Anode Material For Potassium-ion Batteries Research Articles

An Open-Ended Ni3 S2 -Co9 S8 Heterostructures Nanocage Anode with Enhanced Reaction Kinetics for Superior Potassium-Ion Batteries.

Sulfides are perceived as promising anode materials for potassium-ion batteries (PIBs) due to their high theoretical specific capacity and structural diversity. Nonetheless, the poor structural stability and sluggish kinetics of sulfides lead to unsatisfactory electrochemical performance. Herein, Ni3 S2 -Co9 S8 heterostructures with an open-ended nanocage structure wrapped by reduced graphene oxide (Ni-Co-S@rGO cages) are well designed as the anode for PIBs via a selective etching and one-step sulfuration approach. The hollow Ni-Co-S@rGO nanocages, with large surface area, abundant heterointerfaces, and unique open-ended nanocage structure, can reduce the K+ diffusion length and promote reaction kinetics. When used as the anode for PIBs, the Ni-Co-S@rGO exhibits high reversible capacity and low capacity degradation (0.0089% per cycle over 2000 cycles at 10Ag-1 ). A potassium-ion full battery with a Ni-Co-S@rGO anode and Prussian blue cathode can display a superior reversible capacity of 400mAhg-1 after 300 cycles at 2Ag-1 . The unique structural advantages and electrochemical reaction mechanisms of the Ni-Co-S@rGO are revealed by finite-element-simulation in situ characterizations. The universal synthesis technology of bimetallic sulfide anodes for advanced PIBs may provide vital guidance to design high-performance energy-storage materials.

Constructing oxygen-deficient V2O3@C nanospheres for high performance potassium ion batteries

Potassium ion batteries (PIBs) have been regarded as promising alternatives to lithium ion batteries (LIBs) on account of their abundant resource and low cost in large scale energy storage applications. However, it still remains great challenges to explore suitable electrode materials that can reversibly accommodate large size of potassium ions. Here, we construct oxygen-deficient V2O3 nanoparticles encapsulated in amorphous carbon shell (Od-V2O3@C) as anode materials for PIBs by subtly combining the strategies of morphology and deficiency engineering. The MOF derived nanostructure along with uniform carbon coating layer can not only enables fast K+ migration and charge transfer kinetics, but also accommodate volume change and maintain structural stability. Besides, the introduction of oxygen deficiency intrinsically tunes the electronic structure of materials according to DFT calculation, and thus lead to improved electrochemical performance. When utilized as anode for PIBs, Od-V2O3@C electrode exhibits superior rate capability (reversible capacities of 262.8, 227.8, 201.5, 179.8, 156.9 mAh/g at 100, 200, 500, 1000 and 2000 mA/g, respectively), and ultralong cycle life (127.4 mAh/g after 1000 cycles at 2 A/g). This study demonstrates a feasible way to realize high performance PIBs through morphology and deficiency engineering.

Nitrogen and sulfur co-doped graphene nanoribbons with well-ordered stepped edges for high-performance potassium-ion battery anodes

Graphitic carbon materials, particularly few-layered graphene, exhibit great potentials as potassium-ion battery (PIBs) anodes. However, bulk graphene-based materials have the disordered structure owing to randomly stacked graphene layers, which causes the high migration barrier during K+ intercalation/deintercalation reactions and thus the surface-dominated capacitive response. Here, we present a novel nanoarchitecture of nitrogen and sulfur co-doped graphene nanoribbons with well-ordered stepped edges (NS–sGNR) via the electrochemical unzipping of multiwalled carbon nanotubes (MWCNTs) and the subsequent N/S co-doping process for high-performance PIB anodes. As an anode material for PIBs, the prepared sample exhibits high initial capacity (329.1 mAh g−1 at 50 mA g−1), superior rate capability (211.7 mAh g−1 at high current density, 2000 mA g−1), outstanding reversibility of K-staging, and stable long-term cyclability. Theoretical calculations were conducted to demonstrate that sGNRs with NS co-doping (NS–sGNR) exhibit much improved K+ intercalation properties, such as the K+ adsorption energy, charge transfer, and migration barriers, compared with the parallel-edged GNRs. Particularly, the migration barrier (the rate-determining step) can be substantially reduced at the stepped edges during K+ intercalation.

