High-performance Potassium-ion Batteries Research Articles

Nonflammable Phosphate-Based Electrolyte for Safe and Stable Potassium Batteries Enabled by Optimized Solvation Effect.

Current potassium-ion batteries (PIBs) are limited in safety and lifetime owing to the lack of suitable electrolyte solutions. To address these issues, herein, we report an innovative non-flammable electrolyte design strategy that leverages an optimal moderate solvation phosphate-based solvent which strikes a balance between solvation capability and salt dissociation ability, leading to superior electrochemical performance. The formulated electrolyte simultaneously exhibits the advantages of low salt concentration (only 0.6 M), low viscosity, high ionic conductivity, high oxidative stability, and safety. Our electrolyte also promotes the formation of self-limiting inorganic-rich interphases at the anode surface, alongside robust cathode-electrolyte interphase on iron-based Prussian blue analogues, mitigating electrode/electrolyte side reactions and preventing Fe dissolution. Notably, the PIBs employing our electrolyte exhibit exceptional durability, with 80 % capacity retention after 2,000 cycles at high-voltage of 4.2 V in a coin cell. Impressively, in a larger scale pouch cell, it maintains over 81 % of its initial capacity after 1,400 cycles at 1 C-rate with high average Coulombic efficiency of 99.6 %. This work represents a significant advancement toward the realization of safe, sustainable, and high-performance PIBs.

Restructuring Electrolyte Solvation by a Partially and Weakly Solvating Cosolvent toward High-Performance Potassium-Ion Batteries.

Ether-based electrolytes are among the most important electrolytes for potassium-ion batteries (PIBs) due to their low polarization voltage and notable compatibility with potassium metal. However, their development is hindered by the strong binding between K+ and ether solvents, leading to [K+-solvent] cointercalation on graphite anodes. Herein, we propose a partially and weakly solvating electrolyte (PWSE) wherein the local solvation environment of the conventional 1,2-dimethoxyethane (DME)-based electrolyte is efficiently reconfigured by a partially and weakly solvating diethoxy methane (DEM) cosolvent. For the PWSE in particular, DEM partially participates in the solvation shell and weakens the chelation between K+ and DME, facilitating desolvation and suppressing cointercalation behavior. Notably, the solvation structure of the DME-based electrolyte is transformed into a more cation-anion-cluster-dominated structure, consequently promoting thin and stable solid-electrolyte interphase (SEI) generation. Benefiting from optimized solvation and SEI generation, the PWSE enables a graphite electrode with reversible K+ (de)intercalation (for over 1000 cycles) and K with reversible plating/stripping (the K||Cu cell with an average Coulombic efficiency of 98.72% over 400 cycles) and dendrite-free properties (the K||K cell operates over 1800 h). We demonstrate that rational PWSE design provides an approach to tailoring electrolytes toward stable PIBs.

Fluorine-doped porous carbon coating on Sn/SnOx as anode materials for high-performance potassium ion batteries

Potassium-ion batteries (PIBs) are considered alternatives to lithium-ion batteries because of their comparatively cheaper manufacturing costs and lower potential (2.936 V compared to standard hydrogen electrodes). However, their large ionic radii and unstable structures hindered their satisfactory electrochemical performance. In this study, F–Sn/SnOx@C, a novel porous layered composite material, was prepared using NaCl as a template for in situ etching to obtain a promising negative electrode material for PIBs. The significant specific surface area of the composite material and the uniform embedding of tin nanoparticles within the layered porous carbon shell, contributed to its excellent potassium intercalation/deintercalation performance. Fluorine doping enhanced electron transfer, prevented nanoparticle aggregation, and improved electrolyte penetration and potassium ion migration. The PIBs prepared from this electrode showed high potassium storage capacity, outstanding cycle stability (retaining 263 mAh g−1 after 200 cycles at 100 mA g−1), and remarkable rate capability (505.6, 288.4, 193.5, 134.1, and 83.3 mAh g−1 at 0.1, 0.2, 0.3, 0.5, and 1.0 A g−1, respectively). These results provide a straightforward solution for improving the electrochemical performance of PIBs.

