Energy Density Research Articles

In-situ synthesis AgO/AgNPs composite as binder-free cathode for high-performance aqueous AgO-Al batteries

Aqueous AgO-Al batteries are promising systems due to their ultrahigh specific capacity, energy density, and stable output voltage. However, they still suffer from the low utilization and sluggish kinetics of the cathode. In this study, the binder-free AgO/AgNPs composites were synthesized in-situ using a simple electrodeposition method. Due to the excellent conductivity and rich mesoporous structure of AgO/AgNPs materials, the electron and ion transfer kinetics were enhanced, thereby improving the charge storage performance of the electrode. As expected, the AgO-Al battery with the optimized AgO/AgNPs composite cathode demonstrated excellent rate performance, achieving a high discharge capacity of 325.1 mAh g−1, and a stable operating voltage platform of 1.55 V at the current density of 1000 mA cm−2. The maximum energy and power density were 687 Wh kg−1 and 6.2 kW kg−1, respectively. This work presents an effective strategy for designing high-performance AgO electrode materials for AgO-Al batteries.

Comparing different battery thermal management systems for suppressing thermal runaway propagation

Thermal runaway (TR) stands as a critical risk in battery applications. Even though various battery thermal management systems (BTMSs) have been proposed to mitigate thermal runaway propagation, a comprehensive comparison remains elusive. This study evaluates the performance of three types of BTMSs with 5 configurations, which include: liquid cooling with cold plates added on the bottom (BTMS-1a), liquid cooling with cold plates added on the sides (BTMS-1b), liquid cooling with cold plates added between batteries (BTMS-1c), integrating thermal insulation materials between batteries (BTMS-2), and implementing phase change materials between batteries (BTMS-3). The highest temperature, propagation time, temperature uniformity, cooling rate, mass energy density, and volume energy density are used as key performance indicators for comparison. In general, BTMS-2 and BTMS-3 show advantages in energy density, however, their performances on TR suppression and battery thermal management are poor. BTMS-1c can suppress TR effectively at high flowrates, whereas it can lead to poor temperature uniformity. Suggestions are also provided regarding the selection of BTMSs for different applications: BTMS-1b, BTMS-1c, and BTMS-3 are recommended for small EVs, large EVs and large scale battery energy storage systems (BESSs), and small BESSs, respectively.

Constructing stable solid electrolyte interphases to enhance the calendar life of anode-free lithium metal batteries

Advancement of anode-free lithium metal batteries (AFLMBs) has been appreciated due to their exceptional volumetric energy density and manufacturing simplicity. However, AFLMBs suffer from poor cycle performance due to the absence of excess lithium and current research lacks an understanding of lithium corrosion and calendar aging in AFLMBs. Here, we investigate the practical effects of chemical and galvanic corrosion on battery performance (calendar life) through a modified full-cell cycling experiment. The impact of galvanic corrosion is negligible, whereas chemical corrosion during a rest period reduces the capacity retention (CR) from 47% to 32% over 100 cycles. Consequently, a corrosion control strategy is implemented, substituting 1,2-dimethoxyethane with 1,2-dimethoxypropane (DMP), which has weaker lithium ion solvation properties due to its inductive effect. This approach results in the formation of a Li2O-rich solid-electrolyte interphase (SEI) layer, which effectively prevents direct contact of lithium with the electrolyte and the formation of additional SEI layers. Consequently, the decrease in CR due to chemical corrosion is considerably mitigated in DMP-based electrolyte, with only a slight decrease from 51% to 49%. This study provides insights into lithium corrosion in practical AFLMBs and offers guidelines for designing less-corrosive electrolytes to improve AFLMB performance for diverse industrial applications as energy-storage devices.

