The increasing interest in energy storage for the grid can be attributed to multiple factors, including the capital costs of managing peak demands, the investments needed for grid reliability, and ...the integration of renewable energy sources. Although existing energy storage is dominated by pumped hydroelectric, there is the recognition that battery systems can offer a number of high-value opportunities, provided that lower costs can be obtained. The battery systems reviewed here include sodium-sulfur batteries that are commercially available for grid applications, redox-flow batteries that offer low cost, and lithium-ion batteries whose development for commercial electronics and electric vehicles is being applied to grid storage.
Redox-active covalent organic frameworks (COFs) are promising materials for energy storage devices because of their high density of redox sites, permanent and controlled porosity, high surface areas, ...and tunable structures. However, the low electrochemical accessibility of their redox-active sites has limited COF-based devices either to thin films (<250 nm) grown on conductive substrates or to thicker films (1 μm) when a conductive polymer is introduced into the COF pores. Electrical energy storage devices constructed from bulk microcrystalline COF powders, eliminating the need for both thin-film formation and conductive polymer guests, would offer both improved capacity and potentially scalable fabrication processes. Here we report on the synthesis and electrochemical evaluation of a new phenazine-based 2D COF (DAPH-TFP COF), as well as its composite with poly(3,4-ethylenedioxythiophene) (PEDOT). Both the COF and its PEDOT composite were evaluated as powders that were solution-cast onto bulk electrodes serving as current collectors. The unmodified DAPH-TFP COF exhibited excellent electrical access to its redox sites, even without PEDOT functionalization, and outperformed the PEDOT composite of our previously reported anthraquinone-based system. Devices containing DAPH-TFP COF were able to deliver both high-energy and high-power densities, validating the promise of unmodified redox-active COFs that are easily incorporated into electrical energy storage devices.
As more renewable energy is developed, energy storage is increasingly important and attractive, especially grid-scale electrical energy storage; hence, finding and implementing cost-effective and ...sustainable energy storage and conversion systems is vital. Batteries of various types and sizes are considered one of the most suitable approaches to store energy and extensive research exists for different technologies and applications of batteries; however, environmental impacts of large-scale battery use remain a major challenge that requires further study. In this paper, batteries from various aspects including design features, advantages, disadvantages, and environmental impacts are assessed. This review reaffirms that batteries are efficient, convenient, reliable and easy-to-use energy storage systems (ESSs). It also confirms that battery shelf life and use life are limited; a large amount and wide range of raw materials, including metals and non-metals, are used to produce batteries; and, the battery industry can generate considerable amounts of environmental pollutants (e.g., hazardous waste, greenhouse gas emissions and toxic gases) during different processes such as mining, manufacturing, use, transportation, collection, storage, treatment, disposal and recycling. Battery use at a large scale or grid-scale (>50 MW), which is widely anticipated, will have significant social and environmental impacts; hence, it must be compared carefully with alternatives in terms of sustainability, while focusing on research to quantify externalities and reduce risk. Alternatives such as pumped hydro and compressed air energy storage must be encouraged because of their low environmental impact compared to different types of batteries.
•Review of batteries from various aspects such as design features, advantages, disadvantages, and environmental impacts.•Study of the share of batteries in the use of raw materials and the depletion of natural resources.•Study of the role of batteries in causing the environmental pollutants, greenhouse gas (GHG) emissions, and harmful effects on public health.
•The importance of thermochemical energy storage system is highlighted.•Concepts and working principle of various reversible reactions are discussed.•Summarised the worldwide prototype development of ...solid-gas and gas-gas reactions.•Summarised reported cyclic studies on solid-gas reaction materials.•Presented the comparative summary of Solid-gas and Gas-gas reaction systems.
Thermal energy storage promises to be cheaper, with significantly lesser environmental encroachment, compared to electrical energy storage in batteries. Among all thermal energy storage systems, thermochemical energy storage is the most promising due to its high energy density, high exergetic efficiency, and high operating temperature. This paper presents a review of thermal energy storage systems that are suitable for concentrating solar thermal power plant. The review here mainly focuses on experimental studies carried out on solid-gas, gas-gas, and sulfuric acid/sulfur-based thermochemical energy storage systems that operate above 300 °C. Also, various reactor designs and storage concepts for solid-gas and gas-gas reaction systems and cyclic studies for the case of a solid-gas system are addressed. Finally, a comparative summary is presented, preparing the path for the future course of research and development. The review reveals that the carbonate systems are an economically viable option as future thermal energy storage system if their cyclic stability and reversibility are improved. A new metal hydride thermal energy storage system is proposed that would provide cooling and heat upgradation as an additional output. For gas-gas reactions, the major challenges are the development of efficient solar receiver and optimization of the catalyst use.
