Journal Article

Selective Nitridation Crafted a High‐Density, Carbon‐Free Heterostructure Host with Built‐In Electric Field for Enhanced Energy Density Li–S Batteries

Wang, Hongmei, Yuan, Li, Wei, Yunhong, Wu, Hao, Wang, Guochuan, Pu, Yiran, Wang, Qian, Liu, Can, Zhang, Yun

2022

Overview

To achieve both high gravimetric and volumetric energy densities of lithium–sulfur (Li–S) batteries, it is essential yet challenging to develop low‐porosity dense electrodes along with diminishment of the electrolyte and other lightweight inactive components. Herein, a compact TiO2@VN heterostructure with high true density (5.01 g cm–3) is proposed crafted by ingenious selective nitridation, serving as carbon‐free dual‐capable hosts for both sulfur and lithium. As a heavy S host, the interface‐engineered heterostructure integrates adsorptive TiO2 with high conductive VN and concurrently yields a built‐in electric field for charge‐redistribution at the TiO2/VN interfaces with enlarged active locations for trapping‐migration‐conversion of polysulfides. Thus‐fabricated TiO2@VN–S composite harnessing high tap‐density favors constructing dense cathodes (≈1.7 g cm–3) with low porosity (<30 vol%), exhibiting dual‐boosted cathode‐level peak volumetric‐/gravimetric‐energy‐densities nearly 1700 Wh L−1cathode/1000 Wh kg−1cathode at sulfur loading of 4.2 mg cm−2 and prominent areal capacity (6.7 mAh cm−2) at 7.6 mg cm−2 with reduced electrolyte (<10 µL mg−1sulfur). Particular lithiophilicity of the TiO2@VN is demonstrated as Li host to uniformly tune Li nucleation with restrained dendrite growth, consequently bestowing the assembled full‐cell with high electrode‐level volumetric/gravimetric‐energy‐density beyond 950 Wh L−1cathode+anode/560 Wh kg−1cathode+anode at 3.6 mg cm−2 sulfur loading alongside limited lithium excess (≈50%). A high‐density fibrous TiO2@VN heterostructure mediator with built‐in electric fields is constructed via an ingenious selective nitridation from biotemplate‐derived twinborn hybrid titanium/vanadium oxide fibers, which can synchronously serve as carbon‐free, dual‐capable hosts of both sulfur and lithium for practical high‐energy‐density Li–S full batteries.

• Publisher: John Wiley & Sons, Inc,John Wiley and Sons Inc,Wiley
• Subject: Adsorption / built‐in electric field / Carbon / Electric fields / Energy / heterostructures / high tap density / Li–S full batteries / Metal oxides / Sulfur content / volumetric energy density