Graphene network scaffolded flexible electrodes : from lithium to sodium ion batteries

Research on deformable and wearable electronics has promoted an increasing demand for next-generation power sources with high energy/power density, low cost, light weight, as well as thin and flexible features. One key challenge in flexible electrochemical energy storage devices lies in the development of reliable electrodes with open-framework material, robust structure, and high performance. In this thesis 3D array electrode using graphene network as scaffold was fabricated and studied as the cathode or anode for lithium and sodium ion batteries. These include: graphene foam (GF) supported V2O5@PEDOT nanobelt array for cathode of Li-ion battery in Chapter 2, which exhibited superior plateau performance than reported results and ultra-stable cycling performance even after 1000 cycles; VO2@GQD ultrathin array for cathode of Na-ion battery (SIB) in Chapter 3, where VO2 was first applied as cathode for SIB with capacity more than 300 mAh g-1 and high-rate at even 60C; In Chapter 4, Na3(VO)2(PO4)2F nanoarray was first successfully synthesized as 3D array Na-containing cathode for batteries application, where in-situ XRD was used to detect the structure evolution during sodiation/desodiation. Various SnS nanoarray architectures were fabricated as anodes for SIB in Chapter 5, the electrode showed highest ever reported reversible capacity more than 1000 mAh g-1 and unexpected rate performance at 30 A g-1 with the help of proposed pseudocapacitance-dominated capacity contribution mechanism. All in all, by smart design and facile synthesis approach 3D array electrode can be fabricated on flexible graphene foam, which can achieve high performance due to its ultrathin, porous and robust structure, favorable electrolyte affinity, ions/electrons transportation, etc.​Doctor of Philosophy (SPMS