Structural orientation effect of cellulose nanocrystals (CNC) films on electrochemical kinetics and stability in lithium-ion batteries

•Two differently orientated CNC films were prepared and tested in LIB system.•Optical birefringence and 2D-XRD studies were conducted to characterize the orientation of each CNC film.•Different orientation induces different ionic, thermal, and electric conductivity of CNC film.•Aligned CNC film showed higher conductive properties.•With the aid of these properties, electrochemical performances of aligned CNC were improved. To satisfy the technical requirements of advanced energy storage systems with high energy density, high power density and reliable battery life time, significant efforts have been devoted to material optimization by designing novel metal/carbon composites or metal alloy materials. Different from the previous approaches mainly focused on the composition of active materials, herein, we studied how the structural orientation of carbon precursors can influence the electrochemical kinetics and stability of lithium ion batteries (LiBs). Two differently aligned cellulose nanocrystal (CNC) films – aligned CNC (aCNC) and chiral nematic CNC (nCNC) films) – were fabricated, carbonized and evaluated as anode electrodes for LiBs. The architecture of carbonized aCNC (c-aCNC) provides a favorable pathway for ion/electron transport, resulting in excellent rate retention (40% at 200 mA g−1) in comparison with the carbonized nCNC (c-nCNC) (20% at 200 mA g−1). In addition, c-aCNC exhibited a more stable cycle performance (92% capacity retention over 450 cycles) than c-nCNC (48% capacity over 450 cycles), owing to the better electrochemical reactions and heat dispersion of c-aCNC than those of c-nCNC. The proposed concept has clearly demonstrated that the electrochemical behaviors of LiBs can be affected by the structural orientation of electrodes. It would possibly bring up more relevant battery researches for follow-up works in the future.