The electrochemical performance of super P carbon black in reversible Li/Na ion uptake

Super P carbon black (SPCB) has been widely used as a conducting additive in Li/Na ion batteries to improve the electronic conductivity. However, there has not yet been a comprehensive study on its structure and electrochemical properties for Li/Na ion uptake, though it is important to characterize its contribution in any study of active materials that uses this additive in non-negligible amounts. In this article the structure of SPCB has been characterized and a comprehensive study on the electrochemical Li/Na ion uptake capability and reaction mechanisms are reported. SPCB exhibits a considerable lithiation capacity (up to 310 mAh g^(–1)) from the Li ion intercalation in the graphite structure. Sodiation in SPCB undergoes two stages: Na ion intercalation into the layers between the graphene sheets and the Na plating in the pores between the nano-graphitic domains, and a sodiation capacity up to 145 mAh g^(–1) has been achieved. Moreover, the influence of the type and content of binders on the lithiation and sodiation properties has been investigated. The cycling stability is much enhanced with sodium carboxymethyl cellulose (NaCMC) binder in the electrode and fluoroethylene carbonate (FEC) in the electrolyte; and a higher content of binder improves the Coulombic efficiency during dis-/charge.

Cationic potential:An effective descriptor for rational design of layered oxides for sodium-ion batteries

Sodium-ion batteries are very promising in large-scale energy storage.The exploration of Na layered oxides as cathode materials for Na ion batteries usually consumes much resource,while the performances of Na layered oxides are dominated by their crystal structures.Therefore,it is highly desired to predict the stacking mode of the target oxides in advance:whether O3-type with higher ordered structure and stability,or P2-type with more Na content.For this purpose density functional theory computations do not work.Very recently,Hu's group and international collaborators have proposed a cationic potential to provide a very timely,effective,and accurate criterion to predict the stacking mode of Na layered oxides(Science,370(2020)708-711).Under the guidance of the cationic potential phase map,Na layered oxides could be rationally designed.Here we would like to highlight the progress that novel Na layered oxides could be obtained with the combination of large specific capacity,high power density and good cycling stability.

Hard carbon derived from rice husk as low cost negative electrodes in Na-ion batteries

Here,we report the synthesis of hard carbon materials(RH) made from natural rice husk through a single pyrolysis process and their application as an anode in sodium-ion batteries.The studies show that the electrochemical properties of RHs are affected by the treatment temperatures,which determine the materials morphology,in particular,their degree of graphitization and extent of continuous channels(nanovoids).The latter are accessible to sodium ions and significantly contribute to charge storage capacity of the produced anodes.The RHs obtained at 1600 °C deliver the highest reversible capacity of276 mAh g^(-1) mainly due to insertion of sodium ions into the nanovoids.This work deepens the basic understanding of the influence of the carbonization temperature on the sodium storage mechanism.

Growth of SnO_2 Nanoflowers on N-doped Carbon Nanofibers as Anode for Li-and Na-ion Batteries

It is urgent to solve the problems of the dramatic volume expansion and pulverization of SnO_2 anodes during cycling process in battery systems. To address this issue, we design a hybrid structure of N-doped carbon fibers@SnO_2 nanoflowers(NC@SnO_2) to overcome it in this work. The hybrid NC@SnO_2 is synthesized through the hydrothermal growth of SnO_2 nanoflowers on the surface of N-doped carbon fibers obtained by electrospinning. The NC is introduced not only to provide a support framework in guiding the growth of the SnO_2 nanoflowers and prevent the flower-like structures from agglomeration, but also serve as a conductive network to accelerate electronic transmission along one-dimensional structure effectively. When the hybrid NC@SnO_2 was served as anode, it exhibits a high discharge capacity of 750 Ah g^(-1) at 1 A g^(-1) after 100 cycles in Li-ion battery and 270 mAh g^(-1) at 100 mA g^(-1) for 100 cycles in Na-ion battery, respectively.

High-Performance Na-Ion Storage of S-Doped Porous Carbon Derived from Conjugated Microporous Polymers

Na-ion batteries(NIBs)have attracted considerable attention in recent years owing to the high abundance and low cost of Na.It is well known that S doping can improve the electrochemical performance of carbon materials for NIBs.However,the current methods for S doping in carbons normally involve toxic precursors or rigorous conditions.In this work,we report a creative and facile strategy for preparing S-doped porous carbons(SCs)via the pyrolysis of conjugated microporous polymers(CMPs).Briefly,thiophene-based CMPs served as the precursors and doping sources simultaneously.Simple direct carbonization of CMPs produced S-doped carbon materials with highly porous structures.When used as an anode for NIBs,the SCs exhibited a high reversible capacity of 440 mAh g?1 at 50 mA g?1 after 100 cycles,superior rate capability,and excellent cycling stability(297 mAh g?1 after 1000 cycles at 500 mA g?1),outperforming most S-doped carbon materials reported thus far.The excellent performance of the SCs is attributed to the expanded lattice distance after S doping.Furthermore,we employed ex situ X-ray photoelectron spectroscopy to investigate the electrochemical reaction mechanism of the SCs during sodiation-desodiation,which can highlight the role of doped S for Na-ion storage.

