Comparative study of the implementation of tin and titanium oxide nanoparticles as electrodes materials in Li-ion batteries

Transition metal oxides potentially present higher specific capacities than the current anodes based on carbon, providing an increasing energy density as compared to commercial Li-ion batteries. However, many parameters could influence the performance of the batteries, which depend on the processing of the electrode materials leading to different surface properties, sizes or crystalline phases. In this work a comparative study of tin and titanium oxide nanoparticles synthesized by different methods, undoped or Li doped, used as single components or in mixed ratio, or alternatively forming a composite with graphene oxide have been tested demonstrating an enhancement in capacity with Li doping and better cyclability for mixed phases and composite anodes.


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The synthesized materials employed as active material in the tested electrodes where prepared by different chemical routes. Table S1 shows the average crystallite size estimated by using Scherrer formula from the main diffraction peaks, the % wt. in the electrode, nominal and theoretical capacities for comparison and the amount of load in the Cu-foil in every LIB as well as the capacity due to the main active materials (shorted as a.m.) either SnO2 or TiO2 in the electrodes. In the last column of Table S1 it is shown the specific surface area of the active materials obtained by the BET-N2 technique. Table S1. Nomenclature employed for the different active materials, averaged particles size, % wt., theoretical, nominal capacities, loading amount of material and capacities due to the compounds (active material = a.m.). Last column shows the specific surface of the nanoparticles obtained by BET.  The first set of materials that have been studied correspond to SnO2 nanoparticles without doping and doped with Li, synthesized by hydrolysis method. The curves of charge/discharge and Coulombic efficiency up to 200 cycles can be seen in Figure S1(a).
It can be seen that the LIB's that contain nanoparticles with higher content in Li (h-SnLi20 and h-SnLi30) are rated slightly higher than expected, 470 mAh/g during the first 70 cycles while the sample h-SnLi10 maintains this value slightly below the nominal value.
In the case of the sample without doping, h-SnLi0, it remains practically according to the nominal capacity. In addition, it can also be seen that, although for all of them the capacity decreases to 50% approximately between cycles 90 and 100, the LIB's with higher Li content lost practically all its capacity from above cycles, as opposed to those cycled LIB's with lower content in Li, where despite having less capacity, this does not become null unless up to 200 cycle. The Coulombic efficiency that present this set of samples do not differ between them as shown in Figure S1 In this cycle appears a spiked point and then the capacity decreases more quickly until the cycle 125 th , where it began to be low or negligible up to 200 cycles.
We have studied the next set of electrochemical cells whose electrode contains such active material nanoparticles of SnO2 without doping and doped with Li, npLix, were synthesized by the method of LM. In Figure S1 Second, it can be observed a leap and increase in capacity from the 100 th cycle, cycle in which the LIB's rest during 24 hours. This variation is more pronounced in terms of Coulombic efficiency, where in the first cycle presents some variations ranging between 20% and 30% between the different samples. In the case of the sample GO-npLi10 occur variations in the 2 nd and 3 rd cycle above 100% and a more pronounced variation from cycle 100 onwards, reaching values higher than 110%.
In Figure S2 is shown the characteristic voltage drop vs the discharge/charge capacity of the different materials that have been studied as the active material in the cells at a 0.25Crate.
In the case of SnO2 nanoparticles appears a plateau between 0.8 up to 1.0 V in the potential ( Figure S2