Power Source For Electronic Devices Research Articles

A novel benzoquinone‐azo linked polymer‐based active electrode material for high‐performance symmetric pseudocapacitors

AbstractPseudocapacitors (PSCs) have attracted researcher's attention due to their potential electrochemical performance as the power source for electronic devices. However, to maintain the high electrochemical properties of pseudocapacitive materials becomes critical. Therefore, the active electrode materials design and synthesis is a challenging task. To tackle these problems, herein, we rationally designed new polymer based on benzoquinone with azo linker. The polymer AZO‐BQ‐P was synthesized and tested for their energy storage applications in combination with graphite foil (GF). In three‐electrode supercapacitor (SC) device, the AZO‐BQ‐P/GF electrode exhibits excellent specific capacitance (Csp) of about 306.27 F g−1 at 0.5 A g−1 current density and higher cycling stability. The pseudocapacitive performance of SC cells result from synergistic effect of AZO‐BQ‐P and GF and due to faster electrolyte ion diffusion and increased availability at electrode/electrolyte interfaces. Furthermore, AZO‐BQ‐P/GF electrode was employed to fabricate two‐electrode AZO‐BQ‐P/GF//AZO‐BQ‐P/GF symmetric SC device. The optimal SSC device shows a Csp reaching 200 F g−1 at 0.5 A g−1, which is an impressive value. Also, it exhibits remarkable cycling stability with 86.18% Csp retention after 5000 galvanostatic charging–discharging (GCD) cycles at 3 A g−1. The SSC device applying AZO‐BQ‐P/GF electrode delivers an excellent energy density (ED) of 25.00 Wh kg−1 at 900.00 W kg−1 power density (PD). Thus, the novel polymer design offers efficient electrode materials to enhance the pseudocapacitive electrochemical performance of the SSC device. This concept can be extended for fabricating other electrochemical systems and accelerate its applications for modern electronic devices.

NiCo2O4 Nanowires Immobilized on Nitrogen-Doped Ti3C2Tx for High-Performance Wearable Magnesium-Air Batteries.

Flexible magnesium (Mg)-air batteries provide an ideal platform for developing efficient energy-storage devices toward wearable electronics and bio-integrated power sources. However, high-capacity bio-adaptable Mg-air batteries still face the challenges in low discharge potential and inefficient oxygen electrodes, with poor kinetics property toward oxygen reduction reaction (ORR). Herein, spinel nickel cobalt oxides (NiCo2O4) nanowires immobilized on nitrogen-doped Ti3C2Tx (NiCo2O4/N-Ti3C2Tx) are reported via surface chemical-bonded effect as oxygen electrodes, wherein surface-doped pyridinic-N-C and Co-pyridinic-N moieties accounted for efficient ORR owing to increased interlayer spacing and changed surrounding environment around Co metals in NiCo2O4. Importantly, in polyethylene glycol (PVA)-NaCl neutral gel electrolytes, the NiCo2O4/N-Ti3C2Tx-assembled quasi-solid wearable Mg-air batteries delivered high open-circuit potential of 1.5V, good flexibility under various bent angles, high power density of 9.8mW cm-2, and stable discharge duration to 12h without obvious voltage drop at 5mA cm-2, which can power a blue flexible light-emitting diode (LED) array and red smart rollable wearable device. The present study stimulates studies to investigate Mg-air batteries involving human-body adaptable neutral electrolytes, which will facilitate the application of Mg-air batteries in portable, flexible, and wearable power sources for electronic devices.

Chaotropic Effect-Boosted Thermogalvanic Ionogel Thermocells for All-Weather Power Generation.

Ionic thermocells convert heat into electricity and are promising power sources for electronic devices. However, discontinuous and small electricity output limits practical use under varying environmental conditions. Here, a thermogalvanic ionogel with a high Seebeck coefficient (32.4mV K-1) is designed. Thermocells that combine thermogalvanic ionogel-based thermocells, which realize all-weather power generation via passive radiative cooling, are also developed. These thermocells generate electricity continuously under varying weather conditions and over a wide temperature range (-40 to 90 °C), with a normalized power density of 25.84mW m-2 K-2. Advanced characterization shows that the chaotropic effect enhances the Seebeck coefficient, while the self-supplying temperature difference given the radiative cooling structure enables all-weather power generation. These results provide an effective strategy for developing practical thermocells suitable for diverse daily and seasonal variations.

