Portable Electronic Devices Research Articles

Strategically-designed hierarchical polypyrrole-modified manganese-doped tin disulfide (SnS2) nanocomposite electrodes for supercapatteries with high specific capacity

Supercapatteries are novel energy storage devices possessing features of both supercapacitor and battery and evolved to meet the demand for portable electronic devices. An efficient electrode-active material is an important criterion for the fabrication of high performance supercapatteries. We hereby report the rapid synthesis of manganese (Mn)-doped tin disulfide (SnS2) by microwave-assisted hydrothermal method and further use it as an efficient electrode material (positrode) to fabricate a supercapattery. Dunn's kinetic method is adopted to estimate the contribution from the battery-type charge storage which confirm the electrode exhibits charge storage via diffusion-controlled mechanisms. The Mn-doped SnS2 electrode exhibits a specific capacity of 275.4 C g-1 at a scan rate of 10 mV s-1. The specific capacity is further increased by preparing nanocomposite electrodes with polypyrrole at different ratios. The polypyrrole-modified Mn-doped SnS2 electrode delivers a specific capacity of 539 C g-1 at a scan rate of 10 mV s-1. In order to understand its applicability in practical devices, a supercapattery cell is fabricated with polypyrrole-modified Mn-doped SnS2 as positrode and activated carbon as negatrode, which exhibits a mass specific capacity of 204.2 C g-1 along with an area specific capacity of 2.4 C cm-2 at a current density of 2 A g-1. The supercapattery cell possesses an energy density of 42.5 W h kg-1 with a corresponding power density of 2500 W kg-1 at a current density of 2 A g-1. This study proclaims that the polypyrrole-modified Mn-doped SnS2 is an efficient positrode for application in high-performance supercapatteries.

A Novel Design Strategy for Cantilever Based MEMS Piezoelectric Vibration Energy Harvesters: FEM Parametric Analysis and Modeling

Vibration-based energy-harvesting (VEH) technology is a viable alternative power source that addresses the issue of battery capacity constraints in portable electronic devices. A novel design strategy for developing a piezoelectric vibrational energy harvester (PVEH) based on a microelectromechanical system (MEMS) is proposed in this paper. Through FEM simulation and analysis, a correlation between the proof mass coverage (PMC) and piezoelectric coverage (PEC) for energy harvesters with different beam geometries is developed. The results show that the output power and resonant frequencies of the energy harvester are strongly dependent on the amount of PMC, PEC, and beam geometry. The optimum piezoelectric layer length for a PVEH depends on the amount of PMC and geometry of the beam. Moreover, as the PMC increases, the output power is found to be increasing. The structure with 80% PMC provides maximum output power. Also, a trapezoidal beam will give a lower resonant frequency than a rectangular beam. Thus the optimum design methodology for a cantilever-based MEMS PVEH in a given layout is to select the trapezoidal-shaped beam with a PMC of 60% to 80% and piezoelectric layer length equal to the beam length. This method would provide optimised resonant frequency and output power performance. Additionally, an analytical model is developed for the optimised cantilever PVEH based on trapezoidal geometry, and the simulation findings are validated with the analytical results.

Spinel nickel ferrite (NiFe2O4) materials synthesized via spray-pyrolysis for electrochemical supercapacitor application

To explore potential applications of NiFe2O4-based supercapacitors in various energy storage systems, including portable electronic devices, electric vehicles, and grid energy storage, highlighting the advantages and challenges of using NiFe2O4 in these applications. To identify and propose future research directions for further improving the performance of NiFe2O4 supercapacitors. In the study focuses on optimizing concentration of synthesis to achieve desirable structural and electrochemical properties, characterizing the synthesized materials, and assessing their specific capacitance, energy density, power density, cycle stability, and rate capability. The different molar precursor solutions were utilized for the formation of NiFe2O4 thin films by using the cost-effective spray pyrolysis technique. The impact of different molarities on the structural, morphological, elemental, optical, and charge storage performance of NiFe2O4 thin films has been studied. In the XRD studies identified the cubic crystalline structure with Fd-3 m space group symmetry of NiFe2O4. The FE-SEM shows the grain-like surface morphology of NiFe2O4 thin films. The EDAX study reveals that NiFe2O4 thin films were stoichiometric. Bandgap energy values of the thin films were observed in the range of 1.97 to 2.2 eV with allowed direct band gap transitions. The maximum specific capacitance for NiFe2O4 thin film was found to be 707 Fg−1 at 2 mVs−1 with the wider potential window of − 0.8 to + 1 .6 V in 1 M KOH aqueous electrolyte. GCD study confirms the pseudocapacitive behavior of NiFe2O4 thin films. The maximum specific energy and specific power were found to be 83.88 WhKg−1 and 5.294 KWkg−1 at a current density of 0.002 Ag−1. Such as spinel ferrite NiFe2O4 thin film electrodes as an excellent candidate material for electrochemical supercapacitor applications.

