Sung Joon Park, Seung Han Kim, Ji Woo Han, Eun Ji Lee, Si Ra Kim, Yong Min Kim, Ki Jae Kim
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引用次数: 0
Abstract
Silicon is a promising anode material for lithium-ion batteries because of its high theoretical capacity. However, their practical application is hindered by substantial volume expansion during lithiation/delithiation, which leads to mechanical degradation and capacity fading. To address this challenge, we propose a stress-dissipative binder system based on UV-induced cross-linking of viscoelastic poly(dimethyl siloxane) (PDMS) with rigid linear poly(acrylic acid) (PAA). The resulting PAA–PDMS binder can reversibly deform and recover in response to external stress due to the flexible siloxane backbone in PDMS, thereby accommodating the substantial volume expansion of Si electrode. Furthermore, the amphiphilic nature of the PDMS molecule increases its affinity for both carbon and Si particles, resulting in enhanced mechanical integrity of the Si electrode. These inherent characteristics of PDMS can effectively compensate for the rigidity of PAA, resulting in a well-balanced binder system tailored for Si electrodes. Consequently, the PAA–PDMS electrode exhibited a discharge capacity of 2072.68 mAh g−1 after 100 cycles at 0.5 C−rate, whereas the PAA−based electrode reached failure after only 70 cycles. Post-mortem analyses reveal that the improved electrochemical performance of the PAA–PDMS electrode arises from its ability to mitigate Si electrode degradation by suppressing volume expansion and stabilizing the electrode–electrolyte interface.
硅具有较高的理论容量,是一种很有前途的锂离子电池负极材料。然而,它们的实际应用受到锂化/消瘦过程中大量体积膨胀的阻碍,这会导致机械降解和容量衰退。为了解决这一挑战,我们提出了一种基于uv诱导的粘弹性聚二甲基硅氧烷(PDMS)与刚性线性聚丙烯酸(PAA)交联的应力耗散粘合剂体系。由于PDMS中的柔性硅氧烷骨架,所得到的PAA-PDMS粘合剂可以在外部应力下可逆变形和恢复,从而适应Si电极的大量体积膨胀。此外,PDMS分子的两亲性增加了其对碳和Si颗粒的亲和力,从而增强了Si电极的机械完整性。PDMS的这些固有特性可以有效地补偿PAA的刚性,从而为Si电极量身定制一个平衡良好的粘结剂系统。因此,在0.5 C -倍率下,PAA - pdms电极在100次循环后显示出2072.68 mAh g - 1的放电容量,而PAA -电极在70次循环后就失效了。事后分析表明,PAA-PDMS电极的电化学性能的提高源于其通过抑制体积膨胀和稳定电极-电解质界面来减轻Si电极降解的能力。