Highly Elastic Polyrotaxane Binders for Mechanically Stable Lithium Hosts in Lithium‐Metal Batteries

• DOI: 10.1002/adma.201901645
• Publication Date: 2019-05-31T06:32:41Z
• Authors: Dong‐Joo Yoo; Ahmed Elabd; Sunghun Choi; Yunshik Cho; Jaemin Kim; Seung Jong Lee; Seung Ho Choi; Tae‐woo Kwon; Kookheon Char; Ki Jae Kim; Ali Coskun; Jang Wook Choi
• Keywords: 02 engineering and technology; 0210 nano-technology; 7. Clean energy

AbstractDespite their unparalleled theoretical capacity, lithium‐metal anodes suffer from well‐known indiscriminate dendrite growth and parasitic surface reactions. Conductive scaffolds with lithium uptake capacity are recently highlighted as promising lithium hosts, and carbon nanotubes (CNTs) are an ideal candidate for this purpose because of their capability of percolating a conductive network. However, CNT networks are prone to rupture easily due to a large tensile stress generated during lithium uptake–release cycles. Herein, CNT networks integrated with a polyrotaxane‐incorporated poly(acrylic acid) (PRPAA) binder via supramolecular interactions are reported, in which the ring‐sliding motion of the polyrotaxanes endows extraordinary stretchability and elasticity to the entire binder network. In comparison to a control sample with inelastic binder (i.e., poly(vinyl alcohol)), the CNT network with PRPAA binder can endure a large stress during repeated lithium uptake–release cycles, thereby enhancing the mechanical integrity of the corresponding electrode over battery cycling. As a result, the PRPAA‐incorporated CNT network exhibits substantially improved cyclability in lithium–copper asymmetric cells and full cells paired with olivine‐LiFePO4, indicating that high elasticity enabled by mechanically interlocked molecules such as polyrotaxanes can be a useful concept in advancing lithium‐metal batteries.