Interfacial study and modulation of high-voltage layered cathode based all-solid-state batteries.

Employing layered materials as the cathodes for solid-state batteries (SSBs) is vital in enhancing the batteries' energy density, whereas numerous issues are present regarding the compatibilities between cathode electrode and modified solid electrolyte (ME) in this battery configuration. By investigating the electrochemical performance and interfacial properties of SSBs using various cathodes, the fundamental reason for the poor compatibility between layered cathodes, especially LiCoO2 with ME is revealed. Because of the Li(solvent)+ intercalation environments formed in the ME, the resultant weak-interacted TFSI- could be adsorbed and destabilized by Co ions on the surface. Besides, the high energy level offsets between LiCoO2 and ME lead to Li-ion transferring from the bulk electrode to the electrolyte, resulting in a pre-formed interface on the cathode particles before the electric current is applied, affects the formation of effective cathode-electrolyte interface (CEI) film during electrochemical process and deteriorated overall battery performance. From this view, an interlayer is pre-added on the LiCoO2 surface through an electrostatic adsorption method, to adjust the energy level offsets between the cathode and ME, as well as isolate the direct contact of surface Co ions to TFSI-. The cycling properties of the SSB using modified LiCoO2 are greatly enhanced, and a capacity retention of 68.72 % after 100 cycles could be achieved, against 8.28 % previously, certifying the rationality of the understanding and the effectiveness of the proposed modification method. We believe this research could provide basic knowledge of the compatibility between layered cathodes and MEs, shedding light on designing more effective strategies for achieving SSBs with high energy density.

Boosting supercapacitive performance of pristine covalent organic frameworks via phenolic hydroxyl groups: A two-in-one strategy.

Two-dimensional covalent organic frameworks (COFs) are ideal electrode materials for electrochemical energy storage devices due to their unique structures and properties, and the accessibility and utilization efficiency of the redox-active sites within COFs are critical determinants of their pseudocapacitive performance. Via introducing meticulously designed phenolic hydroxyl (Ar-OH) groups with hydrogen-bond forming ability onto the imine COF skeletons, DHBD-Sb-COF exhibited improved hydrophilicity and crystallinity than the parent BD-Sb-COF, the redox-active sites (SbPh3 moieties) in COF electrodes could thus be highly accessed by aqueous electrolyte with a high active-site utilization of 93%. DHBD-Sb-COF//AC provided an excellent supercapacitive performance with an energy density of 78 Wh Kg-1 at the power density of 2553 W Kg-1 and super cycling stability, exceeding most of the previously reported pristine COF electrode-based supercapacitors. The "two-in-one" strategy of introducing hydroxyl groups onto imine COF skeletons to enhance both hydrophilicity and crystallinity provides a new avenue to improve the electrochemical performance of COF-based electrodes for high-performance supercapacitors.

Constructing nitrogen-doped graphene quantum dots embedded in CNT supported layered (Ni0.5Co0.5)3V2O8 self-supporting film for high-performance supercapacitor.

To improve the electrochemical performance of positive electrode materials, constructing graded nanostructures is a worthwhile approach. This study successfully synthesized nitrogen-doped graphene quantum dots (NGQD) modified (Ni0.5Co0.5)3V2O8 on a carbon nanotube (CNT) substrate to construct self-supporting electrodes for high-performance supercapacitors. The (Ni0.5Co0.5)3V2O8 nanosheets were successfully wrapped onto the CNT surface through a solution impregnation process, which increased the specific surface area and interlayer spacing of the material. Furthermore, the electrochemical properties of the electrode material underwent significant enhancement due to the synergistic interplay between metal ions and the numerous redox centers. The embedding of the NGQD enriched the materials with active sites and further improved its specific capacity without compromising the structure intergrity of the layer configuration. Using CNT as the substrate ensured the self-supporting nature of the electrode. Consequently, the (Ni0.5Co0.5)3V2O8/NGQD@CNT composite exhibits an ultra-high specific capacitance of 3018.2 F g-1 at 1 A g-1 and 2332 F g-1 at 10 A g-1. The asymmetric supercapacitor constructed with (Ni0.5Co0.5)3V2O8/NGQD@CNT and activated carbon (AC) presented an impressive energy density of 160.2 Wh kg-1 at a power density of 800 W kg-1. After 8000 charge-discharge cycles, the capacity retention rate was 78.5 %, with a Coulo mbic efficiency consistently above 98 %.

