Potassium-ion Batteries Research Articles

Sugar gourd-like amorphous carbon coated CoS/Co9S8 nanoparticles anchored on carbon nanotubes for potassium-ion batteries

Sugar gourd-like amorphous carbon coated CoS/Co9S8 nanoparticles anchored on carbon nanotubes for potassium-ion batteries

Beyond Lithium: Future Battery Technologies for Sustainable Energy Storage

Known for their high energy density, lithium-ion batteries have become ubiquitous in today’s technology landscape. However, they face critical challenges in terms of safety, availability, and sustainability. With the increasing global demand for energy, there is a growing need for alternative, efficient, and sustainable energy storage solutions. This is driving research into non-lithium battery systems. This paper presents a comprehensive literature review on recent advancements in non-lithium battery technologies, specifically sodium-ion, potassium-ion, magnesium-ion, aluminium-ion, zinc-ion, and calcium-ion batteries. By consulting recent peer-reviewed articles and reviews, we examine the key electrochemical properties and underlying chemistry of each battery system. Additionally, we evaluate their safety considerations, environmental sustainability, and recyclability. The reviewed literature highlights the promising potential of non-lithium batteries to address the limitations of lithium-ion batteries, likely to facilitate sustainable and scalable energy storage solutions across diverse applications.

Entropy and Electronic Structure Modulation of a Prussian Blue Analogue Cathode with Suppressed Phase Evolution for Potassium-Ion Batteries.

Severe structural evolution and high content of [Fe(CN)6]4- defects drastically deteriorate K-ion storage performances of Prussian blue-based cathodes. Herein, a potassium manganese iron copper hexacyanoferrate (KFe2/3Mn1/6Cu1/6HCF), with suppressed anionic vacancies, eliminated band gap, and low K-ion diffusion barrier, is regarded as a cathode for potassium-ion batteries. The entropy stabilization effect and robust Cu-N bond induced by the inert Cu-ion with large electronegativity boost KFe2/3Mn1/6Cu1/6HCF to exhibit great phase state stability, thus inhibiting the structural transition of monoclinic ↔ cubic. Hence, KFe2/3Mn1/6Cu1/6HCF undergoes a zero-stress solid-solution reaction mechanism, where Fe and Mn serve as dual active sites for charge compensation. Consequently, KFe2/3Mn1/6Cu1/6HCF displays a high reversible capacity of 127.5 mAh·g-1 with an energy density of 469.2 Wh·kg-1 at 10 mA·g-1 and superior cyclic stability with a high retention of 90.7% over 100 cycles. A high-energy-density K-ion full battery is assembled, contributing an ultralong lifetime over 1000 cycles with a low-capacity fading rate of 0.038% per cycle.

Electrolyte Design Enables Stable and Energy‐Dense Potassium‐Ion Batteries

AbstractFree from strategically important elements such as lithium, nickel, cobalt, and copper, potassium‐ion batteries (PIBs) are heralded as promising low‐cost and sustainable electrochemical energy storage systems that complement the existing lithium‐ion batteries (LIBs). However, the reported electrochemical performance of PIBs is still suboptimal, especially under practically relevant battery manufacturing conditions. The primary challenge stems from the lack of electrolytes capable of concurrently supporting both the low‐voltage anode and high‐voltage cathode with satisfactory Coulombic efficiency (CE) and cycling stability. Herein, we report a promising electrolyte that facilitates the commercially mature graphite anode (>3 mAh cm−2) to achieve an initial CE of 91.14 % (with an average cycling CE around 99.94 %), fast redox kinetics, and negligible capacity fading for hundreds of cycles. Meanwhile, the electrolyte also demonstrates good compatibility with the 4.4 V (vs. K+/K) high‐voltage K2Mn[Fe(CN)6] (KMF) cathode. Consequently, the KMF||graphite full‐cell without precycling treatment of both electrodes can provide an average discharge voltage of 3.61 V with a specific energy of 316.5 Wh kg−1−(KMF+graphite), comparable to the LiFePO4||graphite LIBs, and maintain 71.01 % capacity retention after 2000 cycles.

Electrolyte Design Enables Stable and Energy-Dense Potassium-Ion Batteries.

