SnO2 Quantum Dots@Graphene Oxide as a High-Rate and Long-Life Anode Material for Lithium-Ion Batteries
SnO2 Quantum Dots@Graphene Oxide as a High-Rate and Long-Life Anode Material for Lithium-Ion Batteries
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SnO2量子点@氧化石墨烯作为锂离子电池高倍率、长寿命负极材料
DOI：
10.1002/smll.201502183
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发表时间：
2016-02-03
期刊：
影响因子：
13.3
通讯作者：
Mai, Liqiang
中科院分区：
文献类型：
--
作者：
Zhao, Kangning;Zhang, Lei;Mai, Liqiang
然而，在合金化过程中，较大的原子比导致原子数目增加440%，并导致巨大的体积膨胀(高达259%)。[19]巨大的体积变化导致晶格的反复膨胀和收缩，以及充放电过程，导致锡颗粒的位错、塑性、破裂和粉化。[16]这样，活性锡与导电添加剂或电极集电体之间的电接触很容易失去。[24，25]此外，固体电解液界面(SEI)层将在颗粒和电解液的界面上连续频繁地形成和分解。为了优化电极材料的循环稳定性，将金属氧化物和石墨烯结合起来构建合适的结构稳定性的纳米结构被认为是一种有效的方法。具有sp2杂化碳原子蜂窝网络的石墨烯具有良好的导电性、较大的比表面积、结构灵活性和化学稳定性。然而，金属氧化物和石墨烯的简单机械混合往往会导致纳米颗粒的团聚和结构的不稳定，特别是在充放电过程中。Wu等人[28]设计并制备了3D多孔石墨烯网络包裹的锡基结构，在长时间的循环过程中保持了完整性。因此，构建稳定的金属氧化物/石墨烯纳米结构是避免上述问题的有效途径。[22，29-38]在这方面，开发简便的合成方法在导电石墨烯上制备金属氧化物纳米晶是非常具有挑战性的，特别是在高速率和长寿命的LiB应用中。在这里，我们报道了一种简单的合成SnO2量子点@石墨烯氧化物(记为SnO2量子点@GO)的方法，具有良好的分散性和高质量负载量。形成过程包括Sn2+的氧化和氧化石墨烯(GO)片的还原。通过原位还原过程，孤立的SnO2量子点能够紧密地锚定并分散在石墨烯纳米片上。通过这种方式，有效地释放了在放电/充电过程中与锂的插入/提取相关的巨大的体积膨胀/收缩，并且很好地保持了结构的完整性。独特的设计能够为快速嵌/脱锂提供导电衬底、简单的应变松弛和稳定的SEI层，从而产生显著的DOI：10.1002/SMLL。201502183
However, during the alloying process, the large atomic ratio involved results in a 440% increase in the number of atoms and induces huge volume expansions (up to 259%).[19] The huge volume variations result in the repeated expansion and contraction of the lattice along with charge/discharge processes and lead to dislocation, plasticity, cracking, and pulverization of the Sn particles.[16] In this way, the electrical contact between active Sn and conductive additives or the electrode current collector or both is easily lost.[24, 25] Moreover, solid electrolyte interface (SEI) layer will continuously and frequently be formed and decomposed on the interface of particles and electrolyte, consuming extra lithium,[26, 27] leading to the poor Coulombic efficiency and undesirable capacity fading.To optimize the cycling stability of electrode materials, the combination of metal oxides and graphene to construct appropriate nanostructures with good structure stability is regarded as an effective method. Graphene with a honeycomb network of sp2 hybridized carbon atoms exhibits excellent electrical conductivity, large surface area, structural flexibility, and chemical stability. However, the simple mechanically mixing metal oxides and graphene usually leads to the agglomeration of nanoparticles and structural instability, especially during the charge–discharge process. Wu et al.[28] designed and fabricated 3D porous graphene network-encapsulated Sn-based architectures preserving the integrity during the long cycling process. Therefore, the construction of stable metal oxides/graphene nanostructures is an effective route to avoid the above problems.[22, 29–38] In this regard, it is highly challenging but desirable to develop facile synthesis methodologies for the fabrication of metal oxides nanocrystalline on conducting graphene sheets, particularly for high-rate and long-life LIB applications. Herein, we report a facile route to synthesize SnO 2 quantum dots@ graphene oxide (denoted as SnO 2 QDs@ GO) with good dispersion and high mass loading. The formation process involves the oxidation of Sn 2+ and the reduction of the graphene oxide (GO) sheets. Through in situ reduction process the isolated SnO 2 quantum dots are able to anchor tightly and disperse well on the graphene nanosheets. In this way, the huge volume expansion/contraction associated with lithium insertion/extraction during discharging/charging is effectively released and the structural integrity is well maintained. The unique design is able to offer conductive substrates, facile strain relaxation, and stable SEI layer for fast lithium intercalation/de-intercalation, which yields significant DOI: 10.1002/smll. 201502183