Preparation of a N-doped Si/Cu/C anode for high-performance lithium-ion batteries
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Abstract
Silicon with high theoretical specific capacity is one of the most promising candidates for lithium-ion battery anode materials. Nevertheless, its low electrical conductivity, large volume expansion, and unstable SEI membrane lead to poor cyclic stability. Therefore, we prepared Si/Cu/NC nanocomposites by coating CuC2O4 and polyaniline on the surface of silicon nanoparticles using a straightforward technique and then a primary pyrolysis process. Si/Cu/NC has a specific capacity of 2486.7 mA h g−1 and an initial coulombic efficiency of 89.38% at a current density of 200 mA g−1. The specific capacity reaches 845.5 mA h g−1 after 800 cycles, the initial coulombic efficiency is 94.76%, and the specific capacity reaches 1907.6 mA h g−1 even at a current density of 1000 mA g−1. Copper matrix in Si/Cu/NC nanoparticles, having strong electrical conductivity and low electrochemical performance, can act as an inert buffer to affect the volume expansion during cycling. Nitrogen-doped carbon coating can reduce material polarization, increase the electrical conductivity of silicon anode materials, and enhance battery power output. It can also lessen contact between the electrode and the electrolyte, stop SEI from growing too much, keep the interface stable, and boost the coulombic efficiency.
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