable chemical properties, rich pore structures and reaction sites and are expected to be high-performance anode materials for the next generation of potassium-ion batteries (PIBs). However, due to the large radius of potassium ions, the pure MOF crystal structure is prone to collapse during ion insertion and processing, so its electrochemical performance is quite limited. In this work, a hollow carbon sphere-supported MOF-derived Co/CoSe heterojunction anode material for potassium-ion batteries was developed by a hydrothermal method. The anode has high potassium storage capacity (461.9 mA h/g after 200 cycles at 1 A/g), excellent cycling stability and superior rate performance. It is worth noting that the potassium ion storage capacity of the anode material shows a gradual upward trend with the charge–discharge cycle, which is 145.9 mA h/g after 3000 cycles at a current density of 10 A/g. This work demonstrates that MOF-derived CoSe anodes with high capacity and low cost may be promising candidates for the introduction of potassium ion storage.

Hollow CuSbSy Coated by Nitrogen-Doped Carbon as Anode Electrode for High-Performance Potassium-Ion Storage

As a potential anode material for potassium-ion batteries (PIBs), bimetallic sulfides are favored by researchers for their high specific capacity, low cost, and long cycle life. However, the non-ideal diffusion rate and poor cycle stability pose significant challenges in practical applications. In this work, bimetallic sulfide CuSbSy@C with a yolk-shell structure was synthesized by in situ precipitation and carbonization. When CuSbSy is applied in the anode of PIBs, it can provide the desired capacity and reduce the volume expansion of the compound through the synergistic effect between copper and antimony. At the same time, the existence of the nitrogen-doped carbon shell confines the material within the shell while improving its electrical conductivity, inhibiting its volume expansion and aggregation. Therefore, CuSbSy@C exhibits a satisfactory capacity (438.8 mAh g−1 at 100 mA g−1 after 60 cycles) and an excellent long cycle life (174.5 mAh g−1 at 1000 mA g−1 after 1000 cycles).

Vapor-phase derived ultra-fine Bismuth nanoparticles embedded in carbon nanotube networks as anodes for sodium and potassium ion batteries

Bismuth (Bi) is a promising material as the anode for sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs) due to its characteristics such as reasonable price and high theoretical volumetric capacity (3800 mAh cm−3). Nevertheless, considerable drawbacks have hindered the practical applications of Bi, including its relatively low electrical conductivity and inevitable volumetric change during the alloying/dealloying processes. To solve these problems, we proposed a novel design:Bi nanoparticles were synthesized via a single-step low-pressure vapor-phase reaction and embedded onto the surfaces of multi-walled carbon nanotubes (MWCNTs). After being vaporized at 650℃ and 10-5 Pa, Bi nanoparticles less than 10 nm were uniformly distributed in the three-dimensional (3D) MWCNT networks to form a Bi/MWNTs composite. In this unique design, the nanostructured Bi can reduce the risk of structural rupture during cycling, and the structure of the MWCMT network is beneficial in shortening the electron/ion transport path. In addition, MWCNTs can improve the overall conductivity of the Bi/MWCNTs composite and prevent particle aggregation, thus improving the cycling stability and rate performance. As an anode material for SIB, the Bi/MWCNTs composite has demonstrated excellent fast charging performance with a reversible capacity of 254 mAh/g at 20 A/g. A capacity of 221mAhg−1 after cycling at 10 A/g for 8000 cycles has also been achieved for SIB. As an anode material for PIB, the Bi/MWCNTs composite has delivered excellent rate performances with a reversible capacity of 251 mAh/g at 20 A/g. A specific capacity of 270mAhg−1 after cycling at 1Ag−1 for 5000 cycles has also been achieved for PIB.

High-entropy NaCl-type metal chalcogenides as K-ion storage materials: role of the cocktail effect

The drastic volume expansion of active materials and the shuttle effect of polychalcogenides hindered the development of anode materials for potassium-ion batteries (PIBs). Thus, various strategies have been used to overcome the negative effects associated with potassiation. Here, we propose a NaCl-type high-entropy metal chalcogenide (HEMC) prepared using a simple melting method as an anode material for PIBs. Unlike traditional high-entropy materials comprising inactive metals, NaCl-type HEMCs can realize the occupancy of cationic sites by active metals. We show that AgSnSbSe1.5Te1.5, a HEMC, produces short-range tiny cells during phase-change energy storage reactions, reconciling the participation of active and inactive metals to form various heterointerfaces and different functional metal nanoparticles. The kinetic and density functional theory analysis showed that the formation of heterointerfaces decreased the diffusion energy barrier of K+ and the inactive metal silver provided appropriate adsorption energy, suppressing the latent shuttle effect. The results show enhanced electrochemical performance owing to the elemental composition of high-entropy materials and the formation of tunable heterointerfaces and functional nanoparticles in electrochemical reactions, offering a new concept for the design of PIB anode materials.

