Think zinc: An ideal aqueous energy storage device, referred to as a zinc ion battery, is presented. The device is characterized by high capacity, fast charge/discharge capability, safety, and ...environmental friendliness. It is composed of an α‐MnO2 cathode, a zinc anode, and a mild ZnSO4 or Zn(NO3)2 aqueous electrolyte (see scheme). The battery chemistry is based on the migration of Zn2+ ions between cathode and anode.
Due to the improvement of network infrastructure and the application of Internet of Things equipment, a large number of sensors are deployed in the industrial pipeline production, and the large size ...of data is generated. The most typical case in the production line is product inspection, that is, defect inspection. To implement an efficient and robust detection system, in this study, we propose a classification computing model based on Lie Group Machine Learning, which can find the possible defective products in production. Usually, a workshop has a lot of assembly lines. How to process large data on so many production lines in real-time and accurately is a difficult problem. To solve this problem, we use the concept of fog computing to design the system. By offloading the computation burden from the cloud server center to the fog nodes, the system obtains the ability to deal with extremely data. Our system has two obvious advantages. The first one is to apply Lie Group Machine Learning to fog computing environment to improve the computational efficiency and robustness of the system. The other is that without increasing any production costs, it can quickly detect products, reduce network latency, and reduce the load on bandwidth. The simulations prove that, compared with the existing methods, the proposed method has an average running efficiency increase of 52.57%, an average delay reduction of 42.13%, and an average accuracy increase of 27.86%.
Highlights
Various MOF materials were synthesized and investigated as ZIB cathodes.
A long-term stable ZIF-8@Zn anode was proposed by coating ZIF-8 material on the surface of zinc foils.
...High-performance aqueous ZIBs were constructed using the Mn(BTC) cathode and the ZIF-8@Zn anode.
Rechargeable aqueous zinc-ion batteries (ZIBs) have been gaining increasing interest for large-scale energy storage applications due to their high safety, good rate capability, and low cost. However, the further development of ZIBs is impeded by two main challenges: Currently reported cathode materials usually suffer from rapid capacity fading or high toxicity, and meanwhile, unstable zinc stripping/plating on Zn anode seriously shortens the cycling life of ZIBs. In this paper, metal–organic framework (MOF) materials are proposed to simultaneously address these issues and realize high-performance ZIBs with Mn(BTC) MOF cathodes and ZIF-8-coated Zn (ZIF-8@Zn) anodes. Various MOF materials were synthesized, and Mn(BTC) MOF was found to exhibit the best Zn
2+
-storage ability with a capacity of 112 mAh g
−1
. Zn
2+
storage mechanism of the Mn(BTC) was carefully studied. Besides, ZIF-8@Zn anodes were prepared by coating ZIF-8 MOF material on Zn foils. Unique porous structure of the ZIF-8 coating guided uniform Zn stripping/plating on the surface of Zn anodes. As a result, the ZIF-8@Zn anodes exhibited stable Zn stripping/plating behaviors, with 8 times longer cycle life than bare Zn foils. Based on the above, high-performance aqueous ZIBs were constructed using the Mn(BTC) cathodes and the ZIF-8@Zn anodes, which displayed an excellent long-cycling stability without obvious capacity fading after 900 charge/discharge cycles. This work provides a new opportunity for high-performance energy storage system.
Highlights
A surface engineering strategy was proposed to design hierarchically porous structure on fibrous carbon cathodes with O/N heteroatom functional groups.
High-energy and anti-self-discharge ...Zn-ion hybrid supercapacitors (ZHSs) were realized.
ZHS electrochemistry was investigated and new insights were provided.
