摘要
利用纳米TiO2颗粒和Li2CO3为原料,分别在不添加及添加中间相沥青的情况下通过固相反应制备出Li4Ti5O12及炭包覆的锂化钛酸锂Li4+x Ti5O12/C。Li4Ti5O12颗粒尺寸在0.5～3μm之间,而Li4+x Ti5O12/C颗粒尺寸比较均匀,在200～500 nm之间,且颗粒表面包覆了一层厚度约2 nm的炭层。充放电研究表明,Li4Ti5O12的可逆容量较低,而Li4+x Ti5O12/C则具有非常高的可逆容量、循环稳定性及容量保持率。同时,Li4+x Ti5O12/C可提供Li+补偿首次不可逆容量损失,导致首次库仑效率超过100%。Li4+x Ti5O12/C中预储锂量随碳源量的增加而增加,在碳源量5%条件下制得的Li4+x Ti5O12/C的首次脱锂容量超过嵌锂容量24.2 mAh·g-1。Li4+x Ti5O12/C有望消除锂离子全电池的首次不可逆容量损失并提高其容量。
Lithium titanate Li4Ti5O12 and lithiated lithium titanate with carbon coating Li4＋xTi5O12/C have been synthesized using TiO2 nanoparticles and Li2CO3 as starting materials without or with the presence of mesophase pitch through a solid-state reaction process, respectively. The particle sizes of Li4TisO12 and Li4＋xTisO12/C range from 0.5-3μm and 200-500 p,m, respectively. The thickness of the carbon coating layers of Li4-xTi5O12/C is ca. 2 nm. Charge discharge cyclic measurements indicate that the microsized Li4Ti5O12 displays low reversible capacity. While Li4＋xTi5O12/C has higher cyclic capacity and stability than Li4Ti5O12. Meanwhile Li4＋xTi5O12/C can supply Li＋ to compensate initial irreversible capacity, which resulted in the first-cycle coulombic efficiency over 100%. The amount of pre-stored Li~ in Li4＋xTi5O12/C increases with increase of amount of mesophase pitch in the starting materials. When the amount of mesophase pitch is 5%, the delithiation capacity of Li4＋xTi5O12/C is 24.2 mAh·g^-1 higher than lithiation capacity. The Li4＋xTi5O12/C anode materials are expected to eliminate initial irreversible capacity of lithium-ion full cells.
出处
《炭素技术》
CAS
北大核心
2013年第5期9-14,共6页
Carbon Techniques