Cheese-like porous SnP2O7 composite as a long-life and high-rate anode material for potassium-ion batteries

The abundant reserve, low price, and low redox potential (-2.94 V vs. SHE) of potassium render potassium-ion batteries (PIBs) a potential for commercialization. However, developing suitable anode materials for PIBs remains an elusive challenge, and the low charge storage capacity of inserted anode materials also is not conducive to the realization of high energy density PIBs. In this work, a porous SnP2O7 filled with rGO (P-SPO/rGO) composite material with both conversion and alloying reactions was prepared by solvothermal and calcination methods. Compared with bulk SnP2O7 (B-SPO), P-SPO/rGO, used for the first time as an anode material for PIBs, delivers a high reversible capacity of 351.5 mAh g−1, long cycling life and excellent rate performance due to the porous structure which can alleviate the large volume change of the material during the cycling processes. Ex-situ transmission electron microscope and in-situ X-ray diffraction were carried out to characterize the intermediate chemical reaction process during discharging/charging. All these findings not only suggest that P-SPO/rGO is a promising anode material for PIBs, but also point out a new direction for the development of anode materials for PIBs.

Heteroatom-doped carbon anode materials for potassium-ion batteries: From mechanism, synthesis to electrochemical performance

Carbonaceous materials are attractive anode candidates for potassium-ion batteries (PIBs) because of their cost-effectiveness, high conductivity, and considerable architecture. However, these carbon materials usually exhibit slow diffusion kinetics and huge volume variation induced by the large ionic size of K-ions, resulting in poor rate capability and cycling stability. Compared to pure carbon, heteroatom (N, S, P, and O)-doped carbons can well improve potassium storage performance by optimizing K-adsorption ability and conductivity, and, hence, exhibit a significant potential in PIBs. This review in-detail summarizes the recent progress of heteroatom-doped carbon anodes based on potassium storage mechanism, design or synthesis strategies, and electrochemical performance, mainly including single-, bi-, and tri-element doped carbons. Moreover, some critical issues and possible solutions for the development of heteroatom-doped carbon in the future are discussed. This review aims at providing a deep insight into the understanding, designing, and application of heteroatom-doped carbon anodes in PIBs and is expected to make an obvious effect on the exploration of other anodes.

Implantation of Fe7S8 nanocrystals into hollow carbon nanospheres for efficient potassium storage

As a desirable candidate for lithium-ion batteries, potassium-ion batteries (PIBs) have aroused great interest because of their low cost and high power and energy densities. However, the insertion/extraction of K+ with a large radius (1.38 Å) usually bring about the destruction of the electrode materials. Here, ultrafine Fe7S8 nanocrystals are successfully implanted into hollow carbon nanospheres (Fe7S8@HCSs) via a facile solvothermal method and subsequent novel low-temperature sulfurization, which avoid the aggregation of Fe7S8 nanoparticles produced during high-temperature sulfidation. The ultrafine Fe7S8 nanoparticles and hollow carbon spheres can not only buffer the severe expansion/shrinkage of electrode materials caused by the repeated insertion/extraction of K+, but also provide additional accessible pathways for the high-rate K+ transmission. When tested as an anode material for PIBs, Fe7S8@HCSs achieve impressive K+ storage capacity of 523.2 mAh g−1 at 0.1 A g−1 after 100 cycles and remarkable rate capacity of 176.3 mAh g−1 at 5 A g−1. Further, assembling this anode with a K2NiFe(CN)6 cathode yields stable cycling performance, revealing its great potential for large-scale energy storage applications.

Rationally Designed Three-Layered TiO2 @amorphous MoS3 @Carbon Hierarchical Microspheres for Efficient Potassium Storage.

Amorphous MoS3 has been an attractive electrode material for sodium-ion batteries and lithium-sulfur batteries. However, the potassium storage capability of amorphous MoS3 remains unreported. Herein, the construction of hybrid hierarchical microspheres composed of amorphous MoS3 nanosheets dual-confined with TiO2 core, and nitrogen-doped carbon shell layer (denoted as TiO2 @A-MoS3 @NC) via a self-templating method, combined with a low-temperature sulfurization process as a new anode material for potassium-ion batteries (PIBs), is reported. Benefitting from the unique structural merits including unique 1D chain structure, disordered arrangement of atoms and a large number of defects of amorphous MoS3 , more active heterointerfacial sites, effectively mitigated volume change, good electrical contact, and easy K+ ion migration, the TiO2 @A-MoS3 @NC microspheres exhibit excellent potassium-storage performance with high specific capacity, superior rate capability, and cycling stability.