Carbon quantum dots/carbon-coated SnS2 as a high-performance potassium-ion battery cathode material

Carbon quantum dots/carbon-coated SnS2 as a high-performance potassium-ion battery cathode material

Lignite-based hard carbon for high-performance potassium-ion battery anode

Lignite-based hard carbon for high-performance potassium-ion battery anode

Flower-like CoSe2/N, P-doped carbon microspheres accommodated on carbon nanosheets for high-performance potassium-ion batteries

Transition metal selenides (TMSs) have emerged as promising electrode materials for potassium-ion batteries (PIBs), whereas the large volume expansion and sluggish reaction kinetics have seriously hindered the cycle life and rate performance. Herein, a hierarchical composite of flower-like CoSe2/N, P-doped carbon microspheres accommodated on carbon nanosheets (CoSe2-NPC@CNS) was rationally fabricated as the anode for PIBs through a one-pot hydrothermal and subsequent selenization method. The intimate hybridization of CoSe2/N, P-doped carbon microspheres can effectively alleviate the volume expansion of CoSe2 during charge-discharge cycles, and the ultrathin carbon nanosheets derived from fluid catalytic cracking (FCC) slurry serves as a highly conductive and buffered substrate. By robustly merging them together, the interconnected hierarchical nanoarchitecture with exposed active sites achieves promoted potassium storage capacity, electrochemical reaction kinetics, and structural stability. As a result, the PIBs with CoSe2-NPC@CNS anode deliver high reversible capacities of 320.8 mAh g−1 after 100 cycles at 0.1 A g−1 and 213.9 mAh g−1 after 850 cycles at 1.0 A g−1, excellent rate capability (188.8 mAh g−1 at 5 A g−1), and enhanced pseudo-capacitive contribution rate of 88.7 %. This work offers valuable insight into the rational design and development of hierarchical anode materials with high performance for PIBs and beyond.

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

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

Selective phosphorylation of MOF to construct KTP/KTOP/C heterojunction for high-performance potassium-ion batteries

Polyanion compounds are considered as promising electrodes for potassium-ion batteries (PIBs) due to their structural diversity and chemical versatility. However, the cycling performance of previously reported electrodes at high current densities still suffers from their relatively sluggish electron and ion transport kinetics. Here, by combining K2Ti2(PO4)3 (KTP) framework with KTiOPO4 (KTOP) composition, we construct a series of KTP/KTOP/C heterojunctions (denoted as KTP/KTOP/C-n) via selectively phosphorylatiny from metal-organic framework (MOF) precuror, and demonstrate the successful synergistic cooperation of both electron and ion transport kinetics by carefully controlling the structure and composition. Comparative analysis and density functional theoretical calculations confirm the reaction kinetics and pseudocapacitive behaviors can be dramatically promoted by synergistically structural, electronic and ionic modulations. Consequently, the optimized KTP/KTOP/C-2 delivers an impressive specific capacity of 140 mAh/g after 150 cycles at 100 mA g−1 and superior cycling stability with 79 mAh/g for 2000 cycles at a high current of 1000 mA g−1. Furthermore, it displays outstanding rate performance, achieving 87 mAh/g at 2000 mA g−1.

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

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

In situ built nanoconfined Nb2O5 particles in a 3D interconnected Nb2C MXene@rGO conductive framework for high-performance potassium-ion batteries

A 3D Nb2C/rGO conductive framework with in situ generated Nb2O5 nanoparticles (Nb2O5/Nb2C/rGO) is synthesized, exhibiting high capacity and excellent cycling stability. The synergetic charge–discharge mechanism is revealed explicitly.

Novel N-doped multichannel carbon nanofiber architecture with porous CoS nanoprisms for high-performance potassium-ion batteries

Novel N-doped multichannel carbon nanofiber architecture with porous CoS nanoprisms for high-performance potassium-ion batteries

Engineering contact curved interface with high-electronic-state active sites for high-performance potassium-ion batteries.

Potassium-ion batteries (PIBs) have attracted ever-increasing interest due to the abundant potassium resources and low cost, which are considered a sustainable energy storage technology. However, the graphite anodes employed in PIBs suffer from low capacity and sluggish reaction kinetics caused by the large radius of potassium ions. Herein, we report nitrogen-doped, defect-rich hollow carbon nanospheres with contact curved interfaces (CCIs) on carbon nanotubes (CNTs), namely CCI-CNS/CNT, to boost both electron transfer and potassium-ion adsorption. Density functional theory calculations validate that engineering CCIs significantly augments the electronic state near the Fermi level, thus promoting electron transfer. In addition, the CCIs exhibit a pronounced affinity for potassium ions, promoting their adsorption and subsequently benefiting potassium storage. As a result, the rationally designed CCI-CNS/CNT anode shows remarkable cyclic stability and rate capability. This work provides a strategy for enhancing the potassium storage performance of carbonaceous materials through CCI engineering, which can be further extended to other battery systems.

Simultaneous Catalytic Acceleration of White Phosphorus Polymerization and Red Phosphorus Potassiation for High-Performance Potassium-Ion Batteries.

