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This work demonstrates the large potential of BiOBr as high-performance K-ion battery anodes. [Display omitted] • Design a novel nano-BiOBr/rGO composite micro flower with strong Bi-C bond interface coupling. • Demonstrate firstly the large potential of BiOBr as high-performance K-ion battery anodes. • Elucidate for the first time the reaction mechanism of BiOBr as a K-ion battery anode. To explore the potential of bismuth oxybromide (BiOBr) as anodes for high-performance potassium (K)-ion batteries and understand its potassium storage mechanism, a novel nano-BiOBr/reduced graphene oxide (rGO) composite micro flower (labelled as SI-coupled nano-BiOBr/rGO micro flower), where nano-BiOBr slices are firmly anchored on rGO by strong interface coupling, is constructed. Unique microstructure accompanied by C-Bi bonds at the interface between BiOBr and rGO endows it with abundant high-speed charge transfer channels and excellent structural stability. As a result, it exhibits an excellent rate performance (a high reversible capacity of 278 mAh/g at 5 A/g) and a remarkable long-term cycling stability maintaining 95.4 % after 1000 cycles at 2.5 A/g. Furthermore, it is also found that SI-coupled nano-BiOBr/rGO micro flower anode undergoes intercalation, conversion, and alloying (BiOBr → K z BiOBr → Bi → KBi 2 → K 3 Bi 2 → K 3 Bi) at the initial discharge process, and the subsequent charge process is only reversible dealloying and conversion reaction (K 3 Bi → K 3 Bi 2 → KBi 2 → Bi → BiO x Br y). This work not only demonstrates the large potential of BiOBr as high-performance K-ion battery anodes, but also elucidates for the first time its K storage mechanism. [ABSTRACT FROM AUTHOR]

A Setaria-like NiTe 2 /MoS 2 @C heterojunction is synthesized through one-step hydrothermal method followed by a carbonisation process. The NiTe 2 /MoS 2 heterojunctions exhibit low lattice misfits (δ =13%), strong electric fields, and uniform carbon shells, thus resulting in unique electronic structures and abundant active sites. [Display omitted] • Setaria-like NiTe 2 /MoS 2 @C heterojunctions are synthesized as anode for KIB. • MoS 2 nanosheets embedded in NiTe 2 nanorods to form stabilized heterojunctions. • The NiTe 2 /MoS 2 heterojunctions show low lattice misfits and strong electric fields. • The NiTe 2 /MoS 2 @C delivers the ultralong cycle stability and rate performance for KIB. Constructing unique heterostructures is a highly effective approach for enhancing the K+ storage capability of transition metal selenides. Such structures generate internal electric fields that significantly reduce the charge transfer activation energy. However, achieving a flawless interfacial region that maintains the optimal energy level gradient and degree of lattice matching remains a considerable challenge. In this study, we synthesised Setaria-like NiTe 2 /MoS 2 @C heterogeneous interfaces at which three-dimensional MoS 2 nanosheets are evenly embedded in NiTe 2 nanorods to form stabilised heterojunctions. The NiTe 2 /MoS 2 heterojunctions display distinctive electronic configurations and several active sites owing to their low lattice misfits (δ = 13 %), strong electric fields, and uniform carbon shells. A NiTe 2 /MoS 2 @C anode in a potassium-ion battery (KIB) exhibited an impressive reversible capacity of 125.8 mAh/g after 1000 cycles at a rate of 500 mA g−1 and a stable reversible capacity of 111.7 mAh/g even after 3000 cycles at 1000 mA g−1. Even the NiTe 2 /MoS 2 @C//perylene tetracarboxylic dianhydride full battery configuration maintained a significant reversible capacity of 92.4 mAh/g after 100 cycles at 200 mA g−1, highlighting its considerable potential for application in KIBs. Calculations further revealed that the well-designed NiTe 2 /MoS 2 heterojunction significantly promotes K+ ion diffusion. [ABSTRACT FROM AUTHOR]

Quasi‐solid‐state electrolytes (QSEs) via gelation of liquid electrolytes (LEs) are perspective protocols for constructing ingenious potassium‐ion batteries (PIBs) due to the combined advantages of both liquid and solid state. However, most of QSEs yet researched face a trade‐off among low temperature adaptability and safely high temperature operation. Herein, in situ reversible gelation of Ni‐crosslinked pentaerythritol tetrakis (3‐mercaptopropionate) (PETMP‐Ni) co‐polymerized with tyramine‐modified hyaluronic acid (HA‐Tyr) (PHA) modified B, N modified carbon spheres (BNC) enclosing by red P (RP) is backed with compatible electrode‐electrolyte interface with laponite filler (L). Such high reversible in situ gelation displays high low temperature adaptability by LEs, and extraordinary safety in high temperature steered by QSEs, benefiting from topologic space crowding effect (TSCE) and reverse trap of Ni single atoms (Ni SAs). This work enlightens the missing prospects in constructing reversible in situ sol–gel strategy coupled by topologic space crowding effect and reverse SAs trapping stimulate toward revival hybrid electrode for wide‐temperature adaptive batteries. [ABSTRACT FROM AUTHOR]

To explore high-performance carbon anodes for potassium-ion batteries, monodisperse novel hollow carbon spheres (MHCSs) were synthesized via a combination of hydrothermal reactions and high-temperature pyrolysis using 2,4-dihydroxybenzoic acid and hexamethylenetetramine as the main raw materials. The synthesized MHCSs range from 140 to 260 nm in size with a large specific area of 466 m2 g-1. The potassium storage performance and dynamics of MHCSs in KN(SO2F)2 (KFSI) and KPF6 electrolytes were systematically investigated. In the KFSI electrolyte, the MHCSs have a higher reversible capacity, better cycling stability, better rate performance, and faster electrode process dynamics than in the KPF6 electrolyte. The excellent electrochemical performance of MHCSs in the KFSI electrolyte is attributed to the hollow structure of the material and the formation of a KF-rich and uniform solid-electrolyte interface film. [ABSTRACT FROM AUTHOR]

The development of potassium‐ion batteries (KIBs) relies on the exploration of stable layer‐structured oxide cathode materials and a comprehensive understanding of ion storage and diffusion behaviors. A multiphase riveting‐structured O3/P2/P3‐Na0.9[Ni0.3Mn0.55Cu0.1Ti0.05]O2 (Tri‐NMCT) is employed as cathode material for KIBs. It demonstrates an initial discharge specific capacity of 108 mA g−1 at current density of 15 mA g−1 in the voltage range of 1.5–4 V. Excellent cyclic stability is exhibited as well with a high 83% capacity retention after 600 cycles at a higher current density of 300 mA g−1. Based on the in‐situ XRD, it reveals that the P2 phase offers a more stable triangular prism site compared to the O3 phase. This stability inhibits the undesired phase transition from P3 to O3 during discharge, thereby ensuring the long‐term cyclic performance. Furthermore, Density of state (DOS) calculations and migration barrier analyses indicate a preferential migration of K+ ions to the P2 phase due to the lower Fermi level. This observation elucidates the structural preservation of the P3 phase during K+ embedding. Overall, this work sheds light on Tri‐NMCT as a promising cathode material for advanced KIBs. [ABSTRACT FROM AUTHOR]