High-Energy-Density All-V2O5 Battery.

Symmetrical batteries hold great promise as cost-effective and safe candidates for future battery technology. However, they realistically suffer low energy density due to the challenge in integrating high specific capacity with high voltage plateau from the limited choice of bipolar electrodes. Herein, a high-voltage all-V2O5 symmetrical battery with clear voltage plateau is conceptualized by decoupling the cathodic/anodic redox reactions based upon the episteme of V2O5 intercalation chemistry. As the proof-of-concept, a hierarchical V2O5-carboncomposite (VO-C) bipolar electrode with boosted electron/ion transport kinetics is fabricated, which shows high performance as both cathode and anode in their precisely clamped working potential windows. Accordingly, the symmetrical full-battery exhibits a high capacity of 174 mAh g-1 along with peak voltage output of above 2.9 V at 0.5C, remarkable capacity retention of 81% from 0.5C to 10C, and good cycling stability of 70% capacity retention after 300 cycles at 5C. Notably, its energy density reaches 429 Wh kg-1 at 0.5C estimated by the cathode mass, which outperforms most of the existing Li/Na/K-based symmetrical batteries. This study leaps forward the performance of symmetrical battery and provides guidance to extend the scope of future battery designs.

Calculation method and evolution rule of the strain energy density of sandstone under true triaxial compression.

Deep rock masses are typically in complex stress states, and research on the evolution of their strain energy density is of highly important for understanding their failure characteristics. In this work, a true triaxial stress‒balanced unloading test is designed to analyze the ud and ue evolution of sandstone under true triaxial compression conditions. The study results indicate that as σ1 increases, the elastic strain decreases in the σ2 and σ3 directions, whereas the residual strain progressively increases, and the magnitude of decrease in elastic strain exceeds the magnitude of increase in residual strain. Throughout the loading process of σ1, ue progressively decreases in the σ2 and σ3 directions, whereas ud gradually increases, and the magnitude of decrease in ue surpasses the magnitude of increase in ud. The ud and ue of sandstone under different stress levels were calculated via true triaxial stress‒balanced unloading tests, and the evolution of ud and ue in the three principal stress directions and the overall strain energy density of sandstone followed a linear energy storage law. On the basis of this law and the true triaxial stress‒balanced unloading test, a new method for calculating the true triaxial ud and ue was proposed. A study on the σ1 unloading stress path revealed that the σ1 unloading stress path significantly affects the storage and dissipation of the strain energy density in the three principal stress directions of sandstone. On the basis of the research results, the criteria for determining rockbursts were discussed.

Anode-Free Li Metal Batteries: Feasibility Analysis and Practical Strategy.

Energy storage devices are striving to achieve high energy density, long lifespan, and enhanced safety. In view of the current popular lithiated cathode, anode-free lithium metal batteries (AFLMBs) will deliver the theoretical maximum energy density among all the battery chemistries. However, AFLMBs face challenges such as low plating-stripping efficiency, significant volume change, and severe Li-dendrite growth, which negatively impact their lifespan and safety. This study provides an overview and analysis of recent progress in electrode structure, characterization, performance, and practical challenges of AFLMBs. The deposition behavior of lithium is categorized into two stages: heterogeneous and homogeneous interface deposition. The feasibility and practical application value of AFLMBs are critically evaluated. Additionally, key test models, evaluation parameters, and advanced characterization techniques are discussed. Importantly, practical strategies of different battery components in AFLMBs, including current collector, interface layer, solid-state electrolyte, liquid-state electrolyte, cathode, and cycling protocol, are presented to address the challenges posed by the two types of deposition processes, lithium loss, crosstalk effect and volume change. Finally, the application prospects of AFLMBs are envisioned, with a focus on overcoming the current limitations and unlocking their full potential as high-performance energy storage solutions.

