ZrO2- and Li2ZrO3-stabilized spinel and layered electrodes for lithium batteries

Strategies for countering the solubility of LiMn₂O₄ (spinel) electrodes at 50 °C and for suppressing the reactivity of layered LiMO₂ (M=Co, Ni, Mn, Li) electrodes at high potentials are discussed. Surface treatment of LiMn₂O₄ with colloidal zirconia (ZrO₂) dramatically improves the cycling stability of the spinel electrode at 50 °C in Li/LiMn₂O₄ cells. ZrO₂-coated LiMn_0.5Ni_0.5O₂ electrodes provide a superior capacity and cycling stability to uncoated electrodes when charged to a high potential (4.6 V vs Li⁰). The use of Li₂ZrO₃, which is structurally more compatible with spinel and layered electrodes than ZrO₂ and which can act as a Li⁺-ion conductor, has been evaluated in composite 0.03Li₂ZrO₃ · 0.97LiMn_0.5Ni_0.5O₂ electrodes; glassy Li_xZrO_2 + x/2 (0<x⩽2) products can be produced from colloidal ZrO₂ for surface coatings.     

High capacity Li[Li0.2Mn0.54Ni0.13Co0.13]O2–V2O5 composite cathodes with low irreversible capacity loss for lithium ion batteries

With an aim to suppress the huge irreversible capacity loss encountered in high capacity layered oxide solid solutions between Li₂MnO₃ and LiMO₂ (M = Mn, Ni, and Co), layered Li[Li_0.2Mn_0.54Ni_0.13Co_0.13]O₂–V₂O₅ composite cathodes with various V₂O₅ contents have been investigated. The irreversible capacity loss decreases from 68 mAh/g at 100% Li[Li_0.2Mn_0.54Ni_0.13Co_0.13]O₂ to 0 mAh/g around 89 wt.% Li[Li_0.2Mn_0.54Ni_0.13Co_0.13]O₂–11 wt.% V₂O₅ as the lithium-free V₂O₅ serves as an insertion host to accommodate the lithium ions that could not be inserted back into the layered lattice after the first charge. The Li[Li_0.2Mn_0.54Ni_0.13Co_0.13]O₂–V₂O₅ composite cathodes with about 10–12 wt.% V₂O₅ exhibit an attractive discharge capacity of close to 300 mAh/g with little irreversible capacity loss and good cyclability.     

Lithium–manganese–nickel-oxide electrodes with integrated layered–spinel structures for lithium batteries

A series of lithium–manganese–nickel-oxide compositions that can be represented in three-component notation, xLi[Mn_1.5Ni_0.5]O₄ · (1 − x){Li₂MnO₃ · Li(Mn_0.5Ni_0.5)O₂}, in which a spinel component, Li[Mn_1.5Ni_0.5]O₄, and two layered components, Li₂MnO₃ and Li(Mn_0.5Ni_0.5)O₂, are structurally integrated in a highly complex manner, have been evaluated as electrodes in lithium cells for x = 1, 0.75, 0.50, 0.25 and 0. In this series of compounds, which is defined by the Li[Mn_1.5Ni_0.5]O₄–{Li₂MnO₃ · Li(Mn_0.5Ni_0.5)O₂} tie-line in the Li[Mn_1.5Ni_0.5]O₄–Li₂MnO₃–Li(Mn_0.5Ni_0.5)O₂ phase diagram, the Mn:Ni ratio in the spinel and the combined layered Li₂MnO₃ · Li(Mn_0.5Ni_0.5)O₂ components is always 3:1. Powder X-ray diffraction patterns of the end members and the electrochemical profiles of cells with these electrodes are consistent with those expected for the spinel Li[Mn_1.5Ni_0.5]O₄ (x = 1) and for ‘composite’ Li₂MnO₃ · Li(Mn_0.5Ni_0.5)O₂ layered electrode structures (x = 0). Electrodes with intermediate values of x exhibit both spinel and layered character and yield extremely high capacities, reaching more than 250 mA h/g with good cycling stability between 2.0 V and 4.95 V vs. Li° at a current rate of 0.1 mA/cm².     

