High-capacity, low-tortuosity LiFePO4-Based composite cathode enabled by self-supporting structure combined with laser drilling technology

Abstract A thick electrode with high areal capacity is a promising way to improve the energy density of batteries, but the development of a thick electrode is limited by poor mechanical stability and sluggish ion and electron transport. Here, we design a self-supporting cathode that consists of cellulose nanofibers, multi-walled carbon nanotubes, and lithium iron phosphate (LFP), and introduce a uniform microchannel structure to the cathode by laser drilling technology. The cellulose nanofibers and multi-walled carbon nanotubes construct a conductive network. The microchannel structure enables outstanding ion and electron transport and significantly improves the rate capability of the electrode. Meanwhile, the local heat by the laser produces an amorphous carbon layer on the inner surface of the microchannel, which helps form a stable cathode-electrolyte interface and enhances the capacity retention of the thick electrode. Notably, the drilled thick cathode with an LFP load of 40 mg cm-2 and an areal capacity of 5.33 mAh cm-2 exhibits substantially improved cycling stability at 0.5 C than the undrilled samples. This work demonstrates a promising design concept for thick electrodes to high-performance energy storage devices.