Self-wound composite nanomembranes as electrode materials for lithium ion batteries

www.MaterialsViews.com C O M M U Self-Wound Composite Nanomembranes as Electrode Materials for Lithium Ion Batteries N IC A T By Heng-Xing Ji , Xing-Long Wu , Li-Zhen Fan , Cornelia Krien , Irina Fiering , Yu-Guo Guo , * Yongfeng Mei , * and Oliver G. Schmidt IO N Bending and rolling is commonly employed in nature to release strain in fi lms to maintain structure stability. Recently, rolledup nanotechnology has proven to be an intriguing approach on the micro-/nanoscale for various promising future applications and concepts. [ 1–5 ] Nanomembranes composed of various functional stacks can self wind (or roll up) into micro/nanotubes upon detaching from a holding substrate by releasing intrinsic differential strain. The deposition and process methods for nanomembranes are compatible to industrial-level technologies like e-beam evaporation, sputtering deposition and atomic layer deposition, etc., which are demanded by advanced materials used for applications. Moreover, the intrinsic strain accommodated in multi-layer nanomembranes is effi ciently released by self winding and thus offers a minimization of the system energy. [ 6 ] Such tubular and strain-relaxed structures are liable to improve the materials tolerance against stress cracking and are therefore promising candidates for increasing the stability of energy storage devices such as lithium ion batteries. Lithium ion batteries are attractive for applications ranging from electric vehicles to microchips. [ 7–10 ] One of the big challenges is strain accommodation during electrode lithiation, which would prevent the electrodes in batteries from being pulverized which causes capacity fading. [ 10–12 ] For example, transition-metal oxides and lithium alloys are attractive anode materials owing to their high theoretical charge capacity, which is several times larger than existing graphite anodes. [ 13–16 ]