Stability of carbon electrodes for aqueous lithium-air secondary batteries (original) (raw)
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Anodic performance of vapor-derived carbon filaments in lithium-ion secondary battery
Carbon, 2001
The electrochemical characteristics of vapor-derived carbon filaments of diameter 0.1 mm were studied by chargedischarge testing of a lithium-ion secondary cell with a lithium metal electrode. After activation, followed by either nitridation or reduction in hydrogen, vapor-derived carbon filaments show high reversible charge and discharge capacities. An ordered structure and a large pore size are favorable for a high capacity, as shown by comparison of vapor-derived and pitch-derived carbons. The combination of a high specific surface area and a large amount of oxygen-containing surface functional groups results in a high irreversible capacity. To improve the anodic performance, it is important to control the surface microstructure by decreasing the surface oxygen content by nitridation or reduction in H , while maintaining order in 2 the crystallographic structure with surface mesoporosity.
In thiswork we have studied the stability and performance of hard carbon in comparison with petroleum coke (soft carbon) as electrode materials for Li-ion batteries in an ethereal and alkyl carbonate based electrolyte solutions. 1 M bis(triflouromethane) sulfonimide lithium salt (LiTFSI) in diethylene glycol dimethyl ether (diglyme)) and a mixture of dimethyl carbonate (DMC)/mono-fluorinated ethylene carbonates (FEC) 4:1 (%v) with 1 M Lithium hexaflourophosphate (LiPF6) where chosen as representative solutions for this study. The motivation for this work is the potential importance of ethereal solutions for high energy density Li-S and Li-O2 batteries and the possibility of using carbons as an alternative to Li metal anodes in these systems. An acceptable performance of hard carbon electrodes in the ether based solutions was demonstrated. In contrast, soft carbon electrodes which preform very well in alkyl carbonates solutions behave poorly in the ethereal solutions. Their failure mechanism was explored and is explained in this report.
Lithium Intercalation in Porous Carbon Electrodes
MRS Proceedings, 1995
ABSTRACTCarbons derived from the phase separation of polyacrylonitrile/solvent mixtures were investigated as lithium intercalation anodes for rechargeable lithium-ion batteries. The carbon electrodes have a bulk density of 0.35-0.5 g/cm3, relatively low surface areas (< 10 m2/g), and micron-size cells. Pyrolysis temperature influences the reversible lithium intercalation and the irreversible capacity (associated with the formation of the passivating layer). Carbon electrodes pyrolyzed at 600°C have first-cycle capacity as high as 550 mAh/g as well as large irreversible capacity, 440 mAh/g. Electrodes prepared at 1050°C have reversible capacities around 270 mAh/g with relatively lower capacity losses (120 mAh/g). Doping the organic precursors with phosphoric acid, prior to pyrolysis at 1050 C, leads to carbon electrodes with reversible capacities as high as 450 mAh/g. The capacity of doped carbon increased with increasing phosphorus concentration in the samples. The doped carbon a...
Electrochemical and Solid-State Letters, 2009
A water-stable multilayer Li-metal electrode consisting of a lithium metal, a PEO 18 LiN͑SO 2 CF 3 ͒ 2-BaTiO 3 composite polymer, and a lithium-conducting glass ceramic Li 1.35 Ti 1.75 Al 0.25 P 0.9 Si 0.1 O 12 ͑LTAP͒ was proposed as the lithium anode for aqueous lithium-air secondary batteries. The addition of finely dispersed nanosize BaTiO 3 in the polymer electrolyte greatly reduced the interfacial resistance between the Li anode and the polymer electrolyte. A Li/PEO 18 LiN͑SO 2 CF 3 ͒ 2-10 wt % BaTiO 3 /LTAP electrode showed a total resistance of 175 ⍀ cm 2 in a 1 M aqueous LiCl solution at 60°C, with no change in the electrode resistance over a month. The Li/PEO 18 LiN͑SO 2 CF 3 ͒ 2-10 wt % BaTiO 3 /LTAP/aqueous 1 M LiCl/Pt air cell had a stable opencircuit voltage of 3.80 V, which was equivalent to that calculated from the cell reaction of 2Li + 1/2O 2 + H 2 O = 2LiOH. The cell exhibited a stable and reversible discharge/charge performance of 0.5 mA cm −2 at 60°C, suggesting excellent reversibility of the lithium oxidation reduction reaction for the Li/PEO 18 LiN͑SO 2 CF 3 ͒ 2-10 wt % BaTiO 3 /LTAP electrode.
Thermal and electrochemical studies of carbons for Li-ion batteries
Journal of Power Sources, 2000
Ž. Ž. Thermal gravimetric analysis TGA and differential thermal analysis DTA involving air oxidation of fluid coke, coal-tar pitch delayed coke and needle coke suggested that active sites are present which can be correlated to the crystallographic parameters, L and a Ž. L , and the d 002 spacing. This finding was extended to determine the relationship between active sites on carbon and their role in c Ž. catalyzing electrolyte decomposition leading to irreversible capacity loss ICL in Li-ion batteries. Electrochemical data from this study with graphitizable carbons and from published literature were analyzed to determine the relationship between the physical properties of carbon and the ICL during the first chargerdischarge cycle. Based on this analysis, we conclude that the active surface area, and not the total BET surface area, has an influence on the ICL of carbons for Li-ion batteries. This conclusion suggests that the carbon surface structure plays a significant role in catalyzing electrolyte decomposition.
Study of camphor-pyrolysed carbon electrode in a lithium rechargeable cell
Materials Chemistry and Physics, 2000
Pure camphor pyrolysed at 900 • C for 2 h in different gaseous environments yields graphite-like carbons which were used as a negative electrode in rechargeable carbon/Li cells. These cells were continuously cycled at a constant current of 300 A cm −2 for 10-20 days and reversible Li + intercalation capacities of 0.45-0.61 were observed. Kinetic analysis of such a cell was studied by complex impedance spectroscopy and current interruption. After initial irreversible passivation during the first discharge, fully reversible intercalation capacity was observed for subsequent charge-discharge cycles. This property makes the camphor-pyrolysed carbon (CPC) a promising electrode material for further investigation for making a rechargeable lithium battery. A CPC/Li cell model is proposed. The structural properties of the camphor-pyrolysed electrode material is discussed on the basis of SEM, TEM, XRD and FTIR analyses.