Potassium Metal Research Articles

Effects of Interfacial Solvation Structures on the Morphological Stability of Potassium Metal Anodes Revealed by Operando Diagnosis

Rechargeable potassium (K) metal batteries have been considered promising candidates for low-cost energy storage. However, they suffer from severe side reactions and the poor morphological stability of the metal anode that jeopardize cell safety and cycle life. Here, we report a whisker-free nonporous K metal anode with superior morphological stability that can self-modulate into ingot-type deposits on a standard current collector. Comparative investigations confirm the importance of interfacial solvation structures in achieving the ideal morphological stability and facile charge transfer kinetics. Further operando diagnosis revealed that the electrochemically refined K metal anode can enable stable K metal full-cell cycling.

Lignin as Polymer Electrolyte Precursor for Stable and Sustainable Potassium Batteries.

Potassium batteries show interesting peculiarities as large‐scale energy storage systems and, in this scenario, the formulation of polymer electrolytes obtained from sustainable resources or waste‐derived products represents a milestone activity. In this study, a lignin‐based membrane is designed by crosslinking a pre‐oxidized Kraft lignin matrix with an ethoxylated difunctional oligomer, leading to self‐standing membranes that are able to incorporate solvated potassium salts. The in‐depth electrochemical characterization highlights a wide stability window (up to 4 V) and an ionic conductivity exceeding 10−3 S cm−1 at ambient temperature. When potassium metal cell prototypes are assembled, the lignin‐based electrolyte attains significant electrochemical performances, with an initial specific capacity of 168 mAh g−1 at 0.05 A g−1 and an excellent operation for more than 200 cycles, which is an unprecedented outcome for biosourced systems in potassium batteries.

Theoretical Study of Determination the Energy Gap of Murrastanine-A Conjugated Metal Using Density Functional Theory (DFT)

The research has been carried out to determine the energy gap of the compound murrastanine-a conjugated with period 4 metals. The calculation of the energy gap is carried out theoretically using computational methods with density functional theory (DFT) and the basis set 6-31G*/B3LYP through NWChem software. The results showed that all period 4 metal conjugations could reduce the energy gap of the murrastanine-a compound except for conjugation with gallium metal. The energy gap of the murrastanine-a compound decreased from 4.479 eV to 4.444 until 0.019 eV. The presence of conjugation with metals makes the energy gap of murrastanine-a diverse so that it can increase its potential use. CaM2, CuM2, and AsM5 complexes can be potential as high-temperature sensors. CrM6 and FeM2 complexes can be potential as solar cells. KM, CaM2, TiM4, ZnM2, GeM2, and AsM3 complexes can be potential as blue LED devices. Complex compounds resulting from the conjugation process with period 4 metals can be formed stably except for complexes with potassium and calcium metals which are characterized by the absence of charge distribution.

Cardanol-Derived Epoxy Resins as Biobased Gel Polymer Electrolytes for Potassium-Ion Conduction.

In this study, biobased gel polymer electrolyte (GPE) membranes were developed via the esterification reaction of a cardanol-based epoxy resin with glutaric anhydride, succinic anhydride, and hexahydro-4-methylphthalic anhydride. Nonisothermal differential scanning calorimetry was used to assess the optimal curing time and temperature of the formulations, evidencing a process activation energy of ∼65–70 kJ mol–1. A rubbery plateau modulus of 0.65–0.78 MPa and a crosslinking density of 2 × 10–4 mol cm–3 were found through dynamic mechanical analysis. Based on these characteristics, such biobased membranes were tested for applicability as GPEs for potassium-ion batteries (KIBs), showing an excellent electrochemical stability toward potassium metal in the −0.2–5 V voltage range and suitable ionic conductivity (10–3 S cm–1) at room temperature. This study demonstrates the practical viability of these biobased materials as efficient GPEs for the fabrication of KIBs, paving the path to increased sustainability in the field of next-generation battery technologies.