Synergistic effects of haematite/hausmannite anchored graphene hybrids in high-energy density asymmetric supercapacitors

Addressing the critical demand for advanced energy storage systems (ESSs) amid escalating global energy needs and population growth, this study pioneers the synthesis of graphene-supported haematite and hausmannite (Gr@Mn3O4@Fe2O3/NF) ternary composite cathodes. These cathodes are tailored for high-performance asymmetric supercapacitors (ASCs), leveraging an economically viable process of fabrication. This innovation represents a significant leap forward, employing cost-effective techniques without compromising efficiency. Synchrotron X-ray absorption spectroscopy (XAS) analysis reveals a distinct blend of Fe and Mn valences, confirming the composite's unique structure. Electrochemical assessment underscores the superior capability of the electrodes, registering an unprecedented specific capacitance of ∼854 F/g in aqueous electrolytes, far surpassing traditional electrodes. Additionally, the composite electrodes maintain ∼70 % capacitance retention and about ∼94 % coulombic efficiency under a high current density of 4 A/g. In an ASC configuration, pairing the Gr@Mn3O4@Fe2O3/NF cathode with an anode made of AC, the ASC achieves the highest capacitance of ∼139 F/g, an energy density of ∼156.3 Wh/kg at a power density of ∼1439 W/kg, coupled with outstanding cyclability in a 1.5 V. This research delineates a scalable pathway for fabricating cost-efficient, high-energy density SCs, heralding a new era of portable electronic devices with enhanced energy storage capabilities.

Method to Independently Measure the Electronic and Ionic Conductivity of Zinc Slurry Electrodes

Zn-MnO2 alkaline batteries are prevalent and reliable primary batteries due to their cost effectiveness, good safety characteristics, long shelf life and ability to deliver sustained power for continuous usage. This properties make alkaline batteries an ideal options to be used in remote controls, smoke detectors, wireless mice, toys and many portable electronic devices. Despite their advantages, the battery performance is constrained by the slurried Zinc anode. Because of this, researchers have prioritized the improvement of the anode, primarily aiming to enhance the capacity and stability of the active material. However, the actual behavior of the anode is limited by the ionic conductivity of Zinc slurry, which is several orders of magnitude lower than the electronic conductivity of the slurry. This causes the reacting front to begin at the anode-separator interface, leading to passivation of the anode, incomplete discharge and increased gassing.The utilization of Zinc in the slurry anode can be increased by bringing the values of ionic conductivity and electronic conductivity closer together. Unfortunately, due to the redox electrolyte mechanism that moves electrons through the anode [1], the literature does not have an established method that is able to independently measure the ionic and electronic conductivity of the slurry. Before methods can be proposed to improve ionic conductivity of slurry, a method must first be devised that is able to truly measure the ionic conductivity in isolation.In this study, a novel methodology is reported to quantify both the ionic and electronic conductivity of the slurried anode. This innovative approach aims to provide a deeper understanding of the complex interconnection between electronic and ionic conductivities of the Zinc slurry. By addressing this critical aspect, the research contributes to advancing the fundamental understanding of Zn-MnO2 alkaline batteries, potentially paving the way for significant improvements in their performance and reliability for a wide array of applications.

