S-doping induced boosted electrochemical redox kinetics in Te1-xSx nanorod cathodes for high volumetric capacity Li-Te batteries

Abstract

Compared with traditional lithium-ion batteries, developing lithium-tellurium batteries with high specific volumetric capacity based on group VIA-group element cathodes is of great importance to power modern portable electric vehicles in limited package sizes. Herein, contrary to designing suitable matrix to immobilize Te as cathodes, we develop a novel and complete different strategy to design S-doped Te nanorod cathodes for Li-Te batteries. S-doping can effectively induce the redistribution of electrons between low electronegative Te and high electronegative S to generate internal electrical fields, accelerating the transport kinetics of Li+ and electrons. Experimental results and density functional theory (DFT) calculations show that S-doping can efficiently lower the lithiation/delithiation energy barriers, significantly improve the redox reaction kinetics and mitigate the redox reaction polarization. More importantly, the DMSO-based electrolyte can significantly uplift the discharge voltage, promising a much higher energy density. Taking advantage of heteroatomic S doping, the optimal Te0.92S0.08 cathode without any carbonous matrix exhibits high volumetric capacity of 1615 mAh cm−3 over 100 cycles under a current density of 0.1C, a dramatic rate capacity of 562 mA h cm−3 at 2C and long cycling stability. We believe the present strategy may provide new avenues for achieving high volumetric capacity secondary ion batteries.