The properties of the electrolyte are the dominant factors for the overall performance and safety of electrical energy storage devices. Highly concentrated “water in salt” (WIS) electrolytes are ...inherently non-flammable, moisture-tolerant, and exhibit wide electrochemical stability windows, making them promising electrolytes for high-performance energy storage devices. However, WIS electrolytes possess intrinsically low conductivity and high viscosity, which usually impair the high-rate performance of many energy storage devices, especially supercapacitors (SCs). Additionally, the inevitable salt precipitation at low temperature for WIS electrolytes narrows down their applicable temperature range. Here, we introduce acetonitrile as a co-solvent to a typical “water in salt” electrolyte to formulate an “acetonitrile/water in salt” (AWIS) hybrid electrolyte that provides significantly improved conductivity, reduced viscosity and an expanded applicable temperature range while maintaining the aforementioned important physicochemical properties of WIS electrolytes. Using the AWIS electrolyte for a model SC remarkably enhances the high-rate performance, accompanied by a 2.4 times capacitance increase at 10 A g −1 with respect to the original WIS electrolyte. This AWIS electrolyte also enables a stable long-term cycling capability of the model SC for over 14 000 cycles at a high operation voltage of 2.2 V.
The key bottleneck troubling the application of solid electrolyte is the contradictory requirements from Li-metal and cathode, which need high modulus to block Li-dendrite penetration and flexibility ...to enable low interface resistance, respectively. This study describes a thin asymmetrical design of solid electrolyte to address these shortcomings. In this architecture, a rigid ceramic-layer modified with an ultrathin polymer is toward Li-metal to accomplish dendrite-suppression of Li-anode, and a soft polymer-layer spreads over the exterior and interior of cathode to endow connected interface simultaneously. This ingenious arrangement endows solid Li-metal batteries with extremely high Coulombic efficiency and cyclability. This work will open up one avenue for realizing safe and long-life energy storage systems.
A critical overview of the latest developments in the aluminum battery technologies is reported. The substitution of lithium with alternative metal anodes characterized by lower cost and higher ...abundance is nowadays one of the most widely explored paths to reduce the cost of electrochemical storage systems and enable long‐term sustainability. Aluminum based secondary batteries could be a viable alternative to the present Li‐ion technology because of their high volumetric capacity (8040 mAh cm−3 for Al vs 2046 mAh cm−3 for Li). Additionally, the low cost aluminum makes these batteries appealing for large‐scale electrical energy storage. Here, we describe the evolution of the various aluminum systems, starting from those based on aqueous electrolytes to, in more details, those based on non‐aqueous electrolytes. Particular attention has been dedicated to the latest development of electrolytic media characterized by low reactivity towards other cell components. The attention is then focused on electrode materials enabling the reversible aluminum intercalation‐deintercalation process. Finally, we touch on the topic of high‐capacity aluminum‐sulfur batteries, attempting to forecast their chances to reach the status of practical energy storage systems.
An overview of battery technologies employing aluminum metal anodes is reported, which are being considered as a viable alternative to Li‐ion technology thanks to aluminum abundance, low cost and high volumetric capacity (8040 mA h cm−3 for Al vs 2046 mA h cm−3 for Li).
A large variety of energy storage systems are currently investigated for using surplus power from intermittent renewable energy sources. Typically, these energy storage systems are compared based on ...their Power-to-Power reconversion efficiency. Such a comparison, however, is inappropriate for energy storage systems not providing electric power as output. We therefore present a systematic environmental comparison of energy storage systems providing different products. As potential products, we consider the reconversion to power but also mobility, heat, fuels and chemical feedstock. Using life cycle assessment, we determine the environmental impacts avoided by using 1 MW h of surplus electricity in the energy storage systems instead of producing the same product in a conventional process. Based on data for several countries including the United States, Brazil, Japan, Germany and the United Kingdom, our analysis determines the highest reduction of global warming and fossil depletion impact for using surplus power in heat pumps with hot water storage and battery electric vehicles. Third highest environmental benefits are achieved by electrical energy storage systems (pumped hydro storage, compressed air energy storage and redox flow batteries). Environmental benefits are also obtained if surplus power is used to produce hydrogen but the benefits are lower. Our environmental assessment of energy storage systems is complemented by determination of CO sub(2) mitigation costs. The lowest CO sub(2) mitigation costs are achieved by electrical energy storage systems.
Two-dimensional MXenes are promising for various energy-related applications such as energy storage devices and electrocatalysis of water-splitting. MXenes prepared from hydrofluoric (HF) acid ...etching have been widely reported. Nonetheless, the acute toxicity of HF acid impedes the large-scale fabrication of MXenes and their wide utilization in energy-related applications. It is thus greatly encouraging to explore a more innocuous protocol for MXenes synthesis. Thereby, a universal strategy based on thermal-assisted electrochemical etching route is developed to synthesize MXenes (e.g., Ti2CT x , Cr2CT x , and V2CT x ). Furthermore, the cobalt ion doped MXenes show an exceptionally enhanced capability of hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) activity, demonstrating their multifunctionalities, which is comparable to the commercialized catalysts. Moreover, we successfully exploited our MXenes as cathodes for the novel aqueous rechargeable battery, with proficient retention and excellent electrical output performance. This work paves a nontoxic and HF-free route to prepare various MXenes and demonstrates practical applications of the materials.
