Wu Gang, Weng Zheng, Li Jiaqi, Zheng Zhicheng, Wen Zuxin, Fang Wenqiang, Zhang Ying, Zhang Ning, Chen Gen, Liu Xiaohe
School of Materials Science and Engineering, Key Laboratory of Electronic Packaging and Advanced Functional Materials of Hunan Province, Changsha, Hunan 410083, P. R. China.
Zhongyuan Critical Metals Laboratory, Zhengzhou University, Zhengzhou, Henan 450001, P. R. China.
ACS Appl Mater Interfaces. 2023 Jul 26;15(29):34852-34861. doi: 10.1021/acsami.3c05228. Epub 2023 Jul 17.
The high specific capacity and relatively low volume expansion of silicon suboxide (SiO) highlight its potential as one of the most promising anode materials for lithium-ion batteries. Nevertheless, the traditional binder of polyacrylic acid (PAA) still cannot adapt to enormous stress during the repeated volume expansion/contraction owing to its intrinsic rigid backbone. Inspired by the "soft and hard composite body armor", we herein design a double-wrapped binder consisting of PAA with a high internal Young's modulus (hard part) and polyurethane (DOU) with a low external Young's modulus (soft part). When the SiO particle expands during lithiation, the rigid PAA firstly accommodates the volume change to dissipate most of the inner stress, and the elastic DOU with triple dynamic bonds serves as a buffer layer to absorb the residual stress via the breakage/formation of dynamic bonds. By optimizing the PAA/DOU ratio, the SiO anode can maintain the integrity during long-term cycling and deliver a relatively high reversible capacity of 1064.1 mAh g with a preeminent capacity retention of 83.7% at 0.5C after 300 cycles. Such a double-wrapped binder can provide a novel design strategy for multicomponent functional polymer binders toward high-performance SiO anodes.
二氧化硅（SiO）具有高比容量和相对较低的体积膨胀率，这突出了其作为锂离子电池最有前景的负极材料之一的潜力。然而，传统的聚丙烯酸（PAA）粘结剂由于其固有的刚性主链，在反复的体积膨胀/收缩过程中仍无法适应巨大的应力。受“软硬复合防弹衣”的启发，我们在此设计了一种双包覆粘结剂，它由具有高内杨氏模量的PAA（硬部分）和具有低外杨氏模量的聚氨酯（DOU）（软部分）组成。当SiO颗粒在锂化过程中膨胀时，刚性的PAA首先适应体积变化以消散大部分内部应力，而具有三重动态键的弹性DOU作为缓冲层，通过动态键的断裂/形成来吸收残余应力。通过优化PAA/DOU比例，SiO负极在长期循环过程中能够保持完整性，并在0.5C下300次循环后提供相对较高的可逆容量1064.1 mAh g，容量保持率高达83.7%。这种双包覆粘结剂可为高性能SiO负极的多组分功能聚合物粘结剂提供一种新颖的设计策略。