Prussian blue analogues (PBAs) represent as a class of materials with an open framework structure and have been intensively explored as the potential active materials for alkaline‐ion batteries. Here, we present the synthesis of Prussian blue nanoplates designed for use as high performance cathode materials in potassium‐ion batteries. Prussian blue nanoplates were synthesized through a facile solution precipitation route using a highly concentrated potassium citrate solution. The potassium‐rich environment during the synthesis facilitated horizontal growth of the crystals, yielding potassium‐rich Prussian blue nanoplates. The resultant Prussian blue nanoplates exhibited a significantly larger particle size of 600 nm and a reduced specific surface area of 6.8 m2 g−1, compared to conventionally synthesized Prussian blue hexahedrons. Half‐cell tests demonstrated that the Prussian blue nanoplates exhibited a high gravimetric capacity of 152.5 mAh g−1 with a nominal voltage 3.952 V at a C‐rate of 0.1 C, yielding an energy density of 602.7 Wh kg−1. Cycling tests demonstrated high cycling stability of the material, maintaining a capacity of 122.7 mAh g−1 and a nominal voltage of 3.923 V after 200 cycles at 0.2 C. In a full‐cell configuration with graphite anodes, a gravimetric capacity changed from 134.1 mAh g−1 to 108.9 mAh g−1 after 100 cycles at 0.2 C, demonstrating a good cycling stability. This work provides a new insight into the electrochemical properties of Prussian blue nanoplates and highlights their potential as high‐performance cathode materials for potassium‐ion batteries. [ABSTRACT FROM AUTHOR]

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Recently, potassium-ion batteries (KIBs) have attracted significant interest due to a number of factors, including the growing demand for energy and limited lithium resources. However, their practical use is hampered by poor cycling stability due to the large size of K+. Therefore, it is critical to develop a structural design that effectively suppresses large volume changes. This study presents a simple method of using a salt template to fabricate porous microspheres (p-MoSe2@C MS) of MoSe2 and a carbon matrix as anode materials in KIBs. These microspheres have a distinct porous design, with uniformly distributed MoSe2 nanocrystals embedded in the carbon matrix to prevent MoSe2 overgrowth due to material diffusion during heat treatment. The manufacturing process combined one-step spray drying with recyclable NaCl as a hard template. Through a two-step thermal process under an inert atmosphere, the initial dextrin, NaCl, and Mo salt microspheres were converted into a p-MoSe2@N MS composite. The carbon structure derived from the dextrin maintained the shape of the microspheres when NaCl was removed, ensuring no overgrowth of MoSe2. This well-designed porous structure improves the interaction with the electrolyte, facilitating the transport of ions and electrons and reducing the K+ diffusion distances. In addition, the porous carbon structure accommodates large volume changes during cycling and maintains its structural strength. As a result, p-MoSe2@C MS composite exhibits superior electrochemical properties, with remarkable capacity, long-term cycling stability (193 mA h g−1 after 500 cycles at 2.0 A g−1), and rate capability. [ABSTRACT FROM AUTHOR]

[Display omitted] Constructing carbon electrodes with abundant heteroatoms and appropriate graphitic interlayer spacing remains a major challenge for achieving high gravimetric and volumetric potassium storage capacities with fast kinetics. Herein, we constructed 3D graphene-like N, F dual-doped carbon sheets induced by Ni template (N, F-CNS-Ni) with dense structure and rich active sites, providing a promising approach to address the facing obstacles. Highly reversible K-ion insertion/extraction is realized in the graphitic carbon structure, and K-adsorption capability is enhanced by introducing N/F heteroatoms. As a result, the N, F-CNS-Ni electrode exhibits ultrahigh gravimetric and volumetric capacities of 404.5 mA h g−1 and 281.3 mA h cm−3 at 0.05 A/g, respectively, and a superb capacity of 259.3 mA h g−1 with a capacity retention ratio of 90 % even after 600 cycles at 5 A/g. This work presents a simple Ni-based template method to prepare graphene-like carbon nanosheets with high packing density and rich heteroatoms, and offers mechanism insight for achieving superior K-ion storage. [ABSTRACT FROM AUTHOR]

As post‐lithium ion batteries, both sodium‐ion batteries (SIBs) and potassium ion batteries (PIBs) possess great potential for large scale energy storage. However, the application of both SIBs and PIBs are hindered by the lack of suitable electrode materials. Here, we synthesized the sulfur decorated Ti3C2Tx (S−T3C2Tx) MXene as electrode material for SIBs and PIBs. Thanks to the sulfur functional group and the formation of Ti−S bond, which facilitates the sodium in‐/desertion and strengthens the potassium ion adsorption ability, as well as enhances ion reaction kinetics and improved structure stability, the S−T3C2Tx exhibit excellent sodium/potassium storage performance, high reversible capacities of 151 and 101 mAh g−1 at 0.1 mA g−1 were achieved for SIBs and PIBs, respectively. Moreover, the S−T3C2Tx exhibits remarkable long‐term capacity stability at a high density of 500 mA g−1, providing an impressive storage of 88 mAh g−1 for SIBs and 41 mAh g−1 for PIBs even after 2000 cycles. This work could give a deep comprehension of the heteroatom modification influence on the MXene‐based framework and promote the application of MXene electrodes. [ABSTRACT FROM AUTHOR]

[Display omitted] • The utilization of 3D nitrogen-doped carbon confined Co 0.85 Se nanocrystals (Co 0.85 Se@NC) as an anode for potassium ion batteries leads to the achievement of a long cycle life exceeding 4000 cycles. • Co 0.85 Se@NC anode provide a capacity of 155.6 mA h g−1 at 10 A g−1. • Co 0.85 Se@NC anode shows the areal capacity up to 1.03 mA h cm−2 at 500 mA g−1. • Finite element analysis shows the 3D confinement strategy has the lowest interfacial stress. • Hundreds of LED bulbs were lighted by a pouch-type potassium-ion full battery composed of Co 0.85 Se@NC anodes. Conversion-type transition metal chalcogenide anodes could bring relatively high specific capacity in potassium ion storage due to multiple electron transport reactions, but often accompanying huge volume changes and resulting in low cycle life and rapid capacity fading. While electrode materials are closely packed, the contact at the interface during potassiation/depotassiation is similar to point-to-point contact, generating strong stress to make self-aggregation occur. In this work, we constructed a 3D carbon framework to confine Co 0.85 Se nanocrystals in three-dimensional space, both fulfilling the requirements of the material's size in the nano-scale and providing the largest contact area for releasing stress. With this optimization, nitrogen-doped carbon confined Co 0.85 Se nanocrystals (Co 0.85 Se@NC) reach an ultra-stable cycle life over 4000 times with a specific capacity of 190.9 mA h g−1 at 500 mA g−1 and provide 155.6 mA h g−1 at 10 A g−1 in the rate capability test. It also renders the areal capacity up to 1.03 mA h cm−2 at 500 mA g−1 in the high-mass loading test. Furthermore, based on the finite element analysis, the 3D confinement strategy has the lowest interfacial stress, ensuring Co 0.85 Se nanocrystals with high structural integrity. This strategy can relieve the stress issue in the conversion-type anode and demonstrate superior electrochemical performance even at high-loading mass electrodes. [ABSTRACT FROM AUTHOR]