Local potential energy density - A DFT analysis and the local binding energy in complexes with multiple interactions.

A recently developed method, so-called local potential energy density, LPED, provides the binding energy density of intra/intermolecular interactions. The LPED cannot directly give the binding energy of intra/intermolecular interactions. However, it can indirectly give the binding energy through the linear equation between LPED and supramolecular binding energy, SME. In addition, the LPED can be used to obtain the SME of local or individual interactions indirectly for the case of complexes with multiple interactions, which cannot be obtained for any other method to our knowledge. The calculation of the LPED was evaluated with three different levels of theory using density functional methods. The linearity of LPED and SME between the reference level of theory (ωB97X-D/aug-cc-pVTZ) and the other levels of theory are similar among the studied levels of theory. In addition, LPED was used indirectly to obtain the local binding energy of intermolecular interactions of complexes with multiple interactions, such as the EDTA-Ca+2 and the fosfomycin-Ca+2.

Toward High-Energy-Density Aqueous Zinc-Iodine Batteries: Multielectron Pathways.

Aqueous zinc-iodine batteries (ZIBs) based on the reversible conversion between various iodine species have garnered global attention due to their advantages of fast redox kinetics, good reversibility, and multielectron conversion feasibility. Although significant progress has been achieved in ZIBs with the two-electron I-/I2 pathway (2eZIBs), their relatively low energy density has hindered practical application. Recently, ZIBs with four-electron I-/I2/I+ electrochemistry (4eZIBs) have shown a significant improvement in energy density. Nonetheless, the practical use of 4eZIBs is challenged by poor redox reversibility due to polyiodide shuttling during I-/I2 conversion and I+ hydrolysis during I2/I+ conversion. In this Review, we thoroughly summarize the fundamental understanding of two ZIBs, including reaction mechanisms, limitations, and improvement strategies. Importantly, we provide an intuitive evaluation on the energy density of ZIBs to assess their practical potential and highlight the critical impacts of the Zn utilization rate. Finally, we emphasize the cost issues associated with iodine electrodes and propose potential closed-loop recycling routes for sustainable energy storage with ZIBs. These findings aim to motivate the practical application of advanced ZIBs and promote sustainable global energy storage.

Thin Zinc Electrodes Stabilized with Organobromine-Partnered H2O-Zn-MeOH Cluster Ions for Practical Zinc-Metal Pouch Cells.

The utilization of thin zinc (Zn) anodes with a high depth of discharge is an effective strategy to increase the energy density of aqueous Zn metal batteries (ZMBs), but challenged by the poor reversibility of Zn electrode due to the serious Zn-consuming side reactions at the Zn||electrolyte interface. Here, we introduce 2-bromomethyl-1,3-dioxolane (BDOL) and methanol (MeOH) as electrolyte additive into aqueous ZnSO4 electrolyte. In the as-formulated electrolyte, BDOL with a strong electron-withdrawing group (-CH2Br) tends to pair with the H2O-Zn-MeOH complex, leading to the formation of organobromine-partnered H2O-Zn-MeOH cluster ions. During the Zn electrodeposition process, the formed ZnO-dominated by-products induce the polymerization of BDOL monomers, which are previously adsorbed on the electrode. As a result, a uniform dual-layer SEI with ZnO-dominated outer layer and polyether-dominated inner layer is built on the surface of Zn electrode. With such an in-situ formed dual-layer SEI, the Zn||Mg0.9Mn3O7·2.7H2O pouch cell using a 10-um Zn anode (corresponding to a low negative to positive areal capacity ratio of 3.56) successfully operated for 300 cycles with a high capacity retention of 86%, promising a high practical energy density of > 120 Wh/kg (based on the total mass of Zn and Mg0.9Mn3O7·2.7H2O).

Remodeling Highly Fluorinated Electrolyte via Shielding Agent Regulation toward Practical Lithium Metal Batteries.

