法拉第效率
歧化
X射线光电子能谱
阳极
氧化物
锂(药物)
热稳定性
化学工程
阴极
氧气
材料科学
热失控
化学
无机化学
作者
Tian Tan,Pui-Kit Lee,Nobuyuki Zettsu,Katsuya Teshima,Denis Y. W. Yu
标识
DOI:10.1016/j.electacta.2021.139777
摘要
Silicon monoxide (SiO) is a promising anode material for Li-ion batteries because of its high capacity. Though, its low first Coulombic efficiency (FCE) due to the formation of inactive Li–Si–O compounds during lithiation hinders its practical application. Herein, we report a facile pre-sodiation technique by annealing SiO with a small amount of Na 2 CO 3 (≤ 5 wt%) under 850 °C, which improves FCE of pristine SiO from 61.4% to 86.0% without the use of lithium metal, solvent and disassembling and re-assembling of cells. Transmission electron microscopy, X-ray photoelectron spectroscopy, and nuclear magnetic resonance demonstrate that the incorporation of Na facilitates the disproportionation of SiO into crystalline Si and SiO 2 through nucleophilic substitution, and reduces the reactivity of the oxygen atoms with lithium and thereby suppresses the irreversible capacity during initial lithiation. The pre-sodiation process also improves thermal stability of SiO. Since the Na-containing SiO material is not sensitive to moisture in ambient condition, special handling of the material is not necessary. Combining with a LiFePO 4 cathode, the full cell shows a FCE of 85.8% with good cycle stability. The energy density of lithium-ion battery can even reach 900 Wh L −1 based on a theoretical calculation with high-capacity Ni-based metal-oxide cathode. • First Coulombic efficiency of SiO is increased to 86% by heat-treating with Na 2 CO 3 . • Na 2 CO 3 facilitates disproportionation of SiO to SiO 2 , inactivating the oxygen atoms in the lattice. • Thermal stability of pre-treated SiO is enhanced with less heat generation. • The treated material is stable in air and exhibits remarkable water compatibility. • A LIB with volumetric energy density of 900 Wh L −1 can be achieved with optimization.
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