Prussian blue analogues (PBAs, A2T[M(CN)6], A = Li, K, Na; T = Fe, Co, Ni, Mn, Cu, etc.; M = Fe, Mn, Co, etc.) are a large family of materials with an open framework structure. In recent years, they have been intensively investigated as active materials in the field of energy conversion and storage, such as for alkaline‐ion batteries (lithium‐ion, LIBs; sodium‐ion, NIB; and potassium‐ion, KIBs), and as electrochemical catalysts. Nevertheless, few review papers have focused on the intrinsic chemical and structural properties of Prussian blue (PB) and its analogues. In this Review, a comprehensive insight into the PBAs in terms of their structural and chemical properties, and the effects of these properties on their materials synthesis and corresponding performance is provided.
A light weight, economic, and high–energy density Zn/MnO 2 fiber battery was integrated with a textile body area network.
and are considered as a new generation of energy storage devices to replace lithium ion batteries (LIBs) in certain applications. [1][2][3][4][5][6][7][8][9][10][11] Hitherto, the commercialization of SIBs has been held back, however, by their low energy density and unsatisfactory cycle life. The cathode, as much as the anode, also plays an important role in the final performance of the battery. Thus, it is crucial to develop cathode candidates with both high energy density and stable cycle life for sodium ion storage.It is accepted that the energy density is determined by the specific capacity and the voltage plateau of an electrode. The commercial cathode materials for LIBs can deliver 510-700 Wh kg −1 energy density with a potential plateau of 3.4-4.1 V (3.4 V for LiFePO 4 and 4.1 V for spinel LiMn 2 O 4 ) and high specific capacity of over 150 mAh g −1 . In comparison, most of the cathode candidates reported for SIBs show a potential plateau below 3.2 V and a capacity below 110 mAh g −1 , delivering energy density lower than 350 Wh kg −1 . [12][13][14][15][16][17] Exceptionally, the sodium superionic conductor Na 3 V 2 (PO 4 ) 3 presented a 3.4 V potential plateau and 115 mAh g −1 capacity; Na 3 (VO 1−x PO 4 ) 2 F 1+2x (0 < x < 1) showed 3.8-3.9 V average voltage and 120-130 mAh g −1 capacity. [18][19][20][21][22] Honeycomb-layered Na 3 Ni 2 SbO 6 provided an average working potential at 3.3 V and a high capacity of ≈120 mAh g −1 . Moreover, Na 3 Ni 2 SbO 6 showed superior rate capability and excellent cycling performance. [23,24] In the long run, however, these cathode materials containing toxic elements (V and Sb) are not suitable for commercial SIBs because commercialization also requires electrode materials to possess the properties of environmental friendliness and low cost in addition to excellent electrochemical performance.Recently, Prussian blue analogues (PBAs) have attracted much attention owing to their low cost and environmentalfriendliness. [6,[25][26][27][28] The PBAs utilized for electrode materials can be classified into three groups, that is, hexacyanoferrates (ATFe(CN) 6 ), hexacyanomanganates (ATMn(CN) 6 ), and hexacyanocobaltates (ATCo(CN) 6 , where A = K, Na; T = Fe, Mn, Ni, Co). Among them, hexacyanoferrates, in particular, have been put under the spotlight due to their nonpoisonous raw material ferrocyanide (Na 4 Fe(CN) 6 or K 3 Fe(CN) 6 ), while the raw materials K 3 Mn(CN) 6 for hexacyanomanganate and K 3 Co(CN) 6 for hexacyanocobaltate are harmful and toxic. In the case of Mn-based hexacyanoferrate Na x MnFe(CN) 6 (NMHFC) has been attracting more attention as a promising cathode material for sodium ion storage owing to its low cost, environmental friendliness, and its high voltage plateau of 3.6 V, which comes from the Mn 2+ /Mn 3+ redox couple. In particular, the Na-rich NMHFC (x > 1.40) with trigonal phase is considered an attractive candidate due to its large capacity of ≈130 mAh g −1 , delivering high energy density. Its unstable cycle life, however, is holding back its practica...
