Indian Scientists Develop ‘Smart’ Energy Material That Changes Colour to Show Battery Charge

As ions move within this structure during charging and discharging, they alter the material’s electronic configuration, producing a visible colour change.

In a breakthrough that could redefine how we interact with batteries and energy storage systems, scientists in India have developed a novel material that not only stores energy but visually indicates its charge level by changing colour.

Researchers from the Centre for Nano and Soft Matter Sciences (CeNS), Bengaluru, an autonomous institute under the Department of Science and Technology (DST), have created an advanced oxygen-deficient bimetallic oxide capable of combining energy storage and real-time visual feedback—a feature rarely seen in conventional devices.

From Blue to Transparent: A Built-in Charge Indicator

The newly developed compound—Mo₀.₁₁W₀.₈₉O₃₋ₓ (molybdenum-tungsten oxide)—exhibits a striking property:

• Blue colour → Fully charged state

• Transparent → Discharged state

This means users can instantly determine the battery's charge status without needing electronic displays or sensors, potentially simplifying device design and improving usability.

Solving a Long-Standing Limitation

Most modern electronic systems face a key limitation—they either:

• Store energy (like batteries), or

• Display information (like screens)

—but rarely both.

This new material bridges that gap by integrating energy storage and electrochromic (colour-changing) functionality into a single system.

The Science Behind the Innovation

The material's unique behaviour stems from its "oxygen-deficient" structure.

By intentionally removing certain oxygen atoms from the crystal lattice, scientists created:

• Extra space for ion movement

• Active sites for charge storage

As ions move within this structure during charging and discharging, they alter the material's electronic configuration, producing a visible colour change.

In essence, the material acts as a self-reporting energy system, visually signalling its own charge level.

High Performance Meets Smart Functionality

Beyond its visual capabilities, the material delivers strong performance metrics:

• Specific capacitance: 234 F/g

• Areal capacitance: 975 mF/cm²

• Cycling stability: Over 10,000 charge-discharge cycles

• Optical modulation: 43% (at 700 nm)

• Colouration efficiency: 147 cm²/C

These figures indicate that the material is not just innovative—but also efficient, durable, and commercially viable.

Flexible, Durable, and Scalable

The researchers demonstrated the material in a 5×5 cm² device, which:

• Maintained performance under mechanical bending

• Showed fast switching speeds

• Functioned reliably under different environmental conditions

The device was even able to:

• Power an LCD timer

• Light up an LED

showing its real-world applicability.

Potential Applications Across Industries

This breakthrough opens doors to a range of next-generation applications:

• Smart batteries with built-in charge indicators

• Wearable electronics with visual energy feedback

• Energy-efficient smart windows (electrochromic glass)

• Grid storage systems with simplified monitoring

• Consumer devices without separate battery indicators

Such systems could reduce reliance on external displays, making devices simpler, more energy-efficient, and user-friendly.

Published Research and Future Outlook

The findings have been published in the prestigious journal Materials Chemistry A, underscoring their scientific significance.

Experts say this innovation could pave the way for multi-functional materials that combine sensing, storage, and display—key to the future of smart electronics and sustainable energy systems.

As the demand for compact, efficient, and intelligent devices grows, such materials could become foundational to the next generation of energy technologies.