Alignment does matter: Design thick electrodes to improve the comprehensive lithium storage performance

Abstract

Developing electrochemical energy storage that enables simultaneously delivering high areal, volumetric, and gravimetric performance is a grand fundamental and technological challenge. It is straightforward but problematic to make electrodes thicker and denser for high areal and volumetric performance while sustaining a high level of gravimetric performance. The insufficient charge transports in these electrodes with high mass loading and electrode density could severely degrade the energy storage performance. Herein, we developed an energy-efficient fast sintering method (e.g., Spark Plasma Sintering) to fabricate a structural cathode with a high electrode density (2.0–2.3 g cm−3) and high mass loading (70–100 mg cm−2). The vertically aligned carbon networks and anisotropic pore channels in the ultrathick electrodes (300–500 μm) are designed and tailored for efficient charge transports throughout the whole thickness. As a result, the sintered structural electrodes perform high areal (8.6 mAh cm−2), volumetric capacity (246 mAh cm−3), uncompromised gravimetric performance (164 mAh g−1) at normal current (<2 mA cm−2), and stable cycling with a capacity retention of 84% after 200 cycles under a current density of 4.5 mA cm−2.