Gamma(ɣ)‑MnO_(2)/rGO Fibered Cathode Fabrication from Wet Spinning and Dip Coating Techniques for Cable‑Shaped Zn‑Ion Batteries

Cable/fber-shaped Zn-ion batteries are designed to power wearable electronics that require high fexibility to operate on human body.However,one of technical challenges of these devices is the complexity and high cost for manufacturing fbered cathode.In this work,we demonstrated gamma manganese oxide(ɣ-MnO_(2))/reduced graphene oxide(rGO)fbered cathode fabrication using facile and cost-efective fber production and active material coating techniques.Specifcally,rGO fbers were fabricated via wet spinning,followed by chemical reduction with hydroiodic acid(HI).The synthesized rGO fber bundle was then dip-coated with a mixture ofɣ-MnO_(2),carbon black or multi-walled carbon nanotubes,and xanthan gum or polyvinylidene fuoride binder to obtainɣ-MnO_(2)/rGO fbered cathode.We studied the efect of binders and conductive materials on physical properties and electrochemical performance of the fbered cathode.It was found that hydrophobic binder had more benefts than hydrophilic binder by providing higher active material loading,better coating layer homogeneity,and more stable electrochemical performance.Cable-shaped Zn-ion batteries(CSZIBs)were then assembled by using theɣ-MnO_(2)/rGO fbered cathode,Zn wire anode,and xanthan gum polymeric gel electrolyte with 2 M ZnSO_(4) and 0.2 M MnSO_(4) salts without a separator.We investigated the battery assembling procedure on a glass slide(prototype ZIB)and in a plastic tube(cable-shaped ZIB),and evaluated their electrochemical performance.The CSZIB showed promising maximum capacity of~230 mAh/g with moderate cycling stability(80%capacity retention after 200 cycles)and high fexibility by maintaining the potential after consecutive pressing for 200 times under controlled pressing distance,duration,and testing speed.Finally,we explored ion intercalation behaviours and proposed a H^(+)/Zn^(2+)co-intercalation mechanism in ZIB withɣ-MnO_(2) active material.