Metal organic framework derived heteroatom doped porous carbon nanocubes enable efficient charge storage in a lithium-ion capacitor

Lithium-ion capacitors (LICs) are regarded as one of the promising technologies towards realizing energy & power dense energy storage systems. However, their energy densities at higher power densities are still limited due to the discrepancy between electrode kinetics of capacitor-like cathode and battery-like anode. Developing carbon materials with well-defined structures, porosity to match the chemical kinetics between electrodes are the major challenges to overcome. In the present work, we have devised a strategy to fabricate S, N dual-doped porous carbon nanocubes (S, N-PCNs) using zeolitic imidazole framework (ZIF)-8 precursors, and employed the PCNs as anode material in LICs. With its well-defined structure, hierarchical porous nature, and abundant heteroatom presence (1.9 % S, 16.2 % N), the pre-lithiated S, N-PCNs based anode has offered a greatly improved reversible storage capacity of ∼930 mAh g−1 at 0.1 A g−1 along with an impressive rate capability and cycling life. When S, N-PCNs anode is paired with activated carbon cathode, the 4 V dual-carbon LIC yields an energy density as high as 120.24 Wh kg−1 and 10.2 kW kg−1 of power density with a good cycle stability of 90.6 % after 5000 charge-discharge cycles. This work would open new scopes of exploring metal-organic framework derived heteroatom-doped porous carbons to make metal-ion capacitors more efficient.

High energy density and efficiency of laminated polymeric blend-based composites via introducing ultra-low content micrometer sheets

Polymeric blend-based composites are promising for dielectric capacitor due to the excellent dielectric and energy storage properties. However, the electric displacement difference (Dmax-Dr) and dielectric constant (εr) of the polymeric blend-based composites are incompatible, which further limits the improvement of the available energy densities (Ue). In this study, we propose the solution-processable laminated polymeric blend-based composites to address this challenge. The concurrent enhancement in Dmax-Dr, εr, Ue and charge-discharge efficiency (η) of designed composites is attributed to the synergistic interaction between macroscopic layered interfaces and microscopic interfaces. The laminated polymeric blend-based composites were fabricated by utilizing a blend of 50 wt% poly(vinylidene difluoride)-hexafluoropropylene (P(VDF-HFP)) and linear poly(methyl methacrylate) (PMMA) as the outer layer and P(VDF-HFP)/PMMA incorporated with an ultralow content alumina-modified strontium titanate plates (SrTiO3@Al2O3) the inner layer. As a result, laminated polymeric blend-based composite with the optimized content (0.5 vol%) delivers a maximum Ue of 14.36 J/cm3 due to highest Dmax-Dr of 7.96 μC/cm2, εr of 6.12 (1 kHz), Eb of 400 MV/m, and η of 76.6 %, outperforms those of representative polymer blend-based composites. Specially, laminated polymeric blend-based composite also exhibits the excellent energy storage reliability of different areas. Therefore, this contribution provides a viable approach to promote polymeric blend-based composites for capacitive energy storage.

Analytical Modeling of Short-Circuit Impedance of Square Foil Winding Phase-Shifting Transformer Based on Planar Energy Density Equivalence Method

Analytical Modeling of Short-Circuit Impedance of Square Foil Winding Phase-Shifting Transformer Based on Planar Energy Density Equivalence Method

External ligand-free nickel-catalyzed synthesis of polypyrazines towards stable, high-capacity and low-potential sodium ion storage

Sodium ion batteries (SIBs) have been regarded as a promising alternative to lithium-ion battery owing to low cost and good sustainability, but its competitiveness in energy storage is still limited largely by the development of suitable electrode materials. Traditional inorganic anode materials for SIBs face the problems of sluggish electrochemical kinetics and large volume strain due to the insertion/extraction of large size Na+. By comparison, organic anodes have the advantages of abundance resources, renewability, and designability, but suffer from the lack of stable electrode materials with both high specific capacity and low redox potential. Here, a class of pyrazine rings-rich organic polymers (polypyrazines) were designed and synthesized through external ligand-free nickel-catalyzed carbon–carbon coupling reactions. Among them, poly(2,6-pyrazine) shows the lowest synthetic cost, the highest porosity and the best conductivity. Consequently, as the anode of SIBs, poly(2,6-pyrazine) delivers a low redox potential (about 1 V, vs Na+/Na), high-specific-capacity (617.2 mA h/g at 0.1 A/g), excellent rate-capability (300 mA h/g at 10 A/g) and long-term cycling stability (81 % after 1000 cycles at 1.0 A/g). The low preparation cost and outstanding electrochemical performance of poly(2,6-pyrazine) make it a promising anode candidate for further boosting the energy density of SIBs.

