Batteries and supercapacitors as electrochemical energy storage and conversion devices are continuously serving for human life. The electrochemical performance of batteries and supercapacitors ...depends in large part on the active materials in electrodes. As an important family, Mn-based oxides have shown versatile applications in primary batteries, secondary batteries, metal-air batteries, and pseudocapacitors due to their high activity, high abundance, low price, and environmental friendliness. In order to meet future market demand, it is essential and urgent to make further improvements in energy and power densities of Mn-based electrode materials with the consideration of multiple electron reaction and low molecular weight of the active materials. Meanwhile, nanomaterials are favourable to achieve high performance by means of shortening the ionic diffusion length and providing large surface areas for electrode reactions. This article reviews the recent efforts made to apply nanostructured Mn-based oxides for batteries and pseudocapacitors. The influence of structure, morphology, and composition on electrochemical performance has been systematically summarized. Compared to bulk materials and notable metal catalysts, nanostructured Mn-based oxides can promote the thermodynamics and kinetics of the electrochemical reactions occurring at the solid-liquid or the solid-liquid-gas interface. In particular, nanostructured Mn-based oxides such as one-dimensional MnO
2
nanostructures, MnO
2
-conductive matrix nanocomposites, concentration-gradient structured layered Li-rich Mn-based oxides, porous LiNi
0.5
Mn
1.5
O
4
nanorods, core-shell structured LiMnSiO
4
@C nanocomposites, spinel-type Co-Mn-O nanoparticles, and perovskite-type CaMnO
3
with micro-nano structures all display superior electrochemical performance. This review should shed light on the sustainable development of advanced batteries and pseudocapacitors with nanostructured Mn-based oxides.
This review summarizes recent efforts made to use nanostructured Mn-based oxides for primary batteries, Li secondary batteries, metal-air batteries, and pseudocapacitors.
Rechargeable sodium‐ion batteries (SIBs), as the most promising alternative to commercial lithium‐ion batteries, have received tremendous attention during the last decade. Among all the anode ...materials for SIBs, metal sulfides/selenides (MXs) have shown inspiring results because of their versatile material species and high theoretical capacity. They suffer from large volume expansion, however, which leads to bad cycling performance. Thus, methods such as carbon modification, nanosize design, electrolyte optimization, and cut‐off voltage control are used to obtain enhanced performance. Here, recent progress on MXs is summarized in terms of arranging the crystal structure, synthesis methods, electrochemical performance, mechanisms, and kinetics. Challenges are presented and effective ways to solve the problems are proposed, and a perspective for future material design is also given. It is hoped that light is shed on the development of MXs to help finally find applications for next‐generation rechargeable batteries.
Metal sulfides and metal selenides have shown great progress as anode materials for sodium‐ion batteries because of their versatile material species, easily controlled morphology, and high theoretical specific capacity. Their advances and challenges are summarized, showing their importance for next‐generation energy storage and conversion devices.
The exploration of next-generation sodium-ion batteries (SIBs) is a worldwide concern to replace the current commercial lithium-ion batteries, mitigating the increasing exhaustion of Li resources. ...Sodium transition metal oxides are considered to be one of the most promising cathode materials for SIBs. The anionic redox reaction in Li-rich transition metal oxides is capable of providing extra capacity in addition to the cationic redox activities in lithium-ion batteries. A similar phenomenon exists in SIBs, which even applies to Na-deficient transition metal oxides. Moreover, transition metal oxides with mixed phase also demonstrate great potential. In this review, studies on anionic redox are first systematically introduced. The up-to-date advances on high-capacity transition metal oxide cathode materials for SIBs are then classified and summarized in different groups associated with or without anionic redox. The existing challenges as well as available solutions and strategies are discussed, and proposals with new insights are made at the end. It is expected that this work can provide new perspectives on controlling the anionic redox activity and finding novel high-capacity oxide cathode materials for SIBs.
This work provides guidance on controlling anionic redox activity and finding novel high-capacity transition metal oxide cathodes for sodium-ion batteries.
We propose a simple yet effective L 0 -regularized prior based on intensity and gradient for text image deblurring. The proposed image prior is based on distinctive properties of text images, with ...which we develop an efficient optimization algorithm to generate reliable intermediate results for kernel estimation. The proposed algorithm does not require any heuristic edge selection methods, which are critical to the state-of-the-art edge-based deblurring methods. We discuss the relationship with other edge-based deblurring methods and present how to select salient edges more principally. For the final latent image restoration step, we present an effective method to remove artifacts for better deblurred results. We show the proposed algorithm can be extended to deblur natural images with complex scenes and low illumination, as well as non-uniform deblurring. Experimental results demonstrate that the proposed algorithm performs favorably against the state-of-the-art image deblurring methods.
