Structural and Electrochemical Properties of Micro‐ and Nano‐Crystalline CoSn Electrode Materials

Abstract

Nanocrystalline CoSn with an average crystallite size of 19 nm is obtained at 265 degrees C by following a one-pot method. The structural and electrochemical properties of nano-CoSn are compared to those of micro-CoSn (319 nm) obtained at 500 degrees C. Micro-CoSn has specific capacities below 100 mAhg(-1), but very stable cycling behavior. In contrast, nano-CoSn exhibits reversible specific capacities of over ca. 400 mAhg(-1)in the first cycles, depending on the cycling conditions. The crystalline structure of micro-CoSn is preserved after electrochemical reaction with lithium. Nano-CoSn becomes amorphous upon cycling and a modified 119Sn Mössbauer spectrum corresponding to a LiCoSn nano-alloy is observed.

Polyacrylonitrile and cobalt–tin compounds based composite and its electrochemical properties in lithium ion batteries

“…For the sample studied here, the optimum potential limits are 0.0 V for the lower limit, and 1.5-2.0 V for the upper limit, and reversible capacities between 500 and 630 mAh/g are observed in the first cycles with quite acceptable stability and efficiencies of around 95-97%. The values of maximum capacities are superior to the values previously reported for CoSn 2 and CoSn single phases [11][12][13]. The capacity falls down after 30 cycles, while the efficiencies values change from around 97 to 90%, probably due to electrolyte consumption.…”

“…The ability of CoSn 2 to react with lithium is quite high and its maximum reported reversible capacity is just below 600 mAh/g [11,12]. The capacity of CoSn is more limited and strongly depends on the grain size [12,13]. The capacity and capacity retention of the cassiterite and other tin oxides are strongly influenced by the imposed potential limits and the grain size [7].…”

A facile carbothermal preparation of Sn–Co–C composite electrodes for Li-ion batteries using low-cost carbons

“…Then, their hyperfine parameters were fixed in the fitting process and only their relative contributions were allowed to change ( Table 3). The highest contribution corresponded to CoSn 2 , although a significant increase of CoSn was detected as compared with the original composite, which evidenced a partial recovery of the cobalt-tin intermetallic compound after charging, as found in nanocrystalline CoSn alone [33]. The presence of residual Li 13 Sn 5 was less pronounced for the fifth charge and may involve an enhanced cycling efficiency after the first cycle, in agreement with the capacity fading observed during the first cycles.…”

“…For nanocrystalline CoSn, the reaction with lithium produces a reversible amorphization of the intermetallic compound. The presence of Co atoms avoids the formation of crystalline phases of Li x Sn [33]. These differences imply that, together with composition, both crystallinity and particle morphology play an important role.…”

How Mössbauer spectroscopy can improve Li-ion batteries

“…In the latter case, tin is associated with an electrochemically inactive metal that is expected to be extruded during the first discharge from the pristine materials in order to form metallic nanoparticles that buffer volume variations. Different metals have been considered including Cu [37], Ni [38][39][40], Co [41,42], Fe [43][44][45] or Nb [46]. The case of Co is of particular interest and Sony commercialized in 2005 the Nexelion battery with a Co-Sn-C amorphous anode improving the capacity of the battery by 30% compared to other systems [47][48][49][50][51].…”