Synthesis and Characterizations of Novel Copolymers with Zwitterionic Moiety-Based Solid Polymer Electrolytes for Solid-State Lithium Metal Battery

Electric vehicles (EVs) have become the dominant choice in the automotive industry, displacing internal combustion engine vehicles (ICEVs) to some extent. The development of high-efficiency batteries is essential to meet these market demands. Conventional lithium-ion batteries (LIBs), which consist of a cathode, anode, separator, and liquid electrolyte (such as 1M LiPF6 in carbonate solvents), have been widely utilized in portable electronic devices, hybrid electric vehicles (HEVs), and EVs. This popularity is attributed to their relatively high energy density and extended cycle life [1]. However, LIBs with energy density exceeding 240 Wh kg-1 face challenges in terms of thermal stability, potentially leading to fire and explosions by overcharging or accidental cell penetration. This drawback significantly hinders their application in automotive settings [2, 3]. In response to these safety concerns, there is a shift towards incorporating solid-state electrolytes (SSEs) as a replacement for liquid electrolytes. SSEs include solid polymer electrolyte (SPE), inorganic solid electrolyte (ISE), and composite polymer electrolyte (CPE).Solid-state lithium metal batteries (SSLMBs) incorporating SPE hold significant promise for advancing energy storage technologies due to their high energy density and improved safety features. However, the low ionic conductivity and ionic transference number of SPEs present challenges in their application for solid-state batteries. This work focuses on designing novel copolymers with polar soft unit and zwitterionic unit to address these challenges.In this study, poly(ethylene glycol) methyl ether acrylate (PEGMEA) and sulfobetaine methacrylate (SBMA) were selected as the polar soft segment and zwitterionic unit, respectively. Various ratios of PEGMEA/SBMA in copolymers were synthesized and characterized, and the resultant SPEs consisting of resultant copolymers and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) were prepared. Subsequently, their electrochemical, thermal, mechanical, and morphological properties were systematically investigated. The copolymers-based SPEs exhibited improved electrochemical properties. The optimized SPE comprising the copolymer with the molar ratio of PEGMEA/SBMA = 1/3 and 50 wt% LiTFSI exhibited the ionic conductivity of approx. 2×10–4 S cm–1, lithium-ion transference number of approx. 0.3, Li+ diffusion coefficient of 15×10-12 cm² s-1, and oxidation stability of 5.2 V (vs. Li/Li+) at 25 oC. Additionally, the mechanical properties of such SPEs were assessed, showing improved tensile strength (up to approx. 6 MPa) and Young’s modulus (up to approx. 83 MPa) with increasing SBMA content. The selected SPE with the best electrochemical properties was sandwiched between a Li metal electrode and a LiFePO4 electrode to assemble a SSLMB. As a result, the discharge capacity (DC) at 0.1 C-rate and room temperature was approx. 170 mA h g–1. Furthermore, the DC at a 0.5 C-rate was approx. 146 mA h g–1, and the capacity retention of 70% obtained after 470 cycles. In summary, this work demonstrates the potential of tailored copolymers with zwitterionic moiety-based SPEs for SSLMB. The comprehensive characterization and performance assessments provide valuable insights into the design and optimization of polymer electrolytes for next-generation energy storage systems.The copolymers and corresponding SPEs underwent characterization through various techniques such as DSC, SEM, XRD, and FTIR. The Ionic conductivity of the SPEs was determined by analyzing the results obtained from EIS measurement. The lithium-ion diffusion coefficient (DLi+) for SPE in a symmetric SSLMB cell, Li/SPE/Li, was also calculated based on the EIS results [4]. The oxidation stability window of the SPE was measured using the linear sweep voltammetry technique, and the ion transfer number was determined using the Evans-Vincent-Bruce method [5].

Grain Analysis of NCM Cathode Materials by ASTAR Technique and Its Effect on Battery Performance