Dynamic Reversible Evolution of Solid Electrolyte Interface in Nonflammable Triethyl Phosphate Electrolyte Enabling Safe and Stable Potassium‐Ion Batteries

AbstractPotassium‐ion batteries (PIBs) are a favorable alternative to lithium‐ion batteries (LIBs) for the large‐scale electrochemical storage devices because of the high natural abundance of potassium resources. However, conventional PIB electrodes usually exhibit low actual capacities and poor cyclic stability due to the large radius of potassium ions (1.39 Å). In addition, the high reactivity of potassium metal raises serious safety concerns. These characteristics seriously inhibit the practical use of PIB electrodes. Here, zinc phosphide composites are rationally designed as PIB anodes for operation in a nonflammable triethyl phosphate (TEP) electrolyte to solve the above‐mentioned issues. The optimized zinc phosphide composite with 20 wt% zinc phosphate presents a high specific capacity (571.1 mA h g−1 at 0.1 A g−1) and excellent cycling performance (484.9 mA h g−1 with the capacity retention of 94.5% after 1000 cycles at 0.5 A g−1) in the KFSI‐TEP electrolyte. XPS depth profile analysis shows that the improved cycling stability of the composite is closely related to the reversible dynamic evolutions and conversions of the sulfur‐containing species in the solid electrolyte interphase (SEI) during the charge/discharge process. This dynamic reversible SEI concept may provide a new strategy for the design of superior electrodes for PIBs.

Preparation and Characterization of Nanohybrid La2O3-K Complexes for Electrochemical Study

In biomedical science, alkali metal potassium plays a conspicuous role in the neurotransmission known as sodium (Na)-potassium (K) pump. The rare earth metal like lanthanum is most applicable in the magnetic resonance imaging technique (MRI) for cancerous cell detection. Keeping in mind this perspective, we synthesized the hybrid of La2O3 nanomaterial and K-complexes [(μ2-4-N,N-dimethylamino benzoate-κO)(μ2-4-N,N-dimethylamino benzoic acid-κO) (4-N,N-dimethylamino benzoic acid-κO) potassium(I) coordination polymer)] (nanohybrid La2O3- K complex) by hydrothermal method, whereas the potassium complex has been synthesized by the 6 hours reflection of the 4-(diethylamino) benzoic acid and potassium hydroxide in the methanol as solvent. The1H, 13C NMR, HRMS, and single-crystal investigation have been carried out for the potassium complex. Moreover, the structural, morphological, and electrochemical estimation of synthesized nanocomposites are also under process, which involves the investigation by X-ray diffraction (XRD), Fourier transform infrared (FTIR), and UV- visible spectroscopy.

Amine-Wetting-Enabled Dendrite-Free Potassium Metal Anode.

Considered as an imperative alternative to the commercial LiFePO4 battery, the potassium metal battery possesses great potential in grid-scale energy storage systems due to the low cost, low standard redox potential, and high abundance of potassium. The potassium dendrite growth, large volume change, and unstable solid electrolyte interphase (SEI) on the potassium metal anode have, however, hindered its applications. Although conductive scaffolds coupling with potassium metal have been widely proposed to address the above issues, it remains challenging to fabricate a uniform composite with uncompromised capacity. Herein, we propose a facile and efficient strategy to construct dendrite-free and practical carbon-based potassium composite anodes via amine functionalization of the carbon scaffolds that enables fast molten potassium infusion within several seconds. On the basis of experiments and theoretical calculations, we show that highly potassiophilic amine groups immediately transform carbon scaffolds from nonwetting to wetting to postassium. Our carbon-cloth-based potassium composite anode (K@CC) can accommodate volume fluctuation, provide abundant nucleation sites, and lower the local current density, achieving nondendritic morphology with a stable SEI. The fabricated K0.7Mn0.7Ni0.3O2|K@CC full cell displays excellent rate capability and an ultralong lifespan over 8000 cycles (68.5% retention) at a high current of 1 A g-1.

Superstable potassium metal batteries with a controllable internal electric field

Stable potassium metal batteries (PMBs) are promising candidates for electrical energy storage due to their ability to reversibly store electrical energy at a low cost. However, dendritic growth and large volume changes hinder their practical application. Here, referring to the morphology and structure of a virus, a bionic virus-like-carbon microsphere (BVC) was designed as the anode host for a PMB. A BVC with a three-dimensional structure can not only control the electric field, which can suppress dendrite formation, but can also provide a larger space to accommodate the volume change during the cycle progress. The designed potassium (K) metal anode exhibits excellent cycle life and stability (during 1800 h of repeated plating/stripping of K at a current density of 0.1 mA cm−2, K-BVC can realize a very stable K metal anode with low voltage hysteresis). Stable cyclability and improved rate capability can be realized in a full cell using Prussian blue over 400 cycles. This research provides a new idea for the development of stable K metal anodes and may pave the way for the practical application of next-generation metal batteries.

