Enhanced lithium storage in ZnFe₂O₄-C nanocomposite produced by a low-energy ball milling

Preparation of novel nanocomposite structure of ZnFe₂O₄-C is achieved by combining a sol-gel and a low energy ball milling method. The crucial feature of the composite's structure is that sol-gel synthesised ZnFe₂O₄ nanoparticles are dispersed and attached uniformly along the chains of Super P Li™ carbon black matrix by adopting a low energy ball milling. The composite ZnFe₂O₄-C electrodes are capable of delivering a very stable reversible capacity of 681 mAh g^-1 (96% retention of the calculated theoretical capacity of ∼710 mAh g^-1) at 0.1 C after 100 cycles with a remarkable Coulombic efficiency (82%) improvement in the first cycle. The rate capability of the composite is significantly improved and obtained capacity was as high as 702 at 0.1, 648 at 0.5, 582 at 1, 547 at 2 and 469 mAh g^-1 at 4 C (2.85 A g^-1), respectively. When cell is returned to 0.1 C, the capacity recovery was still ∼98%. Overall, the electrochemical performance (in terms of cycling stability, high rate capability, and capacity retention) is outstanding and much better than those of the related reported works. Therefore, our smart electrode design enables ZnFe₂O₄-C sample to be a high quality anode material for lithium-ion batteries.