Polymer Reinforced Carbon Fiber Interfaces for High Energy Density Structural Lithium-Ion Batteries

Here, we show that for battery active materials coated onto carbon fiber current collectors, a thin electroconductive poly acrylonitrile, or PAN, coating applied to the surface of battery material coated fiber drastically improves adhesion and multifunctional structural energy storage performance. With this electrode design, we demonstrate structural battery composites composed of lithium iron phosphate cathodes and graphite anodes which exhibit maximum energy density of 58 Wh/kg considering all battery and composite materials in the structural battery. These full-cell structural batteries also demonstrate capacity retention over 80% exceeding 100 cycles with average energy density of 52 Wh/kg. Combined mechanical and electrochemical testing correlates this excellent multifunctional performance to the role of PAN coating that adheres active battery materials to carbon fibers during battery operation and mechanical loading. Our findings demonstrate how interface engineering is key to produce structural batteries with practical multifunctional advantage over separate battery and structural materials in systems.