Design and Development of Cathode Materials for Rechargeable Batteries

Over the past two decades, rechargeable Li-ion batteries (LIBs) have been the de facto standard power source for electronic devices [...]

Novel Acrylonitrile-Based Polymers for Solid–State Polymer Electrolyte and Solid-State Lithium Ion Battery

Rechargeable lithium-ion batteries (LIBs) involving lithium metal oxides, liquid electrolyte and graphite have been widely used in portable electronic devices due to their relatively high energy density and long cycle life. These desirable features make LIBs very attractive as the power source for electronic devices, hybrid electric vehicles (HEVs) and electric vehicles (EVs) applications [1, 2]. For future EV applications, higher energy density of LIBs up to 360 Wh kg-1 is required. Currently, the energy density of the state-of-the-art LIBs using conventional graphite anode, LiFePO4 (denoted as LFP) or LiNi0.5Co0.2Mn0.3O2 (NCM523) cathodes and 1-1.2 M LiPF6 in organic carbonate electrolytes provide practically achievable energy densities of up to around 200-260 Wh kg−1 [3]. When commercial graphite anodes are used, LiNi0.8Co0.15Al0.05O2 (NCA), LiNi0.8Co0.1Mn0.1O2 (NCM811), LiNi0.5Mn1.5O4 (LNMO) and LiNiPO4 (LNP) cathode based batteries with high-voltage provide energy densities of 354, 338, 351 and 414 Wh kg-1, respectively. However, LIBs using these high-voltage cathode materials and the organic carbonate electrolytes exhibit quite low thermal stability and tend to catch fire or even explode when abnormal charge/discharge cycling or accidental penetration of cells occurs, which greatly limits the automotive applications. When replacing graphite with a Li metal anode, the energy densities of all battery systems can be enhanced significantly due to the highest theoretical specific energy density (3860 mAh g-1) among all anode materials for rechargeable LIBs. Nevertheless, commercial LIBs are prone to cause safety problems due to the safety concern arising from Li dendrite growth in liquid organic electrolytes [4-6].The promising solid-state LIBs offer high thermal stability (i.e., low risk in catching fire), high energy density, wide electrochemical stability window and less environmental impact. A competent electrolyte is the key component of solid-state LIBs. The solid-state electrolyte materials are mainly classified as solid polymer electrolytes (SPEs), inorganic solid electrolytes (ISEs), and organic/inorganic composite electrolytes. ISEs include oxide-based and sulfide-based materials [7, 8], which show very high ionic conductivity (10-2 – 10-3 S cm-1). Furthermore, the lithium ion transference number is close to 1. However, the major limitation factors of practical solid-state LIB applications are the large interfacial impedance between electrode and ISE and the difficulty of processing [9]. Considering processability, mechanical flexibility, interfacial compatibility and electrochemical stability, one prefers SPEs to the inorganic ceramic electrolytes. Nevertheless, SPEs have low ion conductivities (10−7 − 10−5 S cm−1 near room temperature) and most of the Li+ transference numbers are lower than 0.5 [10, 11]. The major requirements for SPEs include high ionic conductivity and transference number at room temperature, wide electrochemical potential window, high mechanical strength and excellent thermal stability. However, the ion conductivity is the most important (> 10-4 S cm-1 at room temperature desired) and should be considered first. The coordinating groups of a good polymeric host are expected to interact with Li+ and facilitate dissociation.In this study, we prepared various novel acrylonitrile-based polymers (e.g., acrylonitrile/acrylate copolymer and polymer with two pendant groups b-cyano ethyl ether (-O-CH2CH2-CN) sulfonate alkyl ether (-O-(CH2)3SO3Li). The corresponding SPEs comprising acrylonitrile-based polymer and ca. 50 wt.% lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) with high ionic conductivity (up to 10-3 S cm-1) at room temperature, high ion transfer number (up to 0.45) and large electrochemical potential window (oxidation stability > 5 V vs. Li+/Li) achieved. The selected SPEs were used as the separator in solid-state batteries with LiFePO4 as the cathode and Li foil as the anode; and long-term cycle stability of solid-state LIB was achieved. The polymers and corresponding SPEs were characterized by using DSC, SEM, XRD and FTIR measurements. Ionic conductivities of SPEs were determined from electrochemical impedance spectroscopy results. The linear sweep voltammetry technique was adopted to measure the oxidation stability window of SPE, and the Evans-Vincent-Bruce method was used to determined ion transfer number.

