New battery technologies
1. Na battery
This project aims to analyze the influence of the dynamics on the structural behavior of a Na battery material by DRX operando at the SOLEIL synchrotron. Amazing discoveries have been made.
Although Li-ion battery technology has dominated the market for portable electronics since the 1990s, it has recently become acquainted with BatScap-Bolloré's Li-Metal-Polymer (LMP) technology (Autolib) Especially for electric traction application which ultimately should probably represent about 15% of the battery market. The Li / S system is extremely interesting, since it can theoretically deliver 2500 Wh / kg (2800Wh / l) or about 5 times more energy than Li batteries. Sulfur also has several advantages over materials currently developed . It is particularly light, very cheap and non-toxic.
However, during the cycling of a Sulfur battery, it dissolves, diffuses into the electrolyte and precipitates during the discharge. The discharge product Li 2 S is, moreover, twice as bulky as the starting material at constant molarity. The electrode thus undergoes extremely large volume variations which are exacerbated by the fact that the electroplating reactions are carried out in an anarchic manner within the electrode. There is, of course, a very limited lifetime.
In response to this problem, we started in collaboration with B. Lestriez and Dominique Guyomard in the framework of the CIFRE-BatScap-IMN thesis of Margaud Lecuyer (2011-2014) to propose innovative solutions to prevent the diffusion of electro species -activates out of the electrode. Except for a few previous publications1,2, the Li / S system studies are performed in liquid organic electrolyte. Since the BatScap LMP batteries are made of a dry polymer electrolyte, we have begun the work by characterizing the evolutions of the system in cycling for this type of battery. We have thus found similarities with the liquid organic medium (dissolution in the dry polymer electrolyte then diffusion of the polysulphides up to the electrode of Li) but also certain specificities specific to the LMP batteries (like the inverse voluminal variations of the cathode And electrolyte, or collapse of the cathode on itself when the active material is poorly dispersed, for example) (6). The work currently focuses on the solutions made to optimize the cycling of the system (a patent is being filed). Other solutions are conceived in collaboration with Jean Le Bideau within the framework of the postdoctoral contract of Nela Buchtova (2013-2015).
(Left) holes left in the cathode after dissolution and diffusion of the sulfur in the electrolyte and (right) collapse of the cathode in cycling.
Publications
Pub Structural changes of a Li/S rechargeable cell in Lithium Metal Polymer technology
M. Lécuyer, J. Gaubicher, B. B. Lestriez, T. Brousse, D. Guyomard
J. Power Sources, 241 (2013) 249
1D. Marmorstein, TH. Yu, KA. Striebel, FR McLarnon, J. Hou, EJ. Cairns., J. Power Sources 89 ( 2000) 219
2 S.S. Jeong, Y.T. Lim, Y.J. Choi, G.B. Cho, K.W. Kim, H.J. Ahn, K.K. Cho., J. Power Sources, 174 (2007) 745
3. Solid battery
This theme is conducted in collaboration with J. Le Bideau (PMN team).In the framework of the ANR LISSIL (2006-10), a new concept of safe all-solid battery was developed through a totally new approach which consists of confining an ionic liquid in a mesoporous solid matrix of type SiO2.The work carried out made it possible to show the applicability of this solution to two types of commercial positive electrodes, LiNi1/3Mn1/3Co1/3O2 and LiFePO4.