Activated porous carbons (APCs) are traditionally produced by heat treatment and KOH activation, where the production time can be as long as 2 h, and the produced activated porous carbons suffer from ...relatively low specific surface area and porosity. In this study, the fast high‐temperature shock (HTS) carbonization and HTS‐KOH activation method to synthesize activated porous carbons with high specific surface area of ≈843 m2 g‐1, is proposed. During the HTS process, the instant Joule heating (at a heating speed of ≈1100 K s‐1) with high temperature and rapid quenching can effectively produce abundant pores with homogeneous size‐distribution due to the instant melt of KOH into small droplets, which facilitates the interaction between carbon and KOH to form controllable, dense, and small pores. The as‐prepared HTS‐APC‐based supercapacitors deliver a high energy density of 25 Wh kg‐1 at a power density of 582 W kg‐1 in the EMIMBF4 ionic liquid. It is believed that the proposed HTS technique has created a new pathway for manufacturing activated porous carbons with largely enhanced energy density of supercapacitors, which can inspire the development of energy storage materials.
The coconut shell, characterized by loose structure and high carbon content, is employed to synthesize activated porous carbon by high‐temperature shock (HTS) progress. The instant Joule heating (at a heating speed of ≈1100 K s–1) with high temperature and rapid quenching facilitates the interaction between carbon and KOH to form controllable, dense, and small pores.
Due to the nature of their liquid‐like behavior and high dimensionless figure of merit, Cu2X (X = Te, Se, and S)‐based thermoelectric materials have attracted extensive attention. The superionicity ...and Cu disorder at the high temperature can dramatically affect the electronic structure of Cu2X and in turn result in temperature‐dependent carrier‐transport properties. Here, the effective strategies in enhancing the thermoelectric performance of Cu2X‐based thermoelectric materials are summarized, in which the proper optimization of carrier concentration and minimization of the lattice thermal conductivity are the main focus. Then, the stabilities, mechanical properties, and module assembly of Cu2X‐based thermoelectric materials are investigated. Finally, the future directions for further improving the energy conversion efficiency of Cu2X‐based thermoelectric materials are highlighted.
Deriving from their high performance and eco‐friendliness, superionic Cu2X‐based thermoelectric materials are attracting ever‐increasing attention. A comprehensive summary of the understanding of the superionicity, performance enhancement strategies, and material stability design can set up a solid foundation for future development. Pointing out the development challenges can better guide future studies.
With the ever‐increasing demand for wearable electronics and energy‐saving technologies, self‐powered thermoelectric personal thermal management (PTM) has attracted extensive research interest. In ...this review, the unique characteristics of thermoelectric PTM comparing with other technologies are first highlighted, and the key parameters and fundamental functions of thermoelectric PTM are systematically summarized. Then, the advances in thermoelectric PTM are overviewed from the material design to the wearable device design viewpoints. Finally, the key challenges and future research directions of thermoelectric PTM, where both high‐performance flexible materials and proper device designs are in urgent need, are pointed out. This review will deliver a systematic understanding and guideline for thermoelectric PTM.
The increasing demand for wearable electronics has boosted the development of energy‐saving and self‐powered personal thermal management systems. This review highlights the unique advantages of thermoelectric technology comparing with other technologies, summarizes corresponding key parameters, fundamental functions, material and device advancements of thermoelectric personal thermal management, and further points out corresponding future research directions.
As a promising thermoelectric material, higher manganese silicides are composed of earth‐abundant and eco‐friendly elements, and have attracted extensive attention for future commercialization. In ...this review, the authors first summarize the crystal structure, band structure, synthesis method, and pristine thermoelectric performance of different higher manganese silicides. After that, the strategies for enhancing electrical performance and reducing lattice thermal conductivity of higher manganese silicides as well as their synergism are highlighted. The application potentials including the chemical and mechanical stability of higher manganese silicides and their energy conversion efficiency of the assembled thermoelectric modules are also summarized. By analyzing the current advances in higher manganese silicides, this review proposes that potential methods of further enhancing zT of higher manganese silicides, lie in enhancing electrical performance while simultaneously reducing lattice thermal conductivity via reducing effective mass, optimizing carrier concentration, and nanostructure engineering.
