Influence of synthesis temperature on electrochemical performance of polyoxomolybdate as cathode material of lithium ion battery

In order to improve the electrochemical performance of polyoxomolybdate Na3[AlMo6O24H6]（NAM） as the cathode material of lithium ion battery, the NAM materials with small particle size were synthesized by elevatingthe synthesistemperaturein the solution.The as-prepared NAM materials were investigated by FT-IR, XRD, SEM and EIS. Their discharge-charge and cycle performance were also tested. The resultsshowthat the particle size decreasesto less than10μm at the temperature ofhigher than 40℃.When synthesized at 80℃,the NAMwiththe smallest particle size （-3μm）exhibitsthe best electrochemical performance such ashigh initial discharge capacity of 409 mA·h/gandcoulombic efficiency of 95% in the first cycle at 0.04C.

Effect of binary conductive additive mixtures on electrochemical performance of polyoxomolybdate as cathode material of lithium ion battery

Binary carbon mixtures, carbon black ECP 600JD(ECP) combined with vapor grown carbon fiber(VGCF) or carbon nanotube(CNT), or graphene(Gr) in different mass ratios, are investigated as the conductive additives for the cathode material polyoxomolybadate Na_3[AlMo_6O_(24)H_6](NAM). Field emission scanning electron microscopy and energy dispersive X-ray spectroscopy show that the surfaces of NAM particles are covered homogeneously with the binary conductive additive mixtures except the combination of ECP and CNT. The optimum combination is the mixture of ECP and VGCF, which shows higher discharge capacity than the combinations of ECP and CNT or Gr. Initial discharge capacities of 364, 339, and 291 m A·h/g are obtained by the combination of ECP and VGCF in the mass ratios of 2:1, 1:1, and 1:2, respectively. The results of electrochemical impedance spectra and 4-pin probe measurements demonstrate that the combination of ECP and VGCF exhibits the highest electrical conductivity for the electrode.

Suppress oxygen evolution of lithium-rich manganese-based cathode materials via an integrated strategy

Improving the reversibility of anionic redox and inhibiting irreversible oxygen evolution are the main challenges in the application of high reversible capacity Li-rich Mn-based cathode materials.A facile synchronous lithiation strategy combining the advantages of yttrium doping and LiYO_(2) surface coating is proposed.Yttrium doping effectively suppresses the oxygen evolution during the delithiation process by increasing the energy barrier of oxygen evolution reaction through strong Y–O bond energy.LiYO_(2) nanocoating has the function of structural constraint and protection,that protecting the lattice oxygen exposed to the surface,thus avoiding irreversible oxidation.As an Li^(+) conductor,LiYO_(2) nano-coating can provide a fast Li^(+) transfer channel,which enables the sample to have excellent rate performance.The synergistic effect of Y doping and nano-LiYO_(2) coating integration suppresses the oxygen release from the surface,accelerates the diffusion of Li^(+)from electrolyte to electrode and decreases the interfacial side reactions,enabling the lithium ion batteries to obtain good electrochemical performance.The lithium-ion full cell employing the Y-1 sample(cathode)and commercial graphite(anode)exhibit an excellent specific energy density of 442.9 Wh kg^(-1) at a current density of 0.1C,with very stable safety performance,which can be used in a wide temperature range(60 to-15℃)stable operation.This result illustrates a new integration strategy for advanced cathode materials to achieve high specific energy density.

Smart materials for safe lithium-ion batteries against thermal runaway

In recent years,the new energy storage system,such as lithium ion batteries(LIBs),has attracted much attention.In order to meet the demand of industrial progress for longer cycle life,higher energy density and cost efficiency,a quantity of research has been conducted on the commercial application of LIBs.However,it is difficult to achieve satisfying safety and cycling performance simultaneously.There may be thermal runaway(TR),external impact,overcharge and overdischarge in the process of battery abuse,which makes the safety problem of LIBs more prominent.In this review,we summarize recent progress in the smart safety materials design towards the goal of preventing TR of LIBs reversibly from different abuse conditions.Benefiting from smart responsive materials and novel structural design,the safety of LIBs can be improved a lot.We expect to provide a comprehensive reference for the development of smart and safe lithium-based battery materials.