Lithium-ion batteries (LIBs) are one of the most promising energy storage systems for portable electronic devices, electric vehicles, and renewable energy systems. Among the various cathode materials for LIBs, nickel cobalt manganese (NCM) oxide has attracted considerable attention due to its high specific capacity, good cycling stability, and appropriate cost for commercialization. However, Ni-rich NCM (Ni >80%) showed poor cyclability and huge gas evolution because of surface instability.Single crystal NCM has been suggested as a solution to these issues due to its excellent properties. However, it is difficult to quantify the degree of single crystallinity because it is so far subjective. In this study, we employed ASTAR technique (transmission electron microscopy combined with electron backscatter diffraction) to investigate the microstructural features of NCM cathode materials. Our ASTAR analysis showed that NCM cathode materials consist of complex grain and grain boundary structures with varying orientations and sizes. By analyzing the grain size and its morphology, we were able to define the single crystallinity of NCM cathode materials, including the poly NCM and single crystal NCM particles.Furthermore, we found that the grain size and its distribution significantly affects the battery performance and lifespan of NCM cathode materials. Specifically, the poly NCM particles exhibited a larger grain boundary and surface area compared to the single crystal NCM particles. The poly NCM particles also showed a faster DC-IR increase and a shorter lifespan than the single crystal NCM particles, indicating that the grain size has a critical influence on the battery performance and lifespan of NCM cathode materials.Our results provide insights into the design and optimization of NCM cathode materials for next-generation LIBs. By controlling the grain size and its distribution of NCM cathode materials, it is possible to enhance the battery performance and lifespan. Therefore, our study highlights the importance of understanding the microstructural features of NCM cathode materials for developing high-performance and stable LIBs.

(Digital Presentation) On-Chip Micro-Supercapacitors of 3D Carbon Nanotube/Gold Nanocomposites through Silicon-Based MEMS Technology

The high-power and high-frequency response characteristics of supercapacitors have enabled their promising application in fasting charging/discharging scenarios such as power grid stabilization and Internet of Things (IoT). The widespread use of portable electronic devices and the evolution of the IoT have underscored the growing demand for the ongoing miniaturization and enhanced energy autonomy of existing circuit components [1]. Micro-supercapacitors (MSCs) have surfaced as a promising solution to meet these demands, offering superior power density and cycle life compared to similar battery products [2]. However, integrating MSCs with electronic circuits presents significant challenges, often serving as a roadblock to comprehensive system miniaturization. To cater to the requirements of practical application scenarios, particularly in System-in-Package (SiP) and System-on-Chip (SoC) contexts, the fabrication of MSCs requires the use of silicon-based semiconductors or Micro-Electro-Mechanical Systems (MEMS) technology [3]. This strategic approach not only enhances performance but also ensures shorter interconnection distances, more compact dimensions, and increased energy and power density across all components. Emphasizing high power density, elevated energy density, and responsive high-frequency behavior is crucial for the optimal characteristics of MSCs in future applications. As for electrode materials, carbon, which is abundant and cost-effective, has spurred extensive research into various nanostructured carbon-based materials for Electric Double-Layer (EDL) MSCs, including activated carbon, carbon nanotubes (CNTs), carbide-derived carbon, and onion-like carbon [4]. Additionally, transition metal oxides such as ruthenium oxide and manganese oxide, along with conductive polymers like polypyrrole and polyaniline, have proven useful as materials for pseudocapacitive micro supercapacitors [5]. Notably, CNTs fabricated through Chemical Vapor Deposition (CVD) are unequivocally compatible with MEMS microfabrication technology. In the context of EDL MSCs, a dense CNT network structure boosts energy density but impedes ion transport, thereby reducing power density. Conversely, a sparse CNT network structure facilitates ion transport but compromises high-frequency response due to fewer charge transfer paths. Therefore, the development of CNT-based MSCs tailored to practical application needs a more thorough investigation into CNT network structures and their current collector designs.Here, we report the fabrication of on-chip MSCs that are fully compatible with Silicon-based MEMS technology. Figure 1 illustrates the fabrication and characterization process of on-chip MSCs utilizing silicon-based MEMS technology, showing distinct surface morphologies of b-Si nanostructures after CNT growth and Au layer deposition. Figure 2 presents the electrochemical performance of the on-chip MSCs. The CV curves exhibit an ideal rectangular shape at a scan rate of 1 V/s. Even at a high scan rate of 100 V/s, the CV curve maintains a quasi-rectangular shape with minimal distortion, confirming the ultrafast response performance (Fig. 2 (a-b)). The phase angles of the on-chip MSCs are measured to be -68.9° and -66.2° in 1.0 M Na2SO4, and -64.1° and -70.8° in 0.5 M H2SO4 at 120 Hz (Fig. 2 (c)). The absence of a prominent semicircle in the Nyquist plots at high frequencies region implies fast electron transfer and ion diffusion within CNT/Au nanocomposite electrodes. Furthermore, the equivalent series resistances (ESR) are 0.604 Ω·cm2, 0.201 Ω·cm2, 0.504 Ω·cm2, and 0.126 Ω·cm2 for Si-CNT-20 and Si-CNT-20-Au MSCs (Fig. 2 (d)), indicating excellent interfacial contact between the CNT layer and Au current collector and good electrode conductivity. Fig. 2(e) shows that the MSCs deliver a specific capacitance (CA ) of 0.049 mF/cm2, 1.041 mF/cm2, 0.101 mF/cm2, and 1.368 mF/cm2 in 1.0 M Na2SO4 and 0.5 M H2SO4 at 120 Hz, respectively. The relaxation time constant (τ0 ) is calculated to be as short as 1.65 ms for the MSCs (Si-CNT-20-Au), underscoring rapid ion diffusion within electrodes in 0.5 M H2SO4 electrolyte (Fig. 2 (e)).In conclusion, we have successfully used b-Si as the scaffold structure and 3D CNT/Au nanocomposites as the active material for on-chip MSCs application. Significantly, the incorporation of this silicon-based 3D CNT/Au nanocomposite electrode presents promising prospects for the application of MSCs in varied domains, including wearable electronics, IoT devices, and sensor networks.

