Structural, magnetic and electrochemical properties of lithium iron orthosilicate

We report the structural and electronic characterization of Li₂FeSiO₄ synthesized by solid-state reaction. X-ray diffraction, Raman scattering, Fourier transform infrared (FTIR) spectroscopy, electron paramagnetic resonance (EPR) spectroscopy and magnetization measurements are analyzed. Magnetic susceptibility experiments give evidence that Li₂FeSiO₄ powders possess an antiferromagnetic ordering below T_N = 25 K due to long range Fe–O–Li–O–Fe interactions. Analysis of the paramagnetic region giving the Curie–Weiss parameters θ_p = −93.5 K and C_p = 4.13 emu K mol⁻¹ shows the divalent state of Fe cations. Electron paramagnetic resonance experiments confirm this electronic configuration. Electrochemical measurements were carried out in lithium cells with LiTFSI in a poly(ethylene oxide) (PEO) polymer electrolyte at 80 °C. The resulting cyclic voltammogram indicates a stable structure for the first cycle with redox peaks at 2.80 and 2.74 V versus Li⁰/Li⁺.     

Electrochemical and structural characteristics of niobium(V) oxide in a rechargeable lithium battery

The discharge behaviour of T-Nb₂O₅ in various electrolytes is unaffected by the choice of solvent, but is strongly dependent on the crystal radius of the solute cation species. Thermodynamic and structural studies show that this is due to the insertion of unsolvated Li⁺ ions into the crystal lattice. The graphite content of the Nb₂O₅ electrode has a marked influence on the cycling behaviour on account of the decrease in the oxide conductivity with discharge. Furthermore, the chemical diffusion coefficient of Li⁺ ions in Nb₂O₅ is about 10⁻¹⁰ cm² s⁻¹, which is one order of magnitude smaller than that in V₂O₅ with a layered structure.     

Lithium-ion modified cellulose as a water-soluble binder for Li-O2 battery

An environment-friendly, water-soluble, and cellulose based binder (lithium carboxymethyl cellulose, CMC-Li) was successfully synthesized by using Li⁺ to replace Na⁺ in the commercial sodium carboxymethyl cellulose (CMC-Na). Li-O₂ batteries based on the CMC-Li binder present enhanced discharge specific capacities (11151 mA·h/g at 100 mA/g) and a superior cycling stability (100 cycles at 200 mA/g) compared with those based on the CMC-Na binder. The enhanced performance may originate from the electrochemical stability of the CMC-Li binder and the ion-conductive nature of CMC-Li, which promotes the diffusion of Li⁺ in the cathode and consequently retards the increase of charge transfer resistance of the cathode during cycling. The results show that the water-soluble CMC-Li binder can be a green substitute for poly(vinylidene fluoride) (PVDF) binder based on organic solvent in the lithium oxygen batteries (LOBs).     

Electron and phonon aspects in a lithium intercalated InSe cathode

Lithium intercalated InSe has been shown to function as a cathode in lithium batteries. Lithium insertion in InSe results in structural modification to create a superlattice that induces new Raman peaks by folding of the phonon branches. The presence of alternating sheets of Li⁺ ions causes alterations in the electronic band structure due to complementary Coulomb interaction that is itself evident through changes in exciton binding energies. In the presence of Li⁺ ions, new radiative recombination centres are also observed.     

The effect of multivalent cation dopants on lithium manganese spinel cathodes

The cycling stability of 4 V Li_xMn₂O₄ electrodes in lithium, flooded electrolyte glass cells has been improved by the addition of multivalent cation dopants (Mg²⁺, Zn²⁺ and Al³⁺). Optimal dopant levels to achieve maximum capacity and the greatest stability with repeated cycling have been determined. The effect of doping the oxygen-rich spinel Li₂Mn₄O₉, was also determined and shown to make no significant improvement in the life cycle stability in the 3 V region.     

Structural characterization and electrochemical properties of non-graphitizable carbons for a lithium ion battery

Structural characteristics and electrochemical properties of non-graphitizable carbons were investigated. The carbons were obtained by heat-treating the oxidized graphitizable carbon precursors with various molar ratios of aromatic compounds and cross-linking agent. The discharge profiles of the non-graphitizable carbons heat-treated at 600°C had one plateau discharge region at 1.0 V vs. Li/Li⁺, which is similar to graphitizable ones heat-treated at the temperature. However, the discharge profiles of the non-graphitizable carbons heat-treated above 800°C exhibited two plateau discharge regions at 0.2 and 1.0 V vs. Li/Li⁺. The discharge capacities of the non-graphitizable carbons increased with an increase of cavity volume, which was controlled by molar ratios of aromatic compound and cross-linking agent. The structural parameters proposed were measured to compare with each other, and it was found that they showed good correlation.     