Ag/C包覆对Li[Li0.2Mn0.54Ni0.13Co0.13]O2电化学性能的影响

运用共沉淀和元素化学沉积相结合的方法,制备出了具有Ag/C 包覆层的层状富锂固溶体材料Li[Li_0.2Mn_0.54Ni_0.13Co_0.13]O₂. 通过X 射线衍射（XRD）、场发射扫描电子显微镜（SEM）、透射电子显微镜（TEM）、恒流充放电、循环伏安（CV）,电化学阻抗谱（EIS）和X 射线能量散射谱（EDS）方法,研究了Ag/C 包覆层对Li[Li_0.2Mn_0.54Ni_0.13Co_0.13]O₂电化学性能的影响. 结果表明,Ag/C 包覆层的厚度约为25 nm,Ag/C 包覆在保持了固溶体材料α-NaFeO₂ 六方层状晶体结构的前提下,显著地改善了Li[Li_0.2Mn_0.54Ni_0.13Co_0.13]O₂ 的电化学性能. 在2.0-4.8 V（vs Li/Li⁺）的电压范围内,首次放电（0.05C）容量由242.6 mAh·g^-1提高到272.4 mAh·g^-1,库仑效率由67.6%升高到77.4%;在0.2C倍率下,30 次循环后,Ag/C 包覆的电极材料容量为222.6 mAh·g^-1,比未包覆电极材料的容量高出14.45%;包覆后的电极材料在1C下的容量仍为0.05C下的81.3%. 循环伏安及电化学交流阻抗谱研究表明,Ag/C包覆层抑制了材料在充放电过程中氧的损失,有效降低了Li[Li_0.2Mn_0.54Ni_0.13Co_0.13]O₂颗粒的界面膜电阻与电化学反应电阻.     

Fabrication and electrochemical properties of the Sn–Ni–P alloy rods array electrode for lithium-ion batteries

A new ternary Sn–Ni–P alloy rods array electrode for lithium-ion batteries is synthesized by electrodeposition with a Cu nanorods array structured foil as current collector. The Cu nanorods array foil is fabricated by heat treatment and electrochemical reduction of Cu(OH)₂ nanorods film, which is grown directly on Cu substrate through an oxidation method. The Sn–Ni–P alloy rods array electrode is mainly composed of pure Sn, Ni₃Sn₄ and Ni–P phases. The electrochemical experimental results illustrate that the Sn–Ni–P alloy rods array electrode has high reversible capacity and excellent coulombic efficiency, with an initial discharge capacity and charge capacity of 785.0 mAh g^?1 and 567.8 mAh g^?1, respectively. After the 100th discharge–charge cycling, capacity retention is 94.2% with a value of 534.8 mAh g^?1. The electrode also performs with an excellent rate capacity.     

Comments on stabilizing layered manganese oxide electrodes for Li batteries

An electrochemical study of structurally-integrated xLi₂MnO₃•(1 −x)LiMn_0.5Ni_0.5O₂ ‘composite’ materials has been undertaken to investigate the stability of electrochemically-activated electrodes at the Li₂MnO₃-rich end of the Li₂MnO₃–LiMn_0.5Ni_0.5O₂ tie-line, i.e., for 0.7 ≤ x ≤ 0.95. Excellent performance was observed for x = 0.7 in lithium half-cells; comparable to activated electrodes that have significantly lower values of x and are traditionally the preferred materials of choice. Electrodes with higher manganese content (x ≥ 0.8) showed significantly reduced performance. Implications for stabilizing low-cost, manganese-rich, layered lithium-metal-oxide electrode materials are discussed.     

