Superior Electrochemical Performance Research Articles

Directional Polarization of a Ferroelectric Intermediate Layer Inspires a Built-In Field in Si Anodes to Regulate Li+ Transport Behaviors in Particles and Electrolyte.

The silicon (Si) anode is prone to forming a high electric field gradient and concentration gradient on the electrode surface under high-rate conditions, which may destroy the surface structure and decrease cycling stability. In this study, a ferroelectric (BaTiO3) interlayer and field polarization treatment are introduced to set up a built-in field, which optimizes the transport mechanisms of Li+ in solid and liquid phases and thus enhances the rate performance and cycling stability of Si anodes. Also, a fast discharging and slow charging phenomenon is observed in a half-cell with a high reversible capacity of 1500.8mAhg-1 when controlling the polarization direction of the interlayer, which means a fast charging and slow discharging property in a full battery and thus is valuable for potential applications in commercial batteries. Simulation results demonstrated that the built-in field plays a key role in regulating the Li+ concentration distribution in the electrolyte and the Li+ diffusion behavior inside particles, leading to more uniform Li+ diffusion from local high-concentration sites to surrounding regions. The assembled lithium-ion battery with a BaTiO3 interlayer exhibited superior electrochemical performance and long-term cycling life (915.6mAhg-1 after 300 cycles at a high current density of 4.2Ag-1). The significance of this research lies in exploring a new approach to improve the performance of lithium-ion batteries and providing new ideas and pathways for addressing the challenges faced by Si-based anodes.

Understanding the charge transfer effects of single atoms for boosting the performance of Na-S batteries.

The effective flow of electrons through bulk electrodes is crucial for achieving high-performance batteries, although the poor conductivity of homocyclic sulfur molecules results in high barriers against the passage of electrons through electrode structures. This phenomenon causes incomplete reactions and the formation of metastable products. To enhance the performance of the electrode, it is important to place substitutable electrification units to accelerate the cleavage of sulfur molecules and increase the selectivity of stable products during charging and discharging. Herein, we develop a single-atom-charging strategy to address the electron transport issues in bulk sulfur electrodes. The establishment of the synergistic interaction between the adsorption model and electronic transfer helps us achieve a high level of selectivity towards the desirable short-chain sodium polysulfides during the practical battery test. These finding indicates that the atomic manganese sites have an enhanced ability to capture and donate electrons. Additionally, the charge transfer process facilitates the rearrangement of sodium ions, thereby accelerating the kinetics of the sodium ions through the electrostatic force. These combined effects improve pathway selectivity and conversion to stable products during the redox process, leading to superior electrochemical performance for room temperature sodium-sulfur batteries.

High-performance asymmetric supercapacitors assembled with novel disc-like MnCo2O4 microstructures as advanced cathode material

Herein, porous MnCo2O4 with disc-like (MnCo2O4-discs) and ring-like (MnCo2O4-rings) microstructures were respectively synthesized using an initial hydrothermal method at different temperatures and a calcination treatment in air. The electrochemical properties of these MnCo2O4 materials were investigated in three-electrode and two-electrode systems, and as such, MnCo2O4 presented a battery-like electrochemical response. The specific capacity of MnCo2O4-discs was determined to be 296.1C/g at 1 A/g, superior to 246.3C/g for MnCo2O4-rings. An asymmetric supercapacitor (ASC) was assembled with MnCo2O4 as the cathode and activated carbon (AC) as the anode to evaluate the potential for practical application. The MnCo2O4-discs//AC ASC exhibited an energy density (Ed) of 35.8 W h kg−1 at a power density (Pd) of 927.5 W kg−1. For the MnCo2O4-rings//AC ASC, an inferior Ed of 31.4 W h kg−1 under 890.9 W kg−1 was achieved. Furthermore, the two ASCs presented outstanding cyclic performance after 5000 cycles at 6 A/g. The exceptional properties of MnCo2O4 microstructures can be applied to the assembly of ASC devices, which can have promising potential for application in electrochemical energy storage. This synthetic method is straightforward, cost-effective, and can be extended to fabricate similar electrode materials with superior electrochemical performance.

Enhancing membrane distillation efficiency in treating high salinity organic wastewater: A pressure-driven membrane electrochemical reactor approach

Fouling of membranes continues to be a prominent challenge in the membrane distillation (MD) treatment of high salinity organic wastewater (HSOW). Although membrane electrochemical reactor (MER) can effectively inhibit the membrane fouling of MD, the high cost of the proton exchange membrane (PEM) used in MER limits its widespread application. In this study, cost-effective pressure-driven membranes were employed as a substitute for PEM to establish pressure-driven membrane electrochemical reactors for HSOW pre-treatment. By using ultrafiltration membrane (UFM) and reverse osmosis membrane (ROM), UFMER and ROMER were developed, respectively. Due to the superior electrochemical performance of UFM, UFMER saved 43 % of energy compared to PEMER with the highest removal rate of organics (~85 %) in the simulated HSOW treatment. In practical applications, using UFMER significantly reduced the amount and size of complexes in the real nanofiltration concentrate (NC) of landfill leachate. This contributed to the superior specific flux maintenance (97 %) with a salt rejection (>99 %) and the highest recovered specific water flux (99.6 %) in MD cases. UFMER reduced ~27 % of energy compared to PEMER in MER pre-treatment, and saved the most energy (~39.6 %) in MD post-treatment. Hence, this strategy is potential for forthcoming applications, notably in lowering the membrane cost of MER and energy consumption of both MER and MD.

Evaluation of the effect of precursor ratios on the electrochemical performances of binder-free NiMn-phosphate electrodes for supercapattery

Binary metal phosphate electrodes have been widely studied for energy storage applications due to the synergistic effects of two different transition elements that able to provide better conductivity and stability. Herein, the battery-type binder-free nickel-manganese phosphate (NiMn-phosphate) electrodes were fabricated with different Ni:Mn precursor ratios via microwave-assisted hydrothermal technique for 5 min at 90 °C. Overall, NiMn3P electrode (Ni:Mn = 1:3) showed an outstanding electrochemical performance, displaying the highest specific (areal) capacity at 3 A/g of 1262.4 C/g (0.44 C/cm2), and the smallest charge transfer resistance of 108.8 Ω. The enhanced performance of NiMn3P electrode can be ascribed to the fully grown amorphous nature and small-sized flake and flower structures of NiMn3P electrode material on the nickel foam (NF) surface. This configuration offered a higher number of active sites and a larger exposed area, facilitating efficient electrochemical reactions with the electrolyte. Consequently, the NiMn3P//AC electrode combination was chosen to further investigate its performance in supercapattery. The NiMn3P//AC supercapattery exhibited remarkable energy density of 105.4 Wh/kg and excellent cyclic stability with 84.7% retention after 3000 cycles. These findings underscored the superior electrochemical performance of the battery-type binder-free NiMn3P electrode, and highlight its potential for enhancing the overall performance of supercapattery.

Sc3+ substituted Na3V2(PO4)3 on N-doped porous carbon skeleton boosting high structural stability and superior electrochemical performance for full sodium ion batteries

The poor structural stability and conductivity of Na3V2(PO4)3 (NVP) have been serious limitations to its development. In this paper, Sc3+ is selected to replace partial site of V3+ which can enhance its ability to bond with oxygen, forming the ScO6 octahedral unit, resulting in improved structural stability and better kinetic properties for the NVP system. Moreover, due to the larger ionic radius of Sc3+ compared to V3+, moderate Sc3+ substitution can support the crystal framework as pillar ions and expand the migration channels for de-intercalation of Na+, thus efficiently promoting ionic conductivity. The introduction of polyacrylonitrile (PAN) to provide an N-doped porous carbon substrate is another key aspect. The low-cost carbon resource of PAN can induce a beneficial nitrogen-doped carbon skeleton with defects, enhancing electronic conductivity at the interface to reduce the polarization phenomenon. The established pore structure can serve as a buffer for unit cell deformation caused by Na+ migration. Furthermore, the enlarged specific surface area provides more active sites for electrolyte infiltration, improving the material utilization rate. The after cycling X-ray Diffraction/scanning electron microscope (XRD/SEM) further confirms the stabilized porous carbon skeleton and improved crystal stability of Sc-3 material. Ex-situ XRD analysis shows that the crystal volume change in the Sc-3 cathode is relatively slight but reversible during the charge/discharge process, indicating that Sc3+ doping plays a crucial role in stabilizing the unit cell structure. The hybrid Sc/VO6 and PO4 units jointly build a strong bone structure to resist stress and weaken deformation. Accordingly, the optimized Sc-3 sample reveals an initial capacity of 115.9 mAh/g at 0.1C, with a capacity retention of 78.6 % after 2000 cycles at 30C. The Sc-3//CHC full battery can release a capacity of 191.3 mAh/g at 0.05C, accompanied by successful illumination, showcasing its promising practical applications.