All‐Direct‐Ink‐Writing of Artistic Supercapacitors: Toward On‐Demand Embodied Power Sources

AbstractDespite the extensive studies on printed power sources for user‐customized shape‐versatile electronics, most of them have still focused on printing of electrochemically active materials, with little attention to passive components such as current collectors and packaging, thus hindering their versatile application. Here, all‐direct‐ink‐writing (DIW) of artistic supercapacitors (ASCs) as a facile and scalable strategy to enable power source‐unitized monolithic electronic devices with various form factors is demonstrated. Interdigitated nickel current collectors embedded inside a polyurethane support layer are fabricated using DIW printing, which can facilitate the subsequent printing of multi‐scale, ultrathick electrodes. Interstitial voids between the DIW‐printed adjacent electrode layers are densely infiltrated by click‐crosslinkable electrolyte inks with well‐tuned rheological properties. The void‐free electrode/electrolyte assembly is conformally printed with a waterproof packaging ink to enable hermetic encapsulation, eventually producing all‐DIW‐printed ASCs with efficient space utilization, design diversity, and dimensional scalability. Notably, the resulting ASC can be seamlessly unitized with arbitrary‐shaped 3D objects (e.g., miniature pagodas), allowing for the potential development of on‐demand embodied power sources for electronic devices.

High-performance flexible thermoelectric generator for self-powered wireless BLE sensing systems

This work reports a high-performance flexible thermoelectric generator (TEG) and its application for self-powered wireless Bluetooth (BLE) sensing systems. The proposed flexible TEG based on a polyimide substrate and an electrodeposited thermoelectric material is fabricated successfully. A high output voltage of 1.3 V is observed under a temperature difference ΔT of 52 °C. Its maximum output power and power density are 95.9 mW and 610.8 μW/cm2, respectively, under the same above ΔT. In addition, its remarkable flexible characteristic has been inspected, and its output performance is highly consistent under a repeatability evaluation. Our proposed flexible TEG shows much higher performance than that of other recently published works. Furthermore, two practical applications utilizing the fabricated flexible TEG have been successfully conducted. First, heat waste from an electric thermos pot is converted into electricity and used as an electrical power source for electronic devices. Second, a self-power wireless BLE sensing system driven by thermal heat waste is demonstrated. This work brings out a new opportunity in a futuristic flexible TEG to harvest thermal heat waste into useable electricity, especially in the fields of using wireless self-powered IoT sensing systems.

Sliding silicon-based Schottky diodes: Maximizing triboelectricity with surface chemistry

Triboelectric nanogenerators are an emerging energy technology which harvests electricity from mechanical energy. Within this technology there are sliding metal–semiconductor contacts, which can be miniaturized, and having a direct current (DC) output are suitable as autonomous power sources for electronic devices. Herein we explore the scope of engineering the surface chemistry of silicon towards maximizing the output of a Pt–Si Schottky diode-based triboelectric nanogenerator. Through the attachment of covalent Si–C-bound organic monolayers we have engineered silicon surface chemistry to systematically tune friction, wettability and surface work function, with the overall aim of clarifying the interplay between mechanical and electronic properties defining the DC output of a zero-bias sliding Schottky diode. Current outputs increase two-fold in amine- and alcohol-terminated monolayers compared to shorter and carbon-terminated films. This trend parallels the change in friction measured in response to surface functionalization. A pronounced effect of silicon doping on friction and current was revealed by atomic force microscopy, indicating a link between doping and friction, even at zero applied bias. This work reveals an electrical component of friction by demonstrating a friction excess in response to the flow of current, and it opens up novel avenues into the use of silicon, and its surface chemistry, as platform for triboelectric nanogenerators.

Progress in Piezoelectric Nanogenerators Based on PVDF Composite Films.