Due to its nontoxicity, eco‐friendliness, and low cost, higher manganese silicide thermoelectric material shows robust potential for application in high‐performance thermoelectrics via effective strategies through carrier concentration optimization, synergistic engineering, and structure design.
The synthesis of cathode materials plays an important role in determining the production efficiency, cost, and performance of lithium‐ion batteries. However, conventional synthesis methods always ...experience a slow heating rate and involve a complicated multistep reaction process and sluggish reaction dynamics, leading to high energy and long time consumption. Herein, a high‐temperature shock (HTS) strategy is reported for the ultrafast synthesis of cathode materials in seconds. The HTS process experiences an ultrahigh heating rate, leading to a non‐equilibrium reaction and fast reaction kinetics, and avoids high energy and long time consumption. Mainstream cathode materials (such as LiMn2O4, LiCoO2, LiFePO4, and Li‐rich layered oxide/NiO heterostructured material) are successfully synthesized with pure phases, oxygen vacancies, ultrasmall particle sizes, and good electrochemical performance. The HTS process not only provides an efficient synthesis approach for cathode materials, but also can be extended beyond lithium‐ion batteries.
An ultrafast high‐temperature shock strategy is proposed to synthesize cathode materials in seconds for lithium‐ion batteries, avoiding high energy and long time consumption. It provides an ultrahigh heating rate, leading to a non‐equilibrium reaction and fast reaction kinetics. Mainstream cathode materials are successfully synthesized with pure phases, oxygen vacancies, ultrasmall particle sizes, and good electrochemical performance, indicative of a universal and efficient synthesis approach.
High‐performance GeTe‐based thermoelectrics have been recently attracting growing research interest. Here, an overview is presented of the structural and electronic band characteristics of GeTe. ...Intrinsically, compared to low‐temperature rhombohedral GeTe, the high‐symmetry and high‐temperature cubic GeTe has a low energy offset between L and Σ points of the valence band, the reduced direct bandgap and phonon group velocity, and as a result, high thermoelectric performance. Moreover, their thermoelectric performance can be effectively enhanced through either carrier concentration optimization, band structure engineering (bandgap reduction, band degeneracy, and resonant state engineering), or restrained lattice thermal conductivity (phonon velocity reduction or phonon scattering). Consequently, the dimensionless figure of merit, ZT values, of GeTe‐based thermoelectric materials can be higher than 2. The mechanical and thermal stabilities of GeTe‐based thermoelectrics are highlighted, and it is found that they are suitable for practical thermoelectric applications except for their high cost. Finally, it is recognized that the performance of GeTe‐based materials can be further enhanced through synergistic effects. Additionally, proper material selection and module design can further boost the energy conversion efficiency of GeTe‐based thermoelectrics.
High‐performance GeTe thermoelectrics are attracting increasing research interest. Here, fundamental crystal structures (including electronic band structures and phonon dispersions), thermoelectric performance enhancement strategies, mechanical/thermal stabilities, and device design of GeTe‐based thermoelectric materials are systematically summarized. Subsequently, the future development directions of both material and device designs of GeTe‐based thermoelectrics are identified.
Research interest in the development of real‐time monitoring of personal health indicators using wearable electrocardiographic systems has intensified in recent years. New advanced thermoelectrics ...are potentially a key enabling technology that can be used to transform human body heat into power for use in wearable electrographic monitoring devices. This work provides a systematic review of the potential application of thermoelectric generators for use as power sources in wearable electrocardiographic monitoring systems. New strategies on miniaturized rigid thermoelectric modules combined with batteries or supercapacitors can provide adequate power supply for wearable electrocardiographic systems. Flexible thermoelectric generators can also support wearable electrocardiographic systems directly when a heat sink is incorporated into the design in order to enlarge and stabilize the temperature gradient. Recent advances in enhancing the performance of novel fiber/fabric based flexible thermoelectrics has opened up an exciting direction for the development of wearable electrocardiographic systems.
This work overviews that both rigid and flexible thermoelectric power generators, with the advantages of eco‐friendliness and maintenance‐free, are suitable for harvesting electricity from the human body to power up wearable electrocardiographic systems. Moreover, advances in flexible thermoelectric materials will further boost the large‐scale application in electrocardiographic systems.
