Synthesis of dual-conductive binder polymer by blending carboxymethyl cellulose with cyclodextrin inclusion complex of polypyrrole for high performance Si anode

We introduce a unique self-adaptive and dual-conductive binding network composed of (1) adjustable adhesion molecule of ion-conductive cyclodextrin (CD) and (2) rigid network consisting of electron-conductive polypyrrole (PPy) and ion-conductive lithium carboxymethyl cellulose (LCMC) for electrode formation. Such a binding network of CD@PPy:LCMC is constructed by association of LCMC with inclusion complex of CD@PPy after extending PPy by polymerization of pyrrole which is released from pyrrole micelles with the CD@PPy as the wall material. CD molecules can rotate around and slide along the PPy chain in the CD@PPy:LCMC, dispersing stress arising from volume expansion of Si after lithiation. The abundant carboxyl groups in CMC and hydroxyl groups in glucopyranose unit of CD and CMC provide high absorption capability to fix Si nano-particles. The Si anode with the CD@PPy:LCMC presents small polarization, high capacity, and excellent cycleability. The initial capacity as high as 3881 mAh g −1 , the rate capacity of 1208 mAh g −1 at 6 C (1 C=4200 mAh g −1 ), and the excellent capacity retention of 2200 mAh g −1 after 200 deep charge-discharge cycles with cyclic decay of 0.12 % per cycle have been achieved.