Thermo-hydraulic performance evaluation of lattice structures with triply periodic minimal surfaces for latent heat storage devices

Triply periodic minimal surface (TPMS) structures exhibit significant potential in latent heat storage (LHS) applications. In this study, numerical investigations were conducted to study the thermal storage performance of four TPMS lattice types: Primitive, IWP, FRD, and Gyroid lattices, used as metallic skeletons in LHS devices. The volumes of both the TPMS skeletons and the phase change material (PCM) were kept constant, with PCM embedded either inside or outside the lattices. The melting process of PCM, the heat storage energy density, and the power density of the LHS units for different configurations were examined. Additionally, a performance evaluation coefficient was introduced to assess the heat transfer and flow characteristics of heat transfer fluid (HTF) flowing on both sides of the lattices. The results indicated that when using Primitive and FRD lattices, embedding the PCM within the internal space of the lattices resulted in a 20 % and 9.8 % higher energy storage compared to embedding it outside the lattices. The internal space of IWP and Gyroid lattices was more suitable for HTF flow channels, resulting in performance evaluation coefficients (PECs) that improved by 27.7 % and 86.3 %, respectively, when HTF flowed through the internal channels of these lattices. Moreover, the Gyroid lattice exhibited the most balanced overall heat transfer performance due to its minimal flow resistance, whereas the FRD lattice had the lowest flow performance due to its complex structure. Therefore, the Primitive and Gyroid lattices could be considered as new heat transfer structures for LHS devices, while the FRD lattice was more suitable for replacing traditional fin structures in heat sink devices.

"Synergistic Hybridization of Mn-MOF@rGO and Ti3C2 for High-Performance Supercapattery Devices and Hydrogen Evolution Reaction"

The burgeoning interest in two-dimensional (2D) materials stems from their heightened storage capacity and superior conductivity. Here, we synthesized a metal-organic framework of manganese (Mn-MOF) and introduced reduced graphene oxide (rGO) doping into this heterostructure using a hydrothermal method. Subsequently, Ti3C2Tx MXene was prepared via a template method. The Mn-MOF@rGO was then combined with Ti3C2Tx MXene in a 50/50 wt% ratio using hydrothermal techniques, and their structural and electrochemical characteristics were evaluated. In 3-electrode measurements, the MnMOF@rGO/Ti3C2Tx composite conductor exhibited a precise capacity of 2645 C/g (5.29 C/cm3) at 1.8 A/g. Furthermore, a hybrid device termed a supercapattery was fabricated employing MnMOF@rGO/Ti3C2Tx along with activated carbon (AC) composite electrodes, demonstrating remarkable energy density of 67 Wh/kg and an impressive power density of 880 W/kg. After 8,000 cycles, the electrode exhibited 84% capacity retention and maintained 92% columbic efficiency. In the hydrogen evolution reaction (HER), the MnMOF@rGO/Ti3C2Tx composite displayed a minimal Tafel slope of 54.65 mV/dec. These two-dimensional composite electrodes offer novel avenues for the advancement of high-performance energy device.

