The sandwich, vertical channeled graphene‐based thick electrodes achieve low carbon content (14.4 wt%) and excellent rate/cycle performance under a wide range of high mass loadings (11–72 mg cm−2). The vertical channels provide fast Li+ ion transfer capacity, and the ultrathin sandwich structure buffers volume expansion during long cycle test (1000 cycles). The optimized structure for thick electrodes is investigated in detail. Abstract 3D thick electrode design is a promising strategy to increase the energy density of lithium‐ion batteries but faces challenges such as poor rate and limited cycle life. Herein, a coassembly method is employed to construct low‐tortuosity, mechanically robust 3D thick electrodes. LiFe0.7Mn0.3PO4 nanoplates (LFMP NPs) and graphene are aligned along the growth direction of ice crystals during freezing and assembled into sandwich frameworks with vertical channels, which prompts fast ion transfer within the entire electrode and reveals a 2.5‐fold increase in ion transfer performance as opposed to that of random structured electrodes. In the sandwich framework, LFMP NPs are entrapped in the graphene wall in a “plate‐on‐sheet” contact mode, which avoids the detachment of NPs during cycling and also constitutes electron transfer highways for the thick electrode. Such vertical‐channel sandwich electrodes with mass loading of 21.2 mg cm−2 exhibit a superior rate capability (0.2C–20C) and ultralong cycle life (1000 cycles). Even under an ultrahigh mass loading of 72 mg cm−2, the electrode still delivers an areal capacity up to 9.4 mAh cm−2, ≈2.4 times higher than that of conventional electrodes. This study provides a novel strategy for designing thick electrodes toward high performance batteries.
Published in: "Advanced Functional Materials".