High-areal-capacity thick cathode with vertically-aligned micro-channels for advanced lithium ion batteries

Thick electrode design with a high mass loading of active materials is a promising strategy to increase the energy density of lithium-ion batteries (LIBs). However, the development toward thick electrode is severely limited by electrode mechanical instability and sluggish electronic/ionic transport (causing especially rate capability). Herein, ultrahigh-capacity thick LiFePO4 (UCT-LFP)-based freestanding electrodes with vertically-aligned channels are prepared by a phase inversion method. Their porous yet conductive matrix provides the high electronic conductivity and facilitates the permeation of liquid electrolyte, while the unique vertically-aligned micro-channels serve as the fast ion/electron transport pathways. Consequently, the UCT-LFP electrode with a high mass loading of 20 mg cm−2 shows a superior rate capability (110 mA h g−1 at 10 C) and an enhanced cycling performance. Notably, an ultra-thick LFP electrode (1.3 mm thick) with a remarkably high areal capacity (15.1 mA h cm−2) has been successfully achieved. This study provides a novel strategy for constructing thick electrodes toward high energy density LIBs.