Preparation Of Boron - Containing Thin Films And Study On Their Lithium - Storage Properties

Monatomic elements and their composites, always considered to be promising anode candidates, have been extensively investigating because of their low cost, high specific capacity and easy availability. According to the delivered literatures, C, Si and S, all show a great prosperity in designing the real battery electrode.However, only a lighter elemental B and its oxide (B2O3) drive no more interests, due to their electrochemical inactivity in bulk caused by their poor electronic conduct-ivity. Instead, most groups treated them as addition agents in the preparation of other electrode materials to improve their electrochemical performance.In the previous research of our group, it can be found that many electrochemically inactive materials could show considerable electrochemical activity when they were fabricated into nanostructured thin films. This stimulates us to investi-gate initially the electrochemical behavior of the B and B2O3thin film.In this paper, the research content could be divided into two parts:1. Amorphous B2O3thin films have been successfully fabricated by PLD method for the first time. The electrochemical characterization shows good reversibility in delith-iation and lithiation processes. By using XPS and Raman measurements, the electro-chemical reaction process of B2O3with lithium is proposed.2. Crystalline tetragonal Boron thin film has been successfully fabricated by reactive PLD method and firstly used as Li storing electrode for Li-ion battery. The electroch-emical characterization shows good high-temperature performance between0.01V and3.0V. First-principles calculation indicates that the B50is a metallic conductor, but a poor lithium ionic conductor,～2.59eV energy barrier for Li ion hopping at absolute zero, which explains its low RT reactivity toward lithium. By using HRTEM, SAED, and XPS measurements, the electrochemical reaction process of B with lithium is proposed.The above results may have some reference value for the exploration of novel anode materials of lithium-ion batteries and chemical properties of the electrode materials for thin film batteries.