Unveiling degradation mechanisms of anode-free Li-metal batteries

Anode-free Li-metal batteries (AFLMBs), in which Li+ ions from the cathode are deposited on a Cu substrate and the deposited Li-metal serves as the anode, exhibit higher energy density compared to Li-metal batteries (LMBs). However, achieving stable cycle performance, even at moderate operating conditions, is difficult and has so far hindered their practical uses. In AFLMBs, the homogeneity of solid electrolyte interphase (SEI), initially created by electrolyte reduction on Cu substrate, is not maintained during Li-metal deposition, leading to uncontrolled electrolyte decomposition. The SEI is therefore not conserved, and uneven Li deposition morphology is induced on the Cu substrate and the eventual instability of SEI leads to the overall degradation of AFLMBs. Here, we report on the failure mechanisms of AFLMBs through a comparative study with LMBs using 3 M lithium bis(fluorosulfonyl)imide (LiFSI) dissolved in N,N-dimethylsulfamoyl fluoride. Our investigation reveals that the SEI inhomogeneity in AFLMBs makes Li+ transport through SEI sluggish and non-uniform, triggering local compositional changes of the initially formed SEI on the Cu substrate and unwanted consumption of FSI– anion from the electrolyte. This work provides clear understanding to the interfacial engineering and important roles of Li-metal on the Cu substrate in AFLMBs, promising the creation of stable SEI, reversible electrochemical reaction of Li-metal, and interfacial stability of the cathode in LMBs.

Facile synthesis and first principles calculations of Li-MoS2/rGO nanocomposite for high-performance supercapacitor applications

Two-dimensional (2D) nanostructured materials such as graphene oxide nanosheets and molybdenum disulfide (MoS2) are potential candidates for electrochemical energy storage applications. The layered structure of MoS2 makes it a promising active electrode material for supercapacitors. Lithium (Li) interacted with MoS2/reduced graphene oxide (Li-MoS2/rGO) nanocomposite has been synthesized in two steps using a sonochemical dispersion method, and a one-pot hydrothermal method resulting in few-layered MoS2/rGO nanosheets of 2D heterointerfaces. The Li-MoS2/rGO nanocomposite exhibits a high specific capacitance of 173.3 F g−1 at a current density of 1 A g−1. Furthermore, an asymmetric supercapacitor device fabricated with Li-MoS2/rGO achieves a good energy density of 10.6 Wh kg−1 at a power density of 686.3 W kg−1 and outstanding cycling stability with 81.2 % capacity retention over 10,000 cycles. The dispersion of 2D-MoS2 in water is due to the strong electrostatic interface. The structural and electronic properties are theoretically calculated for pristine and Li-interacted MoS2/rGO heterostructure using density functional theory. A comparison of the density of states plots of the two heterostructures and the difference charge density plot of Li-MoS2/rGO heterostructure clearly brings out the importance of the presence of Li. A value of 64 μF cm−2 for the quantum capacitance for pristine MoS2/graphene heterostructure increases to a value 99 μF cm−2 corroborating the experimental observations and we assign this change to the transfer of charge from the Li atom to the outer S atoms in the MoS2/graphene heterostructure. This comprehensive approach, combining experimental synthesis with computational modelling, significantly advances the development and optimization of high-performance supercapacitor materials in the energy storage field. The Li-MoS2/rGO nanocomposite has excellent electrochemical specific capacitance and long-term cyclic stability and has been effectively used for supercapacitor applications with high electrochemical performance.

Efficient sodium ion transport enhanced by anionophilic sites in polymer-supported plastic crystal electrolyte for high performance sodium metal anode

The design of sodium metal batteries (SMBs) is seen as an excellent solution to solve the request of next-generation energy storage technologies with high energy density, high safety, low cost, and environmental friendliness. However, the direct use of sodium metal as an anode produces the dendritic sodium, which harms the normal operation of battery. Inspired by solid-state lithium metal batteries, solid-state electrolyte (SSE) designed for SMBs effectively solves this shortcoming. Herein, a novel SSE with mask-based polymer membrane supporting plastic crystal electrolyte with ZIF-67 (MPPZ) is designed. The experimental results and density functional theory (DFT) calculations indicate that the addition of ZIF-67 in MPPZ electrolyte availably fixes TFSI− and achieves high Na+ transference number. Additionally, a protective layer of NaF is formed in situ on the surface of sodium metal to avoid side reactions between Na and MPPZ electrolyte while further guide the uniform deposition of Na. Accordingly, Na||Na symmetric battery with NaF-coated Na metal anode and MPPZ electrolyte has a stable deposition and stripping of Na for 3000 h. The assembled room temperature solid-state sodium-sulfur battery (RTSSSSB) exhibits a good cycle stability. This study provides an innovative thinking for the construction of high performance dendrite-free SMBs.