Exploration of CrPO4@N-doped carbon composite as advanced anode material for potassium-ion batteries

Metal phosphates are attracting great attention as anode materials for alkali-ion batteries due to their chemical stability, low working voltage, and high theoretical capacity. However, there are few reports on the application of metal phosphate as potassium-ion batteries (PIBs) anode material, and the potassium storage mechanism remains mysterious. Herein, a core–shell chromium phosphate@N-doped carbon (denoted as CrPO4@NC) composite is newly synthesized and demonstrated as conversion-type anode material for PIBs. The N-doped carbon coating layer effectively relieves the mechanical strain and improves electrical conductivity during repetitive cycling. The formed P–C bonding between CrPO4 core and nitrogen-doped carbon shell can help to maintain structural integrity and accelerate charge transfer. As a consequence, the CrPO4@NC composite exhibits a decent capacity (304.6 mAh g−1 at 50 mA g−1), good rate capability (135.1 mAh g−1 at 500 mA g−1), and superior stability (133.2 mAh g−1 at 200 mA g−1 after 100 cycles). Particularly noteworthy, we also provide experimental evidence that a conversion reaction occurs at CrPO4@NC electrode with metallic Cr and K3PO4 formed during the potassiation process. This work illustrates that CrPO4 may be a kind of anode material for applications in energy storage systems.

Microstructure regulation of pitch-based soft carbon anodes by iodine treatment towards high-performance potassium-ion batteries

Soft carbon has been regarded as one of the most promising anode materials for potassium-ion batteries. However, the rearrangement of planar aromatics at high carbonization temperature usually yields a highly graphitized structure, which generally leads to inferior rate and cycle performance. In addition, the role of intrinsic carbon defects on potassium storage has not been well reported yet. In this work, crosslinked pitch-based soft carbon nanosheets have been synthesized through the iodination/dehydroiodination process at low temperature and carbonization with NaCl template. The iodine-treatment efficiently crosslinks the planar aromatics to three-dimensional framework by alkyl-bridged linkages, and reduces the strong π-π interaction during carbonization. This unique microstructure yields an ordered-in-disordered carbon microstructure, enlarged interlayer spacing, and abundant intrinsic defect sites. Benefited from these merits, the optimal sample displays 140% increase of reversible capacity to the pristine pitch-based carbon at 5 A g−1. Particularly, it also presents 87.4% capacity retention after 1000 cycles at 1 A g−1. This facile but simple strategy is expected to expand to other high-performance carbon materials and further understand the effect of intrinsic defects for potassium storage and beyond.

A Flower-Like Sb4O5Cl2 Cluster-based material as anode for potassium ion batteries

Potassium ion batteries (PIBs) have attracted tremendous attentions based on the fact that lithium ion batteries have been increasingly challenged by the uneven distribution and ultralow reserve of lithium sources. Safety concern has raised requirement for acceptable anode materials with high capacity and favorable working-potential. Here, a 3D flower-like antimony oxychloride (Sb4O5Cl2) that is synthesized via a mild hydrothermal method, is firstly employed as anode material for PIBs, where a high reversible capacity of 530 mAh g−1 could be achieved at current density of 50 mA g−1, with decent cycling performance and rate capability. Kinetic analyses based on electrochemical measurements evidence that the Sb4O5Cl2 electrode could deliver high K+ ion diffusion coefficient, and density functional theory calculations are also conducted to probe the migration paths of K+ ion in Sb4O5Cl2 and the electronic structure involved in the electrochemical kinetics behaviors. The K+ ion storage mechanism during potassiation/de-potassiation is investigated via ex-situ X-ray diffraction, high resolution transmission electron microscope and theoretical calculations, and a reversible process involving both conversion-type and alloy/de-alloy reactions is established.

N-doped pinecone-based carbon with a hierarchical porous pie-like structure: a long-cycle-life anode material for potassium-ion batteries.

Pinecone-based biomass carbon (PC) is a potential anode material for potassium-ion batteries because it is abundant, cheap, renewable, and easy to obtain. However, because of inferior kinetics and the effects of volume expansion due to the large radius of the K+ ion, it does not meet commercial performance requirements. In this study, nitrogen-doped PC (NPC) was prepared by carbonization in molten ZnCl2 with urea as a nitrogen source. A strategy based on synergistic effects between N doping and ZnCl2 molten salt was used to produce a hierarchically porous pie-like NPC with abundant defects and active sites and an enlarged interlayer distance—properties that enhance K+ adsorption, promote K+ intercalation/diffusion, and reduce the effects of volume expansion. This NPC exhibited a high reversible capacity (283 mA h g−1 at 50 mA g−1) and superior rate performance and cyclic stability (110 mA h g−1 after 1000 cycles at 5 A g−1), demonstrating its potential for use in potassium-ion batteries.

