Grafting also reduces the crystallinity of PEO-based SPE. Besides, some high ionic conductivity fillers can also provide additional ion transport pathway for li-ion transport. These nano-sized fillers can inhibit the PEO crystallization and promote the formation of grain boundaries and amorphous regions. Nano-sized fillers have been widely used in PEO-based SPE, including nano-sized Al 2O 3, TiO 2, SiO 2, Li 0.33La 0.557TiO 3, and Li 6.4La 3Zr 1.4Ta 0.6O 12. To decrease the crystallinity of PEO and improve the conductivity of SPEs, different approaches have been developed and applied, such as filling and grafting. Therefore, the mobility of li-ion mainly depends on the movement of polymer chain segments at the grain boundary and amorphous phase region, and the ion conductivity through the grain boundary and amorphous phase region is much higher than that through the crystalline lamellae. In PEO-based SPEs, li-ion forms a coordination bond with oxygen in PEO and migrates through continuous coordination and dissociation with oxygen atoms. However, the low conductivity greatly hindered the application of PEO-based SPEs: the PEO electrolytes exhibit a conductivity which ranges from 10 −8 to 10 −6 S cm −1 at room temperature, and the low conductivity will increase the battery internal polarization, and decrease the discharge-charge capacity and energy efficiency. In addition to solid li-ion battery, PEO-based SPE also has a wide application prospect in many fields such as Mg-ion battery and Li-S battery. Polyethylene oxide (PEO)-based solid polymer electrolyte (SPE) has great application prospects due to its good flexibility, good compatibility of lithium metals, easy process, and low cost. To achieve high performance all-solid-state li-ion battery, solid-state electrolytes should have satisfactory high ionic conductivity, good mechanical/electrochemical stability, and adequate electrode-electrolyte interface. The present work provides an effective and easy-to-use grain reforming method for SPE, worthy of future application.ĭue to the high energy density and excellent safety performance, solid-state li-ion batteries are extensively regarded as promising systems for next-generation rechargeable electrochemical energy storage. The improvement of electrochemical properties can be attributed to the press-rolling method, leading to a doubling conductivity and reduced activation energy compared with that of electrolyte prepared by traditional cast method. With the rolled PEO-based SPE, the LiFePO 4/SPE/Li all-solid li-ion battery delivers a superior rechargeable specific capacity of 162.6 mAh g −1 with a discharge-charge voltage gap of 60 mV at a current density of 0.2 C with a much lower capacity decay rate. In this work, a simple and effective press-rolling method is applied to reduce the crystallinity of PEO-based SPEs for the first time. However, the application of PEO-based SPEs is hindered by the relatively low ionic conductivity, which strongly depends on its crystallinity and density of grain boundaries. The electrical conductivity of MPL, which is lower than that of the carbon black packing, is considered to depend on the contact resistance.Polyethylene oxide (PEO)-based solid polymer electrolyte (SPE) is considered to have great application prospects in all-solid-state li-ion batteries. Furthermore, an equation expressing the relative diffusion coefficient of each component can be obtained with the function of porosity. However, that of CL is an order of magnitude less than those of the other two components. The relative diffusion coefficient of the MPL is almost equal to that of the model structure of particle packing. In the case of the GDL, the binder was found to obstruct gas diffusion with a negative effect on performance. Moreover, based on the model structure and theoretical equations, an approach to the design of new structures is proposed. Numerical simulations were carried out to model the properties of oxygen transport. This study involves a systematic examination of the relationship between the oxygen transfer resistance of the actual porous components and their three-dimensional structure by direct measurement with FIB-SEM and X-ray CT. The reduction of oxygen transfer resistance through porous components consisting of a gas diffusion layer (GDL), microporous layer (MPL), and catalyst layer (CL) is very important to reduce the cost and improve the performance of a PEFC system.