PEDOT/PSS-Coated Porous Silicon as anode of lithium-Ion Batteries

Abstract

Silicon (Si) has been regarded as the most promising anode material of lithium-ion batteries (LIBs) because of its super-high theoretical capacity. However, dramatic volume variations during cycling of lithiation/de-lithiation will trigger electrode pulverization, disruption and structural failure of solid electrolyte interface (SEI), and the according poor cycling performance as well. Nanolization, composite with buffer material and special microstructure design of silicon based materialsare the most common strategy to alleviate the volume change effects[1-2]. The given electrode material design are usually with high-cost, complicated process and low volume specific capacity. In this work, the porous Si in the size of several micrometers are synthesized by Metal-assisted chemical etching(MaCE) method, in which micro-sized Si particles is locally etched in the isopropyl alcohol solution containing AgNO3 and HF[3]. The resulting porous Si is subsequently coated with a thin PEDOT/PSS layer. PSS is used in dispersing porous Si particles well into an aqueous solution and then tethering EDOT monomer onto the surface of porous Si particles to facilitate the formation of a uniform PEDOT coating [4].Fig. 1. SEM image of porous Si (a) and porous Si@PEDOT/PSS(b).Figure 1 shows that the pore size in the as synthesized silicon particles is below 200nm, and the PEDOT/PSS is uniformed coated on the silicon particle surface. This unique micron sized core-shell structure is considered to contribute to cycle stability and rate capability. The micron size silicon particles will help the realization of favorable volume specific capacity. The suitable sized pores in the silicon will be enough to accommodate the volume change resulting from lithiation. And the PEDOT/PSS coating is used to shield the silicon from the direct contact to electrolyte and inhabit the repeated rupture and reconstruction of SEI during volume change charge/discharge cycling. The detailed electrochemical performance of this silicon electrode material will be reported in meeting poster session. Acknowledgement Financial support by the National Science Foundation of China (21473128 and 21373154) is gratefully acknowledged.