Abstract

Herein, highly ordered mesoporous pseudocapacitive electrodes for superior Li-ion storage are discussed. Hierarchical 1-D Co₃O₄nanorods of size ~20 nm with interfaces between the crystallites were synthesized using hydrothermal method followed by calcination. This 1D nanorods exhibited pseudocapacitive behavior with fast faradaic surface redox reactions utilizing the Li⁺ions from the interfaces. A predominated pseudocapacitance contribution of 80% of the total capacity through synergetic effect of the interfacial lithium storage along with excellent rate performance of the Co₃O₄ nanorods is reported. Co₃O₄nanorods with high discharge capacity of 1250 mAh/g at a charge-discharge rate of 50 mA/g and 840 mAh/g at 10A/g proved to be good anode for Li-ion storage. This material provides a specific discharge capacity of 980 mAh/g at 1A/g after 500 cycles with 62% capacity retention of the initial cycles. The nanorods outperformed as anode with surface charge storage mechanism than high surface area Co₃O₄nanoparticles. Post-cycling analysis demonstrated excellent structural stability assisting Co₃O₄nanorods as a stable and high performance anode for Li-ion battery.

Three dimensional (3D) hierarchical structured rGO embed with cobalt monoxide (CoO) nanoparticles exhibited an enhanced pseudocapacitive assisted Li ion storage. 3D CoO/N-rGO composite was synthesized by a simple solvothermal technique followed by carbonization. The 3-D morphology and network with N-doping maintains high surface area for providing effective electronic conductivity and increased the contact between electrode and electrolyte. These 3D design showed an extraordinary performance than the commercial Co₃O₄nanoparticles at 1A/g with 650 mAh/g for 1000 cycles. 3D CoO/N-rGO exhibited excellent electrochemical with 1050 mAh/g at current densities of 25mA/g and maintained 520 mAh/g even at 5A/g. The synergetic effect of the 3D morphology, an excellent pseudocapacitive contribution of 79% of the total capacity from the different interfacial storage phenomena was reported for the first time. Ex-situHRTEM showed that the 3-D morphology was retained after several charge-discharge cycles.