SnSe is challenging to use in thermoelectric devices due to difficulties in simultaneously optimizing its thermoelectric and mechanical properties. Here, the authors show a unique solvothermal ...synthetic environmental design to fabricate super‐large and micro/nanoporous Sn0.965Se microplates by using CrCl3. Cl− ions to trigger Sn‐vacancy formation and optimize the hole concentration to ≈3 × 1019 cm−3, while the as‐formed Cr(OH)3 colloidal precipitations act as “templates” to achieve micro/nanoporous features, leading to low lattice thermal conductivity of ≈0.2 W m−1 K−1 in the as‐sintered polycrystal, contributing to a high ZT of ≈2.4 at 823 K and an average ZT of ≈1.1. Of particular note, the polycrystal exhibits high hardness (≈2.26 GPa) and compression strength (≈109 MPa), strengthened by grain refinement and vacancy‐induced lattice distortions and dislocations; while a single‐leg device provides a stable output power (>100 mW) and conversion efficiency of ≈10% by a temperature difference of 425 K, indicating great potential for applying to practical thermoelectric devices.
A solvothermal synthetic environmental design to fabricate super‐large and micro/nanoporous Sn0.965Se microplates using CrCl3 is employed, and the mechanically robust polycrystals sintered from these microplates exhibit a high ZT of ≈2.4 at 823 K and an average ZT of ≈1.1, leading to a conversion efficiency of ≈10% by a temperature difference of 425 K in the single‐leg device.
As an emission-free energy conversion technology, thermoelectric technology has been considered an essential component in solving the global energy crisis. Carbon allotrope hybrids, with relatively ...low cost, high performance and engineerable mechanical strength and flexibility, are attracting increasing research interest. The key challenge of developing carbon allotrope hybrid thermoelectric applications lies in material performance enhancement, which is further restricted by enhancing the electrical performance, refraining the lattice thermal conductivity and engineering the mechanical properties. Compositing carbon allotropes to enhance electrical transport properties should be mainly attributed to the material orientation effect which increases the carrier mobility or to the energy filtering effect which increases the Seebeck coefficient. The reduced lattice thermal conductivity due to the formation of carbon allotrope hybrid is derived from various additional phonon scattering features. Furthermore, carbon allotrope-compositing is also effective in enhancing the mechanical properties of thermoelectric materials, which can potentially further widen the variety of applications of these materials. A key opportunity in better utilizing the flexibility of carbon materials is deploying them as stents. Carbon allotrope hybrids can provide a pathway such that rigid thermoelectric materials can be designed into flexible thermoelectric materials. Finally, we point out future research directions for carbon-hybrid thermoelectric materials.
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•Overview of carbon allotrope-compositing methods.•Summarized influence of carbon allotropes on thermoelectric performance.•Summarized influence of carbon allotropes on mechanical properties.•Summary of carbon allotrope-hybrids related thermoelectric module design.•Pointing out research directions of thermoelectric carbon allotrope-hybrids.
In this study, a record high figure of merit (ZT) of ≈1.1 at 773 K is reported in n‐type highly distorted Sb‐doped SnSe microplates via a facile solvothermal method. The pellets sintered from the ...Sb‐doped SnSe microplates show a high power factor of ≈2.4 µW cm−1 K−2 and an ultralow thermal conductivity of ≈0.17 W m−1 K−1 at 773 K, leading a record high ZT. Such a high power factor is attributed to a high electron concentration of 3.94 × 1019 cm−3 via Sb‐enabled electron doping, and the ultralow thermal conductivity derives from the enhanced phonon scattering at intensive crystal defects, including severe lattice distortions, dislocations, and lattice bent, observed by detailed structural characterizations. This study fills in the gaps of fundamental doping mechanisms of Sb in SnSe system, and provides a new perspective to achieve high thermoelectric performance in n‐type polycrystalline SnSe.
A high figure of merit (ZT) of ≈1.1 at 773 K is achieved in n‐type highly distorted Sb‐doped SnSe microplates via tuning high carrier concentration of 3.94 × 1019 cm−3 by Sb‐enabled electron doping and realizing ultralow thermal conductivity of ≈0.17 W m−1 K−1 by inducing intensive crystal defects including severe lattice distortions, dislocations, and lattice bent.
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