Accessing the O Vacancy with Anionic Redox Chemistry Toward Superior Electrochemical Performance in O3 type Na‐Ion Oxide Cathode

AbstractAnionic redox chemistry is now viewed as the effective paradigm of improving the capacity of layered oxide materials in Sodium‐ion battery. In this study, O3‐type layered oxide NaLi0.18Co0.23Ru0.59O2 (NLCR) with O redox ability is successfully synthesized via a facile solid‐state synthesis method. By manipulating the calcinate atmosphere with air and argon (sort by NLCR‐Air NLCR‐Ar respectively), a large amount of O vacancy is introduced in the NLCR‐Air cathode. NLCR‐Air with sufficient O vacancy exhibited superior rate performance which showed 87.7% capacity retention after 1000 cycles at 20 C. Both NLCR‐Air and NLCR‐Ar showed activation of O redox properties which is supported by the soft X‐ray absorption spectroscopy (sXAS). Nevertheless, the in‐situ X‐ray diffraction and sXAS studies disclosed the O vacancy can promote the reversible phase transition and effectively suppress the irreversible O redox upon cycling. These are further supported by theoretical study which suggested a fast kinetic of Na diffusion and less electron agglomeration around the O atom for NLCR‐Air with O vacancy.The research proposed a modification strategy with extraordinary reversible O redox property within O3‐type layered cathode and offered a novel insight into understanding the anionic redox mechanism thus provide guidance of material design advanced energy storage systems.

Upcycling Spent Cathode Materials to Bifunctional Catalysts for High‐Stability Lithium–Sulfur Batteries

AbstractIn order to enhance the sluggish kinetics and suppress the polysulfide shuttle effect in high‐loading lithium–sulfur (Li–S) batteries, it is crucial to design and synthesize catalysts exhibiting both high conversion rate and strong anchoring effect toward polysulfide species. Herein, based on theoretical predictions, spent cathode materials (LiCoO2 and LiMn2O4) from spent lithium‐ion batteries are converted into a bifunctional catalyst (Co─MnO) for Li–S batteries through the high‐temperature shock method. Owing to the synergistic catalytic and anchoring effect of polysulfide species exhibit by Co─MnO, superior electrochemical performance, including excellent rate performance (707 mAh g−1 at 4C) and high stability (capacity fading of 0.058% per cycle over 400 cycles at 1C) can be delivered under a low areal catalyst loading (<0.5 wt%). This work not only offers a new design strategy for Li–S catalysts, but also proposes a promising approach to transform spent LIBs into highly efficient catalysts.

Synthesis and Properties of the LiMn2O4 Cathode Material for Lithium-ion Batteries

Spinel LiMn2O4 was synthesized by high-temperature solid-state method with lithium salt and manganese salt as raw materials, which were mixing with anhydrous ethanol as solvent under stirring, and calcining at high temperature in in the oxygen atmosphere. X-ray diffraction (XRD) and scanning electron microscope (SEM) showed that the size of lithium manganese particles with spinel structure was 80 to 200 nm, and the particle size distribution was uniform. The results showed that the prepared LiMn2O4 sample sintered at 700°C exhibited superior electrochemical performance when used as a cathode material for lithium-ion batteries with a voltage window of 2.5–4.8 V. The first charge-discharge specific capacity and first discharge capacity can reach 158.0 mAh‧g-1 and 138.4 mAh‧g-1, respectively, at 0.1 A‧g-1 current density, and the first Coulomb retention efficiency is 87.6%. The discharge specific capacity of the LiMn2O4 material can be maintained at 114 mAh‧g-1 when the test current density was returned to 0.1 A‧g-1 after 60 cycles.

In-Situ Cross-linked F- and P-Containing Solid Polymer Electrolyte for Long-Cycling and High-Safety Lithium Metal Batteries with Various Cathode Materials.

