All-Solid-State Lithium-Ion Microbatteries Using Silicon Nanofilm Anodes: High Performance and Memory Effect

• Published in: Advanced energy materials 2015-10, Vol.5 (19), p.np-n/a
• Main Authors: Cras, Frédéric Le, Pecquenard, Brigitte, Dubois, Vincent, Phan, Viet-Phong, Guy-Bouyssou, Delphine
• Format: Article
• Language: English
• Subjects: all-solid-state batteries; Anodes; Chemical Sciences; Electric cells; Electrodes; Electrolytic cells; Li-ion batteries; Li15Si4; Lithium batteries; Material chemistry; Nanostructure; Reflow soldering; Silicon; thin film
• ISSN: 1614-6832; 1614-6840
• DOI: 10.1002/aenm.201501061

All‐solid‐state thin film lithium batteries are promising devices to power the next generations of autonomous microsystems. Nevertheless, some industrial constraints such as the resistance to reflow soldering (260 °C) and to short‐circuiting necessitate the replacement of the lithium anode. In this study, a 2 V lithium‐ion system based on amorphous silicon nanofilm anodes (50–200 nm thick), a LiPON electrolyte, and a new lithiated titanium oxysulfide cathode Li1.2TiO0.5S2.1 is prepared by sputtering. The determination of the electrochemical behavior of each active material and of whole systems with different configurations allows the highlighting of the particular behavior of the LixSi electrode and the understanding of its consequences on the performance of Li‐ion cells. Lithium‐ion microbatteries processed with industrial tools and embedded in microelectronic packages exhibit particularly high cycle life (−0.006% cycle−1), ultrafast charge (80% capacity in 1 min), and tolerate both short‐circuiting and reflow soldering. Moreover, the perfect stability of the system allows the assignment of some modifications of the voltage curve and a slow and reversible capacity fade occurring in specific conditions, to the formation of Li15Si4 and to the expression of a “memory effect.” These new findings will help to optimize the design of future Li‐ion systems using nanosized silicon anodes. Nanosized silicon based all‐solid‐state lithium‐ion microbatteries are manufactured and packaged using industrial equipment. The perfect stability of these cells allows the study of the specific features of the silicon electrode (Li15Si4, memory effect) and their influence on the electrochemical behavior of the Li‐ion cell for different cell designs and operating conditions.