Electrochemical Properties of Polymer‐Derived SiCN Materials as the Anode in Lithium Ion Batteries
Electrochemical Properties of Polymer‐Derived SiCN Materials as the Anode in Lithium Ion Batteries
复制标题
DOI：
10.1111/j.1551-2916.2009.03317.x
复制
发表时间：
2009-12
影响因子：
3.9
通讯作者：
Dong Su;Ya-li Li;Yan Feng;Jun Jin
中科院分区：
文献类型：
--
作者：
Dong Su;Ya-li Li;Yan Feng;Jun Jin
聚合物衍生的SiCN材料，在600 ° C和1500 ° C之间的温度下从聚甲硅烷基乙二胺热解，被用作锂电池中的阳极，并研究其电化学性能。在不同温度下热解得到的SiCN材料，其组成从有机到无机，相结构从非晶态到晶态。电化学测试表明，1000 °-1300 °C的SiCN材料在40 mA/g的电流密度下首次循环放电容量为608 - 754 mAh/g，高于石墨阳极。在7次充放电循环后，放电容量降低到170 - 230 mAh/g，并在30次循环后保持在该范围内。组成和结构分析表明，在1000 °-1300 °C温度下制备的SiCN材料为非晶相，SiCN网络中含有游离碳。相比之下，600 °-800 °C衍生的含有有机基团的SiCN和1400 °-1500 °C衍生的含有SiC微晶的SiCN显示出比无定形SiCN阳极低得多的充电和放电容量。这表明SiCN中的游离碳和SiCN材料的无定形结构有助于SiCN材料的电化学性能。看来，自由碳相充当了锂离子插入的活性位点，而无定形SiCN网络则为锂离子转移提供了路径。聚合物衍生的SiCN材料的电化学容量对它们的组成和结构的强烈依赖性表明通过分子设计和/或材料结构的控制来增强材料的电化学性能的潜力。
Polymer-derived SiCN materials, pyrolyzed from polysilylethylenediamine at temperatures between 600° and 1500°C, are used as the anode in lithium batteries, and their electrochemical performance is studied. The SiCN materials, having composition ranging from organic to inorganic and phase structures from amorphous to crystalline, are obtained from pyrolysis at different temperatures. Electrochemical measurements show that the 1000°–1300°C derived SiCN materials exhibit a first-cycle discharge capacity of 608–754 mAh/g at a current density of 40 mA/g, which is higher than that of a graphite anode. The discharge capacity reduces to 170–230 mAh/g after seven charge–discharge cycles and stays in this range over 30 cycles. Compositional and structural analyses show that the 1000°–1300°C derived SiCN materials have an amorphous phase and contain free carbon in the SiCN network. In contrast, the 600°–800°C derived SiCN, which contains organic groups, and the 1400°–1500°C derived SiCN, which contains SiC crystallites, show a much lower charge and discharge capacity compared with that of the amorphous SiCN anode. This suggests that free carbon in SiCN and the amorphous structure of the SiCN materials contribute to the electrochemical performance of the SiCN materials. It seems that the free carbon phase acts as an active site for the insertion of Li ions while the amorphous SiCN network provides a path for Li-ion transfer. The strong dependence of the electrochemical capacities of the polymer-derived SiCN materials on their compositions and structures suggests the potential to enhance the electrochemical performance of the materials through molecular design and/or the control of material structure.