Electrochemical behaviour of tin(IV) oxide electrodes in lithium-ion batteries at high temperature and potentials

• In commercial lithium-ion batteries graphite is currently the most common anode material. However, graphite has a rather limited volumetric and gravimetric capacity which is a drawback when higher energy densities are required, for instance, in cars. Here, other materials with higher capacities and energy densities like the alloying materials tin and silicon are, hence, required. Even bigger capacities could be obtained using tin oxide based compounds due to a combination of the tin oxide conversion reaction converting lithium to tin and lithium oxide and the alloying reaction between tin and lithium. However, tin oxides usually suffer a great capacity loss after the first cycle due to the irreversibility of the tin oxide reduction.[1,2] Nevertheless, there have been some reports suggesting a limited reversibility of the tin oxide conversion. [3-6] In our work we have investigated the kinetic behaviour of different tin(IV) oxide based electrodes during electrochemical cycling in lithium-ion batteries for both the conversion and the alloying reaction. To be able to study the influence of the alloying reaction on the conversion reaction cycling was carried out within different potential windows (excluding the alloying reaction by cycling only to 0.9 V vs. Li+/Li). In addition, rather high voltages (up to 3.7 V vs. Li+/Li) were applied to check the tin(IV) oxide conversion reversibility as well as electrode and electrolyte stability under these conditions. The results were also compared with those presented in an earlier model study carried with our group. [6] Cycling experiments were likewise carried out at 60 oC as well as different scan rates and with different particle sizes and additives (i.e. aluminium oxide and diamond). The products formed at different potentials and temperatures for tin(IV) oxide electrodes were also investigated using XPS and SEM. The results confirmed the presence of a partial reversibility of the tin(IV) oxide conversion reaction which was enhanced at 60 oC. The study, thus, indicated that there is a kinetic limitation regarding the reoxidation of tin to tin oxide upon charge which can be overcome more easily when using higher temperatures or smaller particles. It will be demonstrated that cycling at a higher temperature, lower scan rate or with a smaller particle size leads to larger capacities of tin(IV) oxide electrodes. In addition, the influence of different additives on the capacity will be discussed.                                                                                                            REFERENCESCourtney, I.A. and Dahn, J.R., J. Electrochem. Soc., 1997, 144, 2045-2052.Courtney, I.A.; McKinnon, W.R. and Dahn, J.R., J. Electrochem. Soc., 1999, 146, 59-68.Chouvin, J.; Branci, C.; Sarradin, J.; Olivier-Fourcade, J.; Jumas, J.C.; Simon, B. and Biensan, P., J. Power Sources, 1999, 81-82, 277-281.Chouvin, J.; Olivier-Fourcade, J.; Jumas, J.C.; Simon, B.; Biensan, P.; Fernández Madrigal, F.J.; Tirado, J.L. and Pérez Vicente, C., J. Electroanal. Chem., 2000, 494, 136-146.Sun, X.; Liu, J. and Li, Y., Chem. Mater., 2006, 18, 3486-3494Böhme, S.; Edström, K. and Nyholm, L., On the electrochemistry of tin oxide coated tin electrodes in lithium-ion batteries, Electrochim. Acta, 2015, 179, 482-494.

Ämnesord

NATURVETENSKAP  -- Kemi -- Oorganisk kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences -- Inorganic Chemistry (hsv//eng)

Nyckelord

SnO2

electrodes

lithium

batteries

conversion

alloy formation

reactions

Kemi med inriktning mot oorganisk kemi

Chemistry with specialization in Inorganic Chemistry

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