Reviews of selected 100 recent papers for lithium batteries (Feb. 1, 2018 to Mar. 31, 2018)

该文是一篇近两个月的锂电池文献评述,以“lithium”和“batter^*”为关键词检索了Web of Science从2018年2月1日至2018年3月31日上线的锂电池研究论文,共有2731篇,选择其中100篇加以评论。正极材料主要研究了三元材料、富锂相材料和尖晶石材料和有机物正极材料,材料结构和表面结构随电化学脱嵌锂变化以及掺杂和表面包覆及界面层改进对其循环寿命的影响以及富锂材料的氧参与氧化还原反应的机制受到重视。硅基复合负极材料研究侧重于嵌脱锂机理以及SEI界面层,金属锂负极的研究侧重于通过表面覆盖层的设计来提高其循环性能。电解液添加剂、新型固态电解质、固态电池、锂硫电池的论文也有多篇。原位分析偏重于界面SEI和电极反应机理,理论模拟工作涵盖储锂机理、动力学、界面SEI形成机理分析和固体电解质等。除了以材料为主的研究之外,还有多篇关于电池界面及材料分析方法的研究论文。     

Mechanism of ionic conduction in polyether-polyurethane networks containing lithium perchlorate

The swelling behaviour of polyethylene oxide-urethane networks (with and without LiClO₄) was studied with several organic liquids and water. All the results are consistent with a model for the network-salt interaction involving the solvation of Li⁺ ions by oxygen atoms of the ether. More specifically, strong interactions take place between ionic quadrupoles and two polyether chains leading to reversible physicochemical (ionic) crosslinks. The number of such interactions grows with salt concentration up to a limit characterised by one ionic crosslink every twelve ethylene oxide units. An ionic transport mechanism (conduction) is proposed on the basis of this model considered in a dynamic context.     

Electrochromic properties of lithiated Co-oxide (LixCoO2) and Ni-oxide (LixNiO2) thin films prepared by the sol–gel route

Layered Li_xCoO₂ and Li_xNiO₂ thin films (x1) were prepared by a peroxo wet chemistry route from Li(I), Co(II) and Ni(II) acetate precursors and the addition of H₂O₂. Structural changes during the processing of xerogel to final oxide were followed by X-ray diffraction and infrared spectroscopy. Electrochromic properties were determined with in-situ potentiodynamic, potentiostatic and galvanostatic spectroelectrochemical measurements. Single dipped films with composition Li_0.99Co_1.01O₂ or Li_0.94Ni_1.06O₂ exhibited stable voltammetric response in 1 M LiClO₄/propylene carbonate electrolyte after about 60 cycles. The total charge exchanged in a reversible charging/discharging cycle was about ±30 mC cm⁻² for Li_0.99Co_1.01O₂ and ±20 mC cm⁻² for Li_0.94Ni_1.06O₂ oxide films. Galvanostatic measurements showed that about 1/2 (x0.5) and 2/3 (x0.3) of Li⁺ ions could be reversibly removed from the structure of Li_0.99Co_1.01O₂ and Li_0.94Ni_1.06O₂ films, respectively. Practical applicability of Li_0.99Co_1.01O₂ and Li_0.94Ni_1.06O₂ oxide films was studied in electrochromic devices with WO₃(H⁺)Li⁺ormolyteLi_0.99Co_1.01O₂ and WO₃(H⁺)Li⁺ormolyteLi_0.94Ni_1.06O₂ configuration. The monochromatic transmittance T_s (λ=633 nm) of dark blue coloured devices was extremely low (T_s3%), whereas in bleached state the value reached around T_s70%.     

Cycling behaviour of electrodeposited zinc alloy electrode for secondary lithium batteries

The cycling behaviour of an electroplated lithium-zinc alloy film electrode is examined in 1 M LiC1O₄/propylene carbonate. The cycle life depends on the utilization of lithium in the alloy and is improved by dispersion of 2 to 4 wt.% iron. This improvement is more effective when the discharge cutoff potential is 0.5 V versus Li⁺/Li. In this case, the life cycle is about 150 cycles at 250 mA h g⁻¹ of lithium utilization. The reason for improvement is possibly the suppression of electrode disintegration and the appropriate choice of alloy phases.     

