Portable Electronic Devices Research Articles

Achieving high area capacitance of Ti3C2Tx//MnO2 flexible aqueous zinc-ion hybrid microsupercapacitors with wide operating voltage window

Aqueous zinc-ion hybrid supercapacitors (AZIHSs) are extensively studied as a new kind of electrochemical energy storage devices that combine advantages of capacitors and batteries. It is highly desirable to develop AZIHSs with flexibility and miniaturization with the fast development of portable and wearable electronic devices. Herein, flexible aqueous zinc-ion hybrid microsupercapacitors (FAZIHMs) based on Ti3C2Tx anode and MnO2 cathode are constructed, which can successfully operate under 2.0 V voltage window and deliver a high area capacitance up to 252.8 mF/cm2 at 1 mV/s. The Ti3C2Tx//MnO2 FAZIHMs still maintain above 70.8 % capacitance retention with 94.5 % coulombic efficiency after 5000 successive cycles at 11.5 mA/cm2. Furthermore, favorable electrochemical performances are achieved under a series of mechanical bending levels with bending angles ranging from 0° to 90° for the Ti3C2Tx//MnO2 FAZIHMs. A LED and an electronic thermometer can be switched on simultaneously by the two above Ti3C2Tx//MnO2 FAZIHMs in series connection after being fully charged. This study of the FAZIHMs built upon Ti3C2Tx anode and MnO2 cathode with a high area capacitance and a wide operating voltage window aims at opening up a new way to exploit next-generation flexible and miniature electrochemical energy storage devices.

Electrostatic induced self-assembled MXene/EPOSS for high-performance electromagnetic interference shielding materials

It is still a challenge to prepare flexible electromagnetic interference (EMI) shielding materials based on Ti3C2Tx MXene through a facial and scalable method. In this study, epoxied octamethyl-cyclotetrasiloxane (EPOSS) was self-assembled with Ti3C2Tx to construct EMI shielding composites via facial spraying coating. Because the EPOSS decreased the surface free energy of Ti3C2Tx in the acid-base component, the Ti3C2Tx/EPOSS suspension was able to be sprayed on carboxylated polybutadiene (CPB) uniformly. Molecular dynamics (MD) simulations were explored to demonstrate the interaction energy between EPOSS and CPB with different –COOH contents. The prepared EMI shielding composite has high abrasion resistance and good bending durability because EPOSS reinforced the interface interaction between Ti3C2Tx and CPB through covalent bonds. Based on a pre-stretching spray method, the prepared composite has high surface roughness, leading to a high specific EMI shielding effectiveness of 1800 dB cm2 g−1 at a low Ti3C2Tx loading of 8.5 wt%. Additionally, the physically protective effect of Si–O–Si cages in EPOSS provided good flame retardancy. Therefore, the proposed EPOSS-assisted Ti3C2Tx spraying strategy could prepare EMI shielding materials with high effectiveness, excellent abrasion resistance, and good flame retardancy, which has a broad prospect for the application of high-power, portable, and wearable flexible electronic devices.

Flexible and sustainable printed sensor strips for on-site, fast decentralized self-testing of urinary biomarkers integrated with a portable wireless analyzer

Flexible and sustainable electronic devices may fulfill the requirements of Sustainable Development Goals (SDGs) contained in Agenda 2030 from United Nations, however, the use of degradable and eco-friendly devices for rapid, selective and on-site decentralized monitoring of patient health status with portable systems toward diagnosis, fast decision and medical interventions is relatively new. Herein, we introduce flexible and sustainable substrates/support of degradable bio-based PLA films from renewable resources produced by casting method as a sustainable alternative to conventional petroleum-based plastics toward portable electronic devices and sensing applications. The flexible devices containing full electrochemical sensing system were built with screen-printing process on PLA sustainable substrates for on-site, rapid decentralized monitoring of molecular biomarkers in non-invasive sample. Reliable urinary dopamine and uric acid analysis with limit of detections of 0.138 µM and 0.595 µM could be performed with low-cost sustainable devices (<US$ 0.08 per unit) in undiluted human urine using a flexible sensor strip coupled with a Sensit BT portable analyzer connected via Bluetooth to a smartphone, laptop or tablet. The flexible eco-friendly sensor was highly robust against severe bending strains, reproducible and selective without interference from other compounds in human urine. The sustainable sensor response was fast within 3 min with an analytical performance comparable to the gold standard method.