Red phosphorus (P) as an anode material of potassium-ion batteries possesses ultra-high theoretical specific capacity (1154mAhg-1 ). However, owing to residual white P during the preparation and sluggish kinetics of K-P alloying limit its practical application. Seeking an efficient catalyst to address the above problems is crucial for the secure preparation of red P anode with high performance. Herein, through the analysis of the activation energies in white P polymerization, it is revealed that the highest occupied molecular orbital energy of I2 (-7.40eV) is in proximity to P4 (-7.25eV), and the lowest unoccupied molecular orbital energy of I2 molecule (-4.20eV) is lower than that of other common non-metallic molecules (N2 , S8 , Se8 , F2 , Cl2 , Br2 ). The introduction of I2 can thus promote the breaking of the P─P bond and accelerate the polymerization of white P molecules. Besides, the ab initio molecular dynamics simulations show that I2 can enhance the kinetics of P-K alloying. The as-obtained red P/C composites with I2 deliver excellent cycling stability (358mAhg-1 after 1200 cycles at 1Ag-1 ). This study establishes catalysis as a promising pathway to tackle the challenges of P anode for alkali metal ion batteries.

Rational regulation of defect-rich hierarchical porous carbon nanosheets as sustainable anode materials for potassium-ion storage

Potassium-ion storage devices are the most promising equipment for large-scale energy storage due to their low cost and abundant resource. However, the low rate and poor cycling ability of potassium-ion energy storage devices resulting from the dramatic structure changes of electrode materials during operation limit their development. Herein, a defect-rich hierarchical porous carbon nanosheets (HPCS) is successfully synthesized via a facile Mg(OH)2 template approach with low-cost coal tar pitch as carbon precursor. The ultrathin nanosheets framework with a porous structure not only accelerates the rapid infiltration of electrolyte, but also alleviates the volume expansion upon cycling. Benefiting from its unique microstructure, the optimized HPCS-900 exhibits excellent rate performance (156.2 mAh g−1 at 1 A g−1) and cycling stability (130.1 mAh g−1 at 1 A g−1 after 1000 cycles). As a practical device application, the assembled potassium-ion capacitors (HPCS//AC) deliver a high energy density of 130 Wh kg−1 and a maximum power density of 10,735 W kg−1. This work provides an exciting approach to designing advanced defect-structured carbon-based materials for high-performance potassium-ion batteries and capacitors.

KI-Assisted Formation of Spindle-like Prussian White Nanoparticles for High-Performance Potassium-Ion Battery Cathodes.

Prussian white (PW) is considered as a promising cathode material for potassium-ion batteries (KIBs) due to its low cost and high theoretical capacity. However, the high water content and structural defects and the strict synthesis conditions of PW lead to its unsatisfactory cycling performance and low specific capacity, hindering its practical applications. Herein, a template-engaged reduction method is proposed, using MIL-88B(Fe) as a self-template and KI as the reducing agent to prepare K-rich PW with low defects and water content. Furthermore, the hierarchical porous spindle-like morphology can be inherited from the precursor, furnishing sufficient active sites and reducing the ion diffusion path. Consequently, when applied as a KIB cathode material, spindle-like PW (K1.72Fe[Fe(CN)6]0.96·0.342H2O) manifested remarkable potassium storage properties. Notably, a full cell assembled by the spindle-like PW cathode and graphite anode exhibited a large energy density of ∼216.7 Wh kg-1, demonstrating its huge potential for energy storage systems.

Monometallic and bimetallic metal–organic frameworks derived CoP embedded in porous carbon: Monodisperse CoP nanoparticles for highly reversible potassium ion storage

Metal phosphides show promise as anode materials for high-energy potassium-ion batteries due to their high capacity. However, their cycling performance is hampered by volume changes. Although nanoparticle/carbon composites are commonly employed to tackle this issue, achieving uniform embedding within confined carbon structures still presents a challenge. In this study, we investigate the synthesis strategies of CoP/porous carbon composites using isostructural bimetallic and monometallic-zeolitic imidazolate framework (ZIF), and achieve uniform embedding of ∼4 nm CoP nanoparticles in porous carbon by utilizing a bimetallic Co/Zn ZIF. Conversely, monometallic ZIF-67 leads to substantial coarsening and non-uniform distribution of ∼25 nm CoP particles. The resulting bimetallic-ZIF-derived CoP/porous carbon composite exhibits a specific capacity of 490.5 mAh/g at 0.05 A/g for potassium-ion storage and remarkable cycling stability, retaining 100 % capacity over 500 cycles at 0.1 A/g. Differential capacity plots confirm improved reversibility of the CoP conversion reaction. Notably, the evaporation of Zn generates a pore structure that effectively confines CoP, preventing further aggregation during electrochemical cycling. This work showcases a unique synthesis strategy using a bimetallic ZIF for high-performance potassium-ion battery materials.

Control of Gradient Concentration Prussian White Cathodes for High-Performance Potassium-Ion Batteries.

