A High Performance Lithium-Ion Capacitor with Both Electrodes Prepared from Sri Lanka Graphite Ore

Effect of sucrose-based carbon foams as negative electrode additive on the performance of lead-acid batteries under high-rate partial-state-of-charge condition

Lead-acid batteries are noted for simple maintenance, long lifespan, stable quality, and high reliability, widely used in the field of energy storage. However, during the use of lead-acid batteries, the negative electrode is prone to irreversible sulfation, failing to meet the requirements of new applications such as maintenance-free hybrid vehicles and solar energy storage. In this study, in order to overcome the sulfation problem and improve the cycle life of lead-acid batteries, active carbon (AC) was selected as a foaming agent and foam fixing agent, and carbon foams (CF) with layered porous structure was prepared by mixing with molten sucrose. Sucrose as raw material is green and cheap, and the material preparation process is simple. The prepared CF material was then added as an additive to the negative electrode plate, and the electrochemical performance of the electrode plate and the battery was studied. The results proved that the addition of CF could effectively inhibit the sulfate formation of the negative electrode plate, with the 1.0 % CF negative electrode plate showing the best electrochemical performance. Specifically, according to the result of battery cycle testing, the simulated battery with CF had a cycle life of 3642 times, which was 2.87 times that of the blank group and 2.39 times of the AC group. Meanwhile, rate testing showed that the simulated battery with CF could maintain a high capacity even under high-rate discharge conditions.

Fluorine-Free Lithium-Ion Capacitor with Enhanced Sustainability and Safety Based on Bio-Based ƴ-Valerolactone and Lithium Bis(Oxalato)Borate Electrolyte

In this work, the properties of a novel electrolyte based on the combination of bio-based ƴ-valerolactone (GVL) solvent with lithium bis(oxalato)borate (LiBOB) salt and its use for lithium-ion capacitors (LICs) are presented. It is shown that the 1 m LiBOB in GVL electrolyte displays good transport properties, high thermal stability, and the ability to prevent anodic dissolution. Its impact on the performance of both battery-type and capacitive-type electrodes is evaluated. In this regard, special attention is paid to the filming properties associated with LiBOB and GVL decomposition at the electrode surfaces. To the best of the authors' knowledge, the full-cell devices assembled in this study are the first example of a fluorine-free LIC. These devices exhibit a favorable energy-to-power ratio, delivering 80 Wh kg-1 AM at 10 000 W kg-1 AM along with excellent cycling stability, retaining 80% of the initial capacitance after 25 000 cycles. Furthermore, post-mortem analysis of the LIC electrodes is conducted to gain deeper insights into the degradation mechanisms within the device.

Preparation and application of porous materials from coal gasification slag for wastewater treatment: A review

In recent years, coal gasification has been gradually promoted as clean technology, and coal gasification slag (CGS) emissions have increased accordingly. CGS, including coarse slag and fine slag, is rich in SiO₂ and Al₂O₃ and has pozzolanic activity, and thus CGS can be regarded as a cheap source of aluminosilicate. Also, CGS, especially the fine slag, usually contains higher contents of residual carbon which has a large specific surface area and low volatility and hence can be considered as a favorable precursor of activated carbon. Benefiting from these characteristics, CGS can be used to prepare high value-added porous materials, such as zeolite, mesoporous silica, carbon-silicon composite, and porous ceramics, and the obtained structures accommodate both sufficient adsorption capacity and low cost. Here, we review the research advances in characteristics of CGS and preparation methods of CGS-based porous materials, as well as their adsorption performance of heavy metal ions, organic dyes, ammonia nitrogen, and other water pollutants. The current studies indicate that CGS-derived adsorbents are effective and economical alternatives for removing aqueous pollutants. In addition, further research prospects on CGS-based porous materials are proposed.

Blow-spun N-doped carbon fiber based high performance flexible lithium ion capacitors

Constructing flexible hybrid supercapacitors is a feasible way to achieve devices with high energy density, high power density and flexibility at the same time. Herein, flexible asymmetric hybrid supercapacitors are fabricated with blow spun activated carbon fibers. Owing to the highly effective conductive network, abundant nitrogen doping, optimized pore-structure and surface chemical properties of the carbon fibers, the as-prepared flexible hybrid supercapacitor shows outstanding energy and power performance (98 W h kg⁻¹ (0.3 mW h cm⁻²) @ 400 W kg⁻¹, 9 W h kg⁻¹ @ 34 kW kg⁻¹), as well as excellent cycle stability with 93% capacitance retention after 4000 cycles.

Constructing flexible hybrid supercapacitors is a feasible way to achieve devices with high energy density, high power density and flexibility at the same time.

Lithium-Ion Capacitor Safety Testing for Commercial Application

The lithium-ion capacitor (LIC) is a recent innovation in the area of electrochemical energy storage that hybridizes lithium-ion battery anode material and an electrochemical double layer capacitor cathode material as its electrodes. The high power compared to batteries and higher energy compared to capacitors has made it a promising energy-storage device for powering hand-held and portable electronic systems/consumer electronics, hybrid electric vehicles, and electric vehicles. The swelling and gassing of the LIC when subjected to abuse conditions is still a critical issue concerning the safe application in power electronics and commercial devices. However, it is imperative to carry out a thorough investigation that characterizes the safe operation of LICs. We investigated and studied the safety of LIC for commercial applications, by conducting a comprehensive abuse tests on LIC 200 F pouch cells with voltage range from 3.8 V to 2.2 V manufactured by General Capacitors LLC. The abuse tests include overcharge, external short circuit, crush (flat metal plate and blunt indentation), nail penetration test, and external heat test.

Performance of Novel Randomly Oriented High Graphene Carbon in Lithium Ion Capacitors

The structure of carbon material comprising the anode is the key to the performance of a lithium ion capacitor. In addition to determining the capacity, the structure of the carbon material also determines the diffusion rate of the lithium ion into the anode which in turn controls power density which is vital in high rate applications. This paper covers details of systematic investigation of the performance of a structurally novel carbon, called Randomly Oriented High Graphene (ROHG) carbon, and graphite in a high rate application device, that is, lithium ion capacitor. Electrochemical impedance spectroscopy shows that ROHG is less resistive and has faster lithium ion diffusion rates (393.7 × 10−3 S·s(1/2)) compared to graphite (338.1 × 10−3 S·s(1/2)). The impedance spectroscopy data is supported by the cell data showing that the ROHG carbon based device has energy density of 22.8 Wh/l with a power density of 4349.3 W/l, whereas baseline graphite based device has energy density of 5 Wh/l and power density of 4243.3 W/l. This data clearly shows advantage of the randomly oriented graphene platelet structure of ROHG in lithium ion capacitor performance.

Special Issue: Materials for Electrochemical Capacitors and Batteries

Electrochemical capacitors and rechargeable batteries have received worldwide attention due to their excellent energy storage capability for a variety of applications. The rapid development of these technologies is propelled by the advanced electrode materials and new energy storage systems. It is believed that research efforts can improve the device performance to meet the ever-increasing requirements of high energy density, high power density and long cycle life. This Special Issue aims to provide readers with a glimpse of different kinds of electrode materials for electrochemical capacitors and batteries.