The growing demand for cheap, safe, recyclable, and environmentally friendly batteries highlights the importance of the development of organic electrode materials. Here, we present a novel redox-active polymer comprising a polyaniline-type conjugated backbone and quinizarin and anthraquinone units. The synthesized polymer was explored as a cathode material for batteries, and it delivered promising performance characteristics in both lithium and potassium cells. Excellent lithiation efficiency enabled high discharge capacity values of >400 mA g−1 in combination with good stability upon charge–discharge cycling. Similarly, the potassium cells with the polymer-based cathodes demonstrated a high discharge capacity of >200 mAh g−1 at 50 mA g−1 and impressive stability: no capacity deterioration was observed for over 3000 cycles at 11 A g−1, which was among the best results reported for K ion battery cathodes to date. The synthetic availability and low projected cost of the designed material paves a way to its practical implementation in scalable and inexpensive organic batteries, which are emerging as a sustainable energy storage technology. [ABSTRACT FROM AUTHOR]

Combined synchrotron X‐ray nanotomography imaging, cryogenic electron microscopy (cryo‐EM) and modeling elucidate how potassium (K) metal‐support energetics influence electrodeposit microstructure. Three model supports are employed: O‐functionalized carbon cloth (potassiophilic, fully‐wetted), non‐functionalized cloth and Cu foil (potassiophobic, nonwetted). Nanotomography and focused ion beam (cryo‐FIB) cross‐sections yield complementary three‐dimensional (3D) maps of cycled electrodeposits. Electrodeposit on potassiophobic support is a triphasic sponge, with fibrous dendrites covered by solid electrolyte interphase (SEI) and interspersed with nanopores (sub‐10 nm to 100 nm scale). Lage cracks and voids are also a key feature. On potassiophilic support, the deposit is dense and pore‐free, with uniform surface and SEI morphology. Mesoscale modeling captures the critical role of substrate‐metal interaction on K metal film nucleation and growth, as well as the associated stress state. [ABSTRACT FROM AUTHOR]

[Display omitted] Covalent organic frameworks (COFs) are regarded as the potential and promising anode materials for potassium ion batteries (PIBs) on account of their robust and porous crystalline structure. In this work, multilayer structural COF connected by double functional groups, including imine and amidogent through a simple solvothermal process, have been successfully synthesized. The multilayer structure of COF can provide fast charge transfer and combine the merits of imine (the restraint of irreversible dissolution) and amidogent (the supply of more active sites). It presents superior potassium storage performance, including the high reversible capacity of 229.5 mAh g−1 at 0.2 A g−1 and outstanding cycling stability of 106.1 mAh g−1 at the high current density of 5.0 A g−1 after 2000 cycles, which is superior to the individual COF. The structural advantages of the covalent organic framework linking by double functional groups (d -COF) can develop a new road for that COF anode material for PIBs in further research. [ABSTRACT FROM AUTHOR]

The development of anode materials with ideal conductivity, ultra-fast ion diffusion energy and large storage capacity is of great significance for rechargeable ion batteries, but also still challenging. In this work, the potential of two-dimensional MgB2 as an anode material of alkali metal (Na and K) ion batteries was explored via first-principles calculation. The results show that MgB2 has good structural stability and electrochemical performance. Specifically, Na and K ions can be stably adsorbed on two-dimensional MgB2, and the diffusion barrier is 0. 302 and 0. 172 eV, respectively, indicating its high performance in ultra-fast charging and discharging process. More importantly, the maximum storage capacities of two-dimensional MgB2 for sodium ion and potassium ion batteries are 1 167 and 584 mA ⋅ h/g, respectively. These results demonstrate that two-dimensional MgB2 can be used as a promising anode material for sodium ion and potassium ion batteries. [ABSTRACT FROM AUTHOR]

Recently, potassium-ion batteries (KIBs) have attracted significant interest due to a number of factors, including the growing demand for energy and limited lithium resources. However, their practical use is hampered by poor cycling stability due to the large size of K+. Therefore, it is critical to develop a structural design that effectively suppresses large volume changes. This study presents a simple method of using a salt template to fabricate porous microspheres (p-MoSe2@C MS) of MoSe2 and a carbon matrix as anode materials in KIBs. These microspheres have a distinct porous design, with uniformly distributed MoSe2 nanocrystals embedded in the carbon matrix to prevent MoSe2 overgrowth due to material diffusion during heat treatment. The manufacturing process combined one-step spray drying with recyclable NaCl as a hard template. Through a two-step thermal process under an inert atmosphere, the initial dextrin, NaCl, and Mo salt microspheres were converted into a p-MoSe2@N MS composite. The carbon structure derived from the dextrin maintained the shape of the microspheres when NaCl was removed, ensuring no overgrowth of MoSe2. This well-designed porous structure improves the interaction with the electrolyte, facilitating the transport of ions and electrons and reducing the K+ diffusion distances. In addition, the porous carbon structure accommodates large volume changes during cycling and maintains its structural strength. As a result, p-MoSe2@C MS composite exhibits superior electrochemical properties, with remarkable capacity, long-term cycling stability (193 mA h g−1 after 500 cycles at 2.0 A g−1), and rate capability.

Iron group metals chalcogenides, especially NiS, are promising candidates for K‐ion battery anodes due to their high theoretical specific capacity and abundant reserves. However, the practical application of NiS‐based anodes is hindered by slow electrochemical kinetics and unstable structure. Herein, a novel structure of Ni3S2–Ni hybrid nanosphere with intra‐core voids encapsulated by N‐doped carbon shells (Ni3S2‐Ni@NC‐AE) is constructed, based on the first electrodeposited NiS nanosphere particles, dopamine coating outer layer, oxygen‐free annealing treatment to form Ni3S2‐Ni core and N‐doped carbon shell, and selective etching of the Ni phase to form intra‐core void. The electron/K+ transport and K+ storage reaction kinetics are enhanced due to shortened diffusion pathways, increased active sites, generation of built‐in electric field, high K+ adsorption energies, and large electronic density of states at Fermi energy level, resulting from the multi‐structures synergistic effect of Ni3S2‐Ni@NC‐AE. Simultaneously, the volume expansion is alleviated due to the sufficient buffer space and strong chemical bonding provided by intra‐core void and yolk–shell structure. Consequently, the Ni3S2‐Ni@NC‐AE exhibits excellent specific capacity (438 mAh g−1 at 0.1 A g−1 up to 150 cycles), outstanding rate performances, and ultra‐stable long‐cycle performance (176.4 mAh g−1 at 1 A g−1 up to 5000 cycles) for K‐ion storage. [ABSTRACT FROM AUTHOR]