Free from strategically important elements such as lithium, nickel, cobalt, and copper, potassium-ion batteries (PIBs) are heralded as promising low-cost and sustainable electrochemical energy storage systems that complement the existing lithium-ion batteries (LIBs). However, the reported electrochemical performance of PIBs is still suboptimal, especially under practically relevant battery manufacturing conditions. The primary challenge stems from the lack of electrolytes capable of concurrently supporting both the low-voltage anode and high-voltage cathode with satisfactory Coulombic efficiency (CE) and cycling stability. Herein, we report a promising electrolyte that facilitates the commercially mature graphite anode (>3 mAh cm-2) to achieve an initial CE of 91.14 % (with an average cycling CE around 99.94 %), fast redox kinetics, and negligible capacity fading for hundreds of cycles. Meanwhile, the electrolyte also demonstrates good compatibility with the 4.4 V (vs. K+/K) high-voltage K2Mn[Fe(CN)6] (KMF) cathode. Consequently, the KMF||graphite full-cell without precycling treatment of both electrodes can provide an average discharge voltage of 3.61 V with a specific energy of 316.5 Wh kg-1-(KMF+graphite), comparable to the LiFePO4||graphite LIBs, and maintain 71.01 % capacity retention after 2000 cycles.

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

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

The Origin, Characterization, and Precise Design and Regulation of Diverse Hard Carbon Structures for Targeted Applications in Lithium-/Sodium-/Potassium-Ion Batteries

The Origin, Characterization, and Precise Design and Regulation of Diverse Hard Carbon Structures for Targeted Applications in Lithium-/Sodium-/Potassium-Ion Batteries

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

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

Bismuth-based material with alveolar-like structure as advanced anode for superior potassium storage

Bismuth (Bi)-based anodes have a promising application in potassium-ion batteries (PIBs) due to their high theoretical capacity. However, Bi-based materials undergo unavoidable and drastic volume expansion during charging/discharging. In addition to this, the problem of poor reaction kinetics severely hinders its development. To solve these problems, we designed Bi2O3-Bi/Carbon hollow nanospheres (Bi2O3-Bi@CHNSs) inspired by the structure of alveoli and its contraction/expansion respiration mechanism. Bi2O3-Bi@CHNSs have an alveolus-like hollow core–shell structure and alveolus respiration-like reversible contraction/expansion mechanism for potassium storage, which provides good structural stability. In situ characterizations confirm that the Bi2O3 and Bi hybrid structures synergistically store potassium through a conversion/alloying mechanism. Bi2O3-Bi@CHNSs exhibited excellent rate performance as anode with a capacity of up to 270.4 mAh g−1 at a current density of 40 A g−1. Assembled as a full cell, the capacity reached 106.5 mAh g−1 at a current density of 30 A g−1, which is superior to most of the reported intact PIBs. This work utilized biomimetic design concepts to elaborate a bionic alveolar structure. It provides a new perspective for optimizing the volume expansion of Bi-based anodes and developing high-performance PIBs.

Bimetallic Sulfide Hollow Nanocubes Heterostructure Promotes Dual Coupling of Conversion and Alloying/Dealloying Reactions to Achieve Durable Potassium-Ion Battery Anode.

Conversion and alloying-type transitional metal sulfides have attracted significant interests as anodes for Potassium-ion batteries (PIBs) and Sodium-ion batteries (SIBs) due to their high theoretical capacities and low cost. However, the poor conductivity, structural pulverization, and high-volume expansions greatly limit the performance. Herein, Co1-xS/ZnS hollow nanocube-like heterostructure decorated on reduced graphene oxide (Co1-xS/ZnS@rGO) composite is fabricated through convenient hydrothermal and post-heat vulcanization techniques. This unique composite can provide a more stable conductive network and shorten the diffusion length of ions, which exhibits a remarkable initial charge capacity of 638.5mA h g-1 at 0.1 A g-1 for SIBs and 606mA h g-1 at 0.1 A g-1 for PIBs, respectively; It is worth noting that the composite presents remarkable long stable cycle performance in PIBs, which initially delivered 274mA h g-1 and sustained the charge capacity up to 245mA h g-1 at high current density of 1 A g-1 after 2000 cycles. A series of in situ/ex situ detections and first principle calculations further validate the high potassium ions adsorption ability of Co1-xS/ZnS anode materials with high diffusion kinetics. This work will accelerate the fundamental construction of bimetallic sulfide hollow nanocubes heterostructure electrodes for energy storage applications.

