Nanostructured Ni3.5Sn4 intermetallic compound: An efficient buffering material for Si-containing composite anodes in lithium ion batteries

Highlights: ► Nanostructured Ni3.5Sn4 based electrodes have been synthesized by ball milling. ► Nanostructuration allows for ten-fold increase of reversible capacity. ► Ni3.5Sn4 based electrodes exhibit very good capacity retention over more than 400 cycles and fast delithiation kinetics. ► Nanostructured Ni3.5Sn4 phase is a promising constituent for composite anodes of Li-ion batteries. -- Abstract: Recently, Ni3.5Sn4 intermetallic has been reported as an efficient buffering material for Si-containing composite negative electrodes used in Li-ion batteries. In the present work, the electrochemical properties of this Ni-overstoichiometric compound are studied in detail. Micrometric, nanosized and carbon-added nanosized Ni3.5Sn4 have been investigated. For all materials, very good cycle life is obtained over more than 400 cycles. Nanosized Ni3.5Sn4 with crystallite size of 6 nm exhibits a reversible capacity of 240 mAh g−1, ten times higher than for the micrometric state. Moreover, nanosized Ni3.5Sn4 exhibits high-rate capability with 80% of full discharge capacity at 16 C. Carbon addition slows down kinetics but increases the reversible capacity up to 273 mAh g−1. The electrochemical properties of nanostructured Ni3.5Sn4 phase make it a promising constituent for composite anodes of Li-ion batteries