Investigation on the thermal runaway mechanism of electrolyte in lithium-ion batteries via ReaxFF molecular dynamics

Lithium-ion batteries have the advantages of high energy density and high cycle times, and have been widely used in portable electronic devices, electric vehicles, and large-scale energy storage. However, lithium-ion batteries are prone to thermal runaway. Subsequently, electrolyte decomposition and combustion occur, leading to an increase in battery temperature and even causing fires or explosions. In order to explore the reaction mechanism of thermal runaway in lithium-ion battery electrolytes, the volatile and combustible organic solvents are selected as the research object. Three different organic solvents were established, namely pure ethylene carbonate (C3H4O3) solvent and its mixture with dimethyl carbonate (C3H6O3) and diethyl carbonate (C5H10O3), respectively. The effect of heating on the thermal runaway of organic solvents was studied using reactive force field molecular dynamics (ReaxFF MD). All three organic solvents will produce a large amount of CH2 free groups and flammable organic substances such as C2H4 during pyrolysis, which is the main reason for thermal runaway of lithium-ion batteries. The research results may contribute to preventing and suppressing thermal runaway in lithium-ion batteries.

Analysis of Vibration Electromechanical Response Behavior of Poly(Vinylidene Fluoride) Piezoelectric Films

Studying the electromechanical response behavior of piezoelectric thin films under different loading conditions is of great value for the development and optimization of piezoelectric sensors and flexible portable electronic devices. This paper establishes the theory of large deflection vibration of rectangular four-edge simply supported piezoelectric thin films using the energy method, and analyzes the electromechanical response characteristics of vibration force (including resonant frequency and nonlinear vibration). Meanwhile, the electromechanical response behavior of Poly(vinylidene fluoride) (PVDF) films under different loading conditions (static and harmonic vibration) is analyzed. The study investigates the nonlinear vibration characteristics and resonance frequency variations under different film sizes and thickness conditions in the case of various loading conditions. The developed model can predict the resonance frequency associated with the plate dimensions. This study is of great significance for the research and application of laminated piezoelectric film sensors.

Hybrid films composed of reduced graphene oxide and polypyrrole-derived nitrogen-doped carbon nanotubes for flexible supercapacitors

Electrode materials for flexible supercapacitors possessing exceptional and maintaining electrical properties have garnered significant attention in academic research. The graphene oxide (GO) and polypyrrole-derived nitrogen-doped carbon nanotubes (N-CNTs) were mixed to obtain a GO/N-CNTs film. The GO/N-CNTs film was then reduced to prepare a flexible reduced GO (rGO)/N-CNTs film. The specific capacitance of the rGO/N-CNTs film electrode was 223.2 F g−1 at a current density of 0.5 A g−1. The rGO/N-CNTs supercapacitor exhibited a specific capacitance of 130 F g−1 and energy density of 18.04 Wh·kg−1 at a current density of 0.5 A g−1. Furthermore, the capacitance retention of the supercapacitor was 68.7 % when the current density increased to 20 A g−1. In addition, the cyclic voltammetry test indicated that the capacitance retention of the supercapacitor remained at 82.7 % after 8000 cycles, and the capacitance retention still reached 70 % even after bending 600 times. The present study successfully presented the remarkable electrical characteristics of supercapacitors based on rGO/N-CNTs films. Additionally, the investigation has highlighted the noteworthy flexibility of supercapacitors, a feature of considerable significance for applications in wearable technology, portable electronic devices, and flexible displays.

