Thick Binder-Free Electrodes for Li-Ion Battery Fabricated Using Templating Approach and Spark Plasma Sintering Reveals High Areal Capacity

Abstract

The templating approach is a powerful method for preparing porous electrodes with interconnected well-controlled pore sizes and morphologies. The optimization of the pore architecture design facilitates electrolyte penetration and provides a rapid diffusion path for lithium ion, which becomes even more crucial for thick porous electrodes. In the present work, we used NaCl micro-size particles as templating agent for the fabrication of 1 mm-thick porous LiFePO4 (LFP) and Li4Ti5O12 (LTO) composite electrodes using Spark Plasma Sintering (SPS) technique. These sintered binder-free electrodes are self-supported and present a large porosity (40%) with relatively uniform pores. The electrochemical performances of half and full batteries reveals a remarkable specific areal capacity (20 mAh/cm2), which is four times higher than those of 100 µm thick electrodes present in conventional tape-casted Li-ion batteries (5 mAh/cm2). 3D morphological study of both electrode types was carried out using µCT full field TXM technique to obtain tortuosity values and pore size distributions leading to a strong correlation with their electrochemical properties. These results also demonstrate that the coupling between salt templating method and SPS technique turn out to be a promising way to reach the ultimate goal in the fabrication of thick electrodes with high energy density.