Superior high-rate cycling performance of LiFePO4/C-PPy composite at 55 °C

A facile chemical polymerization method was applied to prepare LiFePO₄/C-PPy composite using Fe(III)tosylate as oxidant. The as-prepared LiFePO₄/C-PPy sample with PPy content of approximately 4 wt% showed great rate capability with a discharge capacity of 115 mAh/g at 20C. High temperate cycling performance of the LiFePO₄/C-PPy sample was compared with bare LiFePO₄/C at 5C charge–discharge rate at 55 °C. The LiFePO₄/C-PPy cathode showed superior cycling stability with an initial capacity of 155 mAh/g. Ninety percentage of this initial capacity was retained after 300 cycles, compared to 40% of that of bare LiFePO₄/C. The LiFePO₄/C-PPy electrode showed stable discharge plateau voltage of 3.35–3.25 V vs. Li⁺/Li during long term cycling. The superior performance of the LiFePO₄/C-PPy electrode was due to the enhanced electrical conductivity, negligible iron dissolution and alleviated electrode cracking contributed by PPy coating.     

Nb2O5 nanobelts: A lithium intercalation host with large capacity and high rate capability

In this study, Nb₂O₅ nanobelts, with a ca. ∼15 nm in thickness, ca. ∼60 nm in width and several tens of mircrometers in length, have first been used as the electrode material for lithium intercalation over the potential window of 3.0–1.2 V (vs. Li⁺/Li). It delivers an initial intercalation capacity of 250 mA hg⁻¹ at 0.1 Ag⁻¹ current density, corresponding to x = 2.5 for L_xNb₂O₅, and can still keep relative stable and reaches as large as 180 mA hg⁻¹ after 50 cycles. Surprisingly, the electrodes composed of Nb₂O₅ nanobelts can work smoothly even at high current density of 10 Ag⁻¹, and shows higher specific capacity and excellent cycling stable, as well as sloped feature in voltage profile. Cycling test indicates Nb₂O₅ nanobelts electrode shows a high reversible charge/discharge capacity, high rate capability with excellent cycling stability.     

Enhanced electrochemical reduction of rare earth oxides in simulated oxide fuel via co-reduction of NiO in Li2O–LiCl salt

Rare earth oxides in spent oxide fuel from nuclear plants have poor reducibility in the electrochemical reduction process due to their high oxygen affinity and thermodynamic stability. Here, we demonstrate that the extent of their reduction can be enhanced via co-reduction of NiO in a Li₂O–LiCl electrolyte for the electrochemical reduction of a simulated oxide fuel (simfuel). First, the electrochemical behaviors of Nd₂O₃, NiO, and Nd₂O₃–NiO were studied by cyclic voltammetry and voltage control electrolysis. Then, the electrochemical reduction of the simfuel containing UO₂ and rare earth oxides (Nd₂O₃, La₂O₃, and CeO₂) was conducted in molten LiCl salt with 1 wt.% Li₂O via the co-reduction of NiO. The extent of reduction of the rare earth oxides was found to be significantly improved.     

LiMn2O4 hollow nanosphere electrode material with excellent cycling reversibility and rate capability

Lithium-rich Li_1.05Mn₂O₄ hollow nanospheres have been successfully prepared by air-calcining lithiated MnO₂ precursor at a low temperature of 550 °C, which was synthesized by chemical lithiation of hollow MnO₂ nanospheres with LiI at 70 °C for 12 h. The lithium-rich Li_1.05Mn₂O₄ hollow nanospheres exhibit an excellent cycling stability and rate capability as a cathode material for rechargeable lithium batteries: it maintains 90% of its initial capacity after 500 cycles, and keeps 70% of the reversible capacity at 0.1 C rat, even at 15 C rate.     