In recent years, great progress has been made in the field of energy harvesting to satisfy increasing needs for portable, sustainable, and renewable energy. Among piezoelectric materials, poly(vinylidene fluoride) (PVDF) and its copolymers are the most promising materials for piezoelectric nanogenerators (PENGs) due to their unique electroactivity, high flexibility, good machinability, and long–term stability. So far, PVDF–based PENGs have made remarkable progress. In this paper, the effects of the existence of various nanofillers, including organic–inorganic lead halide perovskites, inorganic lead halide perovskites, perovskite–type oxides, semiconductor piezoelectric materials, two–dimensional layered materials, and ions, in PVDF and its copolymer structure on their piezoelectric response and energy–harvesting properties are reviewed. This review will enable researchers to understand the piezoelectric mechanisms of the PVDF–based composite–film PENGs, so as to effectively convert environmental mechanical stimulus into electrical energy, and finally realize self–powered sensors or high–performance power sources for electronic devices.

A 3D-printed acoustic triboelectric nanogenerator for quarter-wavelength acoustic energy harvesting and self-powered edge sensing

Abstract Low-frequency acoustic energy harvesting is of great significance in the academic field and industry. In this work, we propose a 3D-printed acoustic triboelectric nanogenerator (A-TENG) with the properties of structural controllability, one-time molding, easy fabrication, and low cost. A quarter-wavelength acoustic resonator system based on the A-TENG is demonstrated and systemically investigated for high-performance acoustic energy scavenging. The system is capable of generating a power output of 4.33 mW under 100 dB sound pressure level excitation. Up to 72 LEDs and a commercial calculator can be directly and continuously driven by the acoustic resonator system, indicating its application as a power source for electronic devices. Furthermore, we develop a self-powered edge sensing system consisting of the A-TENG, an AI speech recognition chip, and control circuits. The speech signals can be firstly converted into electrical signals through the A-TENG, and then recognized and processed by the AI chip with a built-in and pre-trained neural network to control the follow-up circuits. The self-powered edge sensing system is capable of real-time speech recognition without cloud computing, exhibiting great potential in the field of low-power and cost-effective intelligent Internet of Things.

Composite Electrolytes Based on Sulfide-Based Solid Electrolytes and Highly Concentrated Electrolytes

Lithium-ion batteries (LIBs) have been widely used as power sources for electronic devices because of their high energy densities. LIBs are typically composed of a transition metal oxide cathode, a graphite anode, and an organic electrolyte. Flammability, volatility and liquid leakage issues of conventional organic electrolytes lead to safety concerns. As an alternative to organic liquid electrolytes, inorganic solid electrolytes are considered to be promising since they impart nonflammablity, and single ion conducting property [1],[2]. Among inorganic solid electrolytes, sulfide-type solid electrolytes show high ionic conductivity and softer mechanical properties compared to oxide-type solid electrolytes [3]. However, there is still large contact loss at the interfaces unlike liquid electrolyte systems, which results in high interfacial resistance between the electrode and electrolyte. Additionally, it is well-known that sulfides react with trace moisture in the atmosphere, resulting in generation of toxic H2S gas. The contact between the electrode active material and the solid electrolyte interface can be improved by mixing a small amount of electrolyte solution or gel electrolyte with the solid electrolyte. Among the liquid electrolytes, highly concentrated electrolytes with a high concentration of lithium salt show properties such as non-flammability and non-volatility. In our previous works, the concentrated electrolyte using sulfolane as a solvent shows a high lithium ion transference number of ~0.7. Therefore, it can be expected that a good interface is formed without sacrificing the intrinsic high Li ion transport property of the solid electrolyte such as lithium ion transference number of unity when a small amount of the concentrated electrolyte is impregnated.In this study, we prepared a composite electrolyte by mixing an Li7P3S11 (LPS) and a concentrated liquid electrolyte [Li(SL)2][TFSA] which is a 1:2 molar mixture of lithium bis(trifluoromethanesulfonyl)amide (LiTFSA) and sulfolane (SL), with different weight ratios of [Li(SL)2][TFSA]. After compression molding of the obtained composite, the ionic conductivity was determined by AC impedance measurement using an electrochemical cell.Figure 1 shows the ionic conductivity of the composite electrolytes with different weight ratios of the concentrated electrolyte added. As the ratio of concentrated electrolyte increased, the ionic conductivity in the composite electrolyte decreased. For the eletrolytes with the weight ratio of [Li(SL)2][TFSA] less than 20% ( i.e., LPS-rich composite electrolytes), the conductivity value was ~ 1 mS cm-1, which is close to the ionic conductivity of LPS (1.4 mS cm-1). On the other hand, when the weight fraction of concentrated electrolyte increases up to 40%, the conductivity value approached 0.42 mS cm-1 which is the ionic conductivity of [Li(SL)2][TFSA]. This result shows that Li ion conduction between LPS particles is a dominant route for the LPS-rich composite electrolyte, whereas the liquid phase appears to be the main conduction pathway for [Li(SL)2][TFSA]-rich composite electrolytes. An the intermediate weight ratios of the concentrated electrolyte of ~30%, the ionic conductivity significantly decreased. These results suggest that both LPS and the concentrated electrolyte serve as ion conducting pathway depending on the weight ratios and the interfacial resistance between the solid electrolyte and the liquid electrolyte is not a fatal problem in these composite electrolytes. Reference [1] N. Riphaus, P. Strobl, B. Stiaszny, T. Zinkevich, M. Yavuz, J. Schenll, S. Indris, H. A. Gasteiger, S. J. Sedlmaier, J. Electrochem. Soc., 2018, 165, A3993-A3999.[2] Y. Wang, D. Lu, M. Bowden, P. Khoury, K. Han, Z. Deng, J. Zhang, and J. Liu, Chem. Mater. 2018, 30, 990−997.[3] T. Ates, M. Keller, J. Kulisch, T.Adermann, S. Passerini, Energy Storage Mater., 2019, 17, 204–210.[4] A. Nakanishi, K. Ueno, D. Watanabe, Y. Ugata, Y. Matsumae, J. Liu, M. L. Thomas, K. Dokko, M. Watanabe, J. Phys. Chem. C, 2019, 123, 14229-14238. Figure 1