Highly fluorinated electrolytes have proved effective in improving electrochemical stability of lithium metal batteries. However, excessive fluorination not only detrimentally impacts the electrolyte ionic conductivity, but also inevitably forms the over-fluorinated interphases with sluggish ion diffusivity. Herein, a strategy on remodeling Li+ solvation structure in highly fluorinated electrolyte aided is proposed by fluorinated amide (FDMA), which denoted as "shielding agent". Benefitting from FDMA's high donor number (DN) value (22.1), the Li+-dipole (fluoroethylene carbonate (FEC) or trans-4,5-Difluoroethylenecarbonate (DFEC)) interaction is interrupted and the participation of FDMA in primary solvation sheath fructify the solid-electrolyte interphase without scarifying the privilege of fluorinated electrolyte on interphase chemistry. Eventually, the optimal high-fluorinated electrolyte (FDMA/DFEC + 1.0 mol L-1 LiTFSI) with this unique shielding effect displays high ionic conductivity and rapid Li+ desolvation behavior, enabling Li||LiNi0.6Co0.2Mn0.2O2 (Li||NCM622) to achieve an ultralong cycle-life of 2000 cycles at 1C with 84.7% capacity retention. Even under extreme conditions (NCM622: 10 mg cm-2; electrolyte: 20 µL; Li: 50 µm), the Li||NCM622 displays excellent electrochemical performance. Additionally, 447 Wh kg-1 Li||LiNi0.8Co0.1Mn0.1O2 (Li||NCM811) pouch cells have been successfully fabricated and demonstrate an exceptional cycle-life over 150 cycles. The proposed "shielding" strategy to modulate the solvation structure paves the way for developing practical LMBs with fluorinated electrolytes.

Comparison of snack characteristics by diet quality findings from a nationally representative study of Australian adolescents.

Snacking is a common dietary behaviour among adolescents contributing to more than one quarter of their total energy intake; however, the relationship between snacks and diet quality remains unclear. Hence, this study aimed to examine the characteristics of snacks among adolescents with different levels of diet quality. Dietary data collected from a nationally representative sample of Australian adolescents (12-18 years old, n = 935) using one 24-hour dietary recall in the National Nutrition and Physical Activity Survey were analysed. Snacks were defined based on participant-identified eating occasions, and diet quality was assessed using the Dietary Guideline Index for Children and Adolescents (DGI-CA). Marginal means and proportion of snack characteristics including snack frequency, snack energy density (ED), and commonly consumed foods at snack from the five food groups and discretionary foods at snack across DGI-CA tertiles (highest tertile indicating high guideline adherence) were estimated for both boys and girls using linear regression and logistic regression. Differences in means were tested using the F-test. The results showed no significant differences in the mean frequency of snacks across tertiles of DGI-CA scores. The mean ED of snacks decreased as DGI-CA scores increased in both boys (lowest tertile = 8.4, 95% CI [7.1, 10.0] kJ/g, highest tertile = 6.3 [5.4, 7.4] kJ/g) and girls (lowest tertile = 9.0 [7.8, 10.3] kJ/g, highest tertile = 5.9 [5.1, 6.9] kJ/g). As diet quality improved, the proportion of adolescents consuming discretionary (i.e., unhealthy) foods and foods from the five food group foods as snacks decreased and increased, respectively. In conclusion, adolescents with higher diet quality consumed snacks with a lower ED while lower proportion of them consume discretionary foods, and higher proportion of them consume from the five food groups. Encouraging the consumption of foods from the five food groups with lower ED as snacks presents an opportunity to enhance adolescent diet quality.

Architecting Sturdy Si/Graphite Composite with Lubricative Graphene Nanoplatelets for High-Density Electrodes.