Recent advances on flexible electrodes for Na-ion batteries and Li–S batteries

Flexible energy storage devices are essential for emerging flexible electronics. The existing state-of-the-art Li-ion batteries are slowly reaching their limitation in terms of cost and energy density. Hence, flexible Na-ion batteries (SIBs) with abundanee Na resources and Li-S batteries with high energy density become the alternative for the Li-ion batteries in future. This review summarizes the recent advances in the development of flexible electrode materials for SIBs with metallic matrix and carb on aceous matrix such as carb on nano-tubes, carbon nano-fiber, graphene, carbon cloth, carbon fiber cloth, and cotton textiles. Then, the potential prototype flexible full SIBs are discussed. Further, the recent progress in the development of flexible electrode materials for Li-S batteries based on carb on nano-fiber, carb on nano-tubes, graphene, and cotton textiles is reviewed. Moreover, the design strategies of suitable interlayer, separator, electrolyte, and electrodes to prevent the dissolution and shuttle effect of polysulfides in flexible Li-S batteries are provided. Finally some prospective investigation trends towards future research of flexible SIBs and Li-S batteries are also proposed and discussed. The scientific and engineering knowledge gained on flexible SIBs and Li-S batteries provides conceivable development for practical application in near future.

Degradation mechanism of tin phosphide as Na-ion battery negative electrode

The degradation mechanism of an Sn_4P_3 electrode as Na-ion battery anode was investigated by using a transmission electron microscopic observation. At the first desodiation, we confirmed that Sn nanoparticles with 6 nm in size were dispersed in an amorphous-like P matrix.Compared to this, we observed aggregated Sn particles with sizes exceeding 50 nm after the drastic capacity fading. The capacity fading mechanism was for the first time confirmed to be Sn aggregation. To improve the capacity decay, we carried out the two kinds of chargeàdischarge cycling tests under the reduced volume changes of Sn particles and P matrix by limiting desodiation reactions of Nae Sn and Na3P, respectively. The Sn_4P_3 electrode exhibited an excellent cyclability with the discharge capacity of 500 mA hg^(-1) for 420 cycles under the limited desodiation, whereas the capacity decay was accelerated under the limited sodiation. The results suggest that the Sn aggregation can be improved by the reduced volume change of the P matrix, and that it is very effective for improving anode performance of Sn_4P_3 electrode.

Metal–organic framework derived hierarchical porous TiO_2 nanopills as a super stable anode for Na-ion batteries

Hierarchical porous TiOnanopills were synthesized using a titanium metal-organic framework MIL-125（Ti） as precursor. The as-synthesized TiOnanopills owned a large specific surface area of 102 m/g and unique porous structure. Furthermore, the obtained TiOnanopills were applied as anode materials for Na-ion batteries for the first time. The as-synthesized TiOnanopills achieved a high discharge capacity of 196.4 m Ah/g at a current density of 0.1 A/g. A discharge capacity of 115.9 m Ah/g was obtained at a high current density of 0.5 A/g and the capacity retention was remained as high as 90% even after 3000 cycles. The excellent electrochemical performance can be attributed to its unique hierarchical porous feature.

The Core Mechanism of Traditional Medicine Is the Rational and Effective Use of Potassium Ions

The use of traditional medicines including natural drugs, especially traditional Chinese medicine (TCM), plays an important role in the prevention and treatment of human diseases;however, so far, the mechanism of its prevention, health care and treatment of diseases is unclear. Here, I propose that the core mechanism of traditional medicines is to correct the relative deficiency of potassium ions in body and at the same time improve the utilization efficiency of potassium ions, so as to improve or restore cell functions in organs and tissues, and let the body return to a normal state. In order to achieve such a core goal, the therapeutic effect of natural drugs has an important relationship with the rational matching of prescriptions and the quality of drugs, with particular emphasis on the concentrations and quantum energy levels of potassium ions or their compounds in the formula. The understanding of the core effect of potassium in natural drugs has a specific and important guiding role for the artificial cultivation and rational use of natural drugs. Moreover, these ideas may also provide an important theoretical basis for the development of modern agriculture and medicine, and the rational and comprehensive utilization of potassium resources.