The practical application of lithium metal batteries (LMBs) has been hindered by limited cycle-life and safety concerns. To solve these problems, we develop a novel fluorinated phosphate cross-linker for gel polymer electrolyte in high-voltage LMBs, achieving superior electrochemical performance and high safety simultaneously. The fluorinated phosphate cross-linked gel polymer electrolyte (FP-GPE) by in-situ polymerization method not only demonstrates high oxidation stability but also exhibits excellent compatibility with lithium metal anode. LMBs utilizing FP-GPE realize stable cycling even at a high cut-off voltage of 4.6 V (vs Li/Li+) with various high-voltage cathode materials. The LiNi0.6Co0.2Mn0.2O2|FP-GPE|Li battery exhibits an ultralong cycle-life of 1200 cycles with an impressive capacity retention of 80.1 %. Furthermore, the FP-GPE-based batteries display excellent electrochemical performance even at practical conditions, such as high cathode mass loading (20.84 mg cm-2), ultrathin Li (20 μm), and a wide temperature range of -25 to 80 °C. Moreover, the first reported solid-state 18650 cylindrical LMBs have been successfully fabricated and demonstrate exceptional safety under mechanical abuse. Additionally, the industry-level 18650 cylindrical LiMn2O4|FP-GPE|Li4Ti5O12 cells demonstrate a remarkable cycle-life of 1400 cycles. Therefore, the impressive electrochemical performance and high safety in practical batteries demonstrate a substantial potential of well-designed FP-GPE for large-scale industrial applications.

In‐Situ Cross‐linked F‐ and P‐Containing Solid Polymer Electrolyte for Long‐Cycling and High‐Safety Lithium Metal Batteries with Various Cathode Materials

AbstractThe practical application of lithium metal batteries (LMBs) has been hindered by limited cycle‐life and safety concerns. To solve these problems, we develop a novel fluorinated phosphate cross‐linker for gel polymer electrolyte in high‐voltage LMBs, achieving superior electrochemical performance and high safety simultaneously. The fluorinated phosphate cross‐linked gel polymer electrolyte (FP‐GPE) by in‐situ polymerization method not only demonstrates high oxidation stability but also exhibits excellent compatibility with lithium metal anode. LMBs utilizing FP‐GPE realize stable cycling even at a high cut‐off voltage of 4.6 V (vs Li/Li+) with various high‐voltage cathode materials. The LiNi0.6Co0.2Mn0.2O2|FP‐GPE|Li battery exhibits an ultralong cycle‐life of 1200 cycles with an impressive capacity retention of 80.1 %. Furthermore, the FP‐GPE‐based batteries display excellent electrochemical performance even at practical conditions, such as high cathode mass loading (20.84 mg cm−2), ultrathin Li (20 μm), and a wide temperature range of −25 to 80 °C. Moreover, the first reported solid‐state 18650 cylindrical LMBs have been successfully fabricated and demonstrate exceptional safety under mechanical abuse. Additionally, the industry‐level 18650 cylindrical LiMn2O4|FP‐GPE|Li4Ti5O12 cells demonstrate a remarkable cycle‐life of 1400 cycles. Therefore, the impressive electrochemical performance and high safety in practical batteries demonstrate a substantial potential of well‐designed FP‐GPE for large‐scale industrial applications.

Surface Nitriding Enables Improved Intercalation Pseudocapacitance of T−Nb2O5 for Lithium‐Ion Batteries

AbstractThe low electrical conductivity limits the application of T−Nb2O5 as anode materials for practical applications. The large‐grain T−Nb2O5 nanowires with nitrogen doping are obtained by simple hydrothermal and annealing treatments. After nitriding with ammonia, an amorphous layer of NbON as an intermediate is formed and then the new crystalline NbN is generated with the deepening of the nitriding degree, causing homogeneous pores on the surface of the T−Nb2O5 and thus increasing the specific surface area. Meanwhile, the formation of the nitriding layer enhances the electrical conductivity, inducing a pseudo‐capacitance mechanism. Therefore, the N−T−Nb2O5 nanowire demonstrates superior electrochemical performance. Specifically, the 45N−T−Nb2O5 nanowires delivered a first reversible specific capacity of 238.33 mAh g−1 at 0.1 C, higher than of theoretical capacity (201.6 mAh g−1). However, the excessive nitride will be completely converted into NbN, reducing the initial lithium storage of the material due to the lack of a lithium storage site, which has not been previously discussed. Besides, at the high rate of 100 C, with the deepening of nitride degree of the T−Nb2O5, the higher the rate performance. Therefore, to find the balance between the high rate performance and the initial lithium storage amount, the nitride degree should be strictly controlled.