Densification of the electrode by calendering is essential for achieving high-energy density in lithium-ion batteries. However, Si anode, which is regarded as the most promising high-energy substituent of graphite, is vulnerable to the crack during calendering process due to its intrinsic brittleness. Herein, a distinct strategy to prevent the crack and pulverization of Si nanolayer-embedded Graphite (Si/G) composite with graphene nanoplatelets (GNP) is proposed. The thickly coated GNP layer on Si/G by simple mechanofusion process imparts exceptional mechanical strength and lubricative characteristic to the Si/G composite, preventing the crack and pulverization of Si nanolayer against strong external force during calendering process. Accordingly, GNP coated Si/G (GNP-Si/G) composite demonstrates excellent electrochemical performances including superior cycling stability (15.6% higher capacity retention than P-Si/G after 300 cycles in the full-cell) and rate capability under the industrial testing condition including high electrode density (>1.6 g cm-3) and high areal capacity (>3.5 mAh cm-2). The material design provides a critical insight for practical approach to resolve the fragile properties of Si/G composite during calendering process.

Nitrogen and Sulfur Doped Porous Carbon Sheet with Trace Amount of Iron as Efficient Polysulfide Conversion Catalyst for High Loading Lithium-Sulfur Batteries.

The major challenges in enhancing the cycle life of lithium-sulfur (Li-S) batteries are the polysulfide (PS) shuttling and sluggish reaction kinetics (S to Li2S, Li2S to S). To alleviate the above issues use of  hetero atom doped carbon as cathode host matrix is a low-cost and efficient approach as it works as a dual-functional framework for PS anchoring as well as electrocatalyst for faster redox kinetics. Here, the dual role of the Fe-containing heteroatom-doped carbon sheets (CS) in chemisorption of Li2S6 and catalyzing its faster conversion to Li2S  is established through UV-Vis, XPS and CV studies. To substantiate the catalytic effect composite cathodes were prepared by encapsulating sulfur in CS which is further blended with carbon nanotubes (CNTs) to form free-standing cathode. The electrochemical performance of the three cathodes viz., S@Fe-N-CS-CNT, S@Fe-S-CS-CNT and S@Fe-NS-CS-CNT were evaluated by constructing Li-S cells. Among all, the S@Fe-NS-CS-CNT delivers a high initial discharge capacity of 1017 mAh g-1 at 0.5 C rate and sustains 751 mAh g-1 capacity after 260 cycles with a capacity retention of 73.8 %. Even at high S-loading (12 mg cm-2), it delivers an initial discharge capacity of 892 mAh g-1 and it retained 575 mAh g-1 after 200 cycles.

A Master Curve for Fatigue Design of Notched Nodular Cast Iron Components Based on the Local Averaged Strain Energy Density.

The industry of off-highway vehicles is one of the fields of major application of nodular cast irons, which guarantee the manufacture of complex geometries and ensure good mechanical properties. The present investigation deals with the fatigue design of off-highway axles made of EN-GJS-500-7. Typically, off-highway axles are weakened by stress risers which must be assessed against fatigue. In this investigation, laboratory specimens have been extracted from an off-highway axle to take into account the manufacturing process effects. Different specimens' geometries have been prepared, including plain, bluntly notched and sharply V-notched specimens, and constant amplitude, load-controlled axial fatigue tests were conducted using two nominal load ratios, namely push-pull and pulsating tension loading. As a result, both the notch and the mean stress effects on the fatigue behaviour of EN-GJS-500-7 have been experimentally investigated for the first time. A well-known local approach, which takes the strain energy density (SED) averaged over a properly defined structural volume as a fatigue damage parameter, has been applied both in the linear elastic and elastic plastic formulations. Since the SED correlated the geometrical notch effects of the specimens as well as the mean stress effects, a master curve based on the averaged SED has been defined for the first time, to the best of the authors' knowledge, for the fatigue design of off-highway axles made of EN-GJS-500-7.

High-Density Capacitive Energy Storage in Low-Dielectric-Constant Polymer PMMA/2D Mica Nanofillers Heterostructure Composite.

