Abstract

In this work, a simple and effective synthesis procedure was performed in order to prepare hybrid alkali titanate materials, as negative electrodes for lithium-ion battery applications. Lithium titanate Li₄Ti₅O₁₂ (LTO) and sodium titanates Na₂Ti₃O₇ (NTO₂₃₇) and Na₂Ti₆O₁₃ (NTO₂₆₁₃) compounds were synthesized through a solid-state method; then a carbon coating was performed using sucrose impregnation followed by a dehydration step with strong acid medium, and finally calcined at high temperature. XRD and Raman spectroscopy analysis of the composites indicated that the strong acid medium in the carbonization step affects the titanate structure. A calcination temperature at 700 °C proved to be adequate to obtain the LTO/C material without significant changes and with a homogeneous carbon coating, so it was used to obtain further the hybrids NTO₂₃₇/C and NTO₂₆₁₃/C materials. The carbon coating improved the good behavior obtained before in bare LTO compound about specific capacity for electric charge storage, but mainly produced huge improvements in the poor specific capacities observed for both bare NTO compounds. All the hybrid alkali titanates exhibited a great stability of charge/discharge cycling and a very good rate capability response, showing a robust behavior recovering the initial specific capacity at low rate after several discharge cycles at high rates (10 C). Such increase in the specific storage capacity in all hybrid alkali titanate materials is associated with the enhancement in the inter-particle connectivity generated by the carbonaceous coating.

中文翻译：

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通过蔗糖碳化增强钛酸碱金属（锂，钠）的能量存储

摘要

在这项工作中，进行了简单有效的合成程序，以制备杂化钛酸碱金属盐材料，作为锂离子电池应用的负极。钛酸锂Li ₄ Ti ₅ O ₁₂（LTO）和钛酸钠Na ₂ Ti ₃ O ₇（NTO ₂₃₇）和Na ₂ Ti ₆ O ₁₃（NTO _2613））通过固态方法合成化合物；然后用蔗糖浸渍进行碳涂层，然后用强酸介质进行脱水步骤，最后在高温下煅烧。复合材料的XRD和拉曼光谱分析表明，碳化步骤中的强酸介质会影响钛酸酯的结构。事实证明，在700°C的煅烧温度足以获得LTO / C材料，而无明显变化且具有均匀的碳涂层，因此可用于进一步获得杂化体NTO ₂₃₇ / C和NTO ₂₆₁₃/ C材料。碳涂层改善了以前在裸露的LTO化合物中获得的有关电荷存储比容量的良好行为，但主要改善了两种裸露的NTO化合物所观察到的较差的比容量。所有杂化碱金属钛酸酯都表现出极好的充电/放电循环稳定性和非常好的倍率能力响应，在以高倍率（10 C）放电几次后，在低倍率下恢复了初始比容量，表现出强大的性能。所有杂化碱金属钛酸酯材料中比存储容量的这种增加与碳质涂层产生的颗粒间连通性的增强有关。