Multi-material 3D printing of piezoelectric and triboelectric integrated nanogenerators with voxel structure

Flexible and highly filled piezoelectric nanogenerators with excellent performance play an indispensable role in portable electronic devices, while the bottlenecks are hard to improve the polarization efficiency and prepare three-dimensional (3D) amplifying effect structure. Compared with other typical 3D printing technologies, direct ink writing multi-material printing (DIW-M3D), can extrude multiple viscoelastic ink materials with a wide selection of materials, which has the advantage of integrated multi-material processing. However, there are fewer reports on the use of DIW-M3D technology to print functional composite materials. Inspired from Lego block structures, we utilized DIW-M3D technology to prepare fabrications with alternating arrangements of piezoelectric and conductive inks between layers. This voxel-isolated conducting network provided the superior polarization path and uniform distribution of polarization field, which sharply ameliorate the piezoelectric effect and output performance. Owing to this voxel-isolated structure, the VOC and ISC could reach 150 V and 16 µA respectively, with the jumping movements of the forefoot. This work paved a path of scale-up preparing piezoelectric devices with 3D amplification effect structure and enhanced the polarization efficiency of the devices.

Battery technologies: lithium &amp; beyond

Global efforts to mitigate climate change are causing a transition from non-renewable energy resources (fossil fuels) to renewable energy resources (wind, solar, hydroelectricity, geothermal). This energy transition to sustainably meet the world’s growing needs for electricity, heating, cooling, and power for transport is widely considered to be one of the biggest challenges facing humanity in this century. The transition is enabled by improvements in generation and storage technologies critical to harvesting inherently intermittent renewable energy. Moreover, growing needs for smaller, lighter, more powerful portable electronic devices and more powerful electric vehicles suitable for long-range transportation have further fostered the demand for dispatchable and efficient electrical energy storage. These have catalyzed rapid development and commercialization of high-energy and lightweight rechargeable batteries, primarily based on lithium. However, lithium-enabled rechargeable batteries are plagued with challenges such as uncontrolled surface/interface (low safety), sluggish transport &amp; reaction kinetics (slow charging), &amp; relatively rare abundance of the metal (high cost). Moving beyond lithium necessitates the development of safe &amp; fast-charging rechargeable batteries based on relatively abundant metals (i.e. Na, Zn, Al, Fe, etc.).

Sandwich structure electromagnetic interference shielding composites based on Fe3O4 nanoparticles/PANI/laser-induced graphene with near-zero electromagnetic waves transmission

High-performance electromagnetic interference (EMI) shielding materials with flexible and lightweight characteristics are still a hot research direction, which will be highly promising in many application fields. In this work, laser-induced graphene (LIG) as the top and bottom layer, and binary composites of co-precipitated Fe3O4 NPs and in-situ chemical polymerized PANI (FePA) functioned as the intermediate layer is assembled to prepare a sandwich structure shielding material (FePA/LIG composite). 3D porous LIG with excellent conductivity is conducive to promote reflection and multiple reflections of incident electromagnetic waves (EMWs), while the transmitted EMWs will be further absorbed and attenuated via FePA composite due to its high impedance matching and microwave absorption (MA) properties. Near-zero EMWs transmission can be achieved and the average EMI shielding effectiveness (SE) of FePA/LIG composite (with thickness less than 2 mm) over the entire X-band and Ku-band is 50 dB and 63 dB, respectively. The admirable EMI shielding performance and flexibility of FePA/LIG composite endows enormous potential in portable electronic devices.