Solvation structure manipulation of ester-based electrolyte by acetonitrile additive enables high-capacity and stable K-storage for phenazine-based anode

Potassium ion batteries configured with organic electrode materials show promising applications due to the advantages of low cost and high theoretical capacity. Nevertheless, the design of electrolytes compatible with organic anodes and the resolution of the issue of uniform deposition of highly active potassium remain significant challenges. In this study, an engineering strategy was proposed to employ additives with electron-rich nitrile group in order to modulate the properties of ester-based electrolytes. It was found that acetonitrile (AN) can change the cation solvation structure, which determines the interfacial behavior of the K-solvent at the electrode interface, and effectively guides the homogeneous plating/stripping of K as well as suppresses dendritic growth. Therefore, a high reversible capacity of 200 mAh/g(composite) with the coulombic efficiency of 99.1 % at 50 mA/g was produced by the K-storage system of the novel phenazine anode with carbon nanotubes supported (PhAz/CNTs) and AN-containing electrolyte. The cyano-based additive strategy may offer novel insights into the tuning of electrolyte properties for the development of high-performance potassium ion battery systems.

Construction of foam-like carbon microspheres with controllable pseudo-graphitic domains: Synergistic enhancement of K-ion adsorption/intercalation storage

Hard carbon shows promise as a potassium-ion battery (PIB) anode, but its high capacity and rate property are limited by insufficient active sites and poor kinetics. Creating a porous channel structure offers an effective route, but such design often disrupts the development of intercalation sites critical for low-voltage plateau capacity, and may reduce the energy density of full cells. Herein, a staged pyrolysis strategy was developed to tailor foam-like carbon microspheres (FCMs) with controllable pseudo-graphitic domains by exploiting polymer with the temperature difference in pyrolysis. Such tactics perfectly retains abundant pseudo-graphitic domains and creates rich defect/pore structures, ensuring efficient K+ low-voltage intercalation and benefiting fast K+ transport. The optimized electrode exhibits balanced adsorption/intercalation capacity, delivering a large reversible capacity (386.7 mAh g−1 at 0.1C), outstanding rate performance (223.1 mAh g−1 at 4C) and excellent capacity retention (79.2 % over 2000 cycles at 4C). Additionally, the FCM-2//PTCDA full cell submits a high energy density of 198 Wh kg−1 and superb rate property/stability compared to same-type full cells. Tracked K-storage behavior confirmed the “adsorption–intercalation” mechanism and kinetic studies clarified that exact balance of defect, mesopore and pseudo-graphitic phase was crucial for the synergistic enhancement of adsorption/intercalation kinetics. This work opens up a unique method to tune the microstructure of hard carbon and offers design principles for developing practical anodes with synergistic storage behavior suitable for PIBs.

Synthesis, Stable Radical Anion and Energy Storage Performance of Pentacene Tetraimides

AbstractImide functionalization has been widely proved to be an effective approach to enrich optoelectronic properties of polycyclic aromatic hydrocarbons (PAHs). However, appending multiple imide groups onto linear acenes is still a synthetic challenge. Herein, we demonstrate that by taking advantage of a “breaking and mending” strategy, a linear pentacene tetraimides (PeTI) was synthesized through a three‐step sequence started from the naphthalene diimides (NDI). Compared with the parent pentacene, PeTI shows a deeper‐lying lowest unoccupied molecular orbital (LUMO) energy level, narrower band gap and better stability. The redox behavior of PeTI was firstly evaluated by generating a stable radical anion specie with the assistance of cobaltocene (CoCp2), and the structure of the electron transfer (ET) complex was confirmed by the X‐ray crystallography. Moreover, due to the presence of multiple redox‐active sites, we are able to show that the state‐of‐the‐art energy storage performance of the dealkylated PeTI (designated as PeTCTI) in organic potassium ion batteries (OPIBs) as an anode. Our results shed light on the application of multiple imides functionalized linear acenes, and the reported synthetic strategy provides an effective way to get access to longer nanoribbon imides with fascinating electronic properties.

Synthesis, Stable Radical Anion and Energy Storage Performance of Pentacene Tetraimides.