Highly Reversible Zn Metal Anodes Enabled by Freestanding, Lightweight, and Zincophilic MXene/Nanoporous Oxide Heterostructure Engineered Separator for Flexible Zn-MnO2 Batteries.

Aqueous zinc (Zn)-ion batteries are regarded as promising candidates for large-scale energy storage systems because of their high safety, low cost, and environmental benignity. However, the dendrite issue of Zn anode hinders their practical application. Herein, a freestanding, lightweight, and zincophilic MXene/nanoporous oxide heterostructure engineered separator is designed to stabilize a Zn metal anode. The nanoporous oxides prepared by a one-step vacuum distillation technique afford the advantages of large surface area, high porosity, and homogeneous porous structure. The zincophilic MXene@oxides layer can homogenize the electric field distribution, facilitate ion diffusion kinetics, reduce local current density, and promote even Zn ionic flux, which will regulate uniform Zn deposition and suppress side reactions. Accordingly, dendrite-free Zn anodes with stable cyclability are achieved for over 500 h at an ultrahigh area capacity of 10 mAh cm-2. Besides, flexible, long-lifespan, and high-rate N/S-doped three-dimensional MXene@MnO2||Zn full cells are constructed with the engineered separator. Moreover, this strategy can be successfully extended to lithium, sodium, potassium, and magnesium metal batteries, indicating that separator regulation is a universal approach to overcome the challenges of metal batteries.

Usage of treated greywater as an alternative irrigation source for tomatoes cultivation

AbstractOptimizing water reuse is an important issue in the context of water scarcity and low water quality. Greywater would provide more sustainable water supply, once using appropriate treatment. This study aimed to appraise the efficacy of treated greywater (TGW) use on soil and tomato cultivation, in comparison with ground water (GW) use. Greywater (from laundry and tableware) was treated using a wetland mini‐reactor with a horizontal underground flow. Growth, photosynthetic activity, plant water status, osmotic potential and yield of tomato cultivars (Dart and Firenze) were evaluated. Sodium, potassium (analysed by flame photometer) and heavy metals (examined by atomic absorption photometer) were quantified in leaves, stems and roots. Results showed that TGW does not affect soil salinity. The TGW improved plant height and yield, of both cultivars. Although net photosynthesis increased only in Dart whereas Firenze had elevated water potential, less relative water content and photosynthetic water use efficiency suggesting a pronounced water restriction. Also, Firenze had higher Zn2+ and Fe2+ content than Dart indicating less selectivity. Our results imply that greywater treatment had an encouraging potential for soil preservation and tomatoes irrigation. Plant resistance is possibly acquired by ionic balance and photosynthetic capacity. Further studies are desirable to inspect long‐term effects on soil and health.

Fast and homogeneous ion regulation toward a 4 V, high-rate and dendrite-free potassium metal battery

The uneven distribution and slow diffusion kinetics of potassium ions (K+) result in the formation and growth of K dendrites as well as poor rate capabilities, restricting the development of K metal anodes (KMAs). Paired with a Mn-based Prussian blue (PB) cathode, the KMA-based full battery exhibits a low average discharging voltage of ≈3.6 V and a high overpotential. Herein, a N-doped graphene nanomesh (NGM) acts as a conductive and potassiophilic host to solve this issue. First, the NGM enables K+ ions to rapidly transport its nanopores and edges to reach the whole electrode, offering unblocked transport channels for K+ ions and thus acquiring an enhanced rate capability. Second, the N atoms and defects within NGM reduce the nuclear energy barrier of K+ ions and induce their homogeneous deposition, avoiding the formation of K dendrites. Third, the nano-/micro-pores within NGM can accommodate the volume exchange of KMA during cycles, improving its cycling stability. Benefiting from these merits, the symmetric K@NGM cell delivers an ultra-low overpotential of 12.4 mV after 1700 h. Matched with a K1.7Mn[Fe(CN)6]0.9/graphene cathode, a 4 V and dendrite-free KMnHCF/G‖K@NGM full cell is designed, which exhibits excellent cycling stabilities and rate capabilities.

