Unconventional thick cobalt telluride electrodes enable homogeneous ion flow for high capacity, fast and safe potassium storage
Huilin Fan, Lei Zhang, Yao Dai, Runguo Zheng, Yuan Wang, Hamidreza Arandiyan, Zhiyuan Wang, Hongyu Sun, Yanguo Liu
Abstract
The demand for high-energy density, fast-charging, and safe potassium-ion batteries (PIBs) is crucial for large-scale applications in electric vehicles and grid systems. Despite the potential of thick electrode designs by a conventional technique (CTEs) to boost energy density, they often encounter challenges such as reduced capacity, limited cycling lifespan, and localized short circuits. Here, we present a novel cobalt telluride composite anode by a simple tellurization and subsequent heat reduction, featuring Co1.67Te2 nanoparticles uniformly embedded within an N-doped carbon layer on a trace amount of reduced graphene oxide (CT@NC/rGO). By constructing low tortuosity electrodes (LTEs), a homogeneous distribution of potassium ions and current density is achieved, resulting in enhanced potassium storage performance. The CT@NC/rGO LTEs demonstrate excellent discharge capacities: 311.7, 276.5, and 243.7 mA h g−1 after 500 cycles at 0.25 A g−1 for mass loadings of 1.4, 1.9, and 2.8 mg cm−2, respectively. At a higher current density of 0.5 A g−1, discharge capacities after 650 cycles are 245.3, 175.6, and 159.2 mA h g−1 for mass loadings at 1.6, 2.4, and 3.0 mg cm−2, respectively. These improvements are attributed to enhanced pseudocapacitive behavior, reduced charge resistance, and accelerated ion diffusion kinetics, as evidenced by experimental and simulation studies. The proposed strategy for synthesizing high-density electrodes holds promise for developing high-performance metallic compound electrodes for PIBs and potentially extending to other types of energy storage systems.