We report the preparation of porous CuO nanowires that are composed of nanoparticles （-50 nm） via a simple decomposition of a Cu（OH）2 precursor and their application as the anode materials of ...rechargeable Na-ion batteries. The as-prepared porous CuO nanowires exhibit a Brunauer-Emmett-Teller （BET） surface area of 13.05 m^2.g^-1, which is six times larger than that of bulk CuO （2.16 m^2.g^-1）. The anode of porous CuO nanowires showed discharge capacities of 640 mA.h.g^-1 in the first cycle and 303 mA.h.g^-1 after 50 cycles at 50 mA.g^-1 The high capacity is attributed to porous nanostructure which facilitates fast Na-intercalation kinetics. The mechanism of electrochemical Na-storage based on conversion reactions has been studied through cyclic voltammetry, X-ray diffraction （XRD）, Raman spectroscopy, and high resolution transmission electron microscopy （HRTEM）. It is demonstrated that in the discharge process, Na＋ions first insert into CuO to form a CuⅡ1-x CuⅠ x O1-x/2solid and a Na2O matrix then CuⅡ1-xCu Ⅰ xO1-x/2 reacts with Na＋ to produce Cu2O, and finally Cu2O decompose into Cu nanoparticles enclosed in a Na2O matrix. During the charge process, Cu nanopartides are first oxidized to generate Cu2O and then converted back to CuO. This result contributes to the design and mechanistic analysis of high-performance anodes for rechargeable Na-ion batteries.
With the unprecedentedly increasing demand for renewable and clean energy sources, the sodium‐ion battery (SIB) is emerging as an alternative or complementary energy storage candidate to the present ...commercial lithium‐ion battery due to the abundance and low cost of sodium resources. Layered transition metal oxides and Prussian blue analogs are reviewed in terms of their commercial potential as cathode materials for SIBs. The recent progress in research on their half cells and full cells for the ultimate application in SIBs are summarized. In addition, their electrochemical performance, suitability for scaling up, cost, and environmental concerns are compared in detail with a brief outlook on future prospects. It is anticipated that this review will inspire further development of layered transition metal oxides and Prussian blue analogs for SIBs, especially for their emerging commercialization.
Layered transition metal oxides and Prussian blue analogs are reviewed in terms of their commercial potential as cathode materials for sodium‐ion batteries. Recent research progresses, and their electrochemical performance, scale‐up availability, cost, and environmental concerns are discussed in detail and prospected. It is anticipated that this review could inspire the development and provide guidance for their emerging commercialization.
Sodium‐ion batteries (SIBs) are attracting increasing attention and considered to be a low‐cost complement or an alternative to lithium‐ion batteries (LIBs), especially for large‐scale energy ...storage. Their application, however, is limited because of the lack of suitable host materials to reversibly intercalate Na+ ions. Layered transition metal oxides (NaxMO2, M = Fe, Mn, Ni, Co, Cr, Ti, V, and their combinations) appear to be promising cathode candidates for SIBs due to their simple structure, ease of synthesis, high operating potential, and feasibility for commercial production. In the present work, the structural evolution, electrochemical performance, and recent progress of NaxMO2 as cathode materials for SIBs are reviewed and summarized. Moreover, the existing drawbacks are discussed and several strategies are proposed to help alleviate these issues. In addition, the exploration of full cells based on NaxMO2 cathodes and future perspectives are discussed to provide guidance for the future commercialization of such systems.
Layered transition metal oxides have attracted increasing interests as cathode materials for sodium‐ion batteries. Recent progresses of NaxMO2 cathodes, including the existing drawbacks and relative alleviation strategies, are reviewed and summarized. The exploration of full cells based on NaxMO2 cathodes and future perspectives are also discussed to provide guidance for the future commercialization of such systems.
Precise control of isolated single-atom ruthenium (Ru
SA
) sites supported on nitrogen (N)-doped Ti
3
C
2
T
x
MXene (N-Ti
3
C
2
T
x
) through a coordination-assisted strategy is reported. The ...catalyst displays superior activity toward the hydrogen evolution reaction (HER). The atomic dispersion of Ru
SA
on N-Ti
3
C
2
T
x
is verified by spherical aberration-corrected electron microscopy and X-ray absorption fine structure measurements. The resultant Ru
SA
-N-Ti
3
C
2
T
x
catalyst exhibits outstanding catalytic performance with low overpotentials of 23, 27, and 81 mV to achieve a current density of 10 mA cm
−2
in 0.5 M H
2
SO
4
, 1 M KOH, and 1 M PBS solutions, respectively. In addition, Ru
SA
-N-Ti
3
C
2
T
x
shows long-term stability with negligible degradation in basic, acidic, and neutral media, which is much better than that of the commercial Pt/C catalyst. Density functional theory calculations suggest that the strong covalent interactions between Ru
SA
and N sites on the Ti
3
C
2
T
x
MXene support contribute to the exceptional catalytic performance and stability. This work provides a coordination-engineered strategy to effectively modulate the catalytic properties of the MXene family by an atomic-level engineering strategy.
A catalyst consisting of single-atom Ru sites supported on an N-MXene (Ti
3
C
2
T
x
) was developed for pH-universal hydrogen generation based on theoretical predictions, whose performances are comparable to and better than those of Pt/C.
Iron-based Prussian blue analogs are promising low-cost and easily prepared cathode materials for sodium-ion batteries. Their materials quality and electrochemical performance are heavily reliant on ...the precipitation process. Here we report a controllable precipitation method to synthesize high-performance Prussian blue for sodium-ion storage. Characterization of the nucleation and evolution processes of the highly crystalline Prussian blue microcubes reveals a rhombohedral structure that exhibits high initial Coulombic efficiency, excellent rate performance, and cycling properties. The phase transitions in the as-obtained material are investigated by synchrotron in situ powder X-ray diffraction, which shows highly reversible structural transformations between rhombohedral, cubic, and tetragonal structures upon sodium-ion (de)intercalations. Moreover, the Prussian blue material from a large-scale synthesis process shows stable cycling performance in a pouch full cell over 1000 times. We believe that this work could pave the way for the real application of Prussian blue materials in sodium-ion batteries.
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