Due to the urgency of our energy and environmental issues, a variety of cost-effective and pollution-free technologies have attracted considerable attention, among which thermoelectric technology has made enormous progress. Substantial numbers of new thermoelectric materials are created with high figure of merit (ZT) by using advanced nanoscience and nanotechnology. This is especially true in the case of metalchalcogenide-based materials, which possess both relatively high ZT and low cost among all the different kinds of thermoelectric materials. Here, comprehensive coverage of recent advances in metal chalcogenides and their correlated thermoelectric enhancement mechanisms are provided. Several new strategies are summarized with the hope that they can inspire further enhancement of performance, both in metal chalcogenides and in other materials. Disciplines Engineering | Physical Sciences and Mathematics Publication DetailsHan, C., Sun, Q., Li, Z. & Dou, S. X. (2016) Several new strategies are summarized with the hope that they can inspire further enhancement of performance, both in metal chalcogenides and in other materials.2
Surfactant-free CuAgSe nanoparticles were successfully synthesized on a large scale within a short reaction time via a simple environmentally friendly aqueous approach under room temperature. The nanopowders obtained were consolidated into pellets for investigation of their thermoelectric properties between 3 and 623 K. The pellets show strong metallic characteristics below 60 K and turn into an n-type semiconductor with increasing temperature, accompanied by changes in the crystal structure (i.e., from the pure tetragonal phase into a mixture of tetragonal and orthorhombic phases), the electrical conductivity, the Seebeck coefficient, and the thermal conductivity, which leads to a figure of merit (ZT) of 0.42 at 323 K. The pellets show further interesting temperature-dependent transition from n-type into p-type in electrical conductivity arising from phase transition (i.e., from the mixture phases into cubic phase), evidenced by the change of the Seebeck coefficient from -28 μV/K into 226 μV/K at 467 K. The ZT value increased with increasing temperature after the phase transition and reached 0.9 at 623 K. The sintered CuAgSe pellets also display excellent stability, and there is no obvious change observed after 5 cycles of consecutive measurements. Our results demonstrate the potential of CuAgSe to simultaneously serve (at different temperatures) as both an n-type and a p-type thermoelectric material.Keywords surfactant, free, thermoelectric, cuagse, nanoparticles, synthesis, reversible, ambient, metallic, n, p, conductivity, transition, scalable Disciplines Engineering | Physical Sciences and Mathematics Publication DetailsHan, C., Sun, Q., Cheng, Z. Xiang., Wang, J. Li., Li, Z., Lu, G. & Dou, S. Xue. (2014 Supporting Information PlaceholderABSTRACT: Surfactant-free CuAgSe nanoparticles were successfully synthesized on a large scale within a short reaction time via a simple environmentally friendly aqueous approach under room temperature. The nanopowders obtained were consolidated into pellets for investigation of their thermoelectric properties between 3 K and 623 K. The pellets show strong metallic characteristics below 60 K and turn into an n-type semiconductor with increasing temperature, accompanied by changes in the crystal structure (i.e. from the pure tetragonal phase into a mixture of tetragonal and orthorhombic phases), the electrical conductivity, the Seebeck coefficient, and the thermal conductivity, which leads to a figure of merit (ZT) of 0.42 at 323 K. The pellets show further interesting temperature-dependent transition from n-type into p-type in electrical conductivity arising from phase transition (i.e. from the mixture phases into cubic phase), evidenced by the change of the Seebeck coefficient from -28 µV/K into 226 µV/K at 467 K. The ZT value increased with increasing temperature after the phase transition and reached 0.9 at 623 K. The sintered CuAgSe pellets also display excellent stability, and there is no obvious change observed after 5 cycles of consecutive measurements. Our r...
Screen printing allows for direct conversion of thermoelectric nanocrystals into flexible energy harvesters and coolers. However, obtaining flexible thermoelectric materials with high figure of merit ZT through printing is an exacting challenge due to the difficulties to synthesize high-performance thermoelectric inks and the poor density and electrical conductivity of the printed films. Here, we demonstrate high-performance flexible films and devices by screen printing bismuth telluride based nanocrystal inks synthesized using a microwave-stimulated wet-chemical method. Thermoelectric films of several tens of microns thickness were screen printed onto a flexible polyimide substrate followed by cold compaction and sintering. The n-type films demonstrate a peak ZT of 0.43 along with superior flexibility, which is among the highest reported ZT values in flexible thermoelectric materials. A flexible thermoelectric device fabricated using the printed films produces a high power density of 4.1 mW/cm2 with 60 °C temperature difference between the hot side and cold side. The highly scalable and low cost process to fabricate flexible thermoelectric materials and devices demonstrated here opens up many opportunities to transform thermoelectric energy harvesting and cooling applications.
Transition Metal Oxides (Na x MO 2 , x ≤ 1, M = Transition Metal)Transition metal oxides Na x MO 2 , (x ≤ 1, M = transition metal, Co, Mn, Fe, Ni, etc.) have recently received increased attention due to their high energy density, above 400 W h kg −1 . [69,75,76] Moreover, its lithium counterpart-Li x MO 2 has been successfully applied in commercial LIBs. Generally speaking, Na x MO 2 can Sodium ion batteries (SIBs) have recently attracted considerable attention and are considered as an alternative to lithium ion batteries (LIBs), owing to the cheap price and abundance of sodium resources. However, the commercialization of SIBs has so far been impeded by the low energy density and unstable cycle life of electrodes, especially as cathodes. Although some cathode candidates with a stable cycle life and high energy density have been developed using nanotechnologies, the commercial feasibility is seldom taken into account. This research news article provides an insight into the commercial prospects of existing cathode materials for SIBs in terms of environmental friendliness, manufacturing cost, synthesis methods and electrochemical performance. Sodium Ion Batteries IntroductionRecently, owing to the ever-increasing consumption of lithium resources, the price of lithium ion batteries (LIBs) has increased rapidly. As researchers strive to seek an alternative to LIBs for energy storage, sodium ion batteries (SIBs) have been attracting more attention due to their similar electrochemical properties to LIBs and low cost. The major challenge for SIB commercialization is the low energy density and unstable cycle life of electrode materials. The energy density is related to the capacity and potential plateau.A wide variety of materials have been investigated as electrode materials for SIBs. Anode candidates, include carbonaceous materials, [26][27][28][29][30][31][32][33][34][35][36] alloy-forming elements (Sn, Sb, Ge and P), and alloy compound (SnSb, phosphide, et al). [59,60,[63][64][65] Moreover, the current anode candidates can deliver more than 200 mA h g −1 capacity, and most of them can show stable cycle life more than 200 cycles through various strategies of structural modification and nanotechnology. Reported cathode materials candidates can be divided into four classes: transition metal (M) oxides (Na x MO 2+y ), [8][9][10][11] Adv. Energy
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