In-Situ Synthesis of Antimony Nanoparticles Encapsulated in Nitrogen-Doped Porous Carbon Framework as High Performance Anode Material for Potassium-Ion Batteries

In-Situ Synthesis of Antimony Nanoparticles Encapsulated in Nitrogen-Doped Porous Carbon Framework as High Performance Anode Material for Potassium-Ion Batteries

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Layered K2V3O8 (KVO) is successfully fabricated via simple hydrothermal reaction and employed as novel anode materials in potassium-ion batteries (KIBs). Benefitting from its specific layered structure and various oxidation states of V (V2+ to V5+), KVO delivers high reversible capacity of 300 mAh g−1. This works have significant implications in exploiting for potential anode materials, consequently speeding up the development of high-performance KIBs.

Investigation of the potassium‐ion storage mechanism of nickel selenide materials and rational design of nickel selenide‐C yolk‐shell structure for enhancing electrochemical properties

Metal selenide is contemplated as expeditious anode material for potassium-ion batteries (KIBs). Here, nickel selenide (NiSe2-Ni0.85Se) was investigated as an anode material for KIBs. The NiSex transformed into K2Se and K2Se3 (K2Sex) and reversibly returned to NiSex after the discharge and charge processes (17NiSe2 + 3Ni0.85Se + 38 K+ + 38e− ↔ 19.55Ni + 10K2Se + 9K2Se3). Furthermore, to enhance the electrochemical properties of nickel selenide, yolk-shell-structured nickel selenide and hollow carbon nanosphere composites, in which nickel selenides intensively existed in the core and were partially formed into nanocrystals in the shell, were produced by simple salt-infiltration and a post-treatment. NiSex@C exhibited improved cycle and rate properties compared to bare NiSex because of its structural merits that led to stable cycle performance and high electrochemical kinetics. NiSex@C exhibited 373 mA h g−1 for the 100th cycle at 0.05 A g−1 and 234 mA h g−1 at 1.0 A g−1.

Electrochemical performances of coal-based carbon prepared by low-temperature catalytic graphitization as anode materials for potassium-ion batteries

Potassium-ion batteries (PIBs) are promising as an attractive replacement to lithium-ion batteries (LIBs) on a wide storage energy stationary scale because of the abundance of potassium resources and easily accessible. Herein, we successfully prepared carbon anodes materials for PIBs from a cheap and abundant coal by the low-temperature graphitization with Ni(CH3COO)2.4H2O catalyst. After 100 cycles, the coal-based carbon anode delivers a specific capacity of 200 mAh g-1 at 0.2 A g-1 current density, with more than 97% coulombic efficiency. This excellent potassium storage efficiency and the low cost make coal-based carbon anodes a most promising anode candidate for PIBs.

Double‐shell and yolk‐shell structured ZnSe ‐carbon nanospheres as anode materials for high‐performance potassium‐ion batteries

Transition-metal chalcogenides are prospective anode materials for potassium-ion batteries. Herein, crystalline ZnSe nanocrystal-loaded hollow carbon nanospheres (ZnSe-HC) are synthesized by infiltration of zinc nitrate and selenium dioxide into hollow carbon nanospheres and subsequent selenization. The electrochemical reaction mechanism of ZnSe with K-ion is systematically examined by ex-situ X-ray photoelectron spectroscopy and transmission electron microscopy. Two samples with distinctive nanostructures, which are double-shelled hollow structure and yolk-shelled structure, can be fabricated by controlling the selenization temperature, and their K-ion storage performances are compared. The double-shelled ZnSe-HC, which is prepared at a lower temperature, exhibits superior cycling and rate performances to those of the yolk-shelled ZnSe-HC. For double-shelled ZnSe-HC, small ZnSe nanocrystals embedded in the carbon shell and dispersed over the inner carbon shell contribute to the structural stability and fast kinetics during repeated cycles. As a result, the double-shelled ZnSe-HC exhibits a stable cycling performance (400 mA h g−1 at 0.1 A g−1 after 100 cycles) and excellent rate capability (240 mA h g−1 at 3.0 A g−1).

