Design Of Porous Carbon Tile Composite Electrodes And The Applied Research In Zn-Mn Structural Batteries

Light-weight and integrated design have always one of developing targets of future battery energy storage equipment system in engineering application,where constructing structural energy storage is considered to be an effective way to achieve this goal.Compared with Li-ion battery,Zn-ion batteries,especially aqueous Zn-Mn batteries,have great potentials in further structural energy storage system due to the merits of high theoretical capacity,low material cost,outstanding environmental adaptability,low toxicity,high safety and easy assembly.However,how to achieve the assembly of high strength and performance Zn-Mn structural battery through optimization design of electrode structure is an important challenge at present.Herein,the optimization of electrode structure was focused to mainly solve the problems of low intrinsic conductivity,poor structural stability and limited internal ion transport of MnO2.The aim is to proposing a novel qusi-2D porous carbon tiles as bricks and skeleton for the deposition of MnO2 for constructing the C@MnO2 composite electrode with hierarchical pore structure and high electrochemical activity aided by the excellent conductivity,crosslink ability and structural deformation adaptability of single-walled carbon nanotubes(SWNTs).Based on such composite electrodes,the Zn-Mn structural batteries with different models were subsequently designed and assembled by the different methods,including the traditional carbon fiberreinforced epoxy vacuum curing and 3D printing of thermoplastic carbon fibers,and their comprehensive performance were also systematically investigated.The main research results are as follows:1.A novel kapok-derived quasi-2D thin-walled porous carbon tile(CT)was developed and used as bricks.Assisted with SWNTs,the packed yet enabling fast ion kinetics porous carbon tile composite electrode was constructed,whose packing density(～0.7 g/cm3)is obviously higher than that of those granular activated carbon electrodes(<0.4 g/cm3).Ascribed to the fast ion transport in-plane,high specific surface areas,excellent conductivity of such porous carbon tile and its hierarchical porous assembly features,the fabricated film electrode in Zn/C batteries delivers outstanding rate and capacitance performance.Even at the high mass-loadings of 12 mg/cm2,the asassembled Zn/C battery can still deliver high capacitive(114 mAh/g;1.37 mAh/cm2)and rate performance.2.Based on the assembly features of 2D carbon tile,the high activity porous carbon tile@MnO2 composite was firstly prepared by ultrasonic deposition of δKxMnO2 nanoflakes on the unique 2D porous carbon tile skeleton.Using such CT@MnO2 composite as bricks,the porous carbon tile@MnO2 composite electrode with hierarchical pore structure as well as high strength(tensile modulus:1.02 GPa),conductivity(140 S/cm)and electrochemical activity was fabricated assisted with carbon nanotubes as conductive additives and network structure support,which showing excellent capacitive performance(385 mAh/g),rate performance and cycle stability in Zn/Mn batteries.3.Ascribed to the high electrochemical activity and structural flexibility of porous carbon tile@MnO2 composite electrodes,high-performance quasi-solid Zn/Mn film battery was firstly fabricated,whose energy density is as high as 377 Wh/kg.aided by the traditional epoxy vacuum curing process,the embedded Zn/Mn film battery into carbon fiber-reinforced composite was assembled.Ascribed to the film structure of embedded batteries(thickness:～0.5 mm),the assembled carbon fiber-reinforced Zn/Mn structural battery has successfully combined excellent electrochemical and mechanical performance,where its tensile strength and bending modulus are as high as 292.8 MPa and 26.6 GPa,respectively.In addition,a novel thermoplastic carbon fiberreinforced Zn/Mn structural battery was also firstly fabricated by 3D printing technology,which provides a new idea for the integrated design for future structural energy storage system.4.Inspired by how slope-protecting plants immobilize soil and themselves against strong wind,the carbon fiber-reinforced porous carbon tile@MnO2 composite with crosslinked structure was designed and fabricated assistant with the excellent crosslinking property and structural deformation adaptability of SWNT via surface modification and followed vacuum pouring processes.The SWNTs here on one hand are penetrated into the carbon fiber tubes,and on the other hand crosslinked with active materials,thus forming a continuous stable structural system.Using the coupled functions(electrodes and structural support)of such composite,the carbon fiberreinforced Zn/Mn structural battery with high strength(tensile strength/bending modulus:199 MPa/26.0 GPa)and electrochemical performance(187 mAh/g)were designed and assembled by the traditional epoxy vacuum curing process.