Aqueous Zn-ion hybrid supercapacitors (ZHSs) are increasingly being studied as a novel electrochemical energy storage system with prominent electrochemical performance, high safety and low cost. Herein, high-energy and anti-self-discharge ZHSs are realized based on the fibrous carbon cathodes with hierarchically porous surface and O/N heteroatom functional groups. Hierarchically porous surface of the fabricated free-standing fibrous carbon cathodes not only provides abundant active sites for divalent ion storage, but also optimizes ion transport kinetics. Consequently, the cathodes show a high gravimetric capacity of 156 mAh g
−1
, superior rate capability (79 mAh g
−1
with a very short charge/discharge time of 14 s) and exceptional cycling stability. Meanwhile, hierarchical pore structure and suitable surface functional groups of the cathodes endow ZHSs with a high energy density of 127 Wh kg
−1
, a high power density of 15.3 kW kg
−1
and good anti-self-discharge performance. Mechanism investigation reveals that ZHS electrochemistry involves cation adsorption/desorption and Zn
4
SO
4
(OH)
6
·5H
2
O formation/dissolution at low voltage and anion adsorption/desorption at high voltage on carbon cathodes. The roles of these reactions in energy storage of ZHSs are elucidated. This work not only paves a way for high-performance cathode materials of ZHSs, but also provides a deeper understanding of ZHS electrochemistry.
Highlights
Pourbaix diagram of Mn–Zn–H
2
O system was used to analyze the charge–discharge processes of Zn/MnO
2
batteries.
Electrochemical reactions with the participation of various ions inside ...Zn/MnO
2
batteries were revealed.
A detailed explanation of phase evolution inside Zn/MnO
2
batteries was provided.
Aqueous rechargeable Zn/MnO
2
zinc-ion batteries (ZIBs) are reviving recently due to their low cost, non-toxicity, and natural abundance. However, their energy storage mechanism remains controversial due to their complicated electrochemical reactions. Meanwhile, to achieve satisfactory cyclic stability and rate performance of the Zn/MnO
2
ZIBs, Mn
2+
is introduced in the electrolyte (e.g., ZnSO
4
solution), which leads to more complicated reactions inside the ZIBs systems. Herein, based on comprehensive analysis methods including electrochemical analysis and Pourbaix diagram, we provide novel insights into the energy storage mechanism of Zn/MnO
2
batteries in the presence of Mn
2+
. A complex series of electrochemical reactions with the co-participation of Zn
2+
, H
+
, Mn
2+
, SO
4
2−
, and OH
−
were revealed. During the first discharge process, co-insertion of Zn
2+
and H
+
promotes the transformation of MnO
2
into Zn
x
MnO
4
, MnOOH, and Mn
2
O
3
, accompanying with increased electrolyte pH and the formation of ZnSO
4
·3Zn(OH)
2
·5H
2
O. During the subsequent charge process, Zn
x
MnO
4
, MnOOH, and Mn
2
O
3
revert to α-MnO
2
with the extraction of Zn
2+
and H
+
, while ZnSO
4
·3Zn(OH)
2
·5H
2
O reacts with Mn
2+
to form ZnMn
3
O
7
·3H
2
O. In the following charge/discharge processes, besides aforementioned electrochemical reactions, Zn
2+
reversibly insert into/extract from α-MnO
2
, Zn
x
MnO
4
, and ZnMn
3
O
7
·3H
2
O hosts; ZnSO
4
·3Zn(OH)
2
·5H
2
O, Zn
2
Mn
3
O
8
, and ZnMn
2
O
4
convert mutually with the participation of Mn
2+
. This work is believed to provide theoretical guidance for further research on high-performance ZIBs.
Abstract
The space charge layer (SCL) is generally considered one of the origins of the sluggish interfacial lithium-ion transport in all-solid-state lithium-ion batteries (ASSLIBs). However, in-situ ...visualization of the SCL effect on the interfacial lithium-ion transport in sulfide-based ASSLIBs is still a great challenge. Here, we directly observe the electrode/electrolyte interface lithium-ion accumulation resulting from the SCL by investigating the net-charge-density distribution across the high-voltage LiCoO
2
/argyrodite Li
6
PS
5
Cl interface using the in-situ differential phase contrast scanning transmission electron microscopy (DPC-STEM) technique. Moreover, we further demonstrate a built-in electric field and chemical potential coupling strategy to reduce the SCL formation and boost lithium-ion transport across the electrode/electrolyte interface by the in-situ DPC-STEM technique and finite element method simulations. Our findings will strikingly advance the fundamental scientific understanding of the SCL mechanism in ASSLIBs and shed light on rational electrode/electrolyte interface design for high-rate performance ASSLIBs.
