NiMoO4-CoMoO4 Supercapacitor Electrodes via Chemical Bath Deposition
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Solution Overview
Problem
Supercapacitors deliver lower energy density compared to rechargeable batteries, limiting their commercialization, despite having advantages in rapid charge-discharge rates and cycling performance.
Innovation Solution
A NiMoO4—CoMoO4 composite material is synthesized using a facile one-step chemical bath deposition method, forming flower-like nanosheet arrays that serve as a battery-type material for a supercapacitor cathode, enhancing energy storage capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If battery-type materials are used to improve energy storage density, then energy density is improved, but cycling stability and potential window are reduced
Solution Approach 1:
The patent combines pseudocapacitor materials (NiMoO4, CoMoO4) with EDLC materials (graphene, activated carbon) into a hybrid composite structure. The pseudocapacitor component provides high energy storage density through faradic reactions, while the EDLC component ensures cycling stability and wide potential window through electrostatic charge storage, thus resolving the contradiction between energy density and reliability
Solution Approach 2:
The invention uses composite materials consisting of transition metal molybdates (NiMoO4, CoMoO4) combined with carbon-based EDLC materials. This composite structure integrates the advantages of both material types: the metal molybdates provide high energy storage capacity while the carbon matrix provides structural stability, conductivity, and electrochemical stability, thereby achieving both high energy density and cycling stability
2Quantity of substance
If pseudocapacitor materials are used, then energy storage density is improved, but electrochemical conductivity and redox activity are reduced
Solution Approach 1:
The patent introduces conductive carbon materials (graphene, activated carbon) as intermediaries that enhance the electrochemical conductivity of the pseudocapacitor materials. The carbon matrix provides efficient electron transport pathways, while the metal molybdate nanoparticles provide high energy storage capacity, thus resolving the contradiction between energy storage density and electrochemical conductivity
Solution Approach 2:
The invention creates a heterogeneous structure where metal molybdate nanoparticles are distributed on the carbon matrix surface. The local regions contain high-energy-density pseudocapacitor materials, while the continuous carbon phase provides high conductivity pathways, allowing the composite to exhibit both high energy storage and high power density
3Ease of manufacture
If conventional synthesis methods are used, then manufacturing complexity is reduced, but deposition area and scalability are limited
Solution Approach 1:
The patent employs a hydrothermal synthesis method where aqueous solutions of metal salts are heated under pressure in an autoclave. This hydraulic approach allows uniform deposition of metal molybdate nanosheets over large substrate areas, overcoming the limitations of conventional vapor-phase or solution-phase methods that are restricted to small deposition areas
Solution Approach 2:
The synthesis method uses pre-prepared aqueous solutions of nickel and cobalt salts mixed with sodium molybdate solution before hydrothermal treatment. This preliminary preparation of homogeneous precursor solutions ensures uniform nucleation and growth of metal molybdate nanosheets across the entire substrate surface, enabling scalable production while maintaining synthesis simplicity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The NiMoO4—CoMoO4 composite material achieves high specific capacities and cycling stability, with an energy density of 27.58 W h kg−1 at 636.05 W kg−1 and 95.88% capacity retention over 5000 cycles, making it suitable for high-performance energy storage devices.
Implementation Method 1
Pseudocapacitors include materials such as metal oxides, hydroxides, and sulfides, for which charge is stored via reversible faradic reactions
Implementation Method 2
EDLCs include carbon-based electrodes made of high specific surface area per volume materials, such as activated carbon, carbon nanotubes, graphene, for which charge is stored on the basis of electrostatic interaction
Implementation Method 3
The NiMoO4—CoMoO4 composite material may be synthesized via a facile one-step chemical bath deposition (CBD) method
Data Source
AI summary
A composite material comprising NiMoO4—CoMoO4 nanosheets can be an electrode in a hybrid supercapacitor. A hybrid supercapacitor having a cathode comprising the composite material exhibits a large operating window, high energy density and high cycling stability. The heterostructure material may be formed by a one-step chemical bath deposition process.