In recent years, the team led by Li Xianglong and Zhi Linjie at the National Center for Nanoscience and Technology has started with low-cost silica nanoparticles, improved the magnesium thermal reduction technology, and prepared a silicene material with a hydrangea-like shape on a large scale. When applied to lithium batteries, it exhibits excellent comprehensive lithium storage performance. Recently, the research team proposed and developed a "skin-grafting" two-dimensional covalent encapsulation strategy. Based on hydrangea-shaped siliceous olefins, they further prepared silicon-oxygen-carbon bond-based hydrangea-shaped covalent dienes, which exhibited excellent comprehensive lithium storage performance: at a current density of 800 mA/g, the specific capacity by weight and volume was as high as 2646 mAh/g and 2350 mAh/cm3, respectively. After 500 cycles at a current density of 2000 mA/g, the specific capacity by weight remained close to 1500 mAh/g; even at a current density of 20000 mA/g, the specific capacity by weight was still as high as 810 mAh/g, and the specific capacity by volume was 1358% and 1442% higher than that of non-covalently encapsulated and unencapsulated materials, respectively. Calculated as a whole device, the energy density of the full cell based on this carbon-silicon material was 40%~60% higher than that based on graphite, and more than 40% higher than the specific energy and energy density of current commercial lithium batteries. Preliminary studies have shown that the two-dimensional covalent packaging strategy not only provides an efficient hybrid transport channel for electrons and lithium ions while effectively mitigating silicon volume expansion, but also transforms the material interface and ensures efficient and stable transport of electrons and lithium ions.
The related findings, titled "Stable high-capacity and high-rate silicon-based lithium battery anode supply two-dimensional covalent encapsulation," were published in *Nature Communications*. The research was supported by the National Natural Science Foundation of China and the Youth Innovation Promotion Association of the Chinese Academy of Sciences, among other projects.
Skin-based two-dimensional covalent encapsulation strategy, construction of high-performance silicon-carbon anodes and lithium storage performance
