Fe3C-doped asymmetric porous carbon membrane binder-free integrated materials as high performance anodes of lithium-ion batteries

In traditional pulverous electrodes, the severe volume expansion that occurs during the intercalation and de-intercalation of lithium ions causes the active material to agglomerate and pulverize, eventually leading to active material that deviates from the current collector and result in poor electrochemical performances. Therefore, a new kind of Fe3C-doped asymmetric porous carbon membrane (Fe3C/APCM) binder-free integrated electrode materials is proposed by using a simple phase inversion method. The Fe3C/APCM electrodes that are obtained act as both active materials and current collector, saving the use of current collectors, conductive agents and binders. The effects of temperature and thickness on the conductivity and diffusion of ions are investigated, confirming the optimum temperature and thickness of the casting membrane solution to be 800 °C and 100 μm (Fe3C/APCM-100), respectively. Abundant finger-shaped and honeycomb-like pores are formed in the Fe3C/APCM-100, effectively accommodating the volume changes induced by the charge-discharge process. The specific surface area of the electrode materials reaches to 134.9 m2 g−1, enhancing the connection between active materials and electrolytes, leading to a high rate of electron transfer and ion diffusion. As the anode materials of a lithium-ion battery, the Fe3C/APCM-100 composites achieve an excellent rate capability and long cycling stability. The rate capability reaches to 605.5 mAh g−1 at a current density of 0.1 A g−1, and 601.0 mAh g−1 is retained when the current density returns to 0.1 A g−1. Even at a high current density of 1.0 A g−1, an excellent cyclic capacity of 212.9 mAh g−1 is still achieved after 200 cycles. No obvious structural and morphological changes are observed in SEM images of Fe3C/APCM-100 electrodes before and after a charge-discharge process. Fe3C/APCM is promising as an anode material for lithium-ion batteries.