From Atomic-Level Synthesis to Device-Scale Reactors: A Multiscale Approach to Water Electrolysis.

ConspectusThe development of an advanced energy conversion system for water electrolysis with high efficiency and durability is of great significance for a hydrogen-powered society. This progress relies on the fabrication of electrocatalysts with superior electrochemical performance. Despite decades of advancements in exploring high-performance noble and non-noble metal electrocatalysts, several challenges persist at both the micro- and macrolevels in the field of water electrolysis.At the microlevel, which encompasses electrocatalyst synthesis and characterization, design strategies for high-performance electrocatalysts have primarily focused on interface chemical engineering. However, comprehensive understanding and investigation of interface chemical engineering across various length scales, from micrometers to atomic scales, are still lacking. This deficiency hampers the rational design of catalysts with optimal performance. Under harsh reaction conditions, such as high bias potential and highly acidic or alkaline media, the surface of catalyst materials is susceptible to undergoing "reconstruction", deviating from what is observed through ex situ characterization techniques postsynthesis. Conventional ex situ characterization methods do not provide an accurate depiction of the catalyst's structural evolution during the electrocatalytic reaction, hindering the exploration of the catalytic mechanism.At the macrolevel, pertaining to catalysis-performance evaluation systems and devices, traditional laboratory settings employ a conventional three-electrode or two-electrode system to assess the catalytic performance of electrocatalysts. However, this approach does not accurately simulate hydrogen production under realistic industrial conditions, such as elevated temperatures (60-70 °C), high current densities exceeding 0.5 A cm-2, and flowing electrolytes. To address this limitation, it is crucial to develop testing equipment and methodologies that replicate the actual industrial conditions.In this Account, we propose a multiscale research framework for water electrolysis, spanning from microscale synthesis to macroscale scaled reactor design. Our approach focuses on the design and evaluation of high-performance HER/OER (hydrogen evolution reaction/oxygen evolution reaction) electrocatalysts, incorporating the following strategies: Leveraging principles of interface chemical engineering across various length scales (micrometers, nanometers, and atoms) enables the design of catalyst materials that enhance both activity and durability. This approach provides a comprehensive understanding of the intricate interplay between the catalyst structure and activity, implementing in situ/operando characterization techniques to monitor dynamic interfacial reactions and surface reconstruction processes. This facilitates a profound exploration of catalytic reaction mechanisms, offering insights into the catalyst's structural evolution during the electrocatalytic reaction. We construct a laboratory-scale membrane electrode assembly (MEA) electrochemical reactor capable of operating at high current densities (>1 A cm-2) to evaluate the electrocatalytic performance under simulated industrial conditions. This ensures objective and authentic assessments of the catalyst application potential. Throughout the following sections, we illustrate the application of interface chemical engineering on different length scales in designing diverse electrocatalyst materials. We rely on in situ characterization techniques to gain a profound understanding of the mechanisms behind the HER and OER. Additionally, we describe the development of both acidic and alkaline MEA electrochemical reactors to enhance the precision of electrocatalytic performance evaluation. Finally, we provide a concise overview of the challenges and opportunities in this field.

Delving into the dissimilarities in electrochemical performance and underlying mechanisms for sodium and potassium ion storage in N-doped carbon-encapsulated metallic Cu2Se nanocubes

