Li+ deintercalation

Both carbon materials were tested for their initial electrochemical performance in the 2-electrode electrochemical cells with Li metal as a counter electrode. Our findings have shown that with both types of carbon materials, achieving near theoretical reversible capacity upon Li+ deintercalation was possible. Thus, in a typical half cell environment (a CR2016 type coin cell with graphite and Li metal electrodes, a 1M LiPF6,... 

Nakai I, Nakagome T (1998) In Situ transmissimi X-ray absorption fine structure analysis of the Li deintercalation process in Li(Nio.5Coo.5)02. Electrochem Solid State Lett 1 259... 

A study of the electrochemical behavior of such a laminated Al-PA-PORP composite showed that the currents corresponding to Li deintercalation decrease significantly as compared with the A1 substrate itself, analogous to the action of PA film synthesized on this alloy. It should be stressed that no gas evolution stimulated by a chemical interaction with an electrolyte takes place on an electrode covered with PA during Li intercalation. 

Khasanova NR, Gavrilov AN et al (2011) Structural transfmmation of Li2CoP04p upon Li-deintercalation. J Powtr Sources 196 355-360... 

Fig. 6.5 shows the constant-current discharge curves. To make clear the function of the power assistance due to discharging from the double layer of the CNT-NANO electrodes, the discharge curves were obtained at the same level of current density. All CNT modified diamond electrodes exhibited discharge curves shaped like a parabola, which suggests that Li deintercalation occurred at a potential around - 3.2 V (vs. Ag/Ag ). 

In Fig. 6.5A, for HD CNT-NANO, the discharge curve exhibited only the plateau for Li+ deintercalation, indicating that the behavior for the pure electrical double layer discharging could not be observed. As the density of the CNTs in the nanopores for HD CNT-NANO was high, the double layer capacitance for pure double layer charging on the surface of the NANO was too low to contribute to a decrease in the potential drop. 

As a result, by adjusting the CNT density in the nanopores, the ratio of the discharge from the double layer capacitance and the Li deintercalation can be controlled and the performance of the electrochemical cell can be designed for any purpose, for example, high energy density or high specific power. 

Using dilatometry in parallel with cyclic voltammetry (CV) measurements in lmolL 1 LiC104 EC-l,2-dimethoxy-ethane (DME), Besenhard et al. [87] found that over the voltage range of about 0.8-0.3 V (vs. Li/Li+), the HOPG crystal expands by up to 150 percent. Some of this expansion seems to be reversible, as up to 50 percent contraction due to partial deintercalation of solvated lithium cations was observed on the return step of the CV. It was concluded [87] that film formation occurs via chemical reduction of a solvated graphite intercalation compound (GIC) and that the permselective film (SEI) in fact penetrates into the bulk of the HOPG. It is important to repeat the tests conducted by Besenhard et al. [87] in other EC-based electrolytes in order to determine the severity of this phenomenon. 

The benefit of a hybrid phase for the intercalation-deintercalation of mobile species such as Li+ cations is well illustrated by the study of conductive polymers such as polyaniline or polypyrrole intercalated into a V2O5 framework as potential electrode materials in lithium batteries [34]. For PANI/V2O5, an oxidative post-treatment performed under an oxygen atmosphere allowed the authors to compare the conductivity attributed to the polymer, as in absence of reduced cations, there was no electronic hopping between ions, and the conductive state was due only to the... 

Finally, NMR has also be used to study other spinels materials that do not contain manganese. For example, the intercalation/deintercalation of lithium titanate spinels such as Li4/3+Ji5/304 and Lii.i-Tii.904+a have been investigated. These materials may be used as anode materials in combination with cathodes operating at 4 V (vs Li) to produce cells with potentials of ca. 2.5 V. These materials are either diamagnetic or metallic, and unlike the mangan-ates, only very small differences in shifts are seen for Li in the different sites of the spinel structure. Nonetheless, these shift differences are enough to allow the concentrations of the different sites to be quantified and monitored following insertion of Li or as a function sample preparation method. ... 

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