Design of Energy Harvesters on Motorcycle Exhaust using Thermoelectric Generator for Power Supply Electronic Device

One of the excess energies in the environment is motorcycle exhaust gas. Motorcycles with internal combustion engines produce energy waste where around 40% of the fuel energy is wasted in the form of heat energy through the exhaust to the environment. Various research studies to utilize the heat of motorcycle exhaust have been conducted, but the electric voltage generated is still below 5V. Therefore, it is not enough to be used as a power source for electronic devices using Universal Serial Bus (USB). This study aims to design an energy harvesting system using two modules of TEG TE-MOD-10W4V-40 that are organized in series and mounted on a motorcycle exhaust. The design of the device includes the construction of the heat exchanger, the boost converter circuit, and the charger box. The test results show that the maximum electrical voltage is successfully generated in a no-load condition of 4.2V with a temperature difference of 57°C. The design of the device is able to charge electronic devices such as speakers, smartphones, and tablets with an output voltage of 5.2V. The time needed since the motorcycle engine started to reach a constant voltage was 3 minutes.

Synthesis and Characterization of Material LiNi0.8Co0.15Al0.05O2 Using One-Step Co-Precipitation Method for Li-Ion Batteries

<p>Li-ion battery is an energy storage device which could be applied as power source for electronic devices. The capacity of a battery is determined by the cathode material. Over this last decade, high nickel content cathode material is applied for electric vehicular technology. This study aims to synthesize a nickel-rich cathode material, LiNi<sub>0.8</sub>Co<sub>0.15</sub>Al<sub>0.05</sub>O<sub>2 </sub>(NCA) via one-step co-precipitation and study its characteristics. The Ni, Co and Al metal ion conversion during co-precipitation were analyzed using Atomic Adsorption Spectroscopy (AAS). Based on X-Ray diffraction analysis, NCA sample exhibited hexagonal-layered structure with high crystallinity. Based on Scherrer equation, the mean crystallite diameter of NCA sample is 40 nm. Scanning electron microscope (SEM) showed micron-sized homogenous particles with smooth surface. The final composition of Ni, Co and Al metal were confirmed using XRF. The capacity of the battery was determined using galvanostic test method with voltage range of 2.7-4.25 V using graphite as the counter anode. The initial specific discharge capacity of NCA is 60 mAh/g while the capacity loss<em> per cycle is </em><em>1</em><em>%.</em></p>

Mini-Generator Based on Self-Propelled Vertical Motion of a Functionally Cooperating Device Driven by H2 -Forming Reaction.

Mini-generators based on locomotion of small objects have aroused widespread attention because of their potential application in powering small-scale electronic devices. Although improvements have been made in the development of mini-generators, there are still some key challenges such as low power output and energy conversion efficiency, which limit the potential application of mini-generators. Herein, through integrating a superhydrophobic surface, chemical reaction and solenoid coil/magnet into a system, an innovative mini-generator is designed, which can convert chemical energy into electrical energy through mechanical form. As a result, the energy conversion efficiency and output power are both three hundred times higher than previously reported results and can be applied to power light-emitting diodes without amplification. We believe that the proposed mini-generator provides more chance for the application of self-supplying power sources for electronic devices.

