ハライドで安定したLiBH4は,室温のリチウム高速イオン導体です.
Hideki Maekawa1, Motoaki Matsuo, Hitoshi Takamura
1Graduate School of Engineering, Tohoku University, Aramaki Aza Aoba 6-6-02, Sendai 980-8579, Japan. maekawa@material.tohoku.ac.jp
Journal of the American Chemical Society
|January 6, 2009
まとめ
研究者は,より安全で高エネルギー電池のための固体リチウム伝導体を強化しました. リチウムヨーダイドによるリチウムボロヒドリド (LiBH(4) のドーピングは,室温でそのスーパーイオン相を安定させ,先進的なバッテリーアプリケーションを可能にします.
科学分野:
- マテリアルサイエンス 材料科学
- 電気化学 電気化学について
- 固体化学 固体化学
背景:
- 固体リチウム伝導体は,高エネルギー密度のバッテリーや超電容器の開発に不可欠です.
- 現在の技術は,安全性や容量喪失という課題に直面しています.
- リチウムボロヒドリド (LiBH(4) は高いイオン伝導性を示しているが,その超イオン相には高温が必要である.
研究 の 目的:
- 低温でLiBH(4) の超電離相を安定させるため.
- 先進的なエネルギー貯蔵装置のための新しい固体電解質を開発する.
- LiBH ((4) ベースの導体における高い移行温度による制限を克服するために.
主な方法:
- リチウムハリドでドーピングすることによって,LiBHの化学的改変.
- X線微分光譜 (XRD) と核磁共鳴光譜 (NMR) を用いて,相の特徴を決定する.
- イオン伝導性とインターフェイス特性を評価するための電気化学測定.
主要な成果:
- 室温以下のLiBH(4) のスーパーイオン相の安定化は,リチウムヨウ酸化物 (LiI) のドーピングによって達成された.
- LiIドーピングされたLiBH(4) は,室温で高いイオン伝導性を示しています.
- リチウム金属電極の偏振が低いことが実証され,バッテリーアノドに適していることが示されています.
結論:
- 化学的改変,特にLiIドーピングは,LiBHにおけるスーパーイオン相への移行温度を効果的に低下させる.
- この室温の超音波導体は,高エネルギー密度バッテリー用の軽量で効率的な電解質を提供します.
- この発見は,既存のリチウムベースの材料を超えて,先進的な固体イオン導体を開発するための新しい道を示しています.
関連する概念動画
01:19Acid Halides to Alcohols: LiAlH4 Reduction
Acid halides are reduced to alcohols in the presence of a strong reducing agent like lithium aluminum hydride.
The mechanism proceeds in three steps. First, the nucleophilic hydride ion attacks the carbonyl carbon of the acid halide to form a tetrahedral intermediate. Next, the carbonyl group is re-formed, and the halide ion departs as a leaving group, generating an aldehyde. A second nucleophilic attack by the hydride yields an alkoxide ion, which, upon protonation, gives a primary alcohol as...
The mechanism proceeds in three steps. First, the nucleophilic hydride ion attacks the carbonyl carbon of the acid halide to form a tetrahedral intermediate. Next, the carbonyl group is re-formed, and the halide ion departs as a leaving group, generating an aldehyde. A second nucleophilic attack by the hydride yields an alkoxide ion, which, upon protonation, gives a primary alcohol as...
02:48Ionic Bonding and Electron Transfer
Ions are atoms or molecules bearing an electrical charge. A cation (a positive ion) forms when a neutral atom loses one or more electrons from its valence shell, and an anion (a negative ion) forms when a neutral atom gains one or more electrons in its valence shell. Compounds composed of ions are called ionic compounds (or salts), and their constituent ions are held together by ionic bonds: electrostatic forces of attraction between oppositely charged cations and anions.
02:45Alkyl Halides
Structural Properties
Alkyl halides are halogen-substituted alkanes wherein one or more hydrogen atoms of an alkane is replaced by a halogen atom such as fluorine, chlorine, bromine, or iodine. The carbon atom in an alkyl halide is bonded to the halogen atom, which is sp3-hybridized and exhibits a tetrahedral shape.
Unlike alkyl halides, compounds in which a halogen atom is bonded to an sp2 -hybridized carbon atom of a carbon-carbon double bond (C=C) are called vinyl halides. Whereas aryl...
Alkyl halides are halogen-substituted alkanes wherein one or more hydrogen atoms of an alkane is replaced by a halogen atom such as fluorine, chlorine, bromine, or iodine. The carbon atom in an alkyl halide is bonded to the halogen atom, which is sp3-hybridized and exhibits a tetrahedral shape.
Unlike alkyl halides, compounds in which a halogen atom is bonded to an sp2 -hybridized carbon atom of a carbon-carbon double bond (C=C) are called vinyl halides. Whereas aryl...
02:54Trends in Lattice Energy: Ion Size and Charge
An ionic compound is stable because of the electrostatic attraction between its positive and negative ions. The lattice energy of a compound is a measure of the strength of this attraction. The lattice energy (ΔHlattice) of an ionic compound is defined as the energy required to separate one mole of the solid into its component gaseous ions. For the ionic solid sodium chloride, the lattice energy is the enthalpy change of the process:
01:14Acid Halides to Ketones: Gilman Reagent
Lithium dialkyl cuprate, also known as Gilman reagents, selectively reduces acid halides to ketones. The acid chloride is treated with Gilman reagent at −78 °C in the presence of ether solution to produce a ketone in good yield.
As shown below, the mechanism proceeds in two steps. First, one of the alkyl groups of the reagent acts as a nucleophile and attacks the acyl carbon of the acid chloride to form a tetrahedral intermediate. This is followed by the reformation of the carbon–oxygen double...
As shown below, the mechanism proceeds in two steps. First, one of the alkyl groups of the reagent acts as a nucleophile and attacks the acyl carbon of the acid chloride to form a tetrahedral intermediate. This is followed by the reformation of the carbon–oxygen double...
01:28Ionic Association
The ionic association is the association of oppositely charged ions in an electrolyte solution to form ion pairs. Bjerrum defined ion pairs as two oppositely charged ions whose electrostatic attraction exceeds the thermal energy of the system, typically expressed as 2kT. Electrostatic attraction depends on ionic charge, separation distance, and the dielectric constant of the medium. Thermal energy, represented by kT, reflects the tendency of ions to move independently due to molecular motion.