Surface Modification of Silicon Nanoparticles by an “Ink” Layer for Advanced Lithium Ion Batteries

Owing to its high specific capacity, silicon is considered as a promising anode material for lithium ion batteries (LIBs). However, the synthesis strategies for previous silicon-based anode materials with a delicate hierarchical structure are complicated or hazardous. Here, Prussian blue analogues (PBAs), widely used in ink, are deposited on the silicon nanoparticle surface (PBAs@Si-450) to modify silicon nanoparticles with transition metal atoms and a N-doped carbon layer. A facile and green synthesis procedure of PBAs@Si-450 nanocomposites was carried out in a coprecipitation process, combined with a thermal treatment process at 450 °C. As-prepared PBAs@Si-450 delivers a reversible charge capacity of 725.02 mAh g^–1 at 0.42 A g^–1 after 200 cycles. Moreover, this PBAs@Si-450 composite exhibits an exceptional rate performance of ∼1203 and 263 mAh g^–1 at current densities of 0.42 and 14 A g^–1, respectively, and fully recovered to 1136 mAh g^–1 with the current density returning to 0.42 A g^–1. Such a novel architecture of PBAs@Si-450 via a facile fabrication process represents a promising candidate with a high-performance silicon-based anode for LIBs

Atomic Layer Deposition of Stable LiAlF₄ Lithium Ion Conductive Interfacial Layer for Stable Cathode Cycling

Modern lithium ion batteries are often desired to operate at a wide electrochemical window to maximize energy densities. While pushing the limit of cutoff potentials allows batteries to provide greater energy densities with enhanced specific capacities and higher voltage outputs, it raises key challenges with thermodynamic and kinetic stability in the battery. This is especially true for layered lithium transition-metal oxides, where capacities can improve but stabilities are compromised as wider electrochemical windows are applied. To overcome the above-mentioned challenges, we used atomic layer deposition to develop a LiAlF₄ solid thin film with robust stability and satisfactory ion conductivity, which is superior to commonly used LiF and AlF₃. With a predicted stable electrochemical window of approximately 2.0 ± 0.9 to 5.7 ± 0.7 V <i>vs</i> Li⁺/Li for LiAlF₄, excellent stability was achieved for high Ni content LiNi_0.8Mn_0.1Co_0.1O₂ electrodes with LiAlF₄ interfacial layer at a wide electrochemical window of 2.75–4.50 V <i>vs</i> Li⁺/Li

Vertically Aligned and Continuous Nanoscale Ceramic–Polymer Interfaces in Composite Solid Polymer Electrolytes for Enhanced Ionic Conductivity

Among all solid electrolytes, composite solid polymer electrolytes, comprised of polymer matrix and ceramic fillers, garner great interest due to the enhancement of ionic conductivity and mechanical properties derived from ceramic–polymer interactions. Here, we report a composite electrolyte with densely packed, vertically aligned, and continuous nanoscale ceramic–polymer interfaces, using surface-modified anodized aluminum oxide as the ceramic scaffold and poly­(ethylene oxide) as the polymer matrix. The fast Li⁺ transport along the ceramic–polymer interfaces was proven experimentally for the first time, and an interfacial ionic conductivity higher than 10^–3 S/cm at 0 °C was predicted. The presented composite solid electrolyte achieved an ionic conductivity as high as 5.82 × 10^–4 S/cm at the electrode level. The vertically aligned interfacial structure in the composite electrolytes enables the viable application of the composite solid electrolyte with superior ionic conductivity and high hardness, allowing Li–Li cells to be cycled at a small polarization without Li dendrite penetration