Preparation of Ni-Sn Alloy-Type Anode by Electrospinning

Abstract

With the advancement of the portable technology, the need for the new-generation batteries has increased accordingly. Li-ion batteries (LIB) first commercialized in the early 1990s have long served as the life-saver till our days. Though, they also possess a number of issues in terms of theoretical capacity, safety, cost, ageing and so on. The commercialized graphite and Li4Ti5O12 anodes used nowadays in LIBs have theoretical capacities of ~372 mAh/g and 350 mAh/g, which is quite low compared to other anode materials [1]. There are other alternatives such as Sn (994 mAh/g), Si (4200 mAh/g), Sb (660 mAh/g), P (2596 mAh/g), Bi (667.3 mAh/g) which exhibit relatively high theoretical capacities, though they possess several other issues, too [2]. The disadvantages of the above mentioned anode materials include large irreversible capacity, huge capacity fading and poor cycling. These problems are due to considerable volume expansion of the anode, which leads to the rupture of the electrode, resulting in the death of the cell. In an effort to prevent the volume expansion, many solutions have been proposed. Among them, enclosing the anode material with another material is one of the most common attempts to overcome this issue of volume expansion. This has been implemented in a variety of ways such as encapsulation in hollow-shell, yolk-shell, core-shell spheres, core-shell nanotubes/nanofibers, suspension in a carbon matrix, etc [3]. In this work, electrospinning technique was used in order to obtain Ni-Sn alloy-type anodes encapsulated within carbon nanofibers. Ni-Sn alloys obtained in this work, namely Ni1.6Sn and Ni3Sn, have a theoretical capacity of ~554.6 mAh/g and ~400 mAh/g, respectively. In this work, Ni-Sn intermetallic alloy acts as a buffering matrix against the volume expansion of Sn, that is Ni particles surrounding the Sn atoms will be preventing the pulverization of the active material.SEM images (a) and TEM images (b) in the graphical abstract clearly show the encapsulation of the Ni-Sn particles inside the carbon nanofibers. Keywords: Ni-Sn alloy, carbon nanofibers, electrospinning, lithium-ion battery, three-dimensional. Acknowledgments This work was supported by the projects 091019CRP2114 “Three-Dimensional All Solid State Rechargeable Batteries” and 240919FD3914 “Self-Charging Rechargeable Lithium-ion Battery” from Nazarbayev University and AP08052143 “Development of wearable self-charging power unit” from the Ministry of Education and Science of the Republic of Kazakhstan and from Nazarbayev University.