Two-Dimensional Graphitic Carbon-Nitride(g-C_(3)N_(4))-Coated LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)Cathodes for High-Energy-Density and Long-Life Lithium Batteries

High-capacity nickel-rich layered oxides are promising cathode materials for high-energy-density lithium batteries.However,the poor structural stability and severe side reactions at the electrode/electrolyte interface result in unsatisfactory cycle performance.Herein,the thin layer of two-dimensional(2D)graphitic carbon-nitride(g-C_(3)N_(4))is uniformly coated on the LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(denoted as NCM811@CN)using a facile chemical vaporization-assisted synthesis method.As an ideal protective layer,the g-C_(3)N_(4)layer effectively avoids direct contact between the NCM811 cathode and the electrolyte,preventing harmful side reactions and inhibiting secondary crystal cracking.Moreover,the unique nanopore structure and abundant nitrogen vacancy edges in g-C_(3)N_(4)facilitate the adsorption and diffusion of lithium ions,which enhances the lithium deintercalation/intercalation kinetics of the NCM811 cathode.As a result,the NCM811@CN-3wt%cathode exhibits 161.3 mAh g^(−1)and capacity retention of 84.6%at 0.5 C and 55°C after 400 cycles and 95.7 mAh g^(−1)at 10 C,which is greatly superior to the uncoated NCM811(i.e.129.3 mAh g^(−1)and capacity retention of 67.4%at 0.5 C and 55°C after 220 cycles and 28.8 mAh g^(−1)at 10 C).The improved cycle performance of the NCM811@CN-3wt%cathode is also applicable to solid–liquid-hybrid cells composed of PVDF:LLZTO electrolyte membranes,which show 163.8 mAh g^(−1)and the capacity retention of 88.1%at 0.1 C and 30°C after 200 cycles and 95.3 mAh g^(−1)at 1 C.

Graphene oxide assisted facile hydrothermal synthesis of LiMn_(0.6)Fe_(0.4)PO_4 nanoparticles as cathode material for lithium ion battery

Assisted by graphene oxide（GO）,nano-sized LiMn0.6Fe0.4PO4 with excellent electrochemical performance was prepared by a facile hydrothermal method as cathode material for lithium ion battery.SEM and TEM images indicate that the particle size of LiMn0.6Fe0.4PO4（S2）was about 80 nm in diameter.The discharge capacity of LiMn0.6Fe0.4PO4 nanoparticles was 140.3 mAh-g^1 in the first cycle.It showed that graphene oxide was able to restrict the growth of LiMn0.6Fe0.4PO4 and it in situ reduction of GO could improve the electrical conductivity of LiMn0.6Fe0.4PO4 material.

Synthesis and Characterization of Li_(1.05)Co_(0.3)Ni_(0.35)Mn_(0.3)M_(0.05)O_2(M=Ge,Sn)Cathode Materials for Lithium Ion Battery

In order to improve the electrochemical performance and thermal stability of Li1.05Co1/3Nil/3Mnl/302 materials, Lil.05CO0.3 Ni0.35Mno.3Mo.0502（M=Ge,Sn） cathode materials were synthesized via co-precipitation method. The structure, electrochemical performance and thermal stability were characterized by X-ray diffraction（XRD）, charge/discharge cycling, cyclic voltammetry（CV）, electrochemical impedance spectroscopy（EIS） and differential scanning calorimetry（DSC）. ESEM showed that Sn-doped and Ge- doped slightly increased the size of grains. XRD and CV showed that Sn-doped and Ge-doped powders were homogeneous and had the better layered structure than the bare one. Sn-doped and Ge-doped improved high rate discharge capacity and cycle-life performance. The reason of the better cycling performance of the doped one was the increasing of lithium-ion diffusion rate and charge transfer rate. Sn-doped and Ge-doped also improved the mateials thermal stability.