A novel composite anode is prepared by mixing zinc particles with activated carbon (AC) to improve the cycle performance of the neutral rechargeable zinc ion batteries. Galvanostatic charge/discharge ...cycling tests indicate that the capacity retention of the cell with adding 12 wt% activated carbon in Zn anode is 85.6% after 80 cycles, which is much higher than that of 56.7% for the cell using unmodified Zn anode. X-ray diffraction analysis indicates that the addition of activated carbon can suppress the formation of inactive basic zinc sulfates (Zn4SO4(OH)6·nH20). Morphology, elemental mapping and N2 adsorption and desorption measurements indicate that the pores of activated carbon can accommodate the deposition of Zn dendrites and insoluble anodic products. As a result, the cycle stability of the Zn anode has been greatly enhanced by activated carbon modification.
Zinc ion batteries (ZIBs) have attracted extensive attention in recent years, benefiting from their high safety, eco-friendliness, low cost, and high energy density. Although many cathode materials ...for ZIBs have been developed, the poor stability of zinc anodes caused by uneven deposition/stripping of zinc has inevitably limited the practical application of ZIBs. Herein, we report a highly stable 3D Zn anode prepared by electrodepositing Zn on a chemically etched porous copper skeleton. The inherent excellent electrical conductivity and open structure of the 3D porous copper skeleton ensure the uniform deposition/stripping of Zn. The 3D Zn anode exhibits reduced polarization, stable cycling performance, and almost 100% Coulombic efficiency as well as fast electrochemical kinetics during repeated Zn deposition/stripping processes for 350 h. Furthermore, full cells with a 3D Zn anode, ultrathin MnO2 nanosheet cathode, and Zn2+-containing aqueous electrolyte delivered a record-high capacity of 364 mAh g–1 at a current density of 0.1 A g–1 and good cycling stability with a retained capacity of 173 mAh g–1 after 300 charge/discharge cycles at 0.4 A g–1. This work provides a pathway for developing high-performance ZIBs.
Discriminative feature learning is the key to remote sensing scene classification. Previous research has found that most of the existing convolutional neural networks (CNN) focus on the global ...semantic features and ignore shallower features (low-level and middle-level features). This study proposes a novel Lie Group deep learning model for remote sensing scene classification to solve the above-mentioned challenges. Firstly, we extract shallower and higher-level features from images based on Lie Group machine learning (LGML) and deep learning to improve the feature representation ability of the model. In addition, a parallel dilated convolution, a kernel decomposition, and a Lie Group kernel function are adopted to reduce the model’s parameters to prevent model degradation and over-fitting caused by the deepening of the model. Then, the spatial attention mechanism can enhance local semantic features and suppress irrelevant feature information. Finally, feature-level fusion is adopted to reduce redundant features and improve computational performance, and cross-entropy loss function based on label smoothing is used to improve the classification accuracy of the model. Comparative experiments on three public and challenging large-scale remote-sensing datasets show that our model improves the discriminative ability of features and achieves competitive accuracy against other state-of-the-art methods.
Density functional theory calculations are employed to systematically investigate the trend of hydrogen evolution reaction (HER) performance of oxygen-terminated MXenes. By studying 30 ...transition-metal carbides and 30 transition-metal nitrides, M n+1C n O2 and M n+1N n O2 (M = Sc, Cr, Hf, Mo, Nb, Ta, Ti, V, W, Zr; n = 1, 2, 3), the tendency of oxygen desorption after hydrogen adsorption is elucidated to play a key role in HER performance of oxygen-terminated MXenes. On the basis of these observations, we propose a suitable HER descriptor, oxygen vacancy formation energy (E f), which scales linearly with the adsorption free energy of hydrogen, ΔG H. In addition, this new descriptor is linearly correlated with the lithium binding strength on oxygen-terminated MXenes. Therefore, E f is a universal descriptor for identifying the trend of adsorption processes where adsorbed species donate electrons to oxygen-terminated MXenes. This work provides a general guideline for large-scale screening of promising MXene-based materials for energy storage and conversion.
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