Increased Interfacial Area between Dielectric Layer and Electrode of Triboelectric Nanogenerator toward Robustness and Boosted Energy Output.

Given the operation conditions wherein mechanical wear is inevitable, modifying bulk properties of the dielectric layer of a triboelectric nanogenerator (TENG) has been highlighted to boost its energy output. However, several concerns still remain in regards to the modification due to high-cost materials and cumbersome processes being required. Herein, we report TENG with a microstructured Al electrode (TENG_ME) as a new approach to modifying bulk properties of the dielectric layer. The microstructured Al electrode is utilized as a component of TENG to increase the interfacial area between the dielectric layer and electrode. Compared to the TENG with a flat Al electrode (TENG_F), the capacitance of TENG_ME is about 1.15 times higher than that of TENG_F, and the corresponding energy outputs of a TENG_ME are 117 μA and 71 V, each of which is over 1.2 times higher than that of the TENG_F. The robustness of TENG_ME is also confirmed in the measurement of energy outputs changing after sandpaper abrasion tests, repetitive contact, and separation (more than 105 cycles). The results imply that the robustness and long-lasting performance of the TENG_ME could be enough to apply in reliable auxiliary power sources for electronic devices.

Output voltage modulation in triboelectric nanogenerator by printed ion gel capacitors

The triboelectric nanogenerator (TENG) has been investigated intensively during the last decade in terms of power improvement and application as sensors, however, its voltage is usually too high and spike-like to be used directly as a power source for electronic devices. Although there was an effort to adjust the voltage through the circuit design, the complexity and the bulkiness of the circuit board make it difficult. Here, we propose a simple approach to change the spike-like voltage profiles to square-like profiles and adjust the output voltage to be suitable range for electronics. We used printed ion gel electrolyte patterns as capacitors and investigated the effects of dimension of the capacitor, connection types (serial, parallel) of multiple capacitors, and electrochemical conditions. The voltage profile of the TENG-ion gel system was modulated by the contact frequency applied to the TENG, the contact area of the ion gel with the electrode, the type of ions in the electrolyte, reduction/oxidation reaction in the gel, and the connection type (parallel, series) between ion gel patterns. We successfully demonstrated the light emission of a large number of printed electrochemiluminescence patterns.

Highly active Rare Earth (RE) Vanadate, Tungstate loaded ZnO (RE= Gd, Dy and Ho) Nanocomposites for Electrochemical methanol Oxidation-A Comparative study for Fuel cell Application

Fuel cell converts chemical energy into electrical energy with negligible generation of pollutant. Direct methanol fuel cells (DMFC) are used as power source for electronic devices as its mass energy can be easily functionalized to these devices. We fabricated rare earth (RE= Gd, Dy and Ho) vanadate and tungstate supported ZnO nanomaterials hydrothermally and analysed their Electrocatalytic efficiency in methanol oxidation. It is noticeable that the current density of the prepared catalyst (GdVO4–ZnO: 3.42mA), (DyVO4–ZnO: 4.64mA), (HoVO4–ZnO: 3.30mA), (Gd2WO6–ZnO: 2.92mA), (Dy2WO6–ZnO: 2.64mA) and (Ho2WO6–ZnO: 2.90mA) is much higher than that of prepared ZnO (1.32 mA). Chronoamperometric curves indicate stability and poison tolerance of the prepared catalysts are much higher than prepared ZnO for methanol oxidation under alkaline medium.

Nanocomposite quasi-solid-state electrolyte for high-safety lithium batteries

Rechargeable lithium batteries are attractive power sources for electronic devices and are being aggressively developed for vehicular use. Nevertheless, problems with their safety and reliability must be solved for the large-scale use of lithium batteries in transportation and grid-storage applications. In this study, a unique hybrid solid-state electrolyte composed of an ionic liquid electrolyte (LiTFSI/Pyr14TFSI) and BaTiO3 nanosize ceramic particles was prepared without a polymer. The electrolyte exhibited high thermal stability, a wide electrochemical window, good ionic conductivity of 1.3 × 10−3 S·cm−1 at 30 °C, and a remarkably high lithium-ion transference number of 0.35. The solid-state LiFePO4 cell exhibited the best electrochemical properties among the reported solid-state batteries, along with a reasonable rate capability. Li/LiCoO2 cells prepared using this nanocomposite solid electrolyte exhibited high performance at both room temperature and a high temperature, confirming their potential as lithium batteries with enhanced safety and a wide range of operating temperatures.