What does nanotechnology have to offer for lithium-ion batteries materials?

The need for renewable energy source for cheap, portable electronic devices like electric vehicles has promoted an attractive research and innovation in batteries, especially in lithium-ion batteries. Ever since the success commercialization of its application in Sony in 1990s, this kind of battery has proved its efficiency and expense in market as a result of years of research and discoveries, however being limited for various kinds of reasons. With the combination of nanotechnology, modifications have been made to improve the drawbacks of the batteries from the angle of materials. Despite the fact that many attempts of changes have not been well-rounded developed, the discoveries are of great help to future research. In this article, recent research about application of nanotechnology in the development of lithium-ion batteries will be discussed. Starting from the cathode materials to anode materials, the enhancements brought by nanoparticles in typical lithium-ion battery materials will be reviewed, along with their targets and working principles.

Ti3C2TX encapsulation of CTAB-functionalized polypyrrole nanospheres towards pseudocapacitive intensification in supercapacitors

The critical criteria for supercapacitor to power the increasingly prevalent portable electronic devices lies within its active material design that yields high specific capacitance without compromising rate performance. Herein, polypyrrole (PPy) was synthesized into nanospheres (PPy NS) to improve bulk ion transport kinetics. However, numerous interfaces generated by nanospherical structure induce high nanocontact resistance, resulting in low specific capacitance. Thus, PPy NS were surface-functionalized with cationic surfactant n-Cetyl-n,n,n-trimethylammonium bromide to facilitate enwrapping by highly electrically conductive Ti3C2TX nanosheets via electrostatic self-assembly, where the Ti3C2TX shells serves as effective conductive pathways. Flake sizes of Ti3C2TX nanosheets were modulated via probe ultrasonication to maximize conformability to PPy NS, minimizing tortuosity of ion diffusion pathways and establishing ubiquitous heterostructure contact. This resulted in enhanced rate performance of 74 % capacitive retention during scan rate increase from 1 to 100 mV s−1 (pure PPy NS at 58 %). Furthermore, positively charged moieties imparted by surface-functionalization of PPy NS instigate electronic coupling with negatively charged surface terminations of Ti3C2TX nanosheets, facilitating rapid interfacial electron transfer. Through simultaneous dimensional and surface charge alignment, the nanocomposite achieved specific capacitance of 619.7 F g−1 at 5 A g−1 (∼37-fold enhancement over pure PPy NS), despite incorporation of low amounts of Ti3C2TX (9 wt%). This work highlights the potential of such material integration techniques in realizing capacitive intensification beyond incremental improvements as well as boosting rate performance, with methodical employment of minimal functional additive. It serves as a framework for future studies optimizing 2D-0D material nanocomposites for supercapacitor applications.

Enhancing the charge transfer in triboelectric nanogenerator based on sulfonated poly ether ether ketone/carbon nanotubes proton exchange composite membrane

This study introduces an innovative type of triboelectric nanogenerator (TENG) that utilizes proton exchange membranes to significantly enhance the transfer of electric charge in a triboelectric layer. To achieve this, composite membranes were fabricated by applying a blade coating technique to a mixture of carbon nanotubes (CNTs) and sulfonated poly ether ether ketone (SPEEK), serving as the critical triboelectric layer in the TENG device. These composite membranes exhibit an exceptional ability to attract water molecules through hydrogen bonding. Thanks to the high electro-positivity of these water molecules, they actively participate in the triboelectrification process, resulting in a substantial increase in charge transfer efficiency within the TENG device. As a result, when compared to the conventional dry-based SP (SPEEK)-TENG, the wet-based SP-TENG demonstrates an astonishing surge in output current, exceeding an 860-fold increase. Furthermore, a SPC (SPEEK/CNTs)-0.5-TENG cell device shows remarkable performance by generating a peak current of 0.91 mA and a power density of 0.39 W/m2. Impressively, four SPC-0.5-TENG cells can rapidly charge a 470 µF capacitor to 2.1 V within 28 seconds, making them a viable power source for a variety of portable electronic devices. This material displays substantial promise for applications in self-powered technologies, ultimately contributing to a reduced dependence on external power sources.