STUDY OF POSITRON ANNIHILATION ONE DIMENSION ANGULAR-CORRELATION RADIATION ON POLYCRYSTAL Na^+ CONDUCTOR Na_5Y_(1-x)Cr_xSi_4O_(12)

With positron annihilation radiation one dimension angular-correlation device, it is measured that positron annihilation radiation one dimension angular-correlation curves of polycrystal sodium ion conductor Na5Y1-x CrxSi4O12 (NYCS) system. After electron momentum distribution curves are normalized, linear parameters are calculated. The parameters H, W and S show the change of Na+ ion vacancy concentration in NYCS series samples. The results show that parameters H, W and S of one dimension angular-correlation curves of those samples vary greatly with Cr2O3 contents. With Cr2O3 content increasing, H and S parameters increase, but W decreases, and reaches extremes at x=0.05; then with Cr2O3 adding continually, parameters H and S decrease gradually, parameter W increases gradually. This shows that, in addtion to Cr2O3, the conductivity has close relation with the concentration of Na+ ion vacancy.

Hard carbons derived from pine nut shells as anode materials for Na-ion batteries

Hard carbons as promising anode materials for Na-ion batteries(NIBs) have captured extensive attention because of their low operation voltage, easy synthesis process, and competitive specific capacity. However, there are still several disadvantages, such as high cost and low initial coulombic efficiency, which limit their large-scale commercial applications.Herein, pine nut shells(PNSs), a low-cost biomass waste, are used as precursors to prepare hard carbon materials. Via a series of washing and heat treatment procedures, a pine nut shell hard carbon(PNSHC)-1400 sample has been obtained and delivers a reversible capacity of around 300 mAh/g, a high initial coulombic efficiency of 84%, and good cycling performance. These excellent Na storage properties indicate that PNSHC is one of the most promising candidates of hard carbon anodes for NIBs.

Relative Deficiency of Intracellular Potassium in Relation to the Functional Changes and Diseases in Non-Nervous System

Because of the huge differences in cellular structures and functions in non-nervous system and interaction between the nervous and non-nervous systems in potassium ion absorption, storage and effective utilization, the organs, tissues and tissue cells in non-nervous system have different functional dependence on potassium ion and its characteristics in competitive distribution differences. Therefore, I propose that the relative deficiency of potassium in cells in non-nervous organs and tissues may show very different functional changes and disease characteristics. Some are susceptible to pathogenic microorganisms, some may result in decrease of cell functions, and other may have comprehensive changes such as chronic inflammation. Therefore, the core causes for the functional changes and lesions of these non-nervous organs and tissues are closely related to the relative deficiency of potassium ions in their cells, which provides important ideas for the prevention and treatment of these functional changes and diseases.

Interface effect on promoting reversible conversion for Na2Se in the metal selenide as sodium ion batteries

The rapid development of modern electronic devices has promoted more research in the field of high energy-density storage devices[1].Lithium ion batteries(LIBs)have been widely used in electronic devices and hybrid electric vehicles since their successful commercialization by Sony[2,3].

Enhancing the cycling stability of Na-ion batteries by bonding MoS2 on assembled carbon-based materials

Room temperature Na-ion batteries(SIBs) show great potential for use as renewable energy storage systems.However, the large-scale application of SIBs has been hindered by the lack of an ideal SIBs anode material. We synthesized MoS2 on carbonized graphene-chitosan(G-C) using the hydrothermal method. The strong interaction between the MoS2 and the G-C greatly improved the electron transport rate and maintained the structural stability of the electrode, which lead to both an excellent rate capability and long cycle stability. The G-C monolith was proven to enhance the electrical conductivity of the composites and served as a matrix for uniformly dispersing active MoS2 nanosheets(NSs), as well as being a buffer material to adapt to changes in volume during the cycle.Serving as an anode material for SIBs, the MoS2-G-C electrode showed good cycling stability(527.3mAh g-1 at100 m A g-1 after 200 cycles), excellent rate capability, and a long cycle life(439.1 m Ah g-1 at 1 A g-1 after 200 cycles).

