Facile Synthesis of Porous Hollow Cobalt‐Doped λ‐MnO₂ Nano Architectures as a High‐performance Anode Material for Li‐ion Batteries and Li‐ion Hybrid Supercapacitors

Abstract

The cost-effectiveness and easy availability of MnO 2 have attracted researchers' attention as an anode electrode for LIBs over other transition metal oxides. However, MnO 2 usage has been limited to its low reaction reversibility and poor conversion kinetics. Besides, Li-ion hybrid supercapacitors (LiHSCs) are in urgent demand which offers higher power densities than LIBs without compromising energy density. Among different polymorphs of MnO 2 , λ-MnO 2 , due to its 3D spinel structure, can be applied in many applications. Usually, λ-MnO 2 can be obtained by extracting lithium from LiMn 2 O 4 using complex electrochemical or acid leaching methods. This study presents a modified Li 2 O 2 assisted method to obtain cobalt-doped 3D architectures of λ-MnO 2 porous hollow nano-structures. The resultant Mn x Co 1-x O y hollow structures with 5 % cobalt addition are used as anode for LIBs exhibited excellent charge reversibility and cycle stability over thousands of reaction cycles. This result is known to be one of the finest among MnO 2 anodes reported to date. Also, a LiHSC device is fabricated with Mn x Co 1-x O y hollow structures as anode and the device exhibits an excellent comprehensive electrochemical performance in terms of high operating voltage (4.2 V), with a specific cell capacity of 33 mAh g À 1 at a high current density of 5 A g À 1 and achieved the maximum power density of 12261 W kg À 1 (with energy density at 81.7 Wh kg À 1 ) with long cycle life.

Hollow nanostructured NiO particles as an efficient electrode material for lithium-ion energy storage properties

“…This outcome indicates the NiO formation at the electrode's outer surface as the possible extruded Ni oxide phase after the Li-ion reaction. 32,33 The response of lithium-ions with NiO electrode can be summarized as follows:NiO + 2Li + + 2e − ↔ Ni 0 + Li 2 O2Li ↔ 2Li + + 2e − NiO + 2Li ↔ Ni 0 + Li 2 O…”

Density Functional Theory Modeling of the Oxidation Mechanism of Co(II) by Birnessite

“…This site may be prone to Co­(II) sorption, thereby maintaining the oxidative activity of the MnO 2 layer. Results of this study will help understanding the oxidation of Co­(II) to Co­(III) in MnO 2 -based batteries and catalysts. − Experimental studies are needed to test the effect of oxygen vacancies , on Co­(II) oxidation and to allow consider this effect in DFT modeling.…”

“…Results of this study will help understanding the oxidation of Co(II) to Co(III) in MnO2-based batteries and catalysts. [139][140][141][142][143][144][145][146][147][148] Experimental studies are needed to test the effect of oxygen vacancies 149,150 on Co(II) oxidation and to allow consider this effect in DFT modeling.…”

Investigation on the Electrochemical Activities of Pristine and Cerium doped Manganese Dixide Nanoparticles for Supercapacitor Electrode Materials

“…Although RuO2 electrode provides high specific capacitance experimentally, it is expensive material whereas the latter is affordable, earth abundant and less toxic. The peculiar properties of MnO2 are wide working potential (-0.2 to 1.2v), multiple oxidation states, large specific area and higher specific faradaic redox pseudo capacitance etc [20][21][22][23][24][25][26][27][28][29][30][31][32]. R.N.Reddy et al studied the electrochemical activity of MnO2 fabricated via sol-gel method.…”