In this article, Dr Kavita Pandey explores how flexible aqueous ion batteries are emerging as a vital complement to today’s dominant lithium‑ion technologies, particularly as the world accelerates toward a safer, more sustainable and circular energy future.
As countries across the world accelerate efforts to decarbonise their economies, energy storage has emerged as a foundational enabler of the global energy transition. Batteries now underpin renewable energy integration, electric mobility, smart infrastructure, healthcare technologies, and the rapidly expanding internet-of-things.
Yet, despite their widespread adoption, today’s dominant lithium-ion batteries face growing scrutiny due to safety risks, supply chain vulnerabilities, environmental impact, and end of life management. These concerns – shared across developed and emerging economies alike – are prompting policymakers, industry leaders and researchers to reassess whether a single battery chemistry can realistically meet the diverse and evolving demands of a low carbon, circular global economy.
Within this broader context, flexible aqueous ion batteries are gaining attention as a complementary energy storage technology, particularly for applications where safety, sustainability and mechanical adaptability are prioritised over maximum energy density. Rather than competing directly with lithium-ion batteries in high energy applications such as electric vehicles or large-scale grid storage, aqueous systems offer an alternative pathway that is relevant across regions from advanced economies to resource constrained settings where safety, cost and environmental compatibility are critical considerations.
One of the defining advantages of aqueous ion batteries is their inherent safety. By using water-based electrolytes instead of flammable organic solvents, these batteries significantly reduce the risk of fire and explosion. This attribute is particularly important for applications where batteries operate close to people, such as wearable electronics, medical devices, consumer gadgets and distributed sensors.
Across the globe, increasing deployment of such devices has heightened awareness of safety and liability concerns, making intrinsically safe battery chemistries increasingly attractive to manufacturers and regulators alike.
Beyond safety, material choice plays a central role in sustainability and long term resilience. Many aqueous ion battery systems rely on earth abundant metals such as aluminium or sodium, which are widely available, relatively inexpensive, and supported by established recycling infrastructures in many parts of the world.
Aluminium, in particular, offers favourable electrochemical properties, including multi-electron redox capability, while avoiding many of the geopolitical and ethical challenges associated with critical materials such as lithium, cobalt or nickel. However, practical implementation has historically been hindered by complex interfacial chemistry and stability issues, highlighting the need for careful materials and interface engineering.
As digital technologies continue to evolve globally, energy storage requirements are changing not only in scale, but also in form. The rapid growth of wearable healthcare devices, smart textiles, flexible sensors, and curved or foldable consumer electronics is reshaping expectations of how batteries should integrate into products.
Rigid battery packs are often incompatible with these emerging form factors. Flexible aqueous ion batteries respond to this challenge by combining thin electrodes, soft current collectors, and gel-based electrolytes, enabling batteries to bend, fold and conform to non-planar surfaces while maintaining electrical performance. In this context, flexibility is not merely a convenience; it is a prerequisite for reliable operation under repeated mechanical stress.
Despite these advantages, significant scientific and technological challenges remain. One of the central hurdles in aqueous multivalent-ion batteries lies in controlling ion transport and maintaining interfacial stability over long operating lifetimes. Performance is often dictated not by bulk materials alone, but by processes occurring at the electrode–electrolyte interface. Poorly controlled interfaces can lead to parasitic reactions, resistive surface layers, and rapid capacity fade, limiting practical deployment.
Recent research led by Dr Kavita Pandey at the Centre for Nano and Soft Matter Sciences (CeNS), an autonomous institute under the Department of Science and Technology (DST), Government of India, demonstrates how targeted interfacial engineering can address some of these limitations by promoting thin, uniform and ion permeable interfacial layers. Importantly, such studies do not claim immediate commercial readiness but instead provide design principles that can guide future optimisation and scale-up.
Translating these insights beyond the laboratory remains another key challenge. Manufacturing flexible aqueous batteries at scale requires consistent materials quality, robust encapsulation strategies, and compatibility with roll to roll or low cost fabrication processes. Additionally, while aqueous systems are safer, they typically operate within narrower electrochemical voltage windows, which constrains achievable energy density.
Overcoming these intrinsic limitations without sacrificing safety or sustainability will be essential for broader adoption. Building on this research foundation, Urjen Technologies, founded by Dr Pandey, is working towards the development of lightweight and flexible aqueous ion battery technologies, with a focus on safety, sustainability and practical manufacturability.
The venture aims to translate laboratory level understanding particularly around interface control, material selection and flexible device architectures into scalable solutions suited for emerging applications. Such academic to innovation pathways are increasingly common worldwide, reflecting the role of early stage ventures in de-risking new energy technologies before wider industrial uptake.
A defining strength of flexible aqueous ion batteries is their alignment with circular economy principles on a global scale. Water-based electrolytes reduce environmental and occupational hazards during manufacturing, while abundant electrode materials simplify recycling and recovery.
Compared with lithium-ion systems, aqueous batteries often require less energy intensive processing and pose fewer risks at end of life. However, realising these sustainability advantages in practice will depend on developing standardised recycling routes, lifecycle assessment frameworks, and region specific supply chains; areas that remain under active development internationally.
It is therefore important to place flexible aqueous ion batteries within the broader, diversified energy storage ecosystem. These systems are not intended to replace lithium-ion batteries universally. Instead, they are well suