Nanoporous Sn/$SnO_x$ as a fracture resistant anode for lithium ion batteries

Abstract

Sn, which has three times higher energy density compared with graphite, has been getting a lot of attention as a next generation anode host material for high performance Li ion batteries (LIBs). However, an extreme Li diffusion induced stress (Li-DIS) induced by expansion/shrinkage during multiple cycle causes outbreak of fracture of Sn active material. Hence, the mechanical deterioration of Sn host materials causes a rapid capacity fading of electrode, which has hindered the popularization of LIBs that use Sn as an active anode material. In this paper, a nanoporous (NP) Sn/$SnO_x$ structure was proposed to improve mechanical stability of Sn host material and facilitate stable formation of solid electrolyte interphase (SEI) layer. The NP Sn/$SnO_x$ structure is expected to exhibit outstanding electrochemical performance in Li ion batteries, since nanoscale Sn/$SnO_x$ ligaments improves mechanical stability of host materials and the $SnO_x$ clamping layer facilitates the formation of stable SEI layer via prevention Sn host materials from direct contact with electrolyte. In practice, 400$^\circ C$ electrode of NP Sn/$SnO_x$ structure with 13~14 nm $SnO_x$ clamping layer and the smallest Sn/$SnO_x$ ligaments size exhibited ~660 $mAhg^{-1}$ at 10th cycle and maintained ~630 $mAhg^{-1}$ at 100th cycle at 0.4 C rate.