As the world accelerates toward cleaner, more efficient energy technologies, the demand for advanced energy-storage systems has never been greater. Batteries remain essential, but their slow charging rates and limited cycling lifetimes have pushed researchers to explore alternatives that can deliver higher power, faster charge–discharge rates, and stronger long-term stability.

This is where supercapacitors step in. They serve as an important bridge between conventional capacitors and batteries, offering rapid power delivery and extended cycling durability. Yet, the performance of any supercapacitor depends heavily on the electrode material at its core.

In recent years, metal–organic frameworks (MOFs)—particularly Zeolitic Imidazolate Frameworks (ZIFs)—have emerged as promising candidates for next-generation electrodes. Their tunable chemistry, high porosity, and adjustable metal-organic compositions offer an unmatched platform for designing high-performance energy storage materials.

One material in particular, ZIF-67, has attracted significant attention due to its cobalt-based structure and well-defined porous architecture. However, its limited conductivity restricts its practical electrochemical performance.

To overcome this, researchers have turned toward elemental doping, introducing new atoms into the framework to modify conductivity, surface area, and charge-storage capabilities.

This blog explores one of the most successful strategies so far:

Manganese-doped ZIF-67 (Co/Mn-ZIF)

—a material engineered through a simple one-step coprecipitation process that dramatically enhances the electrochemical performance of MOF-based electrodes.

In this article, you will learn:

Why supercapacitors need better electrode materials
What ZIF-67 is and how doping enhances its properties
How manganese (Mn) transforms the structure and performance of ZIF-67
The synthesis principles behind Co/Mn-ZIF
How the doped material performs in real supercapacitor devices
The broader significance of mixed-metal MOF electrodes

This is a comprehensive and beginner-friendly guide designed to provide clarity even for readers who are new to MOF-based electrodes or energy-storage science.

1. Why Energy Storage Is Evolving: The Push for Better Electrode Materials

Modern society relies heavily on energy—yet the ways we store and deliver that energy must continue to evolve. Technologies such as solar and wind demand efficient storage solutions due to their natural intermittency. Electric vehicles require fast charging, long cycle life, and quick power bursts.

As needs grow, the limitations of traditional batteries become more apparent:

Slow charging
Limited number of cycles before degradation
Heat generation
Safety constraints under high stress

Supercapacitors help resolve many of these challenges. They offer:

Extremely fast charging and discharging
High power density
Long operational lifetimes (often tens of thousands of cycles)
Low maintenance

Depending on how they store charge, supercapacitors fall into two main categories:

Electric Double Layer Capacitors (EDLCs)

They use carbon-based materials to store charge electrostatically on the surface.
Advantages: rapid cycling, long stability.
Limitations: relatively low energy density.

Pseudocapacitors

They rely on fast, reversible redox reactions occurring on the surface of the electrode material.
Advantages: high specific capacitance and higher energy density.
Limitations: often reduced conductivity compared to EDLCs.

Metal–organic frameworks (MOFs), especially ZIF materials, belong to the pseudocapacitor family because their metal centers can undergo rapid redox reactions.

2. MOFs and ZIFs: Why They’re Promising for Supercapacitors

Metal–organic frameworks (MOFs) are crystalline porous materials made from metal ions linked by organic molecules. They offer:

Large internal surface areas
Highly tunable pore structures
Chemical flexibility
A modular architecture that can be modified at the atomic level

Within the MOF family, Zeolitic Imidazolate Frameworks (ZIFs) are particularly noteworthy. They have both high porosity and excellent chemical stability, making them ideal for electrochemical applications.

ZIF-67: A cobalt-based MOF with excellent structural properties

ZIF-67 consists of:

Cobalt ions (Co²⁺) as the metal nodes
2-methylimidazole as the organic linker

This framework forms well-defined polyhedral crystals with a porous structure that is useful for ion storage and transport.

But ZIF-67 has a major drawback:

Its electrical conductivity is relatively low.

Without conductivity, electrons cannot move efficiently, limiting its performance in supercapacitors.

3. Enhancing ZIF-67 Performance Through Doping

One of the most powerful techniques to improve MOF-based electrodes is heteroatom doping, where a second type of metal or non-metal is introduced into the framework.

Doping can:

Increase conductivity
Create new redox-active sites
Modify pore structure and surface area
Improve ion mobility
Strengthen charge–transfer pathways

For ZIF-67, doping with transition metals such as manganese (Mn) has shown exceptional promise.

Why Manganese?

Mn ions (Mn²⁺ / Mn⁴⁺) have distinctive advantages:

They offer multiple valence states, enabling rich redox chemistry.
Their larger ionic radius helps expand pore structures.
Mixed metal centers create synergistic effects that improve conductivity.
They reduce the energy barrier for surface redox reactions.
They enhance electron transport within the framework.

By combining cobalt and manganese within the ZIF framework, researchers can obtain a new material—Co/Mn-ZIF—with superior electrochemical properties.

