Cellulose/graphite/carbon fibres composite electrodes for Li-ion batteries

Cellulose fibres and an easy aqueous filtration process are used as binder and sheet forming technique, respectively, for the elaboration of mixed graphite (GP)–carbon fibres (CF) composite electrodes for Li-ion batteries. The screening of GP and CF mass fraction in the electrodes showed that the presence of two conducting phases has a synergistic effect on the electrode conductivity when GP and CF percolation networks are simultaneously present. A conductivity peak at 950 S m−1 was attained for GP and CF volume fractions of 13% and 6%, respectively, corresponding to the percolation threshold of each individual phase. Cellulose/CF electrodes display moderate specific capacity of 200 mA h g−1 and a good specific capacity retention at high current rate, whereas cellulose GP electrodes demonstrate high specific capacity of about 310 mA h g−1 and a low specific capacity retention at high current rate which is ascribed to the high binder content, i.e. 20%, and low electron conductivity of 100 S m−1. The use of CF/GP blends as active materials allows obtaining electrodes with high electron conductivity and specific capacity retention with CF:GP weight ratios ranging between 1:1 and 1:2.