Crystal chemistry modification of lithium nickel cobalt oxide cathodes for lithium ion rechargeable batteries

As a cathode material for lithium ion rechargeable batteries, LiNi_0.8Co_0.2O₂ (LNCO) is one of the most attractive candidates for high power electronic devices. In the present work, we have synthesized LNCO powder by solid-state route. The discharge capacity and the capacity retention of LNCO cathode are found to be 100 mAh g⁻¹ and 63%, respectively. Molybdenum doping, replacing parts of cobalt ion in LNCO lattice increases the discharge capacity (157 mAh g⁻¹) and improve its capacity retention characteristics. Through X-ray Rietveld analyses, we have found that Mo doping increases the inter-slab spacing between the (Co,Ni)O₂ octahedral layers which provides easier Li¹⁺ intercalation leading to improved electrochemical properties in the modified cathode.     

Structure-conductivity relationsihp in polymer electrolytes formed by network polymers from poly[dimethylsiloxane-g- poly(ethylene oxide)] and litegum perchlorate

The combination of LiClO₄ and network polymers from poly[dimethyl-siloxane-g-poly(ethylene oxide)] has been applied to polymer electrolytes as an Li⁺ ion conductor, and the structure/conductivity relationship has been investigated. The ionic conductivity is about 10⁻⁶ S cm⁻¹ at room temperature. The polymer electrolytes form a micro-heterogeneous structure from the constituent segments, and the incorporated LiClO₄ preferentially interacts with the poly(ethylene oxide) segments. The segmental motion of poly(ethylene oxide) appears to contribute to the ionic migration, while that of poly(dimethylsiloxane) does not. Not all of the incorporated LiClO₄ functions as carrier ions.     

Insertion of lithium into vanadium molybdenum oxides

Chemical insertion of lithium into V₂O₅, Mo_0.1V_1.8O_4.8 and MoV₂O₈ by LiI has been investigated. The limiting lithium content in all oxides is Li/V = 0.5, suggesting that only the V component is responsible for the lithium insertion. For V₂O₅, two potential plateaux correspond exactly to two-phase coexistent crystal structures with different van der Waals gap distances; the interaction energy between inserted lithium is attractive. By contrast, as the ratio of V substitution in Mo increases, the two-phase behaviour decreases, and the interaction between Li⁺ cations becomes repulsive. These insertion characteristics have been analyzed in relation to structural changes in VO₅ polyhedra.     

Application of tetrasodium salt of 3, 4, 9, 10-perylenetetracarboxylic acid for Li ion batteries

共轭羰基化合物由于其良好的离子和电子传输性能以及高度的可逆性,成为研究最为广泛的一类有机电极材料。采用具有3,4,9,10-苝四甲酸二酐为前驱体与氢氧化钠反应制备了3,4,9,10-苝四甲酸四钠盐（Na₄C₂₄H₈O₈,Na-PTCA）,作为锂离子电池的负极材料。Na-PTCA在50 mA/g的电流密度电压区间0.01~2 V条件下,循环100圈后还能保持468 mA·h/g的容量,表现出良好的循环稳定性。同时,其羧基部分在约1.10/1.38 V的电压平台表现高度的循环可逆性,在循环100圈后容量保持为148 mA·h/g。这些结果对扩展新型高比容锂离子电池负极材料提供了一种有效的设计思路。     

High-temperature superconductor, YBa2Cu307-x as all- solid-state lithium cell

The utility of the high-temperature superconductor, YBa₂Cu₃O_7-itx, as the cathode material for an all-solid-state lithium cell has been examined. The capacity of YBa₂Cu₃O₇-x, is 223 mA h g⁻¹ and the discharge efficiency is> 92%. Measurements of a.c. impedance show that the charge-transfer resistance at the interface of the electrolyte/cathode is very low and increases with the depth-of-discharge of the battery. Studies using X-ray photoelectron spectroscopy (XPS) reveal that the cathode becomes doped with Li⁺ ions as the cell discharges.     

Electrochemical performance of thermally-grown SiO2 as diffusion barrier layer for integrated lithium-ion batteries

Direct integration of lithium-ion battery (LIB) with electronic devices on the same Si substrate can significantly miniaturize autonomous micro systems. For achieving direct integration, a barrier layer is essential to be inserted between LIB and the substrate for blocking Li⁺ diffusion. In this paper, the feasibility of thermal SiO₂ film as the barrier layer is investigated by electrochemical characterization and X-ray photoelectron spectroscopy (XPS). Due to the negligible side reactions of thermal SiO₂ with electrolyte, the solid electrolyte interphase (SEI) layer formed on the surface of the barrier layer is thin and the SEI content mainly consists of hydrocarbon together with slight polyethylene oxide (PEO), Li_xPO_yF_z, and Li₂CO₃. Although 8-nm thermal SiO₂ effectively prevents the substrate from alloying with Li⁺, the whole film changes to Li silicate after electrochemical cycling due to the irreversible chemical reactions of SiO₂ with electrolyte. This degrades the performance of the barrier layer against the electrolyte penetration, thus leading to the existence of Li⁺ (in the form of F-Si-Li) and solvent decompositions (with the products of hydrocarbon and PEO) near the barrier layer/substrate interface. Moreover, it is found that the reaction kinetics of thermal SiO₂ with electrolyte decrease significantly with increasing the SiO₂ thickness and no reactions are found in the bulk of the 30-nm SiO₂ film. Therefore, thermal SiO₂ with an appropriate thickness is a promising barrier layer for direct integration.     