Formic Acid Photo-Fuel Cells Consisting of TiO2 Photoanode and Pt Cathode.

Formic acid (HCOOH) has attracted much attention as a promising power source for portable electronic devices because of its ease of storage and transportation. Here we report that a simple HCOOH photo-fuel cell (PFC) consisting of mesoporous anatase TiO2 photoanode and Pt cathode stably delivers a short-circuit photocurrent (Jsc) of 5.94 mA cm-2 and an open-circuit voltage of 0.94 V under UV-light irradiation (light intensity, I=200 mW cm-2). The incident photon-to-current conversion efficiency and Faradaic efficiency reach ~90 % and ~100 %, respectively. The excellent performances of this HCOOH PFC, designed based on the discovery that HCOOH provides a large photocurrent by current doubling even in the presence of O2, not only solves the problem of conventional HCOOH FCs, but also achieves the performances far exceeding those of PFCs using biomass-derived organics reported so far.

Ag-Coated Super Duplex Stainless Steel AISI2507 with or without Crystallization of Secondary Phase as Advanced Li-Ion Battery Case Material

Li-ion batteries used in portable electronic devices and electric vehicles require high safety standards, necessitating the use of high-performance structural materials for battery casings. Super duplex stainless steel (SDSS) is a structural material suitable for portable electronic products owing to its excellent strength and corrosion resistance. SDSS AISI2507 was used to construct a Li-ion battery casing, a Ag coating was applied via physical vapor deposition (PVD) after the heat treatment of AISI2507 with or without a secondary phase, and the coating thickness was controlled by varying the PVD time. The thickness of the Ag coating layer increased proportionally with time, thereby enhancing the electrical conductivity. The structure and coating behavior were confirmed using FE-SEM, XRD, and GDS. The secondary phase was crystallized by the segregation of the alloy and formed a BCC structure. The FCC lattice structure exhibited excellent coating behavior on the austenite (FCC structure) of AISI2507. Conversely, the secondary phase exhibited low adhesion owing to differences in composition and crystal structure. However, the Ag coating layer on AISI2507 exhibited excellent electrical conductivity, outperforming conventional Ni-plated Li-ion battery casings comprising AISI304. However, the precipitation of the secondary phase must be controlled, as the formation of the secondary phase acts as a factor that decreases electrical conductivity from 58.8 to 53.6 (ICAS) %. The excellent performance of Ag-coated AISI2507 makes it suitable for the fabrication of enhanced Li-ion battery casings.

Advanced Ether‐Based Electrolytes for Lithium‐ion Batteries

AbstractLithium‐ion batteries (LIBs) have emerged as vital elements of energy storage systems permeating every facet of modern living, particularly in portable electronic devices and electric vehicles. However, with the sustained economic and social development, new‐generation LIBs with high energy density, wide operating temperature range, fast charge, and high safety are eagerly expected, while conventional ethylene carbonate (EC)‐based carbonate electrolytes fail to satisfy corresponding requirements. Comparatively, ether‐based electrolyte systems with fascinating properties have recently been revived in LIBs fields, and many advanced LIBs with exciting performances under ether‐based electrolytes have been developed. This review provides an extensive overview of the latest breakthroughs concerning ether‐based electrolytes applied in LIBs with intercalation cathodes. To systematically outline the progression of ether‐based electrolytes, this review is categorized from the perspective of anodes as follows: i) graphite anode‐based LIBs; ii) silicon anode‐based LIBs; iii) lithium metal anode‐based LIBs.

High Performance Piezoelectric Nanogenerators Based on Polyvinylidene Fluoride-Graphene Nanoribbon Composite Thin Films.