The large volumetric variations experienced by metal selenides within conversion reaction result in inferior rate capability and cycling stability, ultimately hindering the achievement of superior electrochemical performance. Herein, metallic Cu2Se encapsulated with N-doped carbon (Cu2Se@NC) was prepared using Cu2O nanocubes as templates through a combination of dopamine polymerization and high-temperature selenization. The unique nanocubic structure and uniform N-doped carbon coating could shorten the ion transport distance, accelerate electron/charge diffusion, and suppress volume variation, ultimately ensuring Cu2Se@NC with excellent electrochemical performance in sodium ion batteries (SIBs) and potassium ion batteries (PIBs). The composite exhibited excellent rate performance (187.7 mA h g−1 at 50 A g−1 in SIBs and 179.4 mA h g−1 at 5 A g−1 in PIBs) and cyclic stability (246.8 mA h g−1 at 10 A g−1 in SIBs over 2500 cycles). The reaction mechanism of intercalation combined with conversion in both SIBs and PIBs was disclosed by in situ X-ray diffraction (XRD) and ex situ transmission electron microscope (TEM). In particular, the final products in PIBs of K2Se and K2Se3 species were determined after discharging, which is different from that in SIBs with the final species of Na2Se. The density functional theory calculation showed that carbon induces strong coupling and charge interactions with Cu2Se, leading to the introduction of built-in electric field on heterojunction to improve electron mobility. Significantly, the theoretical calculations discovered that the underlying cause for the relatively superior rate capability in SIBs to that in PIBs is the agile Na+ diffusion with low energy barrier and moderate adsorption energy. These findings offer theoretical support for in-depth understanding of the performance differences of Cu-based materials in different ion storage systems.

Synergistic Manganese Cobalt Phosphide core-shell for the Electrochemical Detection of Methyl Parathion in Food Sample

The development of a robust electrocatalyst for the electrochemical sensor for hazardous pesticides will reduce its effects on the ecosystem. Herein, we synthesized the robust manganese cobalt phosphide (MnCoP) - Core-shell as an electrochemical sensor for the determination of hazardous pesticide methyl parathion (MP). The MnCoP- Core-shell was prepared with the sustainable self-template route can help with the larger surface area. The Core-shell structure of MnCoP possesses a higher active surface area which increases the electrocatalytic performance and is utilized to improve the electrochemical MP reduction with the synergism of the core and shell structure. Remarkably, it realizes the higher sensitivity (0.014 μA μM−1 cm−2) of MnCoP- Core-shell/GCE achieves towards MP with lower limit of detection (LoD 50 nM) and exceptional recovery rate of MP in vegetable samples are achieved with the differential pulse voltammetry (DPV) technique. The MnCoP- Core-shell electrode reserved their superior electrochemical performances with high reproducibility and repeatability. This prominent activity of the MnCoP core-shell towards the MP in real sample analysis, makes it a promising electrochemical sensor for the detection of MP.

Synthesis of Organopolysilazane Nanoparticles as Lithium-Ion Battery Anodes with Superior Electrochemical Performance via the Two-Step Stöber Method.

The Stöber method, a widely utilized sol-gel technique, stands as a green and reliable approach for preparing nanostructures on a large scale. In this study, we employed an enhanced Stöber method to synthesize organopolysilazane nanoparticles (OPSZ NPs), utilizing polysilazane oligomers as the primary precursor material and ammonia as the catalytic agent. By implementing a two-step addition process, control over crucial parameters facilitated the regulation of the nanoparticle size. Generally, maintaining relatively low concentrations of organopolysilazane and catalyst while adjusting the water/acetonitrile ratio can effectively enhance the surface energy of the organopolysilazane, resulting in the uniform formation of small spherical particles. The average particle size of the synthesized OPSZ NPs is about 140 nm, which were monodispersed and characterized by scanning electron microscopy, transmission electron microscopy, and dynamic light scattering. Furthermore, the composition of OPSZ NPs after pyrolysis was confirmed as SiC2.054N0.206O1.631 with 5.44 wt % free carbon structure by X-ray diffraction and energy-dispersive X-ray spectroscopy. Notably, the electrochemical performance assessment of SiCNO NPs as potential electrode materials for lithium-ion batteries exhibited promising outcomes. Specifically, at 1 A g-1 current density, the specific capacity is 585.45 mA h g-1 after 400 cycles, and the minimum capacity attenuation per cycle is only 0.1076 mA h g-1 (0.0172% of the original capacity), which indicates excellent energy storage capacity and cycle stability. In summary, this research contributes to the development of advanced anode materials for next-generation energy storage systems, marking a stride toward sustainable energy solutions.

