Discarded clothing acrylic yarns: Low-cost raw materials for deformable c nanofibers applied to flexible sodium-ion batteries

Acrylic and discarded acrylic fabrics are appealing for use as raw materials to prepare low-cost carbon nanofibers (CNFs), which can solve the problem of high spinning raw material cost in the industrialization of CNFs. However, the extremely poor thermal properties caused by the high content of comonomers make it difficult to prepare CNFs with good mechanical properties. Here, we successfully used clothing acrylic yarn to prepare deformable CNFs (Zn-CAY-CNF), which is accomplished by using trace amounts of zinc acetate (Zn(Ac)(2)) in the spinning solution and stepwise carbonization. As-obtained materials exhibit excellent cycle stability (101.6 mAh g(-1) , 2 A g(-1), 2000th) and rate-capacity retention (51 mAh g(-1), 10 A g(-1)), with good flexibility. A soft pack battery can light a LED under bending state. The excellent flexibility can be attributed to the role of Zn(Ac)(2) in initiating chemical pre-cyclization, promoting thermal cyclization and aromatization, which are contributed to cyclization and carbonization of PAN chain segments in acrylic molecular chains and improves the carbon yield of CNFs. More importantly, discarded acrylic fabric is also used to successfully prepare flexible CNFs via the same preparation process, indicating that the preparation strategy is universal and feasible. Acrylic and discarded acrylic fabrics are appealing for use as raw materials to prepare low-cost carbon nanofibers (CNFs) as high spinning raw material costs are a key factor limiting the industrialization of CNFs. However, their extremely poor thermal properties caused by high-content co-monomers make it difficult to prepare CNFs with good mechanical properties. Here, clothing acrylic yarn is successfully used to prepare deformable CNFs (Zn-CAY-CNF), which is accomplished by modifying a standard CNF preparation process using trace amounts of zinc acetate (Zn(Ac)(2)) in the spinning solution. The roles that Zn(Ac)(2) plays in initiating a pre-chemical cyclization, promoting thermal cyclization and aromatization are revealed, which are contributed to cyclization and carbonization of PAN chain segments in acrylic molecular chains. As-obtained Zn-CAY-CNF was successfully used in free-standing sodium ion battery anodes with excellent cycle stability and rate-capacity retention. A soft pack battery consisting of a Zn-CAY-CNF anode and Na3V2(PO4)(3) cathode was assembled, which can light a LED under bending state. More importantly, discarded acrylic fabric is also used to successfully prepare flexible CNFs via the same preparation process, indicating that this preparation strategy is practicable and that low-cost CNFs with good mechanical properties derived from discarded acrylics are feasible for practical use. (C) 2020 Elsevier Ltd. All rights reserved.