High‐rate and dendrite‐free liquid alloy anode for high energy potassium metal batteries

AbstractPotassium ion batteries are considered as promising candidates for electrochemical energy storage device due to its low‐cost and high theoretical capacity. However, it is seriously limited by the dendrite growth. Liquid Na‐K alloy has excellent kinetic mass transfer characteristics which could avoid dendrite fundamentally. However, due to its large surface tension, liquid alloy is difficult to be processed and used in practical applications. Herein, a flexible and processable graphene‐based liquid alloy anode (Na‐K@rGO) was designed. Thanks to the reasonable porous structure, good chemical and mechanical stability and rapid charge transfer of graphene matrix, Na‐K@rGO anode exhibits excellent cycle stability and rate performance. The batteries could cycle stably and exhibit dendrites‐free property. Our work offers a simple approach to construct dendrite‐free anodes for high energy density and long‐lifespan potassium metal batteries.image

Poly(ethylene oxide)-Based Electrolytes for Solid-State Potassium Metal Batteries with a Prussian Blue Positive Electrode

Potassium-ion batteries are an emerging post-lithium technology that are considered ecologically and economically benign in terms of raw materials’ abundance and cost. Conventional cell configurations employ flammable liquid electrolytes that impose safety concerns, as well as considerable degrees of irreversible side reactions at the reactive electrode interfaces (especially against potassium metal), resulting in a rapid capacity fade. While being inherently safer, solid polymer electrolytes may present a solution to capacity losses owing to their broad electrochemical stability window. Herein, we present for the first time a stable solid-state potassium battery composed of a potassium metal negative electrode, a Prussian blue analogue K2Fe[Fe(CN)6] positive electrode, and a poly(ethylene oxide)-potassium bis(trifluoromethanesulfonyl)imide polymer electrolyte. At an elevated operating temperature of 55 °C, the solid-state battery achieved a superior capacity retention of 90% over 50 cycles in direct comparison to a conventional carbonate-based liquid electrolyte operated at ambient temperature with a capacity retention of only 66% over the same cycle number interval.

High area capacity and dendrite-free anode constructed by highly potassiophilic Pd/Cu current collector for low-temperature potassium metal battery

Potassium metal battery (KMB) have been recognized as a feasible alternative electrochemical energy device for practical application. However, the dendrite growth and the instability of the potassium anode are the major issues hindering its practicability. In this paper, a layer of Pd is coated on the rib surface of Cu foam through a replacement reaction in the liquid-phase synthesis to form Pd/Cu foam current collector, and then K metal is deposited on this Pd/Cu foam to prepare the K/Pd/Cu foam anode material for KMBs. This K/Pd/Cu foam is assembled into a KMB using Prussian blue (PB) as the cathode material to achieve high capacity and cycle-ability even at low-temperature (− 20 °C). Experimental results confirm that this K/Pd/Cu foam can significantly reduce K dendrite growth, increase K+ ion diffusion within the solid electrolyte interface (SEI) film and reduce the side reaction. Based on the experiment measurements, material characterization, and theoretical DFT calculations, the possible enhancement mechanism of the highly potassiophilic interface of Pd/Cu foam during the cycling of KMB is also explored.

Atom Swapping on Aromatic Rings: Conversion from Phosphinine Pincer Metal Complexes to Metallabenzenes Triggered by O2 Oxidation

AbstractHerein, we report a novel method for the synthesis of metallabenzenes by swapping the phosphorus atom in an aromatic phosphinine ring with transition metal fragments. The oxidation of a phosphine‐phosphinine‐phosphine pincer iridium complex by O2 triggered the replacement of the phosphorus atom of the phosphinine ring by an iridium fragment to afford iridabenzene. Dianionic rhodabenzene was also synthesized from a phosphinine rhodium complex by oxidation of the phosphorus atom, followed by subsequent reduction using metallic potassium. The aromaticity of the newly synthesized irida‐ and rhoda‐benzenes was evaluated both experimentally and theoretically.

Atom Swapping on Aromatic Rings: Conversion from Phosphinine Pincer Metal Complexes to Metallabenzenes Triggered by O2 Oxidation.

