3D Porous Electrode Materials And Interfaces For Energy Storage Applications

Owing to the large specific surface area and unique structural feature of three-dimensional(3D)porous material,it has gained much attention in the field of energy storage and conversion.With the rapid development of new electronic devices towards portable,flexible and powerful,this kind of materials are still expected to contributed in emerging storage devices of high energy density.For example,to tackle the challenges like dendrite growth and volume change of lithium(Li)anode,and to explore the application prospects of flexible supercapacitors.In this paper,we try to find the potential insight of 3D flexible materials in energy storage applications.The main results of study are summarized as follows:A sponge-driven 3D elastic interface for Li metal anode is designed to interfacial modification by simple and scalable mechanical compression.The migration and deposition of Li ions can be effectively regulated by 3D structure and polar groups of sponge.Thus,it can achieve a uniform deposited morphology of Li ions,and suppress the dendrite growth of Li metal anode.On the other hand,the sponge-driven elastic interface could provide a better interfacial contact.It confirms suitable compression on residual Li layer during Li stripping,meanwhile,the elastic interface applies higher pressure during Li plating since the increased thickness of Li layer.The compact deposition morphology leads the structure of solid electrolyte interphase(SEI)more uniform and integral upon cycles,which results in less formed“dead Li”and enhanced Coulombic efficiency(CE).The sponge-driven elastic composite anodes maintain CE of 98.8%for 60 cycles,and is cyclable at 10 mA cm-2 for 250 cycles,both for a high areal capacity of 10 mA h cm-2.Since the nonconductive feature of sponge,it replaces the conventional polypropylene separator in symmetric cells.The superior rate capability and cycling performance demonstrates the effectiveness of stabilizing Li metal anode.Lastly,an in-situ compression-electrochemistry evaluation has been designed to confirm the mechanism of elastic interface on the cycling stability of Li metal batteries(LMBs).Then,3D porous Cu has been used as template to fabricate the 3D porous graphene by chemical vapor deposition(CVD).After the suitable conditions were explored in the experiments,the graphene wrapped 3D porous Cu has been used as the current collector in LMBs.We found that better CE and cycling performance compare to planar Cu foil at 1 mA cm-2 for 2 mA h cm-2.Finally,the flexible interface of 3D porous graphene has been explored as electrode in the supercapacitors.Polydimethylsiloxane(PDMS)was used to protect the as-fabricated 3D porous graphene after etching the porous Cu template,and then different amounts of pseudocapacitive material(PANI)have been polymerized by electrochemical method.The composite film is applied in flexible supercapacitor by combining advantages of porous graphene and PANI together.It shows that the areal specific capacitances with 4 h deposition are 111.9 mF cm-2 at 1 mV s-1 and 35.34 mF cm-2 at 20 mV s-1,respectively.