Towards a prototype module for piezoelectric energy harvesting from raindrop impacts

It has been shown that scavenging energy from raindrop impacts has the potential as a power source for electronic devices and act as an alternative method of generating electrical power. In this paper an energy harvesting module is developed consisting of multiple piezoelectric devices which use impacts of raindrops to generate electrical power. The effect on efficiency of the module with non-rectified or rectified outputs of each device connected in parallel is investigated. Additionally, the voltage, power and energy were found for different surface angles, surface conditions and impact regions for single devices with a view to maximise module efficiency.The main findings of this work are that: a) a technique is found to identify the efficiency of the impact mechanism as the droplet interacts with the device and the efficiency of the mecheno-electric conversion mechanism due to internal losses in the device; b) values for the impact mechanism efficiency and the conversion mechanism efficiency are ascertained; and c) the optimum arrangement for a single device is determined.

Reduced Graphene Oxide Sheets Attached Tin Oxalate Dihydrate As a High Capacity Anode for Lithium Ion Rechargeable Batteries

Lithium ion batteries have been widely applied as power sources for electronic devices to electric vehicle because of their high energy density, and long cycle life. Commercial graphite is the most commonly used as the anode material for lithium ion batteries. However graphite has its low theoretical capacity (372 mAh g-1). Therefore, to satisfy the growing power requirements, we need to explore alternative materials to replace graphite anode. For these reason, the silicon-based materials, transition metal oxides have been intensively investigated to replace the commercial graphite due to their high capacities, 700 ~ 1000 mAh g-1. Metal oxalate MC2O4 (M : Mn, Fe, Co, Ni, Sn, Cu, Zn) are also interesting because of high capacity. In this study, we synthesize tin oxalate by hydrothermal reaction, of SnCl2ㆍ6H2O (0.001 M), NaC2O4 (0.005 M), distilled water (9 ml), and ethylene glycol (EG, 16 ml) were mixed in a beaker and the mixed solution was stirred at room temperature for 6 h to form transparent solution. This solution was filled in a Teflon-lined autoclave (100ml capacity). This autoclave was sealed and heated at 100 oC - 200 oC for 12 h. After then, the autoclave was cooled to room temperature. The reacted solution were filtered and washed several times with de-ionized water and then dried at 80 oC for 24 h in a convection oven. Also, various contents of rGO were attached by layer by layer method. The obtained powder was analyzed by X-Ray diffraction (XRD, Rigaku, D-max 2000) using CuKα radiation. The XRD data were obtained with 0.03 step size and a 1 s count time. The particle morphologies of the products were analyzed by scanning electron microscopy (SEM, Hitachi, S-4700) and transmission electron microscopy (TEM, Hitachi, H-800). Electrochemical properties were measured in 2032 coin type cell. Electrodes were fabricated from a mixture of the prepared SnC2O4ㆍ2H2O powders (80 wt%), ketjen black (5 wt%), super-P (5 wt%) and polyacrylic acid (10 wt%) in distilled water. The obtained slurry was then applied onto Copper foil and dried in a vacuum oven at 80 oC for 1 h. The electrode was further dried over night at 80 oC under vacuum. The used electrode solution was 1M LiPF6 in a 3 : 7 volume mixture of ethylene carbonate (EC) and dimethyl carbonate (DMC) mixture. The XRD pattern of the products showed single phase SnC2O4ㆍ2H2O and rGO attached both were obtained without impurity. The fabricated cells were charged and discharged in the range of 0 - 3 V applying a constant current of 100 mAg-1 at 25 oC. The bare sample delivered capacity approximately 643 mAh g-1 at initial charge. Also, the delivered capacities increased to 1170, 1220, 1440 mAh g-1 with increasing the amount of rGO (10, 20, 30 wt%). The rate capability demonstrate that the 30 wt% rGO composite SnC2O4ㆍ2H2O / rGO electrode delivered 467 mAh g-1 at 10 C-rate. Figure 1