Empowering the Future: Exploring the Construction and Characteristics of Lithium-Ion Batteries

Lithium element has attracted remarkable attraction for energy storage devices, over the past 30 years. Lithium is a light element and exhibits the low atomic number 3, just after hydrogen and helium in the periodic table. The lithium atom has a strong tendency to release one electron and constitute a positive charge, as Li . Initially, lithium metal was employed as a negative electrode, which released electrons. However, it was observed that its structure changed after the repetition of charge-discharge cycles. To remedy this, the cathode mainly consisted of layer metal oxide and olive, e.g., cobalt oxide, LiFePO4, etc., along with some contents of lithium, while the anode was assembled by graphite and silicon, etc. Moreover, the electrolyte was prepared using the lithium salt in a suitable solvent to attain a greater concentration of lithium ions. Owing to the lithium ions’ role, the battery’s name was mentioned as a lithium-ion battery. Herein, the presented work describes the working and operational mechanism of the lithium-ion battery. Further, the lithium-ion batteries’ general view and future prospects have also been elaborated.

Preparation and characterization of LiMn_(1.5)Me_(0.5)O_4 (Me=Ti,Fe,Ni,Zn) for lithium-ion battery cathode materials

Based on synthesizing pure spinel type lithium manganese oxides,the derivations such as LiMn1.5Ti0.5-O4,LiMn1.5Fe0.5O4,LiMn1 .5Ni0.5O4 and LiMn1.5Zn0.5O4 were prepared using solid- step-sintering method. The structures were characterized by using XRD,SEM and laser granulometer. The electrochemical measurement results show that the elemen t of iron or nickel can raise the discharging plateau voltage of LiMn2O4,an d element titanium improves the electrochemistry property of LiMn2O4 little,while element zinc destroys the electrochemistry property of LiMn2O4. The i nfluence of elements of titanium,iron,nickel,or zinc on the structure of LiMn 2O4 pure phase was discussed from the viewpoint of structural chemistry.

Optimum Preparation Conditions of LiNi_(0.8)Co_(0.2)O_2 and LiNi_(0.95)Ce_(0.05)O_2 as Lithium-Ion Battery Cathode Materials

The preparation of LiNi_(0.8)Co_(0.2)O_2 was discussed by the multiply sintering method for solid reaction, in which the sintered material was smashed, ground and pelletted between two successive sintering steps. The optimum technological condition was obtained through orthogonal experiments by L_9(3~4) and DTA analysis. The result indicates that the factors of effecting the electrochemical properties of synthesized LiNi_(0.8)Co_(0.2)O_2 are molar ratio of Li/Ni/Co, oxygen pressure, homothermal time, the final sintering temperature in turn according to its importance. The oxygen pressure is reviewed independently and the technological condition is further optimized. With the same method, rare earth element Ce was studied as substitute element of Co and the cathode material of LiNi_(0.95)Ce_(0.05)O_2 with excellent electrochemical properties was prepared. The electrochemical testing results of LiNi_(0.8)Co_(0.2)O_2 and LiNi_(0.95)Ce_(0.05)O_2 experimental batteries show that discharge capacities of them reach 165 and 148 mAh·g^(-1) respectively and the persistence is more than 9 h at 3.7 V.

