Combinatorial Study of Sn[sub 1−x]Co[sub x] (0<x<0.6) and [Sn[sub 0.55]Co[sub 0.45]][sub 1−y]C[sub y] (0<y<0.5) Alloy Negative Electrode Materials for Li-Ion Batteries

Abstract

Using combinatorial and high-throughput materials science methods, we have studied thin-film libraries of Sn 1−x Co x ͑0 Ͻ x Ͻ 0.6͒ and ͓Sn 0.55 Co 0.45 ͔ 1−y C y ͑0 Ͻ y Ͻ 0.5͒ alloy negative electrode materials for Li-ion batteries. Over one hundred compositions have been studied carefully by X-ray diffraction and electrochemical methods. The Sn 1−x Co x system is found to be amorphous for 0.28 Ͻ x Ͻ 0.43. For 0.43 Ͻ x Ͻ 0.6, the amorphous phase coexists with electrochemically inactive crystalline Co 3 Sn 2 . Amorphous materials with x = 0.4 show a specific capacity of 650 mAh/g, but differential capacity, dQ/dV, vs potential is not stable vs cycling indicating irreversible atomic-scale changes in the alloy, most likely due to tin aggregation. Adding carbon to this system, for example in the ͓Sn 0.55 Co 0.45 ͔ 1−y C y ͑0 Ͻ y Ͻ 0.5͒ library, has a number of positive effects. First, all alloys with 0.05 Ͻ y Ͻ 0.5 are amorphous, with carbon directly incorporated within the amorphous phase. Second, the addition of carbon increases, not decreases, the specific capacity from about 670 ± 15 mAh/g for y = 0.05 to 700 ± 15 mAh/g for y = 0.4. Third, compositions with y Х 0.4 show differential capacity vs potential curves that do not change during charge-discharge cycling, indicating that such alloys are stable on the atomic scale and hence are extremely good candidates for long cycle life. Stability increases with carbon content up to y = 0.4.

Microwave plasma chemical vapor deposition of nano-structured Sn/C composite thin-film anodes for Li-ion batteries

“…One proposed resolution to overcome this problem is to use tin oxide as a soft matrix to ameliorate the expansion of the metal [23,24,25,26,27]. Alternative solutions include the use of tin alloys [28,29,30,31,32,33,34,35,36,37,38,39,40,41] and other tin based composite materials such as LiSn 2 (PO 4 ) 3 [20]. Minimizing the thickness of the electrode, as well as reducing the particle size [42] and uniform particle distribution within the supporting matrix [43], can help accommodate the mechanical stress induced in the crystalline lattice of Li x Sn.…”

Nanostructured Material Fabrication for Energy Conversion

“…3a shows that the SnCo alloy is amorphous, with a peak which could be attributed to the (200) Sn crystallographic plane (ICDD-card #04-0673). The peak at 2θ = 32.92 might be attributed to an unknown tin-cobalt phase, according to (8). Besides, Gómez et al (9) have electrodeposited a crystalline tin cobalt alloy and have proposed a new SnCo tetragonal phase with a main peak at 2θ = 32.77, very close to the second unknown peak of fig.…”

Low‐Cost Metallic Anode Materials for High Performance Rechargeable Batteries

“…[137][138][139] It was revealed that all the consisting components have their own functionalities. [140] Tin is the main active component to store lithium, and cobalt provides an nanocrystalline/amorphous environment with Sn and buffers the volume expansion, while carbon offers a stable matrix to separate CoSn grains. However, the battery performance of "Nexelion" is still not as ideal as graphite anode based batteries.…”