Dual-Design of Nanoporous to Compact Interface via Atomic/Molecular Layer Deposition Enabling a Long-Life Silicon Anode

The rapid and reversible lithiation/delithiation of silicon materials remains a challenging yet marvelous goal. Herein, harnessing the nanoporous to compact gradient design, a dual-film consisting of flexible porous zincone and rigid compact TiO2 (zincone/TiO2) is controllably deposited onto a silicon electrode using molecular layer deposition and atomic layer deposition techniques. This dual-film can tailor the stress and ionic diffusion kinetics for silicon anodes. That is, the elastic zincone acts as a buffer layer to dissipate inner stress through the deformation of pores, while the rigid TiO2 (approximate to 5 nm) provides silicon particles a satisfying mechanical strength and protects the silicon from engulfing by the solid electrolyte interphase. The density functional theory and galvanostatic intermittent titration technique results indicate the fast Li+ diffusion kinetics in Si@zincone/TiO2 electrode, resulting in a high initial Coulombic efficiency of 81.9% and an advantageous rate capability of 1224 mAh g(-1) at 4 A g(-1). More importantly, a low capacity-fading rate of only 0.051% per cycle can be achieved (discharge capacity of 753 mAh g(-1) after 1000 cycles). Additionally, fractal theory verifies the Si@zincone/TiO2 undergoes gentle reversible evolutions during cycling with a box fractal dimension (D-B) of 1.73.

Automated summary

By utilizing a dual-film design consisting of flexible porous zincone and rigid compact TiO2, researchers were able to enhance the lithiation/delithiation process of silicon materials, achieving high electrochemical performance and cycling stability. The structure of the dual-film can alleviate internal stress of the silicon materials, provide sufficient mechanical strength and protection to the silicon particles, resulting in improved stability and capacity during cycling. The study demonstrated that the Si@zincone/TiO2 electrode exhibits excellent electrochemical performance and a low capacity-fading rate.