As a cost-effective and well-developed material, graphite is a promising anode material for potassium ion battery due to its high capacity, high tap density, high conductivity and plateau-typed charge curve characteristic. However, graphite suffers from severe capacity fading and poor rate capability. The related research mainstream focuses on electrolyte or binder, aiming at a more robust passivation layer. In contrast, it is not common to transform or modify graphite directly, due to its rigid structure and inert property, which is resistant to gentle chemical treatment. Adjusting coherence length of graphite and its effect on cyclability and rate ability has not been studied yet. Herein, we come up with a strategy of crippling the crystallinity of graphite by strong oxidation first, followed by adjusting coherence length under different pyrolysis temperatures. In the battery test, the expanded graphite pyrolyzed at 750 °C delivers a reversible capacity of 303 mAh/g at a current density of 10 mA/g and 105 mAh/g at a current density of 1000 mA/g. In the long cycling test, a capacity of 160 mAh/g can be maintained after 1000 cycles, with a capacity decay of only 0.02% per cycle. Based on the analysis between coherence length and battery performance, we find that decreasing the coherence length along ab plane contributes to improving rate capability, from both intercalation and pseudo capacitance perspective. Moreover, decreasing the coherence length along c axis contributes to the cyclability. [Display omitted] [ABSTRACT FROM AUTHOR]

Antimony (Sb)-based nanocomposites have emerged as an attractive class of anode materials for potassium ion batteries as they exhibit large theoretical capacity and impressive working voltage. However, the tardy potassium ion diffusion characteristic, unstable Sb/electrolyte interphase, and huge volume variation pose a grand challenge that hinder the practical use of Sb-based anodes for potassium ion batteries. Herein, we develop a simple yet robust strategy to fabricate a three-dimensional N-doped carbon (N–C) porous microspheres and reduced graphene oxides (rGO) dual-encapsulated Sb hierarchical structures (denoted Sb@N–C/rGO), which are pursued for resolving the stubborn issues of Sb-based compounds for PIBs. As expected, such judiciously crafted Sb@N–C/rGO anode renders a set of intriguing electrochemical properties, representing a high reversible specific capacity of 586 mAh g−1 at a current density of 0.2 A g−1 after 200 cycles and excellent long-cycle stability of 358 mAh g−1 at 1.0 A g−1 after 1000 cycles. It is believed that the work can provide deep understanding and new insight to develop the alloying-type electrode materials for rechargeable batteries. [ABSTRACT FROM AUTHOR]

Soft carbons (SCs) have become a promising anode for potassium ion batteries (PIBs). However, it is challenging to maintain high capacity and long cycle life at rapid charge/discharge rate due to the sluggish insertion/deinsertion of K+. To solve this problem, the morphology of the SCs was regulated by using pitches with different chemical structures. The results showed that the chemical structure of the pitch characterized by less long aliphatic chains led to the largest average distance between polycyclic aromatic nuclei, which caused mild condensation of polycyclic aromatic nuclei and thus the formation of lamellar structures. Abundant short chains of the pitch ignited violent cyclization and aromatization and the shortened average distance, inducing violent condensation to generate the bulk structures. The cyclopenta-fused rings and aromatic methyl groups of the pitch minimized the average distance, which also built the bulk structures. More exposed defect-edge sites and larger active surface of the lamellar SC contributed to the adsorption of K+ and improved reaction kinetics. When the current density increased to 3C,bulk structures did not work while the lamellar still remained high reversible capacity of 160.9 mAh g−1 after 1000 cycles. These findings paved a new way for the design of SCs at the molecular level to satisfy high electrochemical performance at high charge/discharge rate. [Display omitted] • The chemical structures of pitches play an important influence on their thermochemical behaviors and morphologies of soft carbons. • The lamellar structures exposed more edge-defect sites to absorb of K+ and boost reaction kinetics. • The of chemical structures of pitches play an vital role in high-rate soft carbon anode in potassium ion batteries. [ABSTRACT FROM AUTHOR]

Bi-Sb alloys are appealing anode materials for potassium ion batteries (PIBs) but challenged by their enormous volumetric variation during operation. Herein, a facile one-step dealloying protocol was devised and utilized to prepare the Bi-Sb alloys that manifest an exotic bicontinuous hierarchical nanoporous (np) microstructure ideal for volume-change mitigation and K+ transport percolation. The growth mechanism fostering the peculiar morphology of the np-(Bi,Sb) alloys was investigated and clarified via operando X-ray (XRD) and ex-situ scanning electron microscopy (SEM). In particular, the np-Bi6Sb2 electrode, optimized for comprehensive electrochemical performance, achieves decent reversible capacities and a superior lifespan, as benchmarked with the monometallic references and other Bi-Sb alloy electrodes. The (de)potassiation mechanism of the np-(Bi,Sb) alloys was studied by operando XRD and further rationalized by density functional theory (DFT) calculations, whereby a homogeneous (segregation-free) and robust two-step electrochemically-driven phase transformations’ catenation of (Bi,Sb) ↔ K(Bi,Sb)2 ↔ K3(Bi,Sb) was reliably established to substantiate the outstanding reversibility of the np-(Bi,Sb) anodes in PIBs.

Potassium ion batteries (PIBs) have attracted considerable attention owing to their unique advantages. Nevertheless, the large radius of potassium ions and their sluggish kinetics hinder the further development of potassium ion batteries. In this study, mesoporous hard carbon nanospheres (PCN- x , where x corresponds to pyrolysis temperatures of 700 ℃, 800 ℃, and 900 ℃) have been successfully prepared from a facile hydrothermal and pyrolysis processes at different temperatures of phenolic resin precursor. The obtained PCN- x materials offer several advantages, including abundant active sites, favorable interlayer spacing (0.4113 nm), high specific surface area (574.7202 m2 g−1), and exceptional structural stability. These merits collectively contribute to enhancing the stability of potassium ion intercalation/deintercalation behavior and provide a high pseudocapacitive capacity. While used as anode materials for PIBs, these materials exhibit remarkable battery performance, including a superior initial charge capacity of 395.2 mAh g−1 at the current rate of 100 mA g−1, exemplary rate performance (209 mAh g−1 at 5 A g−1), and outstanding cycle stability, retaining a capacity of 249 mAh g−1 after 1000 cycles. The present work introduces a low-cost and straightforward method for the preparation of anode materials of PIBs and provides valuable insights into the energy storage field. [Display omitted] • Hard carbon nanospheres were prepared through annealing of phenolic resin precursor. • The obtained PCN-700 materials offer favorable interlayer spacing and high specific surface area. • PCN-700 presented superior initial charge capacity, excellent rate performance and outstanding cycle stability. [ABSTRACT FROM AUTHOR]