The ubiquitous, rising demand for energy storage devices with ultra-high storage capacity and efficiency has drawn tremendous research interest in developing energy storage devices. Dielectric polymers are one of the most suitable materials used to fabricate electrostatic capacitive energy storage devices with thin-film geometry with high power density. In this work, we studied the dielectric properties, electric polarization, and energy density of PMMA/2D Mica nanocomposite capacitors where stratified 2D nanofillers are interfaced between the multiple layers of PMMA thin films using two heterostructure designs of the capacitors, PMMA/2D Mica/PMMA (PMP) and PMMA/2D Mica/PMMA/2D Mica/PMMA (PMPMP). The incorporation of a 2D Mica nanofiller in the low-dielectric-constant PMMA leads to an enhancement in the dielectric constant, with ∆ε ~ 15% and 53% for PMP and PMPMP heterostructures at room temperature. Additionally, a significant improvement in discharged energy density was measured for the PMPMP capacitor (Ud ~ 38 J/cm3 at 825 MV/m) compared to the pristine PMMA (Ud ~ 9.5 J/cm3 at 522 MV/m) and PMP capacitors (Ud ~ 19 J/cm3 at 740 MV/m). This excellent capacitive and energy storage performance of the PMMA/2D Mica heterostructure nanocomposite may inform the fabrication of thin-film, high-density energy storage capacitor devices for potential applications in various platforms.

Nanofibrous Covalent Organic Frameworks as the Cathode, Separator, and Anode for Batteries with High Energy Density and Ultrafast-Charging Performance.

To meet the demand for longer driving ranges and shorter charging times of power equipment in electric vehicles, engineering fast-charging batteries with exceptional capacity and extended lifespan is highly desired. In this work, we have developed a stable ultrafast-charging and high-energy-density all-nanofibrous covalent organic framework (COF) battery (ANCB) by designing a series of imine-based nanofibrous COFs for the cathode, separator, and anode by Schiff-base reactions. Hierarchical porous structures enabled by nanofibrous COFs were constructed for enhanced kinetics. Rational chemical structures have been designed for the cathode, separator, and anode materials, respectively. A nanofibrous COF (AA-COF) with bipolarization active sites and a wider layer spacing has been designed using a triphenylamine group for the cathode to achieve high voltage limits with fast mass transport. For the anode, a nanofibrous COF (TT-COF) with abundant polar groups, active sites, and homogenized Li+ flux based on imine, triazine, and benzene has been synthesized to ensure stable fast-charging performance. As for the separator, a COF-based electrospun polyacrylonitrile (PAN) composite nanofibrous separator (BB-COF/PAN) with hierarchical pores and high-temperature stability has been prepared to take up more electrolyte, promote mass transport, and enable as high-temperature operation as possible. The as-assembled ANCB delivers a high energy density of 517 Wh kg-1, a high power density of 9771 W kg-1 with only 56 s of ultrafast-charging time, and high-temperature operational potential, accompanied by a 0.56% capacity fading rate per cycle at 5 A g-1 and 100 °C. This ANCB features an ultralong lifespan and distinguished ultrafast-charging performance, making it a promising candidate for powering equipment in electric vehicles.

Long-lifespan 522 Wh kg-1 Lithium Metal Pouch Cell Enabled by Compound Additives Engineering.

Matching high-voltage cathodes with lithium metal anodes represents the most viable technological approach for developing secondary batteries with ultra-high energy density exceeding 500 Wh kg-1. Nevertheless, the instability of electrolyte/electrode interface film and commercial electrolytes with cut-off voltage above 4.3 V is still a major concern. Herein, we present that excellent cycling stability with an ultra-high cut-off voltage of up to 5.0 V can be obtained by using three-component additives containing fluoroethylene carbonate (FEC), hexadecyl trimethylammonium chloride (CTAC), and tri(pentafluorophenyl)borane (TPFPB). Excellent ionic conductivity, robust interfacial films on both electrodes, and long-lasting uniform Li+ regulation ability can be obtained in the modifying electrolyte. Consequently, using a high plating/stripping capacity of 3 mAh cm-2 under the current density of 1 mA cm-2, lithium symmetric cells demonstrate stable cycling performance exceeding 800 hours. Meanwhile, the 7.3 Ah-class Li[NixCoyMn1-x-y]O2 (x=0.83, NCM83)| Li pouch cells are assembled, which show a high energy density of 522 Wh kg-1 and present excellent stability over 178 cycles with a high initial coulombic efficiency (CE) of 98.0%.

Fabrication, Characterization, and Performance Evaluation of Thermally Stable [5,6]-Fused Bicyclic Energetic Materials.

