Glassy materials for lithium batteries: electrochemical properties and devices performances

Amorphous or glassy materials may be used as electrolyte or electrode materials for lithium primary or secondary batteries. A first generation proceeded from classical coin cells in which the organic electrolyte was replaced by a high lithium conductive glassy electrolyte. The solid components were assembled under isostatic pressure. The main advantages of such cells are a good storage stability and ability to operate until 200°C. Nevertheless, the high resistivity of the glassy electrolyte below room temperature and a limited depth for charge and discharge cycles makes these cells not competitive compared to conventional lithium-ion batteries. More promising, are the thin films solid state microbatteries realised by successive depositions of electrodes and electrolyte. The low resistance of the electrolyte amorphous layer allows cycling at temperatures as low as −10°C. The total thickness of thin film batteries, including packaging is less than 100 μm. A capacity of about 100 μAh cm−2 with over 104 charge–discharge cycles at 90% in depth of discharge is well suited for energy independent smart cards or intelligent labels, which represent for these devices a large and unrivalled market.