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1.
Lithium metal phosphates (olivines) are emerging as long-lived, safe cathode materials in Li-ion batteries. Nano-LiFePO4 already appears in high-power applications, and LiMnPO4 development is underway. Current and emerging Fe- and Mn-based intercalants, however, are low-energy producers compared to Ni and Co compounds. LiNiPO4, a high voltage olivine, has the potential for superior energy output (>10.7 Wh in 18650 batteries), compared with commercial Li(Co,Ni)O2 derivatives (up to 9.9 Wh). Speculative Co and Ni olivine cathode materials charged to above 4.5 V will require significant advances in electrolyte compositions and nanotechnology before commercialization. The major drivers toward 5 V battery chemistries are the inherent abuse tolerance of phosphates and the economic benefit of LiNiPO4: it can produce 34% greater energy per dollar of cell material cost than LiAl0.05Co0.15Ni0.8O2, today's “standard” cathode intercalant in Li-ion batteries.  相似文献   

2.
Novel Sm2O3?NiO composite was prepared as the functional electrolyte for the first time. The total electrical conductivity of Sm2O3?NiO is 0.38 S cm?1 in H2/air condition at 550 °C. High performance, e.g. 718 mW cm?2, was achieved using Sm2O3?NiO composite as an electrolyte of solid oxide fuel cells operated at 550 °C. The electrical properties and electrochemical performance are strongly depended on Sm2O3 and NiO constituent phase of the compositions. Notably, surprisingly high ionic conductivity and fuel cell performance are achieved using the composite system constituting with insulating Sm2O3 and intrinsic p-type conductive NiO with a low conductivity of 4 × 10?3 S cm?1. The interfacial ionic conduction between two phases is a dominating factor giving rise to significantly enhanced proton conduction. Fuel cell performance and further ionic conduction mechanisms are under investigation.  相似文献   

3.
Challenges for rechargeable batteries   总被引:1,自引:0,他引:1  
Strategies for Li-ion batteries that are based on lithium-insertion compounds as cathodes are limited by the capacities of the cathode materials and by the safe charging rates for Li transport across a passivating SEI layer on a carbon-based anode. With these strategies, it is difficult to meet the commercial constraints on Li-ion batteries for plug-in-hybrid and all-electric vehicles as well as those for stationary electrical energy storage (EES) in a grid.Existing alternative strategies include a gaseous O2 electrode in a Li/air battery and a solid sulfur (S8) cathode in a Li/S battery. We compare the projected energy densities and EES efficiencies of these cells with those of a third alternative, a Li/Fe(III)/Fe(II) cell containing a redox couple in an aqueous solution as the cathode. Preliminary measurements indicate proof of concept, but implementation of this strategy requires identification of a suitable Li+-ion electrolyte.  相似文献   

4.
In this paper we review some critical aspects related to interactions between cathode materials and electrolyte solutions in lithium-ion batteries. Previous results are briefly summarized, together with the presentation of new results. This review deals with the basic anodic stability of commonly-used electrolyte solutions for Li-ion batteries (mostly based on alkyl carbonate solvents). We discuss herein the surface chemistry of the following cathode materials: LiCoO2, V2O5, LiMn2O4, LiMn1.5Ni0.5O4, LiMn0.5Ni0.5O2, and LiFePO4. The methods applied included solution studies by ICP, Raman, X-ray photoelectron and FTIR spectroscopies, and electron microscopy, all in conjunction with electrochemical techniques. General phenomena are the possible dissolution of transition metal ions from these materials, which leads to changes in the active mass and a retardation in the electrode kinetics due to the formation of blocking surface films. These phenomena are significant mostly at elevated temperatures and in electrolyte solutions containing acidic species. Water-contaminated LiPF6 solutions can reach a high concentration of acidic species (e.g., HF), which is detrimental to the performance of materials such as LiCoO2 and LiFePO4. Both LiMn1.5Ni0.5O4 and LiMn0.5Ni0.5O2, even when used as nanomaterials, show a high stability in commonly-used electrolyte solutions at high temperatures. This stability is attributed to unique surface chemistry that is correlated to the presence of Ni ions in the lattice.  相似文献   

5.
The electrochemical behaviour and thermal stability of functional electrolyte additives for Li-ion batteries is investigated. The Li-ion cell systems is comprised of an anode of mesocarbon microbeads (MCMB) and a cathode (LiCoO2) in a solution of 1.1 M LiPF6 dissolved in ethylene carbonate and ethylmethyl carbonate (EC:EMC; 4:6, v/v). Vinyl acetate (VA) and vinylene carbonate (VC) in an ionic electrolyte containing triphenylphosphate (TPP) are tested as functional electrolyte additives. The main analysis tools used in this study are cyclic voltammetry (CV), differential scanning calorimetry (DSC), electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM). Cells containing VA or VC exhibit excellent irreversible capacity, coulombic efficiency, rate capability and cycleability. These features confirming the effectiveness of VC addition for improving both the cell performance and the thermal stability of electrolytes in TPP-containing solutions for Li-ion batteries.  相似文献   

