Silicon anodes suffer from severe interfacial degradation during repeated lithiation and delithiation, limiting their long-term electrochemical stability. In this work, conformal AlN-derived interphases were constructed on porous silicon electrodes by atomic layer deposition (ALD) to investigate their interfacial evolution and electrochemical behavior. Structural characterization confirmed the formation of a conformal coating layer. Depth-resolved X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) revealed that the deposited layer evolved into an Al/O-rich outer region and an AlN-rich inner region after exposure to ambient atmosphere. The optimized 50×AlN@Si electrode delivered 1273 mAh g−1 after 300 cycles at 0.5C, compared with 658 mAh g−1 for the pristine Si electrode. Control experiments using AlN-coated Cu electrodes confirmed that the deposited AlN layer contributed negligibly to reversible lithium storage, indicating that the improved electrochemical performance originated from enhanced interfacial stability. Post-cycling XPS and ToF-SIMS analyses further revealed the persistence of Al-containing interfacial species together with LiF- and LixSiyOz-rich reaction products. These findings establish a direct correlation between interphase evolution and electrochemical stability, providing design principles for artificial interphase engineering of silicon anodes.
Silicon anodes suffer from severe interfacial degradation caused by repeated volume changes during electrochemical cycling, resulting in rapid capacity decay and increased polarization. Herein, tantalum nitride (TaN)-derived interphases were formed on silicon particles within porous electrodes by atomic layer deposition to stabilize the electrode-electrolyte interface. Electron microscopy revealed a continuous and conformal TaN-derived interphase on the examined Si particles, while X-ray photoelectron spectroscopy depth profiling and time-of-flight secondary ion mass spectrometry showed its depth-dependent chemical composition. The best-performing 50×TaN@Si electrode delivered an initial discharge capacity of 3325 mAh g−1 with an initial Coulombic efficiency of approximately 92%, while exhibiting improved cycling stability, enhanced rate capability, lower voltage polarization, and reduced interfacial resistance compared with the pristine Si electrode. Post-cycling analyses further revealed reduced electrode expansion and lower accumulation of LiF- and lithium-silicate-containing SEI products, consistent with reduced interfacial reconstruction. These findings provide insight into the structural and chemical evolution of ALD-derived TaN interphases and demonstrate their effectiveness in stabilizing the electrode-electrolyte interface of silicon anodes.
Lithium–sulfur (Li–S) batteries are promising for high-energy storage but are limited by complex multistep sulfur redox reactions that induce polysulfide migration, sluggish conversion kinetics, and severe cathode swelling. Here, we report a boron nitride/carbon nanotube (BN/CNT) heterostructure that enables electrostatic regulation of sulfur spatial evolution through the separation of polar domains and conductive networks. The conductive CNT scaffold preserves electron percolation, whereas the BN interlayer provides abundant polarity to regulate polysulfide interactions. Amine functionalization (BN–NH2) further tailors the local electronic environment and interfacial charge distribution. Consequently, sulfur spatial evolution is regulated toward homogeneous redistribution rather than surface overaccumulation, resulting in near-zero cathode swelling during prolonged cycling. The optimized BN–NH2/CNT configuration delivers an initial capacity of 1089 mAh g−1 with stable cycling, reduced polarization, and enhanced rate capability. Potentiostatic nucleation analysis, nano-X-ray fluorescence mapping, depth-resolved X-ray photoelectron spectroscopy, and X-ray absorption spectroscopy reveal stabilized sulfur redox chemistry and regulated sulfur electronic environments. Density functional theory calculations reveal interfacial charge redistribution and optimized interaction strengths that support regulated sulfur redox chemistry. In this work, moderated electrostatic regulation of sulfur spatial evolution is established as a design principle for dimensionally stable and kinetically optimized Li–S cathodes beyond adsorption-centric strategies.
DOI: 10.1002/smll.75698
