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Ambient energy harvesting has great potential to contribute to sustainable development and address growing environmental challenges. Converting waste energy from energy-intensive processes and systems (e.g. combustion engines and furnaces) is crucial to reducing their environmental impact and achieving net-zero emissions. Compact energy harvesters will also be key to powering the exponentially growing smart devices ecosystem that is part of the Internet of Things, thus enabling futuristic applications that can improve our quality of life (e.g. smart homes, smart cities, smart manufacturing, and smart healthcare). To achieve these goals, innovative materials are needed to efficiently convert ambient energy into electricity through various physical mechanisms, such as the photovoltaic effect, thermoelectricity, piezoelectricity, triboelectricity, and radiofrequency wireless power transfer. By bringing together the perspectives of experts in various types of energy harvesting materials, this Roadmap provides extensive insights into recent advances and present challenges in the field. Additionally, the Roadmap analyses the key performance metrics of these technologies in relation to their ultimate energy conversion limits. Building on these insights, the Roadmap outlines promising directions for future research to fully harness the potential of energy harvesting materials for green energy anytime, anywhere.

This paper describes active battery balancing based on a bidirectional buck converter, a flyback converter, and battery cells by using the proposed chain-loop comparison strategy. The role of the bidirectional buck converter is to charge/discharge the battery pack. During the charging period, the converter is in buck mode, and its output is controlled by constant current/voltage; during the discharging period, the converter is in boost mode, and its output is controlled by constant voltage. The role of the flyback converter is voltage equalization of the battery pack, and its output is controlled by constant current. A chain-loop comparison strategy is used to control battery voltage equalization. In this work, three equalization modes, namely, charging balance, discharging balance, and static balance, were considered. The voltage difference between the maximum and minimum is 0.007 V after a balancing time of 19.75 min, 0.005 V after a balancing time of 24 min, and 0.007 V after a balancing time of 20 min for charging balance, discharging balance, and static balance, respectively. [ABSTRACT FROM AUTHOR]

BiCuSeO is a promising oxygen‐containing thermoelectric material due to its intrinsically low lattice thermal conductivity and excellent service stability. However, the low electrical conductivity limits its thermoelectric performance. Aliovalent element doping can significantly improve their carrier concentration, but it may also impact carrier mobility and thermal transport properties. Considering the influence of graphene on carrier‐phonon decoupling, Bi0.88Pb0.06Ca0.06CuSeO (BPCCSO)‐graphene composites are designed. For further practical application, a rapid preparation method is employed, taking less than 1 h, which combines self‐propagating high‐temperature synthesis with spark plasma sintering. The incorporation of graphene simultaneously optimizes the electrical properties and thermal conductivity, yielding a high ratio of weighted mobility to lattice thermal conductivity (144 at 300 K and 95 at 923 K). Ultimately, BPCCSO‐graphene composites achieve exceptional thermoelectric performance with a ZT value of 1.6 at 923 K, bringing a ≈40% improvement over BPCCSO without graphene. This work further promotes the practical application of BiCuSeO‐based materials and this facile and effective strategy can also be extended to other thermoelectric systems. [ABSTRACT FROM AUTHOR]

Different oil well tubes have different influences on CO2 corrosion.In order to optimize the materials with the best corrosion resistance to CO2, it is necessary to explore the corrosion of materials of conventional oil well tubes under different conditions.Therefore, taking the production well of CO2 composite flooding injection in Block nine six of Karamay oilfield as the research object, and simulating the actual service condition of oil well pipes, the corrosion weight loss experiments on N80, 3Cr, tungsten-plated heat insulation tube and P110 oil tube materials were carried out.The Potentiodynamic polarization curve and electrochemical impedance spectroscopy(EIS)were measured by three electrode system, scanning electron microscopy(SEM), energy dispersive spectroscopy(EDS)and X-ray diffraction(XRD)were used to observe the microstructure of corrosion products.Results showed that the corrosion rate of the four kinds of materials increased first and then decreased with the increase of temperature.With the increase of pressure, the corrosion rate of the four kinds of casing steels increased.The corrosion rate of tungsten-plated heat insulation tube and 3Cr was obviously lower than that of N80 and P110.According to the corrosion morphology, the four kinds of casing steels were corroded in varying degrees.The serious corrosion occurred on the surface of N80 and P110 whereas slight corrosion occurred on the surface of the tungsten-plated heat insulation tube and the 3Cr.Therefore, the corrosion law of four oil well tubes in CO2-driven environment was obtained, the suggestions on the design and selection of oil well tubes in CO2-driven environment were proposed to select the materials with the best corrosion resistance to CO2 optimally.

Developing high-performance film dielectrics for capacitive energy storage has been a great challenge for modern electrical devices. Despite good results obtained in lead titanate-based dielectrics, lead-free alternatives are strongly desirable due to environmental concerns. Here we demonstrate that giant energy densities of ~70 J cm-3, together with high efficiency as well as excellent cycling and thermal stability, can be achieved in lead-free bismuth ferrite-strontium titanate solid-solution films through domain engineering. It is revealed that the incorporation of strontium titanate transforms the ferroelectric micro-domains of bismuth ferrite into highly-dynamic polar nano-regions, resulting in a ferroelectric to relaxor-ferroelectric transition with concurrently improved energy density and efficiency. Additionally, the introduction of strontium titanate greatly improves the electrical insulation and breakdown strength of the films by suppressing the formation of oxygen vacancies. This work opens up a feasible and propagable route, i.e., domain engineering, to systematically develop new lead-free dielectrics for energy storage.

Lithium metal batteries have been considered as one of the most promising high-energy-density energy storage devices, however, the low Coulombic efficiency and uncontrolled dendrite growth seriously hinder their commercialization. In lithium metal batteries, the electrolytes would directly participate in the formation of solid electrolyte interface (SEI), which play important roles in affecting the lithium metal anode Coulombic efficiency and inhibiting the growth of lithium dendrites.In the traditional LiPF6 based ester electrolyte, lithium metal anode exhibits low Coulomb efficiency and serious lithium dendrites.In recent years, significant improvement has been achieved for the protection of lithium anode through manipulating the electrolyte additive, solvents, lithium salt and lithium salt concentration,etc. For examples,ether solvent presenting better compatibility with lithium metal was selected to reduce the side reactivity of electrolyte with lithium metal;varieties of additives were adopted to suppress the formation of lithium dendrites;high concentration electrolytes were employed to form stable SEI.In this paper, the growth principles of lithium dendrites, the research status of electrolytes chemistries for protection of lithium metal anode by means of solvents, lithium salts, additives and high concentration electrolytes strategies were reviewed and the advantages and limitations of various approaches were summarized.New insights on the development of electrolytes chemistries were also put forward to stimulate new strategies to face the subsequent challenges of lithium-metal batteries.