Cobalt vacancy boosting Co3-xO4@C with superior pseudocapacitive lithium storage

Abstract

The Co3O4 as anode for lithium ion batteries (LIBs) suffers the sluggish electrode kinetics and severe capacity fade during the cycles. The defective engineering of Co3O4 with oxygen/cobalt defects is an effective strategy to optimize Co3O4 with enhanced electrochemical properties. Herein, a series of 3D inter-connected Co3-xO4@C-y nanostructures with abundant Co defects are synthesized through a hydrothermal approach with subsequent heating-controlled process. Benefiting from its rich surface cobalt-defective sites and the 3D interconnected frameworks, as well as its high surface area and residual carbon layer, the Co3-xO4@C-y synthesized at y = 400 °C as anode for LIBs displays superior pseudocapacitive lithium storage properties with an ultra-high reversible specific capacity of 1900.7 mAh g−1 at 0.2 A g−1, excellent rate capability (e.g., 1415.1 mAh g−1 at 10 A g−1) and ultra-long cycling stability (e.g., 1160.5 mAh g−1 at 15 A g−1 after 2000 cycles).