Soft-templating of biomass derivatives into edge-N doped 3D-interconnected hierarchical porous carbon for multi-scenario supercapacitive energy storage

Rational design of the pore structure for carbon materials is of great significance for solving the low specific capacitance and poor rate capability of supercapacitors. A novel soft-templating strategy is proposed by using biomass-derived sodium lignosulphonate as a carbon precursor and sublimable hexamethylenetetramine as a soft template. The hexamethylenetetramine nanoparticles are formed in the confined spaces of the precursor, and then these templates sublime to leave mesopores after the lignosulfonate transformed from linear structure to bulk structure by thermostabilization treatment. A high nitrogen content of 40 wt% in hexamethylenetetramine is also beneficial for the subsequent in-situ N-doping. The as-obtained nitrogen-doped hierarchical porous carbon microspheres possess a high specific surface area of 1416 m2 g−1 with an N-doping content of 4.32 % (86.26 % edge-N). In a two-electrode system, the soft-templating carbon exhibits a decent specific capacitance of 234 F g−1 at 0.1 A g−1, an excellent rate capability of 62.4 % at 50 A g−1, and a high energy density of 8.1 Wh kg−1 at 15.0 kW kg−1 in 6 M KOH aqueous electrolyte. Moreover, advanced additive manufacturing technology of direct ink writing was applied to construct a quasi-solid-state in-plane interdigital microsupercapacitor by using the soft-templating carbon, and it presents a superior areal/volumetric capacitance, rate performance, mechanical stability, and flexibility with PVA/H2SO4 gel electrolyte. This work broadens the pore structure engineering methodology by novel soft-templating biocarbon for multi-functional and multi-scenario energy storage systems.

High-performance α-Fe2O3 nano cubes as anode for supercapacitors

Abundant availability, high theoretical specific capacitance and low cost of transition metal oxides such as iron oxides, make them attractive as electrode materials for energy storage. In order to achieve improved performance, high conductivity, shorter ion-diffusion path, and faster ion accessibility, rational design of morphology of electrode material is highly desirable. We have successfully synthesized mesoporous α-Fe2O3 nanocubes to achieve high specific capacitance and better retention. The as-prepared and annealed α-Fe2O3 nanocubes show high reversible redox activity along with good thermodynamic stability. These nanostructure give rise to high specific capacitance and ~90 % of the capacitance can be retained even after 1000 redox cycles, suggesting good cyclic stability. The electrochemical performance of mesoporous α-Fe2O3 nanocubes is attributed to the morphological features, which results in efficient K+ ion transport into the pores. A two electrode α-Fe2O3//NiO device is fabricated, which shows excellent power and energy density of ∼627 W/kg and ∼23.32 Wh/kg, respectively. Our work demonstrates that 3D nanoporous α-Fe2O3 electrodes forms promising material system as anode for improved charge storage performance.

Edge‑nitrogen/sulfur co-doping boost high potassium ion storage of carbon nanosheet anode materials

Potassium-ion batteries (PIBs) have garnered considerable attention as a potential alternative to lithium-ion batteries. However, the larger radius of K+ poses challenges, including slow kinetic processes and significant volume changes, which adversely affect the rate performance and cycling stability of electrode materials. Herein, N, S co-doped carbon nanosheets (xNS-HC) are synthesized as anode materials of PIBs by carbonization of citric acid and CH₄N₂S precursors in LiCl/KCl molten salts. Of these, 5NS-HC possesses a high N content of 20.19 at.% with 90.90 % of edge N-species and a S content of 2.53 at.%. The 5NS-HC material exhibits a high specific K+ storage capacity of 368.2 mAh g−1 at 0.1 A g−1, superior rate capability (106.1 mAh g−1 at 10 A g−1), and long-term cycling stability (205.8 mAh g−1 after 2800 cycles at 1 A g−1). In-depth analysis via in-situ XPS and DFT calculations reveals that the active sites doped with edge-N/S exhibit a profound affinity towards K+, thus contributing to the outstanding electrochemical K+ storage performance observed in 5NS-HC. The full cell of K0.4Mn0.9Li0.1O2·0.33H2O||5NS-HC exhibits a high specific capacity of 141.2 mAh g−1, supporting a high energy density of 147.1 Wh kg−1. These compelling results illustrate that edge-N/S co-doping can significantly enhance the K+ storage of carbon anode materials.