Three-dimensional MoS 2 nanosheets uniformly embedded within NiTe nanorods are synthesized via one-step hydrothermal method and subsequently coated with a carbon layer to form stable NiTe@MoS 2 @C heterojunctions. The heterojunctions exhibit moderate lattice mismatch (δ =20.0 %), strong electric fields, and uniform carbon shells, resulting in unique electronic configurations and abundant active sites. As an anode for potassium-ion batteries, NiTe@MoS 2 @C demonstrated an high reversible capacity of 258.4 mAh g−1 after 100 cycles at a rate of 200 mA g−1. Moreover, it showed a stable reversible capacity of 177.5 mAh g−1 at a high rate of 5000 mA g−1, indicating excellent rate performance. Notably, even in the NiTe@MoS 2 @C//perylene tetracarboxylic dianhydride full battery configuration, a significant reversible capacity of 87.4 mAh g−1 was maintained after 100 cycles at a rate of 200 mA g−1, manifesting its remarkable potential for practical applications in potassium-ion batteries. Theoretical calculations further revealed that the well-designed NiTe@MoS 2 heterojunction significantly enhances K+ ion diffusion. [Display omitted] • Three-dimensional NiTe 2 @MoS 2 @C heterojunctions are synthesized as anode for KIB. • MoS 2 nanosheets embedded within NiTe nanorods to form stabilized heterojunctions. • The NiTe@MoS 2 heterojunctions show low lattice misfits and strong electric fields. • The NiTe@MoS 2 @C shows exceptional cycling stability and rate capability for KIBs. [ABSTRACT FROM AUTHOR]

[Display omitted] • A synergistic triple-action Bi 2 Se 3 /Sb 2 Se 3 @NC@G electrode is used as anodes for potassium-ion battery. • The triple action design, including p-n junction, bond softening, and dual confinement, maximize the potassium-ion storage. • Multi-morphological heterostructure can not only enhance the conductivity but also facilitates electrolyte infiltration. • The Bi 2 Se 3 /Sb 2 Se 3 @NC@G electrode exhibits a reversible capacity up to 580 mAh/g at 50 mA/g. • The Bi 2 Se 3 /Sb 2 Se 3 @NC@G electrode demonstrates a high capacity of 310 mA h/g after 5000th cycles at 500 mA/g. 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 Bi 2 Se 3 /Sb 2 Se 3 @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 K 2 Se 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 Bi 2 Se 3 /Sb 2 Se 3 @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. [ABSTRACT FROM AUTHOR]

K-ion batteries (PIBs) are promising alternatives to Li-ion and Na-ion batteries (LIBs/SIBs). However, the ionic radius of K+ (1.38 Å) is larger than that of Li+ (0.76 Å), consequently leading to sluggish diffusion, low capacity, and poor cycling performance in intercalation- and conversion-type K-storage technologies. To address these issues, rGO-coated nickel selenide on carbon nanofiber (rGO@Ni x Se y -CNF) and nickel selenide on carbon nanofiber (Ni x Se y -CNF) were developed as anode electrodes for PIBs. To improve the electrochemical properties and prevent Se leaching during the charging/discharging of nickel selenide, the surface of the Ni x Se y particles was coated with rGO. The rGO coating not only protected Se but also improved the conductivity and cycling performance. rGO@Ni x Se y -CNF delivered an excellent charge-specific capacity of ∼ 126 mAh g−1 at 100 mA g−1 over 200 cycles, with an initial coulombic efficiency of approximately 50 %, as well as 50 % capacity retention, attributed to the retarded leaching of Se through the rGO coating. These findings provide new insights for developing highly reversible Ni-based anode materials for advanced PIBs. [Display omitted] • NixSey-CNF was simultaneously coated with rGO during a facile synthesis. • rGO-coated NixSey-CNF (rGO@NixSey-CNF) improved the potassium storage performance. • Surface engineering further enhanced retarding Se leaching, improving durability. [ABSTRACT FROM AUTHOR]

[Display omitted] • Surface treatment of graphite as an anode was prepared to improve ion diffusivity. • Unexpectedly, AG showed the highest specific capacity with a durability. • Surface charge caused by functionalization also affect the improved ion diffusivity. Potassium-ion batteries (PIBs) have recently gained attention as an alternative to Li-ion batteries (LIBs) because Li and K belong to the same alkali metal group and are replaceable. However, the theoretical capacity of PIBs is hindered by the larger size of potassium ions compared to lithium ions. Generally, the surface treatment of graphite, an anode material in metal-ion batteries, enhances ion diffusivity and improves electrochemical performance. In this study, a straightforward approach is introduced in which graphite is treated with an acid to widen the interlayer spacing and an alkali to create pores. Acid and alkali treatments not only improve ion diffusivity but also control the surface charge of graphite in PIBs. Consequently, acid-treated graphite (AG) displays the highest specific capacity (206.2 mAh g−1 at 0.2 A g−1 after 100 cycles) with good durability. In addition, the trade-off between the physical ion pathway derived from structural defect density and functionalization-induced surface charge improves ion diffusivity. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: In recent years, the anode materials of bismuth(Bi)‐based potassium ion batteries with high theoretical capacity and suitable potassium ion insertion potential have attracted extensive attention. However, due to the volume expansion of Bi, the performance of Bi‐based anode materials is not ideal during potassium ion (de)intercalation. In order to solve these problems, we report a three‐dimensional (3D) ternary bismuth nanoparticles/conductive polymers/carbon nanotubes (Bi/PPy/CNT) hybrid anode material for K‐ion batteries. At a current density of 100 mA·g–1, its reversible capacity reaches 302 mAh·g–1 after 200 cycles, while it reaches 195.7 mAh·g–1 after 600 cycles at 1 A·g–1. Its excellent performance is attributed to the hydrogel network which provides a range of electron transport networks and high porosity. Carbon nanotubes are used as electron enhancers to reduce the volume expansion of Bi particles during the reaction. This study provides a prerequisite for expanding the application of 3D ternary materials. [ABSTRACT FROM AUTHOR]

Due to the large volume change, limited energy density, large safety problems, and other factors restricting the development of potassium ion battery in the process of charge and discharge, the research on the cathode materials of potassium ion battery is an indispensable part. In this article, we designed and predicted P2‐type structures by introducing "cationic potential" that captures the key interactions of the layered materials. The precursors of the designed potassium ion battery cathode materials were obtained by co‐precipitation method. Through component analysis, the experimental conditions most in line with the theoretical content of precursors were found. The cathode material was synthesized by solid phase method. This material has a highly reversible K+ insertion/deinsertion effect. The initial discharge specific capacity of the battery appears at about 47 mAh/g. After 30 charge‐discharge cycle tests, the discharge specific capacity of the battery drops to about 33 mAh/g, and the retention rate is about 70%. [ABSTRACT FROM AUTHOR]

Sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs) have been considered as attractive alternatives for next-generation battery systems, which have promising application potential due to their earth abundance of potassium and sodium, high capacity and suitable working potential, however, the design and application of bi-functional high-performance anode still remain a great challenge up to date. Bismuth sulfide is suitable as anode owing to its unique laminar structure with relatively large interlayer distance to accommodate larger radius ions, high theoretical capacity and high volumetric capacity etc. In this study, dandelion-like Bi2S3/rGO hierarchical microspheres as anode material for PIBs displayed reversible capacity, and 206.91 mAh·g−1 could be remained after 1,200 cycles at a current density of 100 mA·g−1. When applied as anode materials for SIBs, 300 mAh·g−1 could be retained after 300 cycles at 2 A·g−1 and its initial Coulombic efficiency is as high as 97.43%. Even at high current density of 10 A·g−1, 120.3 mAh·g−1 could be preserved after 3,400 cycles. The Na3V2(PO4)3@rGO//Bi2S3/rGO sodium ion full cells were successfully assembled which displays stable performance after 60 cycles at 100 mA·g−1. The above results demonstrate that Bi2S3/rGO has application potential as high performance bi-functional anode for PIBs and SIBs. [ABSTRACT FROM AUTHOR]

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Edge-nitrogen (pyridinic/pyrrolic nitrogen) doped carbon materials have been considered as promising anodes for potassium ion batteries (KIBs), which can provide a high surface-induced capacitive capacity beyond the K+-intercalated mechanism. However, achieving a high-level edge-nitrogen doping is still a great challenge owning to inevitable introduction of graphitic nitrogen into carbon materials via conventional pyrolysis process. Herein, we design porous carbon nanosheets with bundant defects and edge sites to graft nitrogen atoms to achieve a high-level edge-nitrogen doping (88.36%). The optimized edge-nitrogen doped carbon nanosheets (ENCNs-600) exhibits a high reversible capacity of 443 mAh g−1 at 0.1 A g−1 after 200 cycles, excellent rate performance (175 mAh g−1 at 20 A g−1), and ultrastable cycling stability (246 mAh g−1 at 5 A g−1 over 10,000 cycles). Density functional theory calculations and kinetic studies confirm that both edge-nitrogen doping and explanded interlayer distance are greatly conducive for the adsorption and diffusion of K+, thereby ensuring enhanced potassium-storage performance with a synergistic adsorption-intercalation mechanism. The remarkable potassium-storage performance of ENCNs-600 results from its high-level edge-nitrogen doping and explanded interlayer distance, which is greatly conducive for the adsorption and diffusion of K+, thereby ensuring enhanced potassium-storage performance with synergistic adsorption-intercalation mechanism. [Display omitted] [ABSTRACT FROM AUTHOR]

Large-scale low-cost synthesis methods for potassium ion battery (PIB) anodes with long cycle life and high capacity have remained challenging. Here, inspired by the structure of a biological cell, biomimetic carbon cells (BCCs) were synthesized and used as PIB anodes. The protruding carbon nanotubes across the BCC wall mimicked the ion-transporting channels present in the cell membrane, and enhanced the rate performance of PIBs. In addition, the robust carbon shell of the BCC could protect its overall structure, and the open space inside the BCC could accommodate the volume changes caused by K+ insertion, which greatly improved the stability of PIBs. For the first time, a stable solid electrolyte interphase layer is formed on the surface of amorphous carbon. Collectively, the unique structural characteristics of the BCCs resulted in PIBs that showed a high reversible capacity (302 mAh g−1 at 100 mA g−1 and 248 mAh g−1 at 500 mA g−1), excellent cycle stability (reversible capacity of 226 mAh g−1 after 2100 cycles and a continuous running time of more than 15 months at a current density of 100 mA g−1), and an excellent rate performance (160 mAh g−1 at 1 A g−1). This study represents a new strategy for boosting battery performance, and could pave the way for the next generation of battery-powered applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Polyaniline coated hollow mesopore hard carbon spheres are precisely tailored. • Polyaniline coating greatly boosts conductivity, while keeping considerable mesopores. • Polyaniline coating helps to form a stable and inorganic-rich SEI layer. • An excellent rate capacity (233.9 mAh g−1 at 5 A g−1) and a high ICE (70.7%) are realized. Hard carbon with rich mesopores is considered as one of the most promising anodes for potassium-ion batteries, resulting from its shortened ions diffusion distance, good electrolyte penetration ability, and highly released stress. However, the well-developed pore channels tend to separate graphite-domains and enlarge direct contact area between electrode/electrolyte, which easily cause discontinuous electrons transfer paths and extra electrolyte depletion, thus leading to poor rate performance and initial Coulombic efficiency (ICE). Hence, we propose polyaniline conductive layer coated hollow mesoporous carbon spheres (HMCS@PAN) tailored based on local protonation reaction strategy, which can enhance conductivity and simultaneously maintain considerable pore structure, accounting for an ultrahigh-rate performance (233.9 mAh/g at 5 A/g) and long cycling life (216.8 mAh/g at 5 A/g over 2000 cycles). Besides, PAN coating can inhibit the direct contact between inner pore channels and electrolyte and reduce the excessive depletion of active ions in the filling of pores with larger pore size, which is conducive to building an even, stable, and inorganic-rich solid electrolyte interphase (SEI) layer, resulting in an excellent ICE (70.7%). This work provides a guidance for the structure design of mesopore hard carbon to improve its rate and ICE. [ABSTRACT FROM AUTHOR]

Mesoporous carbon nanobowls embedded with ultrafine CoSe 2 nanocrystals (CoSe 2 @MNCBs) were successfully synthesized as anodes for potassium ion batteries (KIBs) via drop and dry impregnation and subsequent selenization process. The successful incorporation of ultrafine CoSe 2 nanocrystals into MCNBs endowed the nanobowls with the advantages of conventional hollow carbon-based composites. Especially, the unique nanobowl structure exhibits a higher packing density than the conventional hollow mesoporous carbon sphere structure, which greatly increases the volumetric energy density of the as-prepared electrode. Therefore, CoSe 2 @MNCB exhibited excellent K-ion storage performance as the anode material of KIB. [Display omitted] • Bowl-like carbon/CoSe 2 composites are successfully synthesized by a facile method. • CoSe 2 @MCNB displays exceptional cycling stability and high reversible capacity. • Compared with hollow structure, the volumetric capacity of sample increased by 68% In the quest for advanced electrode materials for potassium ion batteries (KIBs), an innovative anode featuring ultrafine CoSe 2 nanocrystals embedded within mesoporous carbon nanobowls (CoSe 2 @MCNBs) is presented herein. Diverging from conventional hollow carbon nanospheres, the distinctive bowl structure is crafted to enhance the structural integrity and volumetric energy density of the electrodes. CoSe 2 @MCNBs synthesized using an iterative drop and dry method followed by selenization exhibit well-preserved morphology with a shell thickness of 20 nm. The successful integration of ultrafine CoSe 2 nanocrystals into MCNBs imparts the nanobowls with the benefits of conventional hollow carbon-based composites, including abundant ion storage sites and high electrical conductivity. Simultaneously, the bowl structure boasts a higher packing density than the conventional hollow mesoporous carbon sphere (HMCS) structure, significantly augmenting the volumetric energy density of the fabricated electrode. Capitalizing on these advantages, the CoSe 2 @MCNB electrode displays exceptional cycling stability, achieving a reversible capacity of 523 mA h g−1 after 500 cycles at 0.5 A/g and an impressive rate capacity of 247 mA h g−1 at 2.0 A/g. This study demonstrates the strong potential of CoSe 2 @MCNB as an electrode material for the next generation of KIBs. [ABSTRACT FROM AUTHOR]