Enhanced reversible lithium storage in a nanosize silicon/graphene composite

Si/graphene composite was prepared by simply mixing of commercially available nanosize Si and graphene. Electrochemical tests show that the Si/graphene composite maintains a capacity of 1168 mAh g^?1 and an average coulombic efficiency of 93% up to 30 cycles. EIS indicates that the Si/graphene composite electrode has less than 50% of the charge-transfer resistance compared with nanosize Si electrode, evidencing the enhanced ionic conductivity of Si/graphene composite. The enhanced cycling stability is attributed to the fact that the Si/graphene composite can accommodate large volume charge of Si and maintain good electronic contact.     

MOF-derived ZnCo2O4/C wrapped on carbon fiber as anode materials for structural lithium-ion batteries

In this work, large area MOF-derived ZnCo₂O₄/C anchored on carbon fiber as high-performance anode materials was fabricated via a facile method and subsequent annealing treatment.     

Improved electrochemical performances of core-shell Cu2O/Cu composite prepared by a simple one-step method

Core-shell Cu₂O/Cu composites were successfully prepared by over-reduction of aqueous CuSO₄ with hydrazine hydrate as reductant. Field emission scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM) clearly illuminate that the core is Cu₂O with 400 nm in diameter, and the shell is Cu with about 50 nm in thickness. The core-shell Cu₂O/Cu exhibited weaker polarization and higher coulombic efficiency than pure octahedral Cu₂O, especially in the initial stage of cycles. After 50 cycles, the reversible capacity of Cu₂O/Cu (360 mAh g^?1) was much higher than that of pure Cu₂O (160 mAh g^?1). The improvement of electrochemical properties is attributed to the core-shell structure of Cu₂O/Cu and the catalytic effect of Cu on the decomposition of Li₂O during the charging process.     

Preliminary study of alkaline single flowing Zn–O2 battery

A new single flow alkaline battery, Zn–K₂[Zn(OH)]₄–O₂ battery, in which electrodeposited zinc is employed as an negative electrode and the oxygen in atmosphere as an high-capacity positive electrode active material is developed. The working process of the battery only depends on the circulation of a single electrolyte solution with assistance of a single pump and no cationic membrane is needed. The newly designed dual catalytical layers of composite oxygen electrode employs nano-structured Ni(OH)₂ and the electrolytic manganese dioxide doped with NaBiO₃ as two types of novel highly-efficient catalysts for oxygen evolution and reduction process, respectively. Cell (grade 1000 mAh) test results show that high efficiency is achieved with an average coulombic efficiency of 97.4% and an energy efficiency of 72.2% in 150 cycles.     

Lithia formation mechanism in tin oxide anodes for lithium–ion rechargeable batteries

The lithia formation mechanism in tin oxide anode is investigated using electrochemical measurements and Auger spectroscopy. Based on the charge/discharge capacities for SnO electrode, the atomic ratio of Li to O in lithia is less than 2 at the discharge capacity of 400 mAh/g (～0.9 V). The derivative capacity plots show that the irreversible reaction occurs throughout the entire discharge to 0 V, and the atomic ratio of Li to O is about 1 at ～0.8 V and 2 at 0 V. Auger spectroscopy analysis also confirms that the atomic ratio of Li to O approaches to 2 only when discharged to 0 V. Thus, Li₂O appears to have formed at 0 V in the first discharge, not ～0.8 V as reported previously, such that the initial lithia composition is more like Li₂O₂.     

Self-assembled Li4Ti5O12/TiO2/Li3PO4 for integrated Li–ion microbatteries

This work aims to maximize the number of active sites for energy storage per geometric area, by approaching the investigation to 3D design for microelectrode arrays. Self-organized Li₄Ti₅O₁₂/TiO₂/Li₃PO₄ composite nanoforest layer (LTL) is obtained from a layer of self organized TiO₂/Li₃PO₄ nanotubes. The electrochemical response of this thin film electrode prepared at 700 °C exhibited lithium insertion and de-insertion at 1.55 and 1.57 V respectively, which is the typical potential found for lithium titanates. The effects of lithium phosphate on lithium titanate are explored for the first time. By cycling between 2.7 and 0.75 V the LTL/LiFePO₄ full cell delivered 145 mA h g^− 1 at an average potential of 1.85 V leading to an energy density of 260 W h kg^− 1 at C/2. Raman spectroscopy revealed that the γ-Li₃PO₄/lithium titanate structure is preserved after prolonged cycling. This means that Li₃PO₄ plays an important role for enhancing the electronic conductivity and lithium ion diffusion.     

