Highly Conductive Carbon/Carbon Composites as Advanced Multifunctional Anode Materials for Structural Lithium‐Ion Batteries

Abstract Currently, structural lithium‐ion batteries (LIBs) typically use carbon fibers (CFs) as multifunctional anode materials to provide both Li + storage and high mechanical strength. However, due to the obvious volume expansion of CFs in lithiation process, the fiber structure suffers rapid degradation during cycling. Herein, CFs‐reinforced carbon matrix (C/C) composites are proposed as multifunctional anodes for structural LIBs for the first time. The C/C composite presents distinctive core/shell structure, in which CF as the core supplies a fast and continuous electron conduction pathway along with excellent mechanical strength, while the layered pyrolytic carbon shell accommodates the volume change of CF and provides additional ion storage. The impact of the C/C microstructure on the ion/electron transport and the Li + storage mechanism behind such a unique hybrid structure are explored. Owing to the structural advantages of the C/C composite, the LiFePO 4 ||C/C full cell exhibits surprising electrochemical performances at high electrode mass loadings, which are far superior to those of the present structural LIBs and even surpass the commercial LIBs at the same mass loadings. Moreover, the pouch cell presents excellent mechanical strength and mechanical‐electrochemical coupling characteristics. This work demonstrates great potential of the C/C composites as new multifunctional anodes for high‐performance structural batteries.