Imide functionalization has been widely proved to be an effective approach to enrich optoelectronic properties of polycyclic aromatic hydrocarbons (PAHs). However, appending multiple imide groups onto linear acenes is still a synthetic challenge. Herein, we demonstrate that by taking advantage of a "breaking and mending" strategy, a linear pentacene tetraimides (PeTI) was synthesized through a three-step sequence started from the naphthalene diimides (NDI). Compared with the parent pentacene, PeTI shows a deeper-lying lowest unoccupied molecular orbital (LUMO) energy level, narrower band gap and better stability. The redox behavior of PeTI was firstly evaluated by generating a stable radical anion specie with the assistance of cobaltocene (CoCp2), and the structure of the electron transfer (ET) complex was confirmed by the X-ray crystallography. Moreover, due to the presence of multiple redox-active sites, we are able to show that the state-of-the-art energy storage performance of the dealkylated PeTI (designated as PeTCTI) in organic potassium ion batteries (OPIBs) as an anode. Our results shed light on the application of multiple imides functionalized linear acenes, and the reported synthetic strategy provides an effective way to get access to longer nanoribbon imides with fascinating electronic properties.

The Development and Prospect of Stable Polyanion Compound Cathodes in LIBs and Promising Complementers.

Cathode materials are usually the key to determining battery capacity, suitable cathode materials are an important prerequisite to meet the needs of large-scale energy storage systems in the future. Polyanionic compounds have significant advantages in metal ion storage, such as high operating voltage, excellent structural stability, safety, low cost, and environmental friendliness, and can be excellent cathode options for rechargeable metal-ion batteries. Although some polyanionic compounds have been commercialized, there are still some shortcomings in electronic conductivity, reversible specific capacity, and rate performance, which obviously limits the development of polyanionic compound cathodes in large-scale energy storage systems. Up to now, many strategies including structural design, ion doping, surface coating, and electrolyte optimization have been explored to improve the above defects. Based on the above contents, this paper briefly reviews the research progress and optimization strategies of typical polyanionic compound cathodes in the fields of lithium-ion batteries (LIBs) and other promising metal ion batteries (sodium ion batteries (SIBs), potassium ion batteries (PIBs), magnesium ion batteries (MIBs), calcium ion batteries (CIBs), zinc ion batteries (ZIBs), aluminum ion batteries (AIBs), etc.), aiming to provide a valuable reference for accelerating the commercial application of polyanionic compound cathodes in rechargeable battery systems.

A Bandgap-Tuned Tetragonal Perovskite as Zero-Strain Anode for Potassium-Ion Batteries.

PIBs are emerging as a promising energy storage system due to high abundance of potassium resources and theoretical energy density, however, progress of PIBs is severely hindered by structural instability and poor cycling of anode material during continual insertion and extraction of larger-sized K+. Hence, developing anode material with structural stability and stable cycling remains a great challenge. Herein, band gap-tuned Mo-doped and carbon-coated lead titanate (CMPTO) with zero-strain K+ storage is presented as ultra-stable PIBs anode. Mo doping introduces narrowed band gap and optimized crystal lattice for enhanced intrinsic electron and ion transfer. Demonstrated by in situ XRD characterizations, the crystal structure stays stable with unchanged peak positions, fully revealing zero-strain characteristic of CMPTO anode during potassium storage for stable cyclic capability. Ultimately, CMPTO anode achieved ultra-stable cycling performance of 7000 cycles at 500 mA g-1 with high capacity retention of 90 % and considerable specific capacity of 130.9 mAh g-1 after 600 cycles at 100 mA g-1; with relatively large density, CMPTO realized eminent volumetric capacity of 1111.09 mAh cm-3 and ultra-long cycling life of 10000 cycles at 7041 mA cm-3. This work introduces a promisingly new route into developing anode materials with ultra-stable performance for PIBs.

Optimizing Prussian Blue Analogues for Potassium‐Ion Batteries: Advanced Strategies

AbstractPotassium‐ion batteries (PIBs), with the merits of abundant resources and low cost, have rapidly garnered attention as a potential candidate for large‐scale energy storage. Among the various contenders, Prussian blue analogues (PBAs) are considered one of the most suitable cathode materials owing to their relatively easy and economical synthesis as well as the three‐dimensional open framework which facilitates fast potassium ions intercalation without causing drastic volume expansion. Despite these advantages, integrating PBA as a cathode material for PIBs presents substantial challenges, which hinder their further practical applications. Herein, a fundamental review on the development and advance of PBAs in PIBs is presented with the elucidation of their synthesis methods, structural characteristics, and optimization strategies. Particularly, key areas of focus include regulating crystal structures, doping transition metals, engineering interfaces, and employing innovative techniques such as high‐entropy approaches are highlighted. Finally, critical perspectives for future development of PBAs toward practical potassium‐based energy storage devices are proposed.