Young Children’s Electronic Media Use and Parental Rules and Regulations

Today’s children are born and raised in media-saturated environments, surrounded by televisions, computers, tablets, smartphones, and other portable electronic devices. Because these devices have become an indispensable part of everyday life, they have a significant influence on children's entertainment and leisure, as well as their education. This study, therefore, examined how early and how much young children (from 0 to 6 years of age) use television, computers, and tablet/smartphones, specifically whether this media usage is directly affected by socio-demographic factors related to parents (i.e., their education, income, and age), the children themselves (i.e., their age, gender, and the presence and number of siblings), and the media environment in their homes (i.e., the availability of media, parental opinions about media, and regulation of media use). The sample for this study consisted of 412 parents of 0- to 6-year-old children who brought their children to the Social Paediatrics Department of the Faculty of Medicine in Ankara, Turkey, for developmental check-ups. The data for this study were collected through a questionnaire that was prepared by the researcher. The findings indicate that almost all children live in homes with different types of electronic media devices and the children’s home electronic media environments and their parents’ demographics are important predictors for their usage of electronic media.

Perspectives on the development of advanced lithium metal anode

The demand for high-energy Li batteries is rapidly increasing due to the growing market for electric vehicles and portable electronic devices. Lithium (Li) metal has been considered as an ideal anode for high-energy Li batteries because of its high theoretical capacity (3860 mAh g&lt;sup&gt;-1&lt;/sup&gt;) and low redox potential (-3.04 V vs. SHE). However, the utilization of Li metal anode is still limited by fundamental problems associated with unavoidable dendritic growth and huge volume changes during cycling. To improve the electrochemical performance of Li metal anode, various strategies have been explored including electrolyte design, interfacial engineering, and structural modifications. One of the most promising approaches is to store Li metal in porous host materials, which can effectively suppress the formation of Li dendrite and volume expansion. Herein, we focus on recent progress in the development of advanced Li metal anodes and suggest research directions and design rules.

A rotational energy harvester with a semi-flexible one-way clutch for capturing low-frequency vibration energy

Renewable vibration energy is widely distributed in our living environment, but the low-frequency and irregular features impede its efficient exploitation and practical applications. To solve this issue, this paper proposes an innovative semi-flexible one-way clutch (OWC) and an OWC-based rotational energy harvester (OWC-REH) to achieve high and useable electric power out of low-frequency (<5 Hz) vibrations. The OWC consists of a pendulum equipped with a flexible thruster and a rotor designed with zigzag-shaped bulges on its surface. Through the interaction between the thruster and the bulges, the conversion of the bi-directional pendulum swing to the uni-directional rotor rotation can be realized. When excited by vibrations with an amplitude of 12 mm, the rotor achieves a fast speed of 240 rpm and the OWC-REH can generate high output power of 4.3 mW at 2.4 Hz. The energy conversion efficiency of the OWC-REH reaches a high value of 36.2%. When the OWC-REH is fastened to human limbs, the harvested energy from human motions can maintain the normal operation of portable electronic devices. This study proposes a promising strategy for utilizing the pervasive low-frequency vibrations as the sustainable energy for low-power electronics.

Synergetic effect of interfacial polarization in room temperature cured PDMS-Graphite composite for triboelectric smart mat applications

Triboelectric nanogenerator (TENG) as an emerging energy technology has significantly broadened the self-powered sensor networks through sustainable mechanical energy harvesting and self-powered sensing capabilities. Triboelectric floor mats which can perform multitasks will be beneficial for smart home applications. So far the reported triboelectric mats are usually have, low performance materials, complex device fabrication and high cost of installation. Herein, an economic triboelectric smart-mat is developed for mechanical energy harvesting, human security, gait analysis, and intelligent house automation utilizing Polydimethylsiloxane (PDMS)-Graphite composite fabricated by cost effective room temperature curing technique. The optimized high performance polymer composite delivers an enhanced transferred charge density of 28 nC/cm2 and smart mat using the material generates an impressive power density of 950 mW/m2. The study unveils the influence of surface charge polarization inside a dielectric-dielectric TENG and provides the first experimental proof of interfacial polarization in a PDMS-Graphite composite matrix to enhance the triboelectric effect. The triboelectric smart mat with the minimal design was utilized to power portable electronic devices and two mats were combined to perform intelligent automation of household equipment’s like lights and fans, allowing them to automatically turn on when a person enters the room and turn off when he depart.