In recent decades, there has been considerable interest in investigating advanced energetic materials characterized by high stability and favorable energetic properties. Nevertheless, reconciling the conflicting balance between high energy and the insensitivity of such materials through traditional approaches, which involve integrating fuel frameworks and oxidizing groups into an organic molecule, presents significant challenges. In this study, we employed a promising method to fabricate high-energy-density materials (HEDMs) through the intermolecular assembly of variously substituted purines with a high-energy oxidant. Purines are abundant in nature and are readily available. A series of advanced energetic materials with a good balance between energy and sensitivity were prepared by the simple and effective self-assembly of purines with high-energy oxidants. Notably, these compounds exhibit incredibly improved crystal densities (1.80-2.00 g·cm-3) and good detonation performance (D: 7072-8358 m·s-1; P: 19.82-34.56 GPa). In comparison to RDX, these self-assembled energetic materials exhibit reduced mechanical sensitivities and enhanced thermal stabilities. Compounds 1-5 demonstrate both high energy and low sensitivity, indicating that self-assembly represents a straightforward and effective approach for developing advanced energetic materials with a balanced combination of energy and safety. Moreover, this study offers an avenue for synthesizing energetic materials based on naturally occurring compounds assembled through intermolecular attractions, thereby achieving a balance between energy and sensitivity along with versatile functionality.

Deashing Strategy on Biomass Carbon for Achieving High-Performance Full-Supercapacitor Electrodes.

The porous carbon materials, namely, MC700/800, PC700/800, and SC700/800, have been prepared using several biomasses (mushroom dreg, Chinese parasol leaves, and Siraitia grosvenorii leaves) as individual precursors at 700 and 800 °C activation temperatures. Among these carbon-negative electrodes, SC700 exhibits an impressive specific capacitance, nearly 2-fold that of commercial activated carbon (169.5 F g-1). When assembled with a Ni(OH)2 positive electrode in asymmetric supercapacitors, the SC700//Ni(OH)2 device can achieve a specific capacitance of 80 F g-1 and an energy density of 32.16 Wh kg-1 at 1700 W kg-1. In contrast, the MC700 electrode can display inferior performance potentially attributed to the high ash content in the biomass. To further optimize the activated process of the MC700 product, three deashing carbon negative electrodes (denoted as MC(H2O), MC(HF), and MC(Mix)) were prepared by deashing treatment using H2O, HF, and mixed acid, and then a modified composite positive electrode (MC700@MnO2(MCM)) has been prepared by doping with MnO2. Electrochemical testing demonstrates that the deashing strategy achieves a significant capacitance enhancement compared to the primary carbon material while maintaining excellent cyclic stability. The asymmetric supercapacitors, assembled from these decorated electrode materials, exhibited a maximum energy density of 21.08 Wh kg-1 and a power density of 1150 W kg-1 under a high-voltage window of 2.2 V. Additionally, this type of full device can power 28 LEDs for approximately 5 min.

Supercapattery-Diode: Using Layered Double Hydroxide Nanosheets for Unidirectional Energy Storage.

The supercapacitor-diode (CAPode) is a device that integrates the functionality of an ionic diode with that of a conventional supercapacitor. The unique combination of energy storage and rectification properties in CAPodes is relevant for iontronics, alternate current rectifiers, logic operations, grid stabilization, and even biomedical applications. Here, we propose a novel aqueous-phase supercapattery-diode with excellent energy storage [total specific capacity (CT) = 162 C g-1, energy density = 34 W h kg-1 at 1.0 A g-1] as well as rectifying properties [rectification ratio I (RRI) of 23, and rectification ratio II (RRII) of 0.98]; the unidirectional energy storage is achieved by the utilization of an ion-selective redox reaction of battery-type layered double hydroxide (LDH) nanosheets serving as the electroactive material as well as asymmetric device configuration of supercapattery-diode in the KOH electrolyte. This work expands the types of CAPodes and importantly exemplifies the significance of integrating battery-type LDH and their redox chemistry, allowing a simultaneous increase in charge storage and rectification properties.