Solid-state preparation of in-situ grown graphene-embedded bi-metallic NiMnS hybrids for high-performance asymmetric supercapacitor

Endowed with intrinsic redox-rich features and superior electronic conductivities, mixed-metallic sulphides offer high prospects in electrochemical charge storage, especially in supercapacitors. Hence, their rational design and scalable preparation are of great scientific significance. Herein, we report the in-situ growth of nanostructured hybrids of NiMnS directly embedded into graphene sheets by a straightforward, scalable solid-state synthesis method. In this environment-friendly approach, the metal precursors, elemental sulphur, and graphene oxide (GO) are homogeneously mixed under ball-milling, followed by controlled thermal treatment. Incited from their unique synergistic contribution, the resulting NiMnS/G hybrids exhibit impressive electrochemical performance as a battery-type electrode in an aqueous electrolyte. The NiMnS/G hybrid electrode displayed a high specific capacity of 871.7C g−1 at 2 A g−1 with superior rate capability. Moreover, the asymmetric supercapacitor (ASC) device assembled based on the surface-enhanced NiMnS/G nanohybrid as the positive electrode and activated carbon (AC) as the negative electrode achieves an intriguing performance, delivering a maximum energy density of 53.4 Wh kg−1 at a power density of 500 W kg−1. The ASCs were successfully cycled over 10,000 cycles with 87 % capacitance retention and around 99 % Coulombic efficiency. This simple yet scalable strategy holds high promise and may pave the way for preparing other multimetallic sulphide-based hybrid electrode materials for electrochemical energy storage applications.

Critical role of submicropores in lignin-based carbon for enhanced supercapacitive performance in aqueous electrolyte

Lignin-based microporous carbon is prepared by KOH activation method. Nitrogen sorption analysis shows that the specific surface area is 1473 m2 g−1 and the micropore size is mainly distributed at 0.65 nm, leading to a capacitance value of 252 F g−1 in H2SO4 electrolyte. To tune the microstructure for better electrochemical performance, cobalt acetate is introduced in the mixture of lignin/KOH. The catalysis of cobalt acetate reduces the heteroatom content of the final porous carbon, resulting in an increased graphitization degree. Moreover, the microporous structure is also tuned by generating more submicropores with pore size of 0.65–0.85 nm. Even though the specific surface area is only 1543 m2 g−1, the submicropore surface area is increased to 1097 from 662 m2 g−1. With the increased graphitization degree and submicropore content, the prepared porous carbon can accommodate more electrolyte ions, contributing to a specific capacitance of 332 F g−1 in H2SO4 electrolyte. This capacitance value is increased by 31.7 % compared with previous carbon without adding cobalt acetate. The assembled supercapacitor cell can deliver a high energy density of 13.4 Wh kg−1. Our findings provide a guide on the microstructure modulation of porous carbon to match aqueous electrolytes with different ionic size.

Structural regulation of 1T-MoS2/Graphene composite materials for high-performance lithium-ion capacitors