Numerical investigation on model predictive control of portable electronic devices based on MATLAB/FLUENT co-simulation framework

Temperature control of electronic devices is becoming increasingly important. A better temperature control strategy could improve system performance without any change in the hardware-based thermal design. However, the development of temperature control algorithms is still challenging due to the multiple inner heat sources and thermal constraints, which causes a widespread use of the basic look-up table method on current devices. In this paper, the control performance of model predictive control (MPC) on a laptop is numerically evaluated based on the MATLAB/FLUENT co-simulation framework. In the MPC algorithm, a skin temperature reconstruction model is contained to online estimate the temperature of exterior surfaces based on the information of inner sensors, and a simplified temperature prediction model is utilized to predict the future temperature of both the exterior surfaces and inner sensors. The individual control of the charging current and fan speed show that compared to the baseline look-up table method, the MPC could improve the cumulative charging capacity in 20 min by 20% − 40% under different scenarios, and reduce the average and maximum fan speed by about 30% and 23% respectively. The outstanding performance and low computational cost altogether demonstrate that the MPC algorithm has tremendous potential for practical applications.

Different metal cation-doped MnO2/carbon cloth for wide voltage energy storage

Aqueous gel supercapacitors, as an important component of flexible energy storage devices, have received widespread attention for their fast charging/discharging rates, long cycle life and high electrochemical stability under mechanical deformation condition. However, the low energy density of aqueous gel supercapacitors has greatly hindered their further development due to the narrow electrochemical window and limited energy storage capacity. Therefore, different metal cation-doped MnO2/carbon cloth-based flexible electrodes herein are prepared by constant voltage deposition and electrochemical oxidation in various saturated sulphate solutions. The influence of different metal cations as K+, Na+ and Li+ doping and deposition conditions on the apparent morphology, lattice structure and electrochemical properties are explored. Furthermore, the pseudo-capacitance ratio of the doped MnO2 and the voltage expansion mechanism of the composite electrode are investigated. The specific capacitance and pseudo-capacitance ratio of the optimized δ-Na0.31MnO2/carbon cloth as MNC-2 electrode could be reached 327.55 F/g at 10 mV/s and 35.56% of the pseudo-capacitance, respectively. The flexible symmetric supercapacitors (NSCs) with desirable electrochemical performances in the operating range of 0–1.4 V are further assembled with MNC-2 as the electrodes. The energy density is 26.8 Wh/kg at the power density of 300 W/kg, while the energy density can still reach 19.1 Wh/kg when the power density is up to 1150 W/kg. The energy storage devices with high-performance developed in this work can provide new ideas and strategic support for the application in portable and wearable electronic devices.

Two-dimensional conjugated coordination polymer monolayer as anode material for lithium-ion batteries: A DFT study

Nowadays, lithium-ion batteries (LIBs) play a crucial role in modern society in the aspect of portable electronic devices and large-scale smart grids. However, the current performance of lithium-ion batteries has been unable to meet the growing expectations of society and scientific community. Herein, we have synthetically investigated availability of 2D Ni-TABQ monolayer as anode based on DFT for LIBs applications. Our findings have demonstrated that 2D Ni-TABQ monolayer is a semiconductor with a small band gap of 0.2 eV, which suggest that the electronic property of 2D Ni-TABQ monolayer would take place an evident shift from semiconductor property to metallic property after Li adsorption. Furthermore, we checked the stability of 2D Ni-TABQ monolayer and investigated the viability of exfoliation from bulk multilayer Ni-TABQ to form 2D Ni-TABQ monolayer in the light of exfoliation energy and binding energy. We continuously studied electrochemical properties of 2D Ni-TABQ monolayer with respect of theoretical specific capacity, Li-ion diffusion barriers and open-circuit voltage. During the charging process, 2D Ni-TABQ monolayer can achieve a high specific capacity of 722 mAh/g with an open-circuit voltage range from 1.12 V to 0.22 V. These aforementioned results make the 2D Ni-TABQ monolayer a promising anode for LIBs.

