Abstract
Development of silicon-based anodes materials for lithium-ion batteries with long cycle and large capacity is central to realize low cost and high performance energy storage. Silicon oxycarbide (SiCO) is considered as a promising anode material due to its perspective in reliable cycling stability and high lithium capacity. Here we report a Si/SiCO thin films system with Si-C/O tetrahedrons and free carbon network in SiCO. The samples with high carbon SiCO layers deliver high reversible capacities of 2000 and 1750 mAhg−1 after 100 cycles, together with capacities of 1480 and 1250 mAhg−1 at high current density of 4 C rate, attributing to the free carbon network of SiCO layer. First-principles calculations demonstrate the presence of Si-C/O tetrahedrons for enhanced capacity of lithium. It is revealed that small voids less than 10 Å formed near the Si-C/O tetrahedrons, which provides a unique atomic configuration for reversible storage of lithium. An algorithm is proposed to evaluate the irreversible and reversible capacities of the Si/SiCO heterostructure, the predicted reversible capacity of 1851 mAhg−1 is comparable to the reversible capacity of 1750 mAhg−1 in our experiment. This study provides a reliable and facile route to prepare and analyze Si/SiCO thin films anode with outstanding performance.
Published Version
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