Effect of Mn-doping on performance of Li_3V_2(PO_4)_3/C cathode material for lithium ion batteries

Li3V2-2/3xMnx（PO4）3（0≤x≤0.12） powders were synthesized by sol-gel method. The effect of Mn2＋-doping on the structure and electrochemical performances of Li3V2（PO4）3/C was characterized by XRD, SEM, XPS, galvanostatic charge /discharge and electrochemical impedance spectroscopy（EIS）. The XRD study shows that a small amount of Mn2＋-doped does not alter the structure of Li3V2（PO4）3/C materials, and all Mn2＋-doped samples are of pure single phase with a monoclinic structure （space group P21/n）. The XPS analysis indicates that valences state of V and Mn are ＋3 and ＋2 in Li3V1.94Mn0.09（PO4）3/C, respectively, and the citric acid in raw materials was decomposed into carbon during calcination, and residual carbon exists in Li3V1.94Mn0.09（PO4）/C. The results of electrochemical measurements show that Mn2＋-doping can improve the cyclic stability and rate performance of these cathode materials. The Li3V1.94Mn0.09（PO4）3/C cathode material shows the best cyclic stability and rate performance. For example, at the discharge current density of 40 mA/g, after 100 cycles, the discharge capacity of Li3V1.94Mn0.09（PO4）3/C declines from initial 158.8 mA·h/g to 120.5 mA·h/g with a capacity retention of 75.9%; however, that of the Mn-undoed sample declines from 164.2 mA·h/g to 72.6 mA·h/g with a capacity retention of 44.2%. When the discharge current is increased up to 1C, the intial discharge capacity of Li3V1.94Mn0.09（PO4）3/C still reaches 146.4 mA·h/g, and the discharge capacity maintains at 107.5 mA·h/g after 100 cycles. The EIS measurement indicates that Mn2＋-doping with a appropriate amount of Mn2＋ decreases the charge transfer resistance, which is favorable for the insertion/extraction of Li＋.

Electrochemical performance of a nickel-rich LiNi0.6Co0.2Mn0.2O2 cathode material for lithium-ion batteries under different cut-off voltages

A spherical-like Ni0.6Co0.2Mn0.2(OH)2precursor was tuned homogeneously to synthesize LiNi0.6Co0.2Mn0.2O2as a cathode material for lithium-ion batteries. The effects of calcination temperature on the crystal structure, morphology, and the electrochemical performance of the as-prepared LiNi0.6Co0.2Mn0.2O2were investigated in detail. The as-prepared material was characterized by X-ray diffraction, scanning electron microscopy, laser particle size analysis, charge–discharge tests, and cyclic voltammetry measurements. The results show that the spherical-like LiNi0.6Co0.2Mn0.2O2material obtained by calcination at 900°C displayed the most significant layered structure among samples calcined at various temperatures, with a particle size of approximately 10 μm. It delivered an initial discharge capacity of 189.2 mAh•g−1at 0.2C with a capacity retention of 94.0% after 100 cycles between 2.7 and 4.3 V. The as-prepared cathode material also exhibited good rate performance, with a discharge capacity of 119.6 mAh•g−1at 5C. Furthermore, within the cut-off voltage ranges from 2.7 to 4.3, 4.4, and 4.5 V, the initial discharge capacities of the calcined samples were 170.7, 180.9, and 192.8 mAh•g−1, respectively, at a rate of 1C. The corresponding retentions were 86.8%, 80.3%, and 74.4% after 200 cycles, respectively. © 2017, University of Science and Technology Beijing and Springer-Verlag Berlin Heidelberg.

Preparation and electrochemical properties of Y-doped Li_3V_2(PO_4)_3 cathode materials for lithium batteries

Y-doped Li3V2（PO4）3 cathode materials were prepared by a carbothermal reduction（CTR） process.The properties of the Y-doped Li3V2（PO4）3 were investigated by X-ray diffraction（XRD） and electrochemical measurements.XRD studies showed that the Y-doped Li3V2（PO4）3 had the same monoclinic structure as the undoped Li3V2（PO4）3.The Y-doped Li3V2（PO4）3 samples were investigated on the Li extraction/insertion performances through charge/discharge, cyclic voltammogram（CV）, and electrochemical impedance spectra（EIS）.The optimal doping content of Y was x=0.03 in Li3V2-xYx（PO4）3 system.The Y-doped Li3V2（PO4）3 samples showed a better cyclic ability.The electrode reaction reversibility was enhanced, and the charge transfer resistance was decreased through the Y-doping.The improved electrochemical perormances of the Y-doped Li3V2（PO4）3 cathode materials were attributed to the addition of Y3＋ ion by stabilizing the monoclinic structure.