Lightweight polyurethane composite foam for electromagnetic interference shielding with high absorption characteristic

Due to the rapid growth of electronic equipment technology, efficient electromagnetic shielding materials are needed for equipment and human protection. Among them, foam shielding materials with absorption as the primary mechanism have higher application value than highly reflective materials. Highly absorbing shielding materials can reduce the secondary pollution caused by electromagnetic wave reflection. In this study, we added Fe3O4@Polyvinyl alcohol (Fe3O4@PVA) and graphene oxide@silver (GO@Ag) into the polyurethane (PU) matrix and constructed Fe3O4@PVA and GO@Ag/PU composite foam by foaming. Fe3O4@PVA and GO@Ag form an excellent network structure in the PU foam skeleton, significantly improving its electromagnetic shielding effectiveness (EMI SE) and mechanical properties. The shielding effectiveness reached 30.9 dB with a specific EMI SE (SSE) of 274.9 dB × cm3 × g−1 at a Fe3O4@PVA filling of 7 wt%, where the electromagnetic wave absorption accounted for more than 80 % of the total EMI SE, proving absorption as the primary shielding mechanism. The results show that Fe3O4, as a ferromagnet, has both the dielectric loss of ferroelectric materials and the hysteresis loss of ferromagnetic materials in electromagnetic shielding, effectively improving the wave absorption performance of composite shielding materials. Therefore, this work provides a promising idea for efficient and lightweight wave-absorbing shielding materials in aerospace, portable electronic devices and lightweight wearable devices.

Layered Structures of Enriched V5+ States of Vanadium Oxide as a Hybrid Cathode Material for Long-Cyclable Aqueous Zinc-Ion Batteries.

Recently, aqueous zinc-ion batteries (AZIBs) have garnered much attraction because of their ecofriendly nature, cost effectiveness, and reliability. However, there are still many challenges in developing suitable cathode materials for practical usage in ZIBs. In this work, we have synthesized a layered V5+-rich vanadium oxide (V6O13) flaky structure that provided the electrolyte with a large active surface area. In addition to that, the mixed (V4+/V5+) valence states of V have significantly improved the ionic diffusion of Zn2+, thereby improving the V6O13 electrical conductivity. Therefore, the AZIBs based on the layered structure V6O13 cathode with 1 M ZnSO4 electrolyte exhibited a very high specific capacity of 394 mAh g-1 @ 0.1 A g-1 without the addition of any additives or electrode modification. The rate capability and cycle life are investigated at the current density of 2 A g-1, where the capacity retention was found to be around 94% along with a coulombic efficiency of 96% for over 100 cycles. Such a material with high electrochemical performance can be used for portable electronic devices and electric vehicular applications.

Impact of gradient porosity in ultrathick electrodes for lithium batteries

Technologies such as electric vehicles and portable electronic devices have an ever-present need for improved energy density and specific energy. To enhance these performance factors and reduce the cost of inactive components, ultrathick electrodes have become a large area of interest within the battery research field. However, ultrathick electrodes have not been incorporated into commercial batteries due to their sluggish kinetics, difficulty of fabrication, and poor high rate performances. To combat these challenges, this manuscript explores the utilization of gradient porosity in highly loaded LiCoO2 (LCO) electrodes of 54 mg/cm2 and an extreme ∼230 μm thickness. Novel gradient porosity electrodes were fabricated by a novel methodology to create monolithic electrodes of predesigned porosity. Homogeneous porosity electrodes of similar thicknesses were also fabricated and analyzed to compare to the gradient electrodes. Transport properties, such as tortuosity and high/low rate capabilities, were investigated for both the gradient and homogeneous porosity electrodes. For the first time, thick gradient porosity electrodes of predesigned porosity distribution have demonstrated much improved high rate capacity densities over benchmark homogeneous porosity electrodes of equivalent average porosity, while retaining low rate capabilities and very high capacity density.