SnTe nanoparticles physicochemically encapsulated by double carbon as conversion-alloying anode materials for superior potassium-ion batteries

Telluride tin (SnTe) is a promising conversion-alloying anode for potassium-ion batteries (PIBs) due to its high theoretical specific capacity induced by multi-electron transport reaction and low operating voltage, whereas huge volume expansion and poor kinetics behavior become key scientific bottleneck limiting the battery performances. Herein, SnTe nanoparticles physicochemically wrapped by graphene and nitrogen-doped carbon (SnTe@rGO@NC) are proposed as anode materials for PIBs. The pre-electrostatic interaction urges the formation of Sn-C and Te-C chemical bonds between SnTe and double carbon to strengthen the interfacial stability and electron transfer, and the conductive architecture with hierarchical encapsulation effect is beneficial to maintaining the electrode integrity and electrochemical dynamics. It is demonstrated from first principles calculations and experimental results that SnTe@rGO@NC contributes fast electron transmission, strong K-ion adsorption, and superior K-ion diffusion capability. Ex-situ characterizations uncover that SnTe undergoes conversion-alloying dual-mechanism with the products of K2Te and K4Sn23 replied on Sn redox site (23SnTe + 50K+ + 50e– ↔ K4Sn23 + 23K2Te). Thus, the SnTe@rGO@NC electrode delivers a high initial charge specific capacity of 243.9 mAh g–1 at 50 mA g–1, superior rate performance (112.6 mAh g–1 at 1.0 A g–1), and outstanding cyclic stability at various current densities.

Highly active and stable Cu9S5-MoS2 heterostructures nanocages enabled by dual-functional Cu electrocatalyst with enhanced potassium storage

• Cu 9 S 5 /MoS 2 hollow nanocage heterostructure was studied as anode material for potassium-ion batteries. • Rational introduced Cu 0 intermediates effectively anchor K x S y polysulfides and facilitate rapid charge transfer. • Unique Cu 9 S 5 /MoS 2 nanocage showed superior conversion reaction reversibility in K-storage application. The intrinsic poor electrical conductivity, severe dissolution of K x S y intermediates, and inferior conversion reaction reversibility extremely impede the practical application of the transition-metal chalcogenides (TMDs) anode for potassium-ion batteries (PIBs). Herein, a rationally designed Cu 9 S 5 /MoS 2 /C heterostructure hollow nanocage was synthesized with assistance from metal-organic frameworks (MOFs) precursor. During the K-storage process, the homogeneously distributed the sulfiphilic nature of Cu 0 reaction product could act as a dual-functional catalyst, not only facilitating the rapid charge transfer but also effectively anchoring (K x S y ) polysulfides, thus boosting K-storage reactions reversibility during the conversion reaction process. When applied as an anode for PIBs, the as-prepared heterostructure exhibits excellent reversible capacity and long cycle lifespan (350.5 mAh g –1 at 0.1 A g –1 and 0.04% per cycle capacity decay at 1 A g –1 after 1000 cycles). Additionally, the potassium storage mechanism is distinctly revealed by in-situ characterizations. The nanoarchitecture designing strategy for the advanced electrode in this work could provide vital guidance for relevant energy storage materials. The hollow Cu9S5/MoS2/C nanocage has been rational designed and regarded as an anode material for potassium-ion batteries (PIBs). Due to the dual-functional catalytic effects of in-situ formed Cu0 nanograin during conversion reaction and homogeneously distributed heterointerfaces within Cu9S5/MoS2, the poor charge transfer, severe dissolution of KxSy polysulfides, and inferior phase transformation reaction reversibility can be significantly improved. It can not only strengthen the integral stability, but also enhance the K-storage properties with long-life and high-capacity.

KOH-treated mesocarbon microbeads used as high-rate anode materials for potassium-ion batteries

AbstractGraphite is one of the most promising anode materials for potassium-ion batteries (PIBs) due to its low cost and stable discharge plateau. However, its poor rate performance still needs to be improved. A novel graphitic anode was designed from commercial mesocarbon microbeads (MCMBs) by KOH treatment. Using limited oxidation and slight intercalation, the interlayer spacing of graphitic layers on the surface of the MCMBs was increased, causing the K+ diffusion rate to be significantly improved. When this modified material was combined with carboxymethyl cellulose as a binder (79.2%) and used as a PIB anode, it had a high plateau capacity below 0.25 V (271 mAh g−1), superior rate capability (160 mAh g−1 at 1.0 A g−1), excellent cycling stability (about 184 mAh g−1 after 100 cycles at 0.1 A g−1), and a high initial coulombic efficiency. This work provides a simple strategy to prepare graphitic materials with an excellent potassium storage performance.

Sulfur and phosphorus co-doped hard carbon for potassium ion storage

Due to the low cost, good chemical stability and structural diversity, hard carbon has been considered as an important anode material for potassium-ion batteries (PIBs). However, due to the large diameter of K+, PIBs with both excellent rate performance and long-life is still challenging. Herein, sulfur (S), phosphorus (P) co-doped hard carbon anode are synthesized via polymerization of thiophene and phytic acid and the following concise pyrolysis strategy. S in hard carbon can used as reactive sites for K+ storage and P doping will effectively improve wettability of electrolyte. After temperature regulation, the fabricated SP-700 with dual and abundant heteroatom doping exhibits high initial reversible capacity (412 mAh g−1 at 0.05 A g−1), excellent rate performance (130 mAh g−1 at 5 A g−1) and stable cyclic performance (94 mAh g−1 after 1500 cycles at 2 A g−1).