4. How Co/Mn-ZIF Is Synthesized: A Simple One-Step Coprecipitation Strategy

A key advantage of the Co/Mn-ZIF material is its simple and scalable fabrication method.

Synthesis Overview

The material is created through a one-step coprecipitation process, where:

Cobalt nitrate, manganese chloride, and 2-methylimidazole are dissolved in methanol.
The metal ions bind competitively with the organic ligands.
Because manganese ions have a larger radius, the resulting crystals grow larger and more porous.
The mixed-metal framework forms spontaneously under mild conditions.

This process requires no high temperature, no complex equipment, and no toxic reagents—making it attractive for industrial adoption.

What Makes the Coprecipitation Method Effective?

It allows manganese ions to substitute cobalt ions in situ during crystal formation.
The resulting material retains the well-ordered architecture of ZIF-67 but incorporates new chemical activity.
The presence of Mn modifies both the electronic structure and physical morphology of the framework.

The final Co/Mn-ZIF crystals are typically around 2 micrometers in size, larger than traditional ZIF-67 crystals, due to the influence of Mn ions.

5. How Manganese Doping Transforms the Properties of ZIF-67

The introduction of manganese ions brings several structural and electrochemical benefits:

(1) Increased Surface Area

Because Mn ions are larger than Co ions, their incorporation expands the framework and creates more pores.
A larger surface area means:

More active sites for charge storage
Better contact with electrolyte ions
Enhanced accessibility for redox reactions

(2) Improved Conductivity

Mixed-metal frameworks often exhibit better charge transport due to:

Stronger electron pathways
Reduced resistance at active sites
Enhanced electron cloud density

This helps overcome one of the key limitations of MOF materials.

(3) Strong Synergistic Effects Between Co and Mn

Cobalt and manganese together form an ideal combination for pseudocapacitive behavior:

Cobalt ions provide strong redox activity
Manganese ions stabilize electron movement and enhance reaction speed
Their combined interaction accelerates ion diffusion in the electrode

This synergy makes Co/Mn-ZIF a much more effective energy-storage material than pristine ZIF-67.

(4) Better Electrolyte Interaction

The enlarged porous structure ensures:

Faster ion penetration
Greater exposure of redox-active sites
More efficient doping/de-doping processes during cycling

This leads to higher capacitance and improved rate performance.

6. Co/Mn-ZIF in Supercapacitors: Performance That Stands Out

When tested as a positive electrode in alkaline supercapacitor systems, Co/Mn-ZIF demonstrates exceptional performance.

Below are key outcomes reported in the study:

1. Ultra-High Specific Capacitance

The material reaches a specific capacitance of:

926.25 F g⁻¹ at 0.5 A g⁻¹

This value is dramatically higher than many MOF-based electrodes and far exceeds the capacitance of pristine ZIF-67.

2. Strong Rate Performance

Even at a much higher current density of 10 A g⁻¹, the electrode maintains:

125 F g⁻¹

This shows that the electrode can retain a large portion of its capacitance even under fast charging conditions.

3. Good Cycling Stability

After 1500 charge–discharge cycles, the electrode preserves:

64.1% of its initial capacitance

Considering the nature of pseudocapacitive materials, this stability is quite promising.

4. Impressive Performance in Asymmetric Supercapacitors (ASC)

When paired with activated carbon in a real asymmetric device, the Co/Mn-ZIF electrode delivers:

52.95 Wh kg⁻¹ at 1080 W kg⁻¹
26.4 Wh kg⁻¹ at a very high power of 43.2 kW kg⁻¹

These values highlight a combination of:

High energy density
Excellent power capability

making the material suitable for high-performance, fast-response energy systems.

7. Why Mixed-Metal MOFs Are the Future of Supercapacitor Electrodes

Co/Mn-ZIF showcases how subtle modifications at the atomic level can produce major improvements in electrochemical performance.

This success points to a broader trend in materials science:

Hybrid and doped MOFs will play an increasingly important role in next-generation energy technologies.

Their advantages include:

Highly customizable metal centers
Adjustable pore size
Large specific surface areas
Multi-metal synergy
Structural flexibility
Environmentally friendly synthesis routes

As research expands, the combination of different transition metals is expected to unlock even more efficient electrode materials.

8. Final Thoughts: The Growing Potential of Mn-Doped ZIF-67 in Energy Storage

The development of manganese-doped ZIF-67 (Co/Mn-ZIF) demonstrates how simple chemical modifications can transform a good material into a truly exceptional one.

By enhancing conductivity, expanding surface area, and creating richer redox pathways, manganese doping significantly upgrades the performance of traditional ZIF-67.

The resulting material delivers:

Remarkable specific capacitance
Strong rate capability
Reliable cycle life
High energy and power density in asymmetric devices

These improvements underline the promise of mixed-metal MOFs as a foundation for next-generation supercapacitors.

Unlocking High-Performance Supercapacitors with Manganese-Doped ZIF-67: A Deep Dive into Co/Mn-ZIF as an Advanced Energy Storage Electrode