40 Years of Low‐Temperature Electrolytes for Rechargeable Lithium Batteries

AbstractRechargeable lithium batteries are one of the most appropriate energy storage systems in our electrified society, as virtually all portable electronic devices and electric vehicles today rely on the chemical energy stored in them. However, sub‐zero Celsius operation, especially below −20 °C, remains a huge challenge for lithium batteries and greatly limits their application in extreme environments. Slow Li+ diffusion and charge transfer kinetics have been identified as two main origins of the poor performance of RLBs under low‐temperature conditions, both strongly associated with the liquid electrolyte that governs bulk and interfacial ion transport. In this review, we first analyze the low‐temperature kinetic behavior and failure mechanism of lithium batteries from an electrolyte standpoint. We next trace the history of low‐temperature electrolytes in the past 40 years (1983–2022), followed by a comprehensive summary of the research progress as well as introducing the state‐of‐the‐art characterization and computational methods for revealing their underlying mechanisms. Finally, we provide some perspectives on future research of low‐temperature electrolytes with particular emphasis on mechanism analysis and practical application.

40 Years of Low-Temperature Electrolytes for Rechargeable Lithium Batteries.

Rechargeable lithium batteries are one of the most appropriate energy storage systems in our electrified society, as virtually all portable electronic devices and electric vehicles today rely on the chemical energy stored in them. However, sub-zero Celsius operation, especially below -20 °C, remains a huge challenge for lithium batteries and greatly limits their application in extreme environments. Slow Li+ diffusion and charge transfer kinetics have been identified as two main origins of the poor performance of RLBs under low-temperature conditions, both strongly associated with the liquid electrolyte that governs bulk and interfacial ion transport. In this review, we first analyze the low-temperature kinetic behavior and failure mechanism of lithium batteries from an electrolyte standpoint. We next trace the history of low-temperature electrolytes in the past 40 years (1983-2022), followed by a comprehensive summary of the research progress as well as introducing the state-of-the-art characterization and computational methods for revealing their underlying mechanisms. Finally, we provide some perspectives on future research of low-temperature electrolytes with particular emphasis on mechanism analysis and practical application.

Flexible thermoregulatory microcapsule/polyurethane-MXene composite films with multiple thermal management functionalities and excellent EMI shielding performance

The development of miniaturized, flexible, and portable electronic devices has led to an increasing demand for multifunctional flexible films that can provide temperature regulation, electromagnetic interference (EMI) shielding, and thermal management. In this study, a novel hierarchical multifunctional flexible composite film is presented. The first step involves the synthesis of phase change microcapsule (PCMC) latex through in-situ polymerization. Next, PCMC and waterborne polyurethane (WPU) latex were mixed and dried using a binary colloidal approach to produce a flexible composite phase change film (WPU/PCMC) with complete anti-leakage and satisfying melting enthalpy (147.86 J g–1). To enhance the EMI performance and mechanical strength, a thin layer of antioxidant MXene@poly tannin acid (PTA) was directly sprayed onto the surface of WPU/PCMC, resulting in the WPU/PCMC/MXene@PTA film (WPM). Consequently, the WPM displays exceptional thermal management performance for multiple drives and outstanding EMI performance (56.86 dB), making it an ideal candidate for future multifunctional products.

Converting the Liquid Electrolyte of Li Batteries into a Catalyst for CO2RR via Laser Irradiation

Li-based batteries are currently the most widely used energy storage technology in electric vehicles and portable electronic devices, but discarded batteries represent a growing environmental hazard. The flammability of the liquid electrolyte particularly requires exploration of alternative recycling methods. Herein, we report the photochemical conversion of usual carbonate-based electrolytes into a new catalyst with remarkable activity and selectivity for the CO2 reduction reaction. Solutions of LiPF6 in different organic solvents are first deposited on a Cu substrate and irradiated by a 1.88 eV laser. After air exposure, a layer consisting of LiF and graphitic carbon deposited on CuxO is obtained. When tested for the electrochemical reduction of CO2, this material converts in situ into an effective catalyst with a faradic efficiency as high as 46.7% for CH4, which is maintained above 40% for at least 100 h.