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

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%). [ABSTRACT FROM AUTHOR]