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Thin film encapsulation for secondary batteries on wafer level

: Marquardt, K.; Hahn, R.; Luger, T.; Reichl, H.


TU Dresden, Institut für Aufbau- und Verbindungstechnik der Elektronik -IAVT-; Institute of Electrical and Electronics Engineers -IEEE-:
1st Electronics Systemintegration Technology Conference, ESTC 2006. Vol.2 : Dresden, 5.-7.9.2006
New York, NY: IEEE, 2006
ISBN: 1-4244-0552-1
ISBN: 1-4244-0553-X
Electronics Systemintegration Technology Conference (ESTC) <1, 2006, Dresden>
Fraunhofer IZM ()

This paper presents results concerning the realization and characterization of thin film encapsulated waferlevel batteries. Initially, the technology concept for the construction and hermetic encapsulation of chip-size lithium-ion secondary batteries on wafer level is introduced. Parylene and thin-film metal deposition was used for hermetic encapsulation of the batteries. With this technology, battery sizes between 1 mm2 and 1 cm2, and as thin as 225 m, can be fabricated. The chemical compatibility of the EC/DEC electrolyte with the encapsulation material was proven. To characterize the encapsulation layer, optical light microscopy and transmitting light microscopy have been used. Li(1-X)(Ni)CoO2 and LiXC 6 were used as active intercalation materials for cathode and anode electrode respectively. Using a small fraction of PVdF binder is essential for achieving a high energy density. In this work, the focus was set on increasing the energy density of active battery lamina tes. To obtain a high discharge capacity, the preparation of battery materials was revised and the lamination process was optimized. Electric measurement on laminated battery foils with an area of 0.96 cm2 and a thickness of less than 220 m has been carried out. As a result a capacity density of 1.33 mAh/cm2 was reached while cycling a battery sample under laboratory conditions. The presented technology allows the transformation of the high energy density of cylindrical or prismatic cells to integrated micro batteries.