Kinetic Process and Conductivity of Ag^+ Ion Exchange for Polycrystalline Na-β"-Al_2O_3

This paper reports the kinetic process of Ag ion exchange for the polycrystalline Na-β'-Al2O3.The interdiffusion coefficients in the process of Ag+ and Na+ ion exchange have been calculated with an 'one dimensional double side diffusion model'. Microstructures of the samples were observed and analysed by XRD, EMPA, SEM. The results of the conductivity measurements for samples with Na+, Ag+ and Na+-Ag+ mobile ions are presented and explained

Three-Dimensional Self-assembled Hairball-Like VS4 as High-Capacity Anodes for Sodium-Ion Batteries

Sodium-ion batteries(SIBs)are considered to be attractive candidates for large-scale energy storage systems because of their rich earth abundance and consistent performance.However,there are still challenges in developing desirable anode materials that can accommodate rapid and stable insertion/extraction of Na+and can exhibit excellent electrochemical performance.Herein,the self-assembled hairball-like VS4 as anodes of SIBs exhibits high discharge capacity(660 and 589 mAh g−1 at 1 and 3 A g−1,respectively)and excellent rate property(about 100%retention at 10 and 20 A g−1 after 1000 cycles)at room temperature.Moreover,the VS4 can also exhibit 591 mAh g−1 at 1 A g−1 after 600 cycles at 0°C.An unlike traditional mechanism of VS4 for Na+storage was proposed according to the dates of ex situ characterization,cyclic voltammetry,and electrochemical kinetic analysis.The capacities of the final stabilization stage are provided by the reactions of reversible transformation between Na2S and S,which were considered the reaction mechanisms of Na–S batteries.This work can provide a basis for the synthesis and application of sulfur-rich compounds in fields of batteries,semiconductor devices,and catalysts.

Na_(0.44)MnO_(2)颗粒尺寸对其作为水系钠离子电池正极性能的影响

水溶性钠离子电池是一种与锂离子电池相辅相成的技术,因其相对较低的成本、改善的安全性和环境友好的电解液而备受青睐。然而,较低的电极容量限制了这种电池的应用。Na_(0.44)MnO_(2)是一种用于钠离子电池的高容量阴极材料,其理论容量为121 mAh/g。文章研究了Na_(0.44)MnO_(2)的尺寸效应对阴极性能的影响。纳米棒通过热处理MnO_(2)纳米片前驱体制备而成,其尺寸通过CTAB和KMnO_(4)的比例进行调控。然后,Na_(0.44)MnO_(2)纳米棒被用作水溶性钠离子电池的活性材料。纳米棒阴极在1 C的初始循环中提供了60 mAh/g的容量,并在经过200个循环后保持了55 mAh/g,比Na_(0.44)MnO_(2)块状阴极高出37.5%。在高倍率的5 C下,该阴极在经过200个循环后仍能提供47 mAh/g的高容量。容量的增加归因于减小的电荷传递阻抗和纳米棒具有较高比表面积所带来的改善的钠离子扩散性能。

Ion Mobility in the Fluorite Solid Solutions 50PbF₂–30BiF₃–20K(Na)F According to ¹⁹F, ²³Na NMR Data

Ion mobility in solid solutions of the fluorite structure 50Pb2–30BiF3–20KF (I) and 50Pb2–30BiF3–20NaF (II) was studied by NMR method. Analysis of 19F, 23Na NMR spectra made it possible to reveal the character of ion motions in the fluoride and sodium sublattices with temperature variation, to determine the types and temperature ranges in which they took place. It was found that the dominant form of ionic mobility in the samples I and II above 380 K was the diffusion of fluoride and sodium ions. According to preliminary results of electro-physical studies, the conductivity reached values of ~ 2×10–2 – 10–3 S/cm above 500 K. The solid solutions I and II can be recommended as a basis for use in the development of new functional materials.

LaNbO_(4)掺杂对Na-β"-Al_(2)O_(3)固态电解质性能的改善

离子导体陶瓷材料的高断裂强度和优异热稳定性对于解决目前困扰碱金属电池发展的热失控问题具有重要意义,但其在室温下表现出的较高离子传输阻力限制了全固态电池的实际性能。以Na-β"-Al_(2)O_(3)(SBA)这一具备独特层状二维Na^(+)传导结构的离子导体陶瓷为研究对象,通过合成具备“微弹性”特点的LaNbO_(4)陶瓷作为第二相来对SBA的晶粒间隙进行填充修饰,以改善SBA在室温下的离子传导性能。结果表明,0.50 wt.%的LaNbO_(4)掺入量对SBA的提升效果最佳,修饰后的SBA室温离子电导率达到了2.061 mS·cm^(-1)。对应的活化能也从纯相SBA的0.1714 eV降低到了0.1545 eV。陶瓷横截面的SEM图像表明,合适比例的LaNbO_(4)掺入不仅提高了SBA的烧结致密度,也改善了SBA的晶体生长趋势,因此修饰后的SBA的阻抗值发生了降低。在室温全固态对称钠电池的恒流循环实验中,使用掺杂SBA组装的对称电池能够以更低的电压运行也从实验层面上印证了上述观点。