Cage-Confinement Pyrolysis Strategy to Synthesize Hollow Carbon Nanocage-Coated Copper Phosphide for Stable and High-Capacity Potassium-Ion Storage.

Metal phosphides with a high theoretical capacity and low redox potential have been proposed as promising anodes for potassium-ion batteries (PIBs). A reasonable configuration design and introduction of a hollow structure with adequate internal void spaces are effective strategies to overcome the volume expansion of metal phosphides in potassium-ion batteries. Herein, we report a cage-confinement pyrolysis strategy to obtain hollow nanocage-structured nitrogen/phosphorus dual-doped carbon-coated copper phosphide (Cu3P/CuP2@NPC), which exhibits a high initial charge capacity (409 mA h g-1 at 100 mA g-1) and an outstanding cycle performance (100 mA h g-1 after 5000 cycles at 1000 mA g-1) as an anode material for PIBs. The novel hollow nanocage structure could prevent volume expansion during cycling and reduce the electron/ion diffusion distance. Besides, the nitrogen/phosphorus dual-doped carbon-coated layer could promote electronic conductivity. In situ X-ray diffraction (XRD) measurements are conducted to study the potassiation/depotassiation mechanism of Cu3P/CuP2@NPC and reveal the structure stability during the cycle process, which further proves that the design ideas of the conductive carbon layer and the hollow structure with adequate internal void spaces are successful.

P/N Co‐doped Carbon Nanotubes with Dominated Capacity‐controlled Absorption Effect Enabling Superior Potassium Storage

AbstractCarbonaceous materials are considered to be the most promising anode materials of Potassium‐ion batteries (PIBs). However, for most carbon‐based PIBs anode materials reported so far, they usually deliver low reversible capacities, insufficient cycle life and poor rate capability. In this work, we report a novel P/N co‐doped carbon nanotube (PNCNTs) material as the anode material for PIBs. The material with fully exposed active edges and open fast ion/electron transfer structure can effectively shorten the K+ transfer distance. Furthermore, the P/N co‐doping provides abundant electrochemical active adsorption sites and extended interlayer spacing, which facilitates the rapid insertion/removal of K+, increases the surface charge capacity and maintains the structural stability of the electrode material. As expected, when used as the anode material for PIBs, PNCNTs exhibited a high specific capacity (612.2 mA h g−1 at 100 mA g−1), excellent rate capability (190, 183 and 165 mA h g−1 at 0.5, 1.0, and 2.0 A g−1 after 500 cycles, respectively) as well as remarkable long‐term cycling stability (162 mA h g−1 at 2.0 A g−1 after 1400 cycles). Through further kinetic analysis and a simple first‐principles calculation, we revealed the dominated capacity‐controlled absorption mechanism of potassium storage in PNCNTs.

Bismuth telluride anode boosting highly reversible electrochemical activity for potassium storage

To ensure high capacity with reasonable cycling stability using the conversion or K-alloy reaction, the anode should minimize or embrace the volume expansion during the discharge (potassiation) and charge (depotassiation) processes. Herein, we report on a Bi2Te3 composite modified by nanosized carbon that boosts the highly reversible capacity with long cycling stability. The as-synthesized Bi2Te3 powders and acetylene black carbon were compositized via high-energy ball-milling, resulting in improvement of the electrical conductivity to ∼10−4 S cm−1 from ∼10−7 S cm−1. Electrochemical investigation revealed that the proposed Bi2Te3@C retained over 79.8% of its initial capacity (311 mAh g− 1) for 500 cycles at a current of 1000 mA g− 1. We unveil the reaction chemistry behind the acceptable performance using operando X-ray diffraction, X-ray absorption near edge structure spectroscopy, and time-of-flight secondary-ion mass spectrometry. The Bi2Te3 undergoes a conversion reaction to form Bi0 metal and K2Te as a conversion byproduct, after which Bi is further potassiated to K3Bi. The highly reversible behavior is attributed to the enlargement of the active area along with the filling of voids among Bi2Te3 particles by nanosized carbons in the composite electrode, enabling not only facile electron transport but also preservation of the electrode shape even after long-term cycling. Our approach highlights the feasibility of applying Bi2Te3@C as a sustainable anode material for potassium-ion batteries.

Activated carbon deriving from microcrystalline graphite ore as high-performance anode material for potassium-ion batteries

Activated carbon deriving from microcrystalline graphite ore as high-performance anode material for potassium-ion batteries