Polyoxovanadate(NH_4)_7[MnV_(13)O_(38)] as cathode material for lithium ion battery and improved electrochemical performance

The polyoxovanadate（NH4）7[MnV13O38]（AMV） was synthesized and characterized by X-ray diffraction pattern, Fourier transform infrared spectra, and field emission scanning electron microscope equipped with energy dispersive X-ray spectroscopy. In order to improve the electrochemical performance of AMV, the particle size of as-prepared AMV is decreased to nanoscale by re-precipitation in the water-ethanol solution. The results of the electrochemical impedance spectra and the 4-pin probe measurements show that the electrical conductivity of AMV is improved by decreasing the particle size. The nanoparticle AMV shows higher initial discharge capacity and energy density than the as-prepared AMV when cycled at 0.5C. On the other hand, the nanoparticle AMV exhibits higher rate capability than the as-prepared AMV.

Recent progress of surface coating on cathode materials for high-performance lithium-ion batteries

Lithium-ion batteries (LIB) have received substantial attention in the last 10 years,as they offer great promise as power sources that can lead to the electric vehicle (EV) revolution in the next 5 years.Since the cathode serves as a key component in LIB,its properties significantly affect the performance of the whole system.Recently,the cathode surface modification based on coating technique has been widely employed to enhance the electrochemical performances by improving the material conductivity,stabilising the physical structure of materials,as well as preventing the reactions between the electrode and electrolyte.In this work,we reviewed the present of a number of promising cathode materials for Li-ion batteries.After that,we summarized the very recent research progress focusing on the surface coating strategies,mainly including the coating materials,the coating technologies,as well as the corresponding working mechanisms for cathodes.At last,the challenges faced and future guidelines for optimizing cathode materials are discussed.In this study,we propose that the structure of cathode is a crucial factor during the selection of coating materials and technologies.

Synthesis and characterization of triclinic structural LiVPO_4F as possible 4.2 V cathode materials for lithium ion batteries

A potential 4.2 V cathode material LiVPO4F for lithium batteries was prepared by two-step reaction method based on a carbon-thermal reduction （CTR） process. Firstly, V2O5, NH4H2PO4 and acetylene black are reacted under an Ar atmosphere to yield VPO4. The transition-metal reduction is facilitated by the CTR based on C→CO transition. These CTR conditions favor stabilization of the vanadium as V^3＋ as well as leaving residual carbon, which is useful in the subsequent electrode processing. Secondly, VPO4 reacts with ElF to yield LiVPO4F product. The property of the LiVPO4F was investigated by X-ray diffractometry （XRD）, scanning electron microscopy （SEM） and electrochemical measurement. XRD studies show that LiVPO4F synthesized has triclinic structure（space group p I ）, isostructural with the naturally occurring mineral tavorite, EiFePO4-OH. SEM image exhibits that the particle size is about 2μm together with homogenous distribution. Electrochemical test shows that the initial discharge capacity of LiVPO4F powder is 119 mA·h/g at the rate of 0.2C with an average discharge voltage of 4.2V （vs Ei/Li^＋）, and the capacity retains 89 mA·h/g after 30 cycles.