Heterogeneous composite structures are considered an effective strategy by utilizing the advantages of heterogeneous components. However, the relationship between structural modifications and electrochemical performance remains inadequately understood. In this study, we leveraged DFT calculations to elucidate the key advantages of the 1T-MoS2/Gr heterostructure, including its exceptional electrical conductivity, enhanced Li+ adsorption capabilities, and improved Li+ diffusion kinetics. To synthesize the 1T-MoS2/Gr composite, we developed a facile, one-step hydrothermal method using glucose as a reducing agent, achieving an optimal heterostructure that maximized the synergistic properties of the components. By comparing different levels of graphene content, the relationship between structural regulation and electrochemical performance has been studied, and a remarkably significant heterostructure composite material (1T-MoS2/Gr-0.8) was identified. As the anode material for lithium-ion batteries (LIBs), 1T-MoS2/Gr-0.8 presents excellent cycle performance with 467 mAh g−1 under the condition (0.5 A g−1, 600 cycles). Simultaneously, when assembling the lithium-ion capacitor (LIC) device with an activated carbon (AC) cathode, even at a high power density of 11.7 kW kg−1, the energy density of the 1T-MoS2/Gr-0.8//AC LIC is as high as 137.0 Wh kg−1. Moreover, the capacity retention rate remains at 89.9 % even after 2000 cycles at 2 A g−1, demonstrating its candidacy as a high-performance anode material for LICs.

Synergetic Interplay of MnNi-MOF Composite with 2D MXene for Improved Supercapacitor Application

The growing demand for high-performance energy storage systems has driven the development of advanced materials to improve supercapacitor efficiency. In this study, MXene-MnNi nanocomposites are synthesized and evaluated for their potential as next-generation supercapacitor electrodes. The MnNi alloy, known for its excellent pseudocapacitive properties, is combined with MXene, a two-dimensional material recognized for its exceptional conductivity, mechanical robustness, and large surface area. The uniform dispersion of MnNi and MXene achieved through a straightforward hydrothermal method, optimizes charge transfer and enhances electrochemical performance. Electrochemical testing demonstrates that the 100 MX-MN nanocomposite exhibits a high specific capacity of 1028 C g-1 at 1 A g-1, along with excellent rate capability and long-term stability, outperforming many conventional materials. This outstanding performance is attributed to the synergistic effects of MnNi’s redox activity and MXene’s high conductivity, which together increase active site availability, accelerate ion diffusion, and maintain structural integrity. Additionally, a hybrid aqueous device is assembled using 100 MX-MN as the positive electrode and activated carbon as the negative electrode. The device delivers a maximum energy density of 87.35 W h kg-1 at a power density of 1.98 kW kg-1 and exhibits excellent capacity retention of 88 % after 10,000 charge-discharge cycles. These findings highlight the potential of MXene-MnNi nanocomposites as advanced materials for supercapacitor applications, offering a promising path for more efficient energy storage solutions in modern electronic devices.

Prop-1-ene-1,3-sultone as interfacial-engineering additive in nonflammable electrolyte for 4.45 V LiCoO2/Si-Graphite lithium-ion batteries with high performance

To achieve high energy density for lithium-ion batteries, employing high-voltage cathodes and Si-based anodes is available. Fluoroethylene carbonate-based electrolytes show potential for use in high-voltage lithium-ion batteries due to their superior oxidation stability. However, fluoroethylene carbonate is prone to reductively decompose on the anode and brings about adverse effects on the battery performance. In this work, prop-1-ene-1,3-sultone is incorporated as an efficacious film-forming additive into fluoroethylene carbonate/dimethyl carbonate electrolyte for the purpose of ameliorating the compatibility with Si-Graphite anode in high-voltage lithium-ion batteries. The flame retardant (ethoxy)pentafluorocyclotriphosphazene is also incorporated into the electrolyte to guarantee the nonflammable feature. This nonflammable electrolyte has an ideal conductivity higher than 8 mS cm−1 at 25 °C, and it grants competitive performances to a high-voltage LiCoO2/Si-Graphite pouch cell. This cell after 300 cycles test exhibits a capacity retention of over 80 % at 1C, and the discharge capacity at 8C exceeds 50 % of that at 1C. By virtue of X-ray photoelectron spectroscopy, scanning electron microscopy and transmission electron microscopy techniques, it is confirmed that prop-1-ene-1,3-sultone enhances interfacial properties of Si-Graphite anode and contributes to an optimized interface, which restrains the volume expansion of Si-Graphite and inhibits persistently reductive decomposition of electrolytes.