Enabling high performance all-solid-state thin films microbatteries with silicon oxycarbide/lithium-metal composites anodes

Abstract

All-solid-state thin films micro-batteries (ASSTFBs) integrating thin-films technologies with solid-electrolytes are regarded as promising power sources that can inherently alleviate safety issues for the miniaturized devices for internet of things (IoT). However, poor interfacial compatibility and low ionic conductivity induced by using of solid-state electrolytes urgently demand new development of novel materials and preparation technologies. In this work, novel silicon oxycarbide/lithium-metal composites anodes for ASSTFBs of IoT micro-devices are prepared by magnetron sputtering, and the electrochemical performances are systematically investigated via experiments and first-principles. The thin films batteries systems present high first cycle discharge capacities up to 104.15 mAh/g. The sample with the highest carbon content of SiCO shows superior coulomb efficiency of 97 % after 40 cycles and retention rates of 73.29 % at 0.1 C, and sample with the optimal feature size of free carbon presents the most outstanding comprehensive electrochemical properties. First-principles calculations reveal that the optimal LiPON/SiCO interface presents the highest adhesion strength and superior lithium diffusion properties with the lowest energy barrier for lithium diffusion. The relatively larger free carbon network limit volume expansion upon insertion of lithium, and silicon tetrahedral in SiCO show large lithium storage density, leads to improved cycling performance and high lithium capacity of the system.