6.
《Journal of power sources》2006,159(2):1383-1388
In this study the effect of the carbon coating on the electrochemical properties of LiFePO4 as a cathode for Li-ion batteries were investigated. The carbon-coated LiFePO4 particles were synthesized by the mechanochemical process and one-step heat treatment. Microscopic observations using SEM and TEM revealed that the carbon coating reduced the particle size of the LiFePO4. The carbon-coated LiFePO4 showed much better performances in terms of the discharge capacity and cycle stability than bare LiFePO4. It was confirmed that the carbon coating decreased the migration distance of Li-ion and enhanced the charge transfer from CV and ac impedance measurements. The improved electrochemical properties of the carbon-coated LiFePO4 were, therefore, attributed to the reduced particle size and enhanced electrical contacts by carbon.  相似文献   

7.
The use of conventional lithium-ion batteries in high temperature applications (>50 °C) is currently inhibited by the high reactivity and volatility of liquid electrolytes. Solvent-free, solid-state polymer electrolytes allow for safe and stable operation of lithium-ion batteries, even at elevated temperatures. Recent advances in polymer synthesis have led to the development of novel materials that exhibit solid-like mechanical behavior while providing the ionic conductivities approaching that of liquid electrolytes. Here we report the successful charge and discharge cycling of a graft copolymer electrolyte (GCE)-based lithium-ion battery at temperatures up to 120 °C. The GCE consists of poly(oxyethylene) methacrylate-g-poly(dimethyl siloxane) (POEM-g-PDMS) doped with lithium triflate. Using electrochemical impedance spectroscopy (EIS), we analyze the temperature stability and cycling behavior of GCE-based lithium-ion batteries comprised of a LiFePO4 cathode, a metallic lithium anode, and an electrolyte consisting of a 20-μm-thick layer of lithium triflate-doped POEM-g-PDMS. Our results demonstrate the great potential of GCE-based Li-ion batteries for high-temperature applications.  相似文献   

8.
We report the effects of electrode thickness, cathode particle size and morphology, cathode carbon coating matching ratio and laminate structure on the electrochemical characteristics of nanosized Li4Ti5O12–LiMn2O4 batteries. We show that a correct adjustment of these parameters resulted in significant improvements in power capability and cycle-life of such devices, making them competitive, low-cost and safe battery chemistry for next generation Li-ion batteries. In addition, Li4Ti5O12 reversible specific capacity beyond three Li-ions intercalation is reported.  相似文献   

9.
In this paper, a new anode for oxygen evolution reaction was developed from recycling of spent Li-ion cathode. After heating at 400 °C for 24 h, the spent cathode has LiCoO2 and Co3O4 in its composition. This new material was mixed with graphite and conformed in tablet for application as anode in oxygen evolution reaction in alkaline solution (NaOH 6.0 mol L−1). The concentrations of cathode in this mixture were 0, 10, 20 and 50% in mass. The best condition was 10% in mass. Under this condition the evolution of oxygen reaches 1010 mA cm−2, however, for pure graphite the current density reaches only 600 mA cm−2. Thus, this work offers an optimal choice for the waste generated by the Li-ion batteries.  相似文献   

10.
The influence of adding the room-temperature ionic liquid 1-ethyl-3-methyllimidazolium bis(trifluoromethylsulfonyl)imide (EMImTFSI) to poly(ethylene oxide) (PEO)–lithium difluoro(oxalato)borate (LiDFOB) solid polymer electrolyte and the use of these electrolytes in solid-state Li/LiFePO4 batteries has been investigated. Different structural, thermal, electrical and electrochemical studies exhibit promising characteristics of these polymer electrolyte membranes, suitable as electrolytes in rechargeable lithium-ion batteries. The crystallinity decreased significantly due to the incorporation of ionic liquid, investigated by X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The ion–polymer interaction, particularly the interaction of cations in LiDFOB and ionic liquid with ether oxygen atom of PEO chains, has been evidenced by FT-IR studies. The polymer electrolyte with ~40 wt% of ionic liquid offers a maximum ionic conductivity of ~1.85 × 10?4 S/cm at 30 °C with improved electrochemical stabilities. The Li/PEO-LiDFOB-40 wt% EMImTFSI/LiFePO4 coin-typed cell cycled at 0.1 C shows the 1st discharge capacity about 155 mAh g?1, and remains 134.2 mAh g?1 on the 50th cycle. The addition of the ionic liquid to PEO20-LiDFOB polymer electrolyte has resulted in a very promising improvement in performance of the lithium polymer batteries.  相似文献   

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