Owing to their abundant resources and low cost, potassium-ion batteries (PIBs) have become a promising alternative to lithium-ion batteries (LIBs). However, the larger ionic radius and higher mass of K+ propose a challenging issue for finding suitable cathode materials. Prussian whites (PWs) have a rigid open framework and affordable synthesis method, but they suffer quick capacity fade due to lattice volume change and structural instability during K+ insertion/extraction. Here, we prepared controllable gradient concentration KxFeaNibMn1-a-b[Fe(CN)6]y·zH2O particles via a facile coprecipitation process, demonstrating high-performance potassium-ion storage. The high-Mn content in the interior can minimize capacity loss caused by electrochemically inert Ni and achieve a high reversible capacity; meanwhile, the high-FeNi content in the exterior can alleviate the volume change of the core material upon cycling, thus enhancing structural stability. Taking the above synergistic effect, the controllable gradient concentration PWs deliver a high reversible capacity of 109.8 mAh g-1 at 100 mA g-1 and good capacity retention of 77.8% after 200 cycles. The gradient concentration PWs can retain structural integrity and stability during long-term cycling. This work provides a prospective strategy to fabricate PWs with stable structure and excellent electrochemical performance for developing high-performance PIBs.

MnFe Prussian blue analogue-derived P3-K0.5Mn0.67Fe0.33O1.95N0.05 cathode material for high-performance potassium-ion batteries

Potassium-ion batteries (PIBs), with their high theoretical energy density and abundant natural resources, are emerging as one of the most promising candidates for next-generation energy storage systems. Nevertheless, they suffer from large volume expansion and sluggish K+ transport due to the huge ionic radius of K+, resulting in limited cyclic life and rate performance. Therefore, accelerated transport kinetics may be the key to designing electrodes with excellent potassium storage properties. Herein, we develop a new synthetic method to in-situ construct a high-efficiency PIB cathode, N-doped P3-typed K0.5Mn0.67Fe0.33O1.95N0.05 nanosheets (denoted KMFON), using the low cost Prussian blue analogue Mn2[Fe(CN)6] as a precursor. Combining experimental results and theoretical calculations, the as-synthesized KMFON exhibits large interlayer spacing, small K+ migration energy barrier, high electronic conductivity, and fast K+ transport kinetics, which are attributed to the larger-sized N substitution O. It also manifests an initial reversible capacity of 104.2 mAh g−1 at 20 mA g−1, a rate capability of 41.5 mAh g−1 at 500 mA g−1, and a high discharge capacity of 52.2 mAh g−1 after 300 cycles at 100 mA g−1. Moreover, the KMFON//pitch-derived soft carbon full cell exhibits a satisfactory rate performance of 49.4 mAh g−1 at 200 mA g−1 and a good cycling performance of 46.8 mAh g−1 after 200 cycles at 100 mA g−1, indicating the great potential of KMFON as a cathode material for PIBs.

Oxygen Vacancy-Tailored Schottky Heterojunction Activates Interface Dipole Amplification and Carrier Inversion for High-Performance Potassium-Ion Batteries.

An oxygen vacancy-tailored Schottky heterostructure composed of polyvinylpyrrolidone-assisted Bi2 Sn2 O7 (PVPBSO) nanocrystals and moderate work function graphene (mWFG, WF = 4.36eV) is designed, which in turn intensifies the built-in voltage and interface dipole across the space charge region (SCR), leading to the inversion of majority carriers for facilitating K+ transport/diffusion behaviors. Thorough band-alignment experiments and interface simulations reveal the dynamics between deficient BSO and mWFG, and how charge redistribution within the SCR leads to carrier inversion, demonstrating the impact of different defect engineering degrees on the amplification of Schottky junctions. The ordered transport of bipolar carriers can boost electrons and K ions easily passing through the inner and outer surfaces of the heterostructure. With high activity and low resistance in electrochemical reactions, the PVPBSO/mWFG exhibits an attractive capacity of 430mA h g-1 and a rate capability exceeding 2000mA g-1 , accompanied by minimal polarization and efficient utilization of conversion-alloying reactions. The substantial cell capacity and high-redox plateau of PVPBSO/mWFG//PB contribute to the practical feasibility of high-energy full batteries, offering long-cycle retention and high-voltage output. This study emphasizes the direct importance of interface and junction engineering in improving the efficiency of diverse electrochemical kinetic and diffusion processes for potassium-ion batteries.

Low-Cost Pitch Derived Lamellar N-Doped Carbon as a High-Performance Potassium-Ion Battery Anode

Low-Cost Pitch Derived Lamellar N-Doped Carbon as a High-Performance Potassium-Ion Battery Anode