Synthesis and Electrochemical Reaction of a Pitch Carbon-Coated Zinc Vanadium Oxide Anode with Excellent Electrochemical Performance for Rechargeable Lithium Batteries

We report on the synthesis and electrochemical reactions of a carbon-coated Zn 3 V 2 O 8 (C-ZVO) anode prepared using a one-step coating process. The anode delivers a high charge capacity of 757 mA h g –1 at 0.1 A g –1 with excellent long-term life of 96%, delivering a capacity of approximately 735 mA h g –1 after the 100th cycle. Even at 6.4 A g –1, the C-ZVO delivers a high charge capacity of 447 mA h g –1 . This extremely improved electrochemical performance is attributed to the high electronic conductivity resulting from the carbon coating, which enables facile electron transfer and simultaneous conversion above 0.8 V: Zn 3 V 2 O 8 + 7Li + + 7e – ↔ 3Zn + LiV 2 O 5 + 3Li 2 O ↔ 3Zn + 2Li + + 2e – ↔ Li 2 Zn 3 on discharge. Furthermore, we apply the C-ZVO material to a full-cell, adopting a Li[Ni 0.6 Co 0.2 Mn 0.2 ]O 2 cathode. The full-cell exhibits excellent capacity retention of approximately 80% for 300 cycles and is active even at a rate of 10 C, delivering 70 mA h (g-Li[Ni 0.6 Co 0.2 Mn 0.2 ]O 2 ) −1 . A combination of in situ X-ray diffraction, time-of-flight secondary-ion mass spectrometry, and ex situ X-ray absorption spectroscopy analyses verify the excellent lithium storage mechanism of coated Zn 3 V 2 O 8 on discharge/charge. Our findings provide insight for the development of efficient anodes for lithium-ion batteries.