In this study, a highly efficient, sensitive, and lightweight piezoelectric nanogenerator (PENG) is developed using graphene nanoribbons (GNRs) incorporated into the polyvinylidene fluoride (PVDF) matrix. Unzipping multi-walled carbon nanotubes is an effective and scalable strategy for synthesizing graphene nanoribbons. The synthesized GNRs are employed to prepare nanometer-scale piezoelectric polymer composite films showing higher piezoelectric performance than neat PVDF. The impact of GNR concentration in the PVDF matrix on the electroactive phase content and piezoelectric properties of the composites is systematically investigated. X-ray diffraction (XRD) and Fourier-transformed infrared spectroscopy (FT-IR) analysis demonstrate an increase in the electroactive β and γ phases of PVDF by incorporating GNRs in the composites. With the optimized concentration of GNRs (1 wt%), the fabricated piezoelectric device can generate open-circuit voltage and an output power density of 26V and 16.52 µWcm2, respectively. It is also found that the PVDF-GNR 1 nanogenerator can be used to generate electrical power by converting mechanical energy from different human activities such as wrist bending, palm tapping, and toe tapping. The findings indicate that (PVDF-GNR 1) PENGcan be applied in self-powered portable and wearable electronic devices.

All-glycerogel stretchable supercapacitor with stable performance in a wide temperature window from −20 to 80 °C

Stretchable supercapacitors (s-SCs) are extensively used in portable and wearable smart electronic devices. However, existing s-SCs exhibit low electrical conductivity/stretchability, weak electrode/electrolyte interfaces, and limited operational temperatures, which severely limit their practical applications. Accordingly, we have developed a stretchable glycerogel supercapacitor (s-GGSC) addressing these limitations. Electrode is fabricated by glycerol-mediated robust integration of poly(vinyl alcohol) and poly(3,4-ethylenedioxythiophene) polystyrene sulfonate through a simple strategy of partial drying–reswelling and thermal annealing. This eliminates the conventional trade-off between electrical conductivity and stretchability and provides adaptability to wide temperature ranges (−20 to 80 °C). A compatible electrolyte is also fabricated using poly(vinyl alcohol), lithium perchlorate, and glycerol. Heat-mediated facile exchange of inter- and intramolecular hydrogen bonding enables robust bonding between the electrode and electrolyte in the developed s-GGSC, thus solving interfacial problems under harsh mechanical conditions. The high electrical conductivity (1089 ± 49 S m−1) and fracture strain (232%) of the electrode preclude the use of an additional current collector. s-GGSC exhibits areal capacitance retentions of 90.92% and 93.27% after 7 d of incubation at −20 and 80 °C, respectively, and excellent cycling stability (81.48% capacitance retention) after 10,000 cycles. Furthermore, the areal capacitance of the device remains constant after intense mechanical deformations, such as bending, twisting, and stretching. s-GGSC outperforms existing flexible and/or stretchable supercapacitors under harsh conditions, confirming its suitability as a potential power source for wearable and stretchable smart electronic devices.

Sustainable and efficient recovery of lithium from rubidium raffinate via solvent extraction

In recent years, with the increasing prevalence of rechargeable lithium-ion batteries in the burgeoning markets of electric vehicles and portable electronic devices, the consumption of lithium batteries has significantly surged. Hence, the efficient development and utilization of associated lithium resources bear paramount significance. This study aims to recover lithium from rubidium raffinate via solvent extraction. A systematic investigation was conducted to examine the effects of various parameters such as organic phase concentration, contact time, and phase ratio (O/A) during the separation process. The results indicated that the organic phase composed of 0.1 mol/L 4,4,4-Trifluoro-1-phenyl-1,3-butanedione (HBTA) and 0.1 mol/L Trioctylphosphine oxide (TOPO) could efficiently extract lithium from the rubidium raffinate. The optimal conditions were observed at a temperature of 20℃, O/A=1, and a contact time of 5 min. After three-stage countercurrent extraction, a lithium extraction rate of 99.24 % could be achieved, with over 95 % of the sodium easily scrubbed by 0.1 mol/L HCl at an O/A=10. With the use of 3 mol/L HCl, stripping efficiency exceeding 99 % could be attained at an O/A=10, consequently a successful preparation of battery-grade lithium carbonate product was achieved. Regeneration experiments confirmed the organic phase's excellent reproducibility efficiency. Slope analysis and density function theory (DFT) simulations indicated that optimal lithium extraction is achieved when HBTA and TOPO are at equal molar concentrations. The proposed process is expected to provide a green and sustainable route for the recovery of associated lithium resources.