Structural composite battery: Reinforced carbon fibre electrodes within a porous polyethersulfone matrix

Abstract

A method to produce multifunctional structural battery composites comprising carbon fibre reinforced anodes and cathodes, and electrolyte filled bicontinuous polymer matrix is disclosed. Lithium iron phosphate (LFP) and lithium titanate (LTO) were deposited onto carbon fibres by electrophoretic deposition (EPD) to produce multifunctional cathodes and anodes, respectively. EPD allowed for an even coating of individual carbon fibres depositing 30 wt% of active materials with respect to carbon fibre current collectors. Carbon fibre reinforced cathode (LFP@CF), separator and anode (LTO@CF) were stacked and impregnated using polyethersulfone (PES) in N-methyl-2-pyrrolidone (NMP) solution; the PES was subsequently precipitated by non-solvent induced phase separation forming a porous high-performance polymer matrix within the stack. The porous matrix binds the carbon fibres and separator while providing sufficient openness for the electrochemical interface. The LFP@CF | separator | LTO@CF/PES assembly had an average Young's modulus of 27 ± 10 GPa and tensile strength of 282 ± 65 MPa. Structural battery composites possessed an energy density of 63 Wh/kg_LFP or 2 Wh/kg_battery at charge rate of 0.1C and were able to be cyclically dis/charged for more than 400 h.