Synthesis and properties of a lithium-organic coordination compound as lithium-inserted material for lithium ion batteries

A lithium-organic coordination compound based on an aromatic carbonyl derivative, [Li₂(C₁₄H₆O₄)], was synthesized by the dehydration of [Li₂(C₁₄H₆O₄)·H₂O], and used as a novel lithium-inserted material for lithium ion batteries. The synthesized material has initial discharge capacity of 126 and 115 mAh/g at current densities of 22 and 111 mAh/g, corresponding to the columbic efficiency of 99.2% and 98.3% at the first cycle, and its capacity fading is only 5% and 13% after 50 cycles, respectively, showing that this compound is a promising candidate as lithium-inserted material for lithium ion batteries.     

Structural and electrochemical investigation of Li2MgSnO4 anode for lithium batteries

Hexagonal Li₂MgSnO₄ compound was synthesized at 800 °C using Urea Assisted Combustion (UAC) method and the same has been exploited as an anode material for lithium battery applications. Structural investigations through X-ray diffraction, Fourier Transform Infra Red spectroscopy and ⁷Li NMR (Nuclear Magnetic Resonance spectroscopy) studies demonstrated the existence of hexagonal crystallite structure with a = 6.10 and c = 9.75. An average crystallite size of ∼400 nm has been calculated from PXRD pattern, which was further evidenced by SEM images. An initial discharge capacity of ∼794 mA h/g has been delivered by Li₂MgSnO₄ anode with an excellent capacity retention (85%) and an enhanced coulombic efficiency (97–99%). Further, the Li₂MgSnO₄ anode material has exhibited a steady state reversible capacity of ∼590 mA h/g even after 30 cycles, thus qualifying the same for use in futuristic lithium battery applications.     

Bismuth oxide nanoflake@carbon film: A free-standing battery-type electrode for aqueous sodium ion hybrid supercapacitors

An efficient strategy is developed to fabricate binder-free Bi₂O₃@C nanoflake film anode, which is utilized to assemble a high-performance aqueous sodium ion hybrid supercapacitor.     

High-energy and high-power Li-rich nickel manganese oxide electrode materials

A lithium-rich nickel-manganese oxide compound Li_x(Ni_0.25Mn_0.75)O_y (x > 1) was synthesized from layered Na_0.9Li_0.3Ni_0.25Mn_0.75O_δ precursor using a lithium ion-exchange reaction. The electrochemical behavior of the material as a cathode for lithium batteries, and a preliminary discussion of its structure are reported. The product Li_1.32Na_0.02Ni_0.25Mn_0.75O_y (IE-LNMO) shows broad X-ray diffraction peaks, but possesses a high intensity sharp (003) layering peak and multiple peaks with intensity in the 20–23° 2θ region which suggest Ni–Mn ordering in the transition metal layer (TM). Li/IE-LNMO cells demonstrate very stable reversible capacities of 220 mAh/g @ 15 mA/g and possess extremely high power of 150 mAh/g @ 1500 mA/g (15C). The Li/IE-LNMO cell dQ/dV plot exhibits three reversible electrochemical processes due to Ni/Mn redox behavior in a layered component, and Mn redox exchange in a spinel component. No alteration in the dQ/dV curves and no detectable change in the voltage profiles over 40 cycles were observed, thus indicating a stable structure for lithium insertion/extraction. This new material is attractive for demanding Li-ion battery applications.