Reviews of selected 100 recent papers for lithium batteries (Aug.01, 2019 to Sep. 30, 2019)

该文是一篇近两个月的锂电池文献评述，以"lithium"和"batter^*"为关键词检索了Web of Science从2019年8月1日至2019年9月30日上线的锂电池研究论文，共有3077篇，选择其中100篇加以评论。正极材料主要研究了三元材料、富锂相材料和表面结构随电化学脱嵌锂变化以及掺杂和表面包覆及界面层改进对其循环寿命的影响。硅基复合负极材料研究侧重于嵌脱锂机理以及SEI界面层，金属锂负极的研究侧重于通过表面覆盖层的设计来提高其循环性能。电解液添加剂、固态电解质电池、锂硫电池的论文也有多篇。原位分析偏重于界面SEI和电极反应机理，理论模拟工作涵盖储锂机理、动力学、界面SEI形成机理分析等。除了以材料为主的研究之外，还有多篇针对电池分析技术的研究论文。     

Reviews of selected 100 recent papers for lithium batteries (Apr. 1, 2018 to May 31, 2018)

该文是一篇近两个月的锂电池文献评述,以"lithium"和"batter^*"为关键词检索了Web of Science从2018年4月1日至2018年5月31日上线的锂电池研究论文,共有1807篇,选择其中100篇加以评论。正极材料主要研究了三元材料、富锂相材料和尖晶石材料的结构和表面结构随电化学脱嵌锂变化以及掺杂和表面包覆及界面层改进对其循环寿命的影响。硅基复合负极材料研究侧重于电极结构和电解液添加剂改进,金属锂负极的研究侧重于通过表面覆盖层的设计来提高其循环性能。电解液添加剂、固态电解质电池、锂硫电池的论文也有多篇。原位分析偏重于固态电池的界面,理论模拟工作涵盖储锂机理、动力学、界面SEI形成机理分析和固体电解质等。除了以材料为主的研究之外,还有多篇关于电池分析的研究论文。     

Thin film of CeO2-SiO2: a new ion storage layer for smart windows

Thin solid films of CeO₂-SiO₂, used as a counter-electrode layer in electrochromic devices, were prepared by the sol–gel dip coating, using an aqueous-based process. The influence of the SiO₂ addition on electrochemistry of the CeO₂ oxide coatings was determined by chronoamperometric measurements. The films exhibit a larger charge storage capacity, which was determined as a function of the coatings thickness. The peak occurrence in the chronoamperometric curve during the deintercalation of lithium ions in the cerium/silicon films is analyzed in terms of trapping energy levels for Li⁺ ions into the film.

In situ UV–Vis spectroelectrochemical measurements of the CeO₂-SiO₂ coatings indicated that the films remained transparent in the visible spectral range during the intercalation process. Powders were characterized by X-ray diffraction after the same thermal treatment of the films, indicating a decrease of crystallinity with the doping. The feasibility for use of these electrodes as ion storage for electrochromic devices was investigated.     

Reviews of selected 100 recent papers for lithium batteries (Dec.1,2018 to Jan.31,2019)

该文是一篇近两个月的锂电池文献评述,以“lithium”和“batter^*”为关键词检索了Web of Science从2018年12月1日至2019年1月31日上线的锂电池研究论文,共有2472篇,选择其中100篇加以评论。正极材料主要研究了三元材料、富锂相材料和尖晶石材料的结构和表面结构随电化学脱嵌锂变化以及掺杂和表面包覆及界面层改进对其循环寿命的影响。硅基和锡基复合负极材料研究侧重于嵌脱锂机理以及SEI界面层,金属锂负极的研究侧重于通过集流体和表面覆盖层的设计以及电解液添加剂来提高其循环性能。固态电解质、电解液添加剂、固态电池、锂硫电池的论文也有多篇。原位分析偏重于界面SEI和电极反应机理,理论模拟工作涵盖储锂机理、动力学、界面SEI形成机理分析和固体电解质等。除了以材料为主的研究之外,还有多篇针对电池分析、电池管理系统技术的研究论文。