Introducing strong metal–oxygen bonds to suppress the Jahn-Teller effect and enhance the structural stability of Ni/Co-free Mn-based layered oxide cathodes for potassium-ion batteries

Mn-based layered oxides (KMO) have emerged as one of the promising low-cost cathodes for potassium-ion batteries (PIBs). However, due to the multiple-phase transitions and the distortion in the MnO6 structure induced by the Jahn-Teller (JT) effect associated with Mn-ion, the cathode exhibits poor structural stability. Herein, we propose a strategy to enhance structural stability by introducing robust metal–oxygen (M–O) bonds, which can realize the pinning effect to constrain the distortion in the transition metal (TM) layer. Concurrently, all the elements employed have exceptionally high crustal abundance. As a proof of concept, the designed K0.5Mn0.9Mg0.025Ti0.025Al0.05O2 cathode exhibited a discharge capacity of approximately 100 mA h g−1 at 20 mA g−1 with 79% capacity retention over 50 cycles, and 73% capacity retention over 200 cycles at 200 mA g−1, showcased much better battery performance than the designed cathode with less robust M–O bonds. The properties of the formed M–O bonds were investigated using theoretical calculations. The enhanced dynamics, mitigated JT effect, and improved structural stability were elucidated through the in-situ X-ray diffractometer (XRD), in-situ electrochemical impedance spectroscopy (EIS) (and distribution of relaxation times (DRT) method), and ex-situ X-ray absorption fine structure (XAFS) tests. This study holds substantial reference value for the future design of cost-effective Mn-based layered cathodes for PIBs.

Ultralow Concentration Nonflammable Electrolytes Mediated by Intermolecular Interactions for Safer Potassium‐Ion Sulfur Batteries

AbstractDesigning electrolytes that are compatible with graphite anodes and possess flame‐retardant features is strongly demanded in potassium‐ion batteries (PIBs) to inhibit solvent co‐insertion and graphite exfoliation, and also stabilize the highly active potassium‐based species (e.g., KC8). Herein, a nonflammable electrolyte is designed by introducing the fluoroethers to stabilize graphite anodes, particularly at an ultralow concentration (<0.43 m) that is rarely reported before. It is discovered that intermolecular interactions can form between the 1,1,2,2‐tetrafluoroethyl‐2,2,3,3‐tetrafluoropropyl ether (i.e., HFE) diluent and trimethyl phosphate (TMP) flame‐retardant by electronegative fluorine (δ−F) and electropositive hydrogen (δ+H). The intermolecular interactions can change the potassium ion (K+) solvation structure (e.g., weakening the K+‐TMP interaction), and then determine the properties of the K+‐solvent‐anion complex at the electrode interface. a molecular interfacial model is presented with a new coordination mechanism involving the diluent to elucidate the relationship between the intermolecular interactions and electrode performance (i.e., K+‐solvent co‐insertion, or reversible K+ (de)intercalation) at the molecular scale, facilitating the design of high safety and high energy density potassium‐ion sulfur batteries. This study sheds light on the importance of intermolecular interactions to tune electrolyte properties and also opens new avenues for designing electrolytes for safe and practical PIBs.

Oxygen-containing groups assist in enhancing Li+/K+ storage: Balancing adsorption and intercalation mechanisms

Porous carbon nanosheets were prepared using a high-temperature solid-phase method and subsequently modified through oxidative acid treatment to introduce oxygen-containing groups. The application and performance of these nanosheets as anodes in lithium-ion and potassium-ion batteries were investigated. The results indicated that the oxidative acid treatment successfully enhanced the porous carbon nanosheets' capacity for storing Li+/K+. Electrochemical analysis revealed that the oxygen-containing groups balanced intercalation and surface storage behaviors, optimizing the nanosheets' storage performance. These modified porous carbon nanosheets (termed SN@PCNs) demonstrated significantly boosted reversible Li+ and K+ storage capacities, achieving 1038.1 mAh⋅g−1 and 371.7 mAh⋅g−1 at 0.1 A g−1, respectively, while maintaining capacities of 443.3 mAh⋅g−1 for Li+ and 153.9 mAh⋅g−1 for K+ at 5.0 A g−1. Furthermore, the study emphasized the significance of a balanced surface capacitance and solid-phase diffusion storage mechanism in attaining high storage capacity and cycle stability. Moderate oxidation and the introduction of oxygen-containing groups were identified as crucial factors in optimizing performance. Additionally, potassium adsorption storage exhibited an advantage over lithium adsorption storage, and the impact of oxygen-containing groups on potassium storage performance was even more pronounced.