Lithium composition

In-situ x-ray diffraction (XRD) was performed on a coin type cell with a 4x6 mm Kapton window coated with conductive thin copper layer. The graphite electrode was pressed against the Kapton window so as to be reached by the x-ray beam. After several lithiation/delithiation cycles under a C/10 rate between 1.5 and 0V, the cell was fully delithiated up to 1.5V. The cycle capacity achieved with the graphite electrode is about 360mAh/g. The cell was then re-lithiated under a slower rate of C/20. XRD patterns were taken for about five minutes every hour while the cell is under continuous discharge. As result the lithium composition x in LixC6 was incremented by 0.05 between two successive XRD scans. 

Elemental composition Li 46.45%, 0 53.55%. The oxide may he identified from its physical properties and characterized by x-ray analysis. Lithium composition in the oxide may be determined by analyzing the nitric acid extract by AA or ICP (See Lithium). 

Gao B, Bower C, Lorentzen JD, Fleming L, Kleinhammes A, Tang XP, McNeil LE, Wu Y, Zhou O. Enhanced saturation lithium composition in ball-milled single-walled carbon nanotubes. Chem Phys Lett 2000 327 69-75. 

Gao, B., Bower, C., Lorentzen, J.D., et al. (2000). Enhanced saturation lithium composition in baU-miUed single-waUed carbon nanotubes. Chem. Phys. Lett., 327, 69-75. 

Complete lithiation to the limiting lithium stoichiometry of Li2.oRe03 may require more than one n-BuLi treatment. This can be due in part to dilution of n-BuLi as the reaction proceeds. Upon titrating the initial /i-BuLi reaction solution, 10.491 mmol of Li remains from an original 3.059 N n-BuLi solution containing 12.5 mL (38.238 mmol) of n-BuLi in hexane and 4.080 g (17.421 mmol) of ReOj. This indicates 1.59 mmol of Li per millimole of ReOj. Further lithiation and subsequent titration results in Lia.jReOj. X-ray powder diffraction data indicates the lithium composition, in excess of two Li per ReOj, is due to impurities in the ReO,. 

The first step for the analysis is the accurate determination of the open-circuit voltage (OCV) profile versus lithium composition x for three samples with different... 

As for the 200 nm particle at x = 0.93, two independent peaks were clearly observed as indexed (200)t and (200)h, respectively, which indicates that the Lio,93FeP04 phase consists of two intermediate phases, LiaFeP04 and Lij y3FeP04. This is a reasonable result because the lithium composition for the immiscible-miscible transition was estimated to be 1 — P200 - 0.98, which is much larger than the present lithium composition, x = 0.93. The lattice parameters are almost identical with those of Lio.6FeP04, which also reveal that the Lio,93FeP04 with a particle size of 200 nm is inside the miscibility gap at room temperature. 

Fig. 14.6 Left, magnified view of the 200 peak measured for Lio.93FeP04 with different particle sizes of 200, 80, and 40 nm at room temperature. Right, derivation of changes in ti-axis lattice parameter as a function of lithium composition x for different particle sizes...

Fig. 14.9 Open-circuit voltage curve and change in lattice dimensions above (a) and below (b) the two-phase equilibrium potential. Lithium composition was adjusted potentiostatically (equilibrium condition <0.1 pA) and estimated by the OCV curves as indicated by dashed lines. The linear lines along the plot of lattice constants show the "Vegard s law between FeP04 and LiFeP04...

Figure 25.2 shows the OCP vs. SOC profile of four fresh cells during charge. The OCP data points fall on top of each other in the 5%-100% SOC range, showing excellent reproducibility. The only noticeable difference occurs at SOC = 0%. This may be due to small differences in lithium composition in the graphite anode LigCe, e 0, where the anode... 

The first step for analysis is the accurate determination of the open-circuit voltage (OCV) profile vs. lithium composition x for three samples with different particle sizes of 40 nm, 80 nm, and 200 nm. Initially, the cell was charged galvanostatically at a rate of C/20 at 25°C followed by maintenance at 4.5 V for 24 h forming FeP04. Capacity close to the theoretical capacity of 170 mAh/g was confirmed for all samples. Then, it was discharged under a rate of... 

For a direct comparison between the stoichiometric LiFeP04 and the isolated solid solution of Lio,93FeP04 with an identical particle size of 40 nm, synchrotron X-ray diffraction profiles of the two samples are shown in Fig. 1.7 with some magnified presentations of the typical peaks. Peak shifts are visually evident and large enough to confirm the wide lithium compositional range of at least 7% for solid solution. The shift observations without appearing of any... 

D. Golodnitsky and E. Peled, Pyrite as Cathode Insertion Material in Rechaigeable Lithium/Composite Polymer Electrolyte Batteries, Electrochimica Acta, Vol. 45, 1999, p. 335. 

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