Microwave synthesis of Li_2FeSiO_4 cathode materials for lithium-ion batteries

A novel synthetic method of microwave processing to prepare Li2FeSiO4 cathode materials is adopted. The Li2FeSiO4 cathode material is prepared by mechanical ball-milling and subsequent microwave processing. Olivin-type Li2FeSiO4 sample with uniform and fine particle sizes is successfully and fast synthesized by microwave heating at 700 ℃ in 12 rain. And the obtained Li2FeSiO4 materials show better electrochemical performance and microstructure than those of Li2FeSiO4 sample by the conventional solidstate reaction. ？2009 Yan Bing Cao. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

Synthesis and electrochemical properties of Li[Ni_xCo_yMn_(1-x-y)]O_2 (x, y = 2/8, 3/8) cathode materials for lithium ion batteries

The tmiform layered Li（Ni2/8Co3/8Mn3/8）O2, Li（Ni3/8Co2/8Mn3/8）O2, and Li（Ni3/8Co3/8Mn2/8）O2 cathode materials for lithium ion batteries were prepared using the hydroxide co-precipitation method. The effects of calcination temperature and transition metal contents on the structure and electrochemical properties of the Li-Ni-Co-Mn-O were systemically studied. The results of XRD and electrochemical performance measurement show that the ideal preparation conditions were to prepare the Li（Ni3/8Co3/8Mn2/8）O2 cathode material calcined at 900℃ for 10 h. The well-ordered Li（Ni3/8Co3/8Mn2/8）O2 synthesized under the optimal conditions has the I003/I104 ratio of 1.25 and the R value of 0.48 and delivers the initial discharge capacity of 172.9 mA·h·g^-1, the discharge capacity of 166.2 mA·h·g^-1 after 20 cycles at 0.2C rate, and the impedance of 558 Ω after the first cycle. The decrease of Ni content results in the decrease of discharge capacity and the bad cycling performance of the Li-Ni-Co-Mn-O cathode materials, but the decreases of Mn content and Co content to a certain extent can improve the electrochemical properties of the Li-Ni-Co-Mn-O cathode materials.

Influence of Doping Rare Earth on Performance of Lithium Manganese Oxide Spinels as Cathode Materials for Lithium-Ion Batteries

Some rare earth doping spinel LiMn_(2-x)RE_xO_4 (RE=La, Ce, Nd) cathode materials for lithium ion batteries were synthesized by the solid-state reaction method. The structure characteristics of these produced samples were investigated by XRD, SEM, and particle size distribution analysis. According to the microstructure and charge-discharge testing, the effect of doping rare earth on stabilizing the spinel structure was analyzed. Through a series of doping experiments, it is shown that when the doping content x within the range of 0.01～0.02 the cycle performance of the materials is greatly improved. The discharge capacity of the sample LiMn_(1.98)La_(0.02)O_4, LiMn_(1.98)Ce_(0.02)O_4 and LiMn_(1.98)Nd_(0.02)O_4 remain 119.1, 114.2 and 117.5 mAh·g^(-1) after 50 cycles.

A closed-loop process for recycling LiNi_xCo_yMn_((1-x-y))O_2 from mixed cathode materials of lithium-ion batteries

With the rapid development of consumer electronics and electric vehicles(EV), a large number of spent lithium-ion batteries(LIBs) have been generated worldwide. Thus, effective recycling technologies to recapture a significant amount of valuable metals contained in spent LIBs are highly desirable to prevent the environmental pollution and resource depletion. In this work, a novel recycling technology to regenerate a LiNi_(1/3)Co_(1/3)Mn_(1/3)O_2 cathode material from spent LIBs with different cathode chemistries has been developed. By dismantling, crushing,leaching and impurity removing, the LiNi_(1/3)Co_(1/3)Mn_(1/3)O_2(selected as an example of LiNi_xCo_yMn_(1-x-y)O_2) powder can be directly prepared from the purified leaching solution via co-precipitation followed by solid-state synthesis. For comparison purposes, a fresh-synthesized sample with the same composition has also been prepared using the commercial raw materials via the same method. X-ray diffraction(XRD), scanning electron microscopy(SEM) and electrochemical measurements have been carried out to characterize these samples. The electrochemical test result suggests that the re-synthesized sample delivers cycle performance and low rate capability which are comparable to those of the freshsynthesized sample. This novel recycling technique can be of great value to the regeneration of a pure and marketable LiNi_xCo_yMn_(1-x-y)O_2 cathode material with low secondary pollution.