Molybdenum oxides as anode materials have received considerable attention because of their high-theoretical capacities. However, the abrupt volume changes during the charge/discharge process and the poor electrical conductivity lead to rapid capacity decay and poor cycling performance. Molybdenum oxides are anchored on carbon matrix to form composite that can effectively accelerate reaction kinetics and slow down capacity decay. Biomass-based carbon is a promising matrix, due to inexpensive, environment-friendly and abundant. In this study, the thin-flake MoO x was successfully anchored on the N-doped pinecone-derived carbon (NPC) by using a single-step hydrothermal method. When used as a potassium ion battery anode for the first time, the reversible capacity of optimised MoO x /NPC (210.4 mAh·g−1) was higher than that of pure MoO 2 (122.7 mAh·g−1) at 100 mA g−1. Even when cycled at 500 mA g−1, optimised MoO x /NPC exhibited a high capacity of 147.2 mAh·g−1 after 500 cycles. Moreover, the potassium ions storage mechanism was analyzed in detail. This finding demonstrates MoO x /NPC as a potential electrode for the development of high-performance PIBs, and provides a new strategy to reduce environmental pollution caused by treating pinecone and increase its additional value. [Display omitted] • 2D thin-flake MoOx/N-dopped pinecone-based carbon composite was prepared by a one-step hydrothermal method. • The synergistic effects between N-dopped pinecone-based carbon and MoOx improved electrochemical performance of composite. • The electrode was suitable for application in K-ion batteries. [ABSTRACT FROM AUTHOR]

This study proposes a facile salt-templated approach for fabricating single-hole hollow microspheres (MoSe 2 @NC/CNT) comprising MoSe 2 , an N-doped carbon (NC) matrix, and a carbon nanotube (CNT) backbone as anode materials in potassium-ion batteries (KIBs). These microspheres feature a well-defined hollow structure with a single aperture and comprise uniform few-layered MoSe 2 nanocrystals embedded within a carbonaceous matrix consisting of CNT and NC. The synthesis involves one-pot spray drying using NaCl as a recyclable hard template, which is novel in that it allows for easy formation of porous structures without the use of expensive and difficult to fabricate nano-sized hard templates such as SiO 2 and latex beads for making pores. The carbon matrices effectively not only preserve the microsphere architecture during NaCl removal but also prevent MoSe 2 restacking and overgrowth. This well-engineered composite offers multiple conductive pathways, facilitating ion and electron transport while minimizing K+ diffusion distances. Furthermore, the porous CNT/carbon matrix mitigates significant volume changes during cycling, reinforcing the structural integrity. Thus, the MoSe 2 @NC/CNT microsphere demonstrates outstanding electrochemical performance, exhibiting a high specific capacity and enduring cycling stability (277/207 mA h g−1 after 1000 cycles at 0.5 and 2.0 A∙g−1), along with remarkable rate capability. Hence, it is a promising anode material for KIBs. [Display omitted] • Single-hole MoSe 2 @NC/CNT hollow microspheres is prepared by a spray-drying method. • NaCl salt plays a major role in forming the single-hole structure of microsphere • CNT and NC matrices effectively prevent the restacking and overgrowth of MoSe 2. • Porous structure relieves structural stress of electrode and promotes ion diffusion. • Unique nanostructure shows excellent K+ storage performances. [ABSTRACT FROM AUTHOR]

In this chapter, N and S co-doped mesh porous carbon materials (NSC) were prepared using freeze-drying assisted high-temperature carbonization, where sodium polyacrylate was used as the carbon source and sodium thiosulfate (Na 2 S 2 O 3) and sodium nitrate (NaNO 3) is the sulfur and nitrogen sources, respectively. Its unique layered porosity and the ability to dope sulfur atoms up to 5.9 % allows for the introduction of more defect sites and expanded interlayer spatial interactions, achieving impressive electrochemical properties. Enlightened by the properties of N/S double doping and high pore defects, NSC anodes exhibit a high storage of K+ (441.6 mA h/g at 0.05 A/g) and superior rate performance. The density functional theory (DFT) and electrochemical experimental investigation showed the N/S dual doping can successfully modify the electronic structure and improve the capacity of adsorbing K+. Significantly, the assembled dual-carbon PIHC can deliver an impressive energy density of 141.2 Wh kg−1 at a power density of 400 W kg−1 and a satisfactory cycle life when using the NSC-700 porous carbon as the cathode, which can light the "CUMT" pattern, sheding new light on creating improved carbon materials for using in practical applications. [Display omitted] • N and S co-doped mesh carbon materials were prepared for K-ion hybrid capacitors. • High specific surface area and S-rich carbon is designed with a sulfur content of 5.9 %. • The K+ storage mechanism was deeply studied by electrochemical and DFT calculations. • The dual-doped carbon employed in PIHC exhibits an energy density of 141.2 Wh kg-1. The primary research challenge concerning K-ion batteries revolves around ensuring their optimal cycle stability and specific capacity, particularly the inherent sluggish kinetics induced by the relatively large radius of K+. In this study, we report a pore-size controllable synthetic approach employing salt-template precursors. Herein, nitrogen and sulfur co-doped porous carbon materials with rich carbon defect engineering was synthesized through the salt template method, where the doped heteroatoms can both offer a lot of carbon defect content and redox active sites that are helpful for enhancing potassium ion storage kinetics. As a result, the electrode with abundant doping atom content realizes a good capacity and long cycle lifespan (274.8 mA h g−1 after 200 cycles at 0.05 A/g). Inspiringly, PIHCs assembled by N/S co-doped carbon anode exhibit excellent cycling stability (93.4 % capacity retention for 1000 cycles) and a high energy density of 141.2 Wh kg−1 and a power density of 1.6 kW kg−1. Importantly, the density functional theory calculation combining electrochemical kinetic analysis further demonstrates that role of N and S doping plays dominant roles in total storage mechanism. This work gives a deep insight about the roles of external defects in doping carbon materials for potassium storage. [ABSTRACT FROM AUTHOR]

