Nanocrystal Conversion-Assisted Design of Sn–Fe Alloy with a Core–Shell Structure as High-Performance Anodes for Lithium-Ion Batteries

Abstract

Sn-based alloy materials are strong candidates to replace graphitic carbon as the anode for the next generation lithium-ion batteries because of their much higher gravimetric and volumetric capacity. A series of nanosize Sn y Fe alloys derived from the chemical transformation of preformed Sn nanoparticles as templates have been synthesized and characterized. An optimized Sn 5 Fe/Sn 2 Fe anode with a core–shell structure delivered 541 mAh·g –1 after 200 cycles at the C/2 rate, retaining close to 100% of the initial capacity. Its volumetric capacity is double that of commercial graphitic carbon. It also has an excellent rate performance, delivering 94.8, 84.3, 72.1, and 58.2% of the 0.1 C capacity (679.8 mAh/g) at 0.2, 0.5, 1 and 2 C, respectively. The capacity is recovered upon lowering the rate. The exceptional cycling/rate capability and higher gravimetric/volumetric capacity make the Sn y Fe alloy a potential candidate as the anode in lithium-ion batteries. The understanding of Sn y Fe alloys from this work also provides insight for designing other Sn–M (M = Co, Ni, Cu, Mn, etc.) system.

Unraveling the Evolution of Transition Metals during Li Alloying–Dealloying by In-Operando Magnetometry

“…Since Sony proposed the Sn–Co/C battery in 2005, various Sn–M materials have been extensively investigated in both academia and industry. Especially, the magnetic elements (Fe, Co, Ni) are particularly promising due to their good electronic conductivity, high tap density, and gravimetric/volumetric capacity. − However, the mechanism of the reversibility of transition metals in Sn–M alloy is still a matter of debate, which restrains the rational design of reliable Sn–M anodes for lithium-ion batteries.…”

“…However, using in situ XRD and in situ Mössbauer spectroscopy, Dahn et al found that the Fe nanoparticles formed during discharge can recombine with Sn during delithiation. , Interestingly, Whittingham et al . revealed that some Fe particles still remain after the first charge by a combination of XRD, X-ray absorption spectroscopy (XAS), and magnetic measurements . As for the Sn–Co alloy, Park et al reported that CoSn 2 shows no recombination during Li extraction through ex situ XRD and extended X-ray absorption fine Structure (EXAFS) experiments .…”

Reaction Mechanism of the Sn2Fe Anode in Lithium-Ion Batteries

“…One of the ways to prevent this coarsening could be by creation of composites with even smaller, uniform-sized particles, as we have recently demonstrated. 58 Based on our data and analysis of the reaction mechanisms reported in the literature, we believe that the differences in the reaction mechanism are caused by differences in particle size, morphology, conductive additives, and other details affecting the material’s ability to undergo the reversible conversion.…”

Effects of Electrolyte Additives and Nanowire Diameter on the Electrochemical Performance of Lithium‐Ion Battery Anodes based on Interconnected Nickel–Tin Nanowire Networks

“…[10] Another strategy is to use Sn-based materials in the form of oxides, [15,17,19] phosphides, [20,21] sulfides, [22,23] or Sn-M alloys (M ¼ Cu, Fe, Ni, etc.). [24][25][26][27][28][29] In addition to buffering volume change, the introduction of M to form Sn-M alloys enhances the electronic conductivity and avoids Sn particles' aggregation during cycling, improving the rate performance (RP) and capacity retention of the electrode. [10,[24][25][26][27][28][29]…”

“…[24][25][26][27][28][29] In addition to buffering volume change, the introduction of M to form Sn-M alloys enhances the electronic conductivity and avoids Sn particles' aggregation during cycling, improving the rate performance (RP) and capacity retention of the electrode. [10,[24][25][26][27][28][29]…”