The NCNST research group led by Prof. Xianglong Li and Prof. Linjie Zhi made a progress in the study of silicon-based lithium battery anodes. The research was published and entitled with “Stable high-capacity and high-rate silicon-based lithium battery anodes upon two-dimensional covalent encapsulation” (Nature Communications, 2020, 11, 3826).
Silicon is a very promising anode material for lithium-ion and post lithium-ion batteries but suffers from a large volume change upon lithiation and delithiation. The resulting instabilities of bulk and interfacial structures severely hamper performance and obstruct practical use.
To address the above challenge, the research group has developed various protocols of materials design and construction (e.g., see Chem. Soc. Rev. 2018, 47, 3189; Adv. Mater. 2019, 31, 1804973; Mater. Sci. Eng., R 2019, 137, 1; Adv. Funct. Mater. 2019, 29, 1806061). In this work, a two-dimensional covalent encapsulation strategy is proposed and developed. Two-dimensional, covalently bound silicon-carbon hybrids, serving as proof-of-concept of a new material design, show a remarkable level of integrated performances when referred to weight, volume and area. Typically, the specific capacity and volumetric capacity reach 2646 mAh/g and 2350 mAh/cm3, respectively; the capacity retains 1500 mAh/g at a rate of 2 A/g over 500 cycles; even at a considerably high rate of 20 A/g, the specific capacity retains up to 810 mAh/g, the volumetric capacity is much higher than non-covalent encapsulated and non-encapsulated counterparts by 1358 and 1442%, respectively; Considering the whole device, the full cells based on such hybrids exhibit markedly improved energy density, 40~60% higher than graphite-based ones, 40% higher than currently commercialized lithium-ion batteries in terms of both specific energy and energy density. The study shows the two-dimensional covalent encapsulation creates robust and efficient transport pathways for both electrons and lithium ions, whilst effectively alleviating the volume change of silicon. More impressively, it revolutionizes the interface of silicon with the electrolyte, thus securing the as-created contact to persist upon cycling.
Dr. Xinghao Zhang from NCNST is the first author of this work; Prof. Xianglong Li and Prof. Linjie Zhi from NCNST are the corresponding authors. This work was supported by the National Natural Science Foundation of China and Youth Innovation Promotion Association CAS.
Click on the following link to see the original article: https://www.nature.com/articles/s41467-020-17686-4.
Skin-like two-dimensional covalent encapsulation, the resulting carbon-silicon hybrids, and lithium storage performance