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.