Herein, we report a novel method for the synthesis of metallabenzenes by swapping the phosphorus atom in an aromatic phosphinine ring with transition metal fragments. The oxidation of a phosphine-phosphinine-phosphine pincer iridium complex by O2 triggered the replacement of the phosphorus atom of the phosphinine ring by an iridium fragment to afford iridabenzene. Dianionic rhodabenzene was also synthesized from a phosphinine rhodium complex by oxidation of the phosphorus atom, followed by subsequent reduction using metallic potassium. The aromaticity of the newly synthesized irida- and rhoda-benzenes was evaluated both experimentally and theoretically.

Synthetic diversity in the preparation of metallic uranium.

Uranium metal is associated with several aspects of nuclear technology; it is used as fuel for research and power reactors, targets for medical isotope productions, explosive for nuclear weapons and precursors in synthetic chemistry. The study of uranium metal at the laboratory scale presents the opportunity to evaluate metallic nuclear fuels, develop new methods for metallic spent fuel reprocessing and advance the science relevant to nuclear forensics and medical isotope production. Since its first isolation in 1841, from the reaction of uranium chloride and potassium metal, uranium metal has been prepared by solid-state reactions and in solution by electrochemical, chemical and radiochemical methods. The present review summarizes the methods outlined above and describes the chemistry associated with each preparation.

Engineering of Crosslinked Network and Functional Interlayer to Boost Cathode Performance of Tannin for Potassium Metal Batteries

AbstractPotassium metal batteries (PMBs) are a compelling technology for large‐scale energy storage due to the abundance of potassium resources and high energy density. A vital obstacle to construct high‐performance PMBs is developing superior cathode materials. Tannin, a plant polyphenol, holding many active sites for redox reactions, is an auspicious high‐capacity cathode. However, the relatively poor conductivity and slight solubility in electrolyte deteriorate its capacity and cycle stability. Herein, the tannin is activated through a crosslinking reaction with polyaniline to obtain a composite cathode (i.e., ATN). It exhibits a high initial capacity of 172 mAh g−1 at 50 mA g−1, based on the electrochemical reaction mechanisms of embedding/releasing of K+ on CO and PF6− on NH. Moreover, to improve the cycling performance, a graphene oxide modified separator is developed to effectively retard the ATN shuttle. As a result, the capacity retention is significantly enhanced, for example, 82% over 300 cycles at 50 mA g−1. From a practical aspect, a full PMB of K@KxPy||ATN is built up, displaying high energy/power density and superior cycling stability, which is a step forward in the development of PMBs.

MOF‐Derived Potassiophilic CuO Nanoparticles on Carbon Fiber Cloth as Host for Stabilizing Potassium Metal Anode

AbstractPotassium (K) metal anodes suffer the main obstacle of uncontrollable dendrite growth. One of the best ways to overcome this challenge is to build a stable potassiophilic host. Herein, we designed a Metal‐Organic Frameworks (MOF)‐derived CuO nanoparticles on carbon fiber cloth (CC) as a high potassiophilic host to prestore molten potassium for dendrite‐free K metal anode. The three‐dimensional host has a relatively large surface area and excellent mechanical strength, which helps to lower the local current density as well as buffer the volume expansion during the plating/stripping of K. The highly potassiophilic CuO nanoparticles could provide abundant nucleation sites for K, thereby guiding uniform K deposition with a low nucleation overpotential and inhibits the growth of dendrites. The CC@CuO@K anode could cycle for 2000 h at a current of 0.5 mA cm−2, which exceeds K metal anodes mentioned in other reports. Last but not least, by using the composite K metal as the anode to assemble the full cell, highly boosted performance can be achieved. Our result provides a tempting method for realizing dendrite‐free K metal anodes in PIBs, and also provides an opportunity for the application of other MOF‐based materials in the field of high‐performance K metal anodes.

Polyacrylonitrile‐Reinforced Composite Gel Polymer Electrolytes for Stable Potassium Metal Anodes (Small 8/2022)

Potassium Metal Anodes In article number 2107186, Jian Liu and co-workers design a robust composite gel polymer electrolyte to achieve a long life of over 1,200 h for symmetrical potassium (K) cells. The remarkable stability can be attributed to the suppressed K dendrite growth, enhanced structural integrity, and electrochemical stability by polyacrylonitrile nanofibers.