Potassium‐ion batteries (PIBs) have attracted tremendous attentions for scalable electrical energy storage owing to the abundant K resources. Heteroatom co‐doped hard carbon is considered to be a reliable material to boost ion transport and provide active sites for reversible potassium storage. Herein, N/P dual‐doped 3D graphene aerogels (NPGAs) with hierarchical pores, enlarged interlayer distance, and high doping level are successfully synthesized, which exhibit outstanding electrochemical performance for PIBs. A detailed comparative study found that promoted coulombic efficiency, improved specific capacity (507 mAh g−1 at 100 mA g−1 after 100 cycles) and excellent cycle performance (106 mAh g−1 at 5000 mA g−1 after 3000 cycles) can be reached by replacing KPF6 with potassium bis(fluorosulfonyl)imide (KFSI). Further kinetic analysis reveals that NPGAs present more capacitive behavior of K‐ion, low resistance, and fast K‐ion conductivity by virtue of the advanced solid electrolyte interphase (SEI) film formed in KFSI‐EC/DEC electrolyte. Ex situ XPS, SEM, and TEM all confirm a physical flexible, chemical stable, and inorganic SEI layer formed on the surface of the electrode. In general, this work promotes a deep understanding of the mechanism of potassium storage and provides more opportunities for practical PIBs. [ABSTRACT FROM AUTHOR]

Pitch-based porous carbons with the abundant resources and high conductivity have potential advantages as potassium-ion battery anode materials. However, they suffer from small interlayer distance and rare potassium storage sites. Herein, nitrogen and phosphorus dual-doped coal tar pitch-based porous carbons (NPPC) was prepared in one-step carbonization using ammonium polyphosphate as N and P source and studied as the anodes for the potassium ion batteries. NPPC delivers a high capacity retention of 81.8% over 400 cycles at 1.0 A g−1. When the current density is raised to 10 A g−1, it can still retain a reversible capacity of 126 mAh g−1. The effects of carbonation temperature and ratio of ammonium polyphosphate to coal tar pitch on nitrogen and phosphorus doping contents were investigated by in situ Fourier transform infrared and synchronous thermal analysis. This work may shed light on the design of advanced potassium-ion battery by employing heteroatom doped functionalized soft carbons. The nitrogen-phosphorus dual-doped porous carbon frameworks (NPPC) was successfully prepared by one-step carbonization. Due to the introduction of heteroatoms, the NPPC exhibits excellent rate capability and cycling stability. [Display omitted] • N and P dual-doped coal tar pitch-based porous carbons was synthesized through a simple one-step carbonization method. • The effects of carbonation temperature and ratio of APP to CTP on N/P doping contents were explored by in situ FTIR and STA. • The sample with the highest P content of 3.15% and moderate N content of 3.68% shows superior rate performance. [ABSTRACT FROM AUTHOR]

Hard carbon is a promising anode material for potassium ion batteries, because of its abundant resource, low price and excellent electrochemical performance. Electrolyte, plays important role in determining the storage performance of electrode materials for alkaline metal based batteries, yet there is no report on how the solvents of the electrolyte impacts the potassium storage behavior of hard carbon. In this study, hard carbon prepared with corn cob as precursor (denoted as CCHC) was investigated in both ester and ether electrolytes. CCHC exhibits superior potassium storage performance in ether electrolyte than in ester electrolyte, in terms of capacity, rate and cycle performance. CCHC electrode presents different galvanostatic charge-discharge and CV profiles in ether and ester electrolytes. Kinetic studies and X-ray photoelectron spectra analyses suggest that the superior potassium storage behavior of CCHC in ether electrolyte would be attributed to larger capacitive storage contribution, favorable solid electrolyte interphase (SEI) film. This study would benefit to explore the potassium storage feasibility of hard carbon and achieve better understanding of alkaline metal storage mechanisms in carbon materials with different electrolytes. [Display omitted] [ABSTRACT FROM AUTHOR]

Large‐scale and low‐cost preparation of carbon‐based potassium anode with long life and high capacity is one of the footstones for the development of potassium ion batteries (PIBs). Herein, a low‐cost carbon‐based material, cross‐linked hollow graphitic carbon (HGC), is large scale synthesized to apply for PIBs anode. Its hollow structure can afford sufficient space to overcome the damage caused by the volume expansion of graphitic carbon (GC). While the cross‐linked structure forms a compact interconnection network that allows electrons to rapid transfer between different GC frameworks. Electrochemical measurements demonstrated that the HGC anode exhibited low charge/discharge plateau (about 0.25 V and 0.1 V) and excellent specific capacity as high as 298 mA h g−1 at the current density of 50 mA g−1. And more important, after 200 cycles the capacity of HGC anode still shows 269 mA h g−1 (the decay rate of per cycle is only 0.048%). Meanwhile, the use of commercial traditional electrolyte (KPF6) and cheap raw materials that provide new hope for trying and realizing the large‐scale production of PIBs based on carbon anode materials. [ABSTRACT FROM AUTHOR]

Metal phosphates have been widely explored in lithium ion batteries and sodium ion batteries owing to high theoretical capacities, mild toxicity and low cost. However, their potassium ion battery applications are less reported due to the limited conductivity and the slow diffusion kinetics. Considering these drawbacks, novel structured M2P2O7/C (M=Fe, Co, Ni) nanoflake composites are prepared through an organic‐phosphors precursor‐assisted solvothermal method and a subsequent high temperature annealing process. The designed Co2P2O7/C composite exhibits the highest rate capacity with 502 mAh g−1 at 0.1 A g−1 and good cyclability for 900 cycles at 1 A g−1 and 2 A g−1 when compared with Ni and Fe based composites. The superior electrochemical performance can be attributed to their unique nanoparticle‐assembled nanoflake structure, which can afford enough active sites for K+ intercalation. In addition, the robust pyrophosphate crystal structure and the in situ formed carbon composition also have positive effects on enhancing the long‐term cycling performance and the electrode's conductivity. Finally, this organic‐phosphors precursor induced simple approach can be applied for easy fabrication of other pyrophosphate/carbon hybrids as advanced electrodes. [ABSTRACT FROM AUTHOR]

Tellurium (Te) has attracted intensive attention for its potential as stationary energy storage system due to its high volumetric capacity and the intrinsic electronic conductivity. Nevertheless, this battery suffers from the low utilization of active Te and the vast volume variations during cycling. Hierarchical N‐doped carbon (N−C) porous microspheres etched from MnCO3 microsphere template are designed as a host for Te. The hierarchical microspheres, with abundant pores and voids, shortens the ions diffusion/electrons transport distances and buffers the volume expansion of the active materials. When constructed the K−Te battery, the Te@N−C electrode delivers a remarkable reversible capacity of 390 mA h g−1 (corresponding to 2437.5 mA h cm−3) at 0.1 A g−1 after 100 cycles and 170 mA h g−1 (corresponding to 1062.5 mA h cm−3) after 2000 cycles at 0.5 A g−1. This novel design in this work may open up new opportunities for the development of the new energy storage systems with high volumetric energy density. [ABSTRACT FROM AUTHOR]