Three dimensional CuCo2S4@CNT as cathode for sustainable aluminum batteries

It is a challenging and meaningful subject that developing high-performance cathode materials for aluminum batteries（ABs）. In this work, a three dimensional CuCo2S4@CNT (CNT refers to carbon nanotube) material was designed for ABs. The three-dimensional structure is constructed by combining CuCo2S4 microspheres with CNT scaffolds. CuCo2S4 microspheres are constructed from ultrathin nanosheets and CuCo2S4 microspheres uniformly distribute in these three dimensional all-carbon CNT architectures. The CNT framework improves material conductivity and inhibits aggregation of CuCo2S4 particles, and also acts as a buffer, eliminating volume changes and providing more stable contacts between particles. Compared with the pristine CuCo2S4 electrode, the CuCo2S4@CNT electrode exhibits superior electrochemical performance. At a current density of 100 mA/g, CuCo2S4@CNT electrode still provides a reversible capacity of 128 mAh/g after 200 cycles. Meanwhile, the coulombic efficiency remains above 96 %.

Recent Progress and Synthetic Methods for Single-crystalline Cathode in Lithium-ion Batteries

Ni-rich layered transition metal oxides have been regarded as the most feasible way for achieving high energy density of lithium-ion batteries. Conventional Ni-rich cathodes are composed of spherical secondary particles, consisting of numerous primary particles. Unfortunately, the grain boundaries in the polycrystalline structure are vulnerable to the pulverization, leading to microcracks during cycling. The newly exposed surface from the microcrack can induce undesirable side reactions with the electrolyte, which severely deteriorates the battery performance. On the other hand, single-crystalline Ni-rich cathodes have gained significant attention for industrial applications due to their robust mechanical strength, resulting from the elimination of grain boundaries. The improved mechanical properties of single-crystalline cathodes effectively mitigate the interfacial side reactions, thereby attaining superior structural, thermal, and electrochemical performance. Herein, we have introduced various synthetic methods of the single-crystalline cathode, encompassing not only high-temperature sintering and the molten-salt method for the Ni-rich cathode but also the other strategies for different single-crystalline cathode materials. This review aims to provide a comprehensive understanding of single-crystalline cathode synthesis, with implications for the development of high-performance cathode materials.

Polymer-based LFP cathode/current collector microfiber-meshes with bi- and interlayered architectures for Li-ion battery

In this study, we report the development of a free-standing fiber-based mesh cathode made of electrospun composite microfibers containing 80 wt% lithium iron phosphate (LFP), as well as conductive microfibers containing carbon nano-fillers acting as the current collector (CC). Neither the electrode nor the current collector undergoes post-fabrication treatment or calcination. Scanning electron microscopy confirmed that the meshes are constructed of well-shaped microfibers and exhibit a high porosity, enabling efficient electrolyte penetration and improved electron and ion-transport channels.Two cathode architectures of the LFP/polymer-based CC meshes were explored: bilayered and interlayered. Both architectures are characterized by a high surface-to-volume ratio. The interlayered structure showed superior electrochemical performance due to enhanced LFP-CC fiber-to-fiber contacts and reduced resistance. Comparative analysis with electrospun LFP on aluminum foil revealed comparable specific capacity but higher polarization in the electrospun LFP/CC meshes, attributed to increased internal resistance and limited fiber-to-fiber contacts. However, the electrospun interlayered LFP/CC mesh exhibited significantly higher gravimetric energy density (197 Wh/kg (LFP + CC) and 94 Wh/kg (LFP + Al), respectively), offering lightweight and higher-energy-density electrode materials, thus guiding the design of high-performance flexible lithium-ion batteries.

Enzyme Immobilization by Inkjet Printing on Reagentless Biosensors for Electrochemical Phosphate Detection.

Enzyme-based biosensors commonly utilize the drop-casting method for their surface modification. However, the drawbacks of this technique, such as low reproducibility, coffee ring effects, and challenges in mass production, hinder its application. To overcome these limitations, we propose a novel surface functionalization strategy of enzyme crosslinking via inkjet printing for reagentless enzyme-based biosensors. This method includes printing three functional layers onto a screen-printed electrode: the enzyme layer, crosslinking layer, and protective layer. Nanomaterials and substrates are preloaded together during our inkjet printing. Inkjet-printed electrodes feature a uniform enzyme deposition, ensuring high reproducibility and superior electrochemical performance compared to traditional drop-casted ones. The resultant biosensors display high sensitivity, as well as a broad linear response in the physiological range of the serum phosphate. This enzyme crosslinking method has the potential to extend into various enzyme-based biosensors through altering functional layer components.