TEMPO-oxidized bacterial cellulose nanofiber membranes as high-performance separators for lithium-ion batteries

In this paper, 2, 2, 6, 6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidized bacterial cellulose (TOBC) nanofiber membranes as separators of lithium-ion batteries were successfully prepared from a water dispersion of TOBC nanofibers via a vacuum filtration approach. The TOBC membranes had adequate porosity and desirable affinity with the liquid electrolyte and lithium electrode, giving rise to superior electrolyte uptake and small interfacial resistance. Among the TOBC nanofiber samples, the TOBC1.0 membrane exhibited the best properties, including high electrolyte uptake (339 %), superior electrochemical stability window (>6.0 V), outstanding ionic conductivity (13.45 mS cm^-1) and small interfacial resistance (96 Ω). The half cells obtained using the TOBC1.0 membrane achieved a discharge capacity of 166 mA h g^-1 (0.2 C), corresponding to 97.6 % of the theoretical value of LiFePO₄ (170 mA h g^-1), excellent cycle stability (with capacity retention of 94 % after 100 cycles) at 0.2 C and good C-rate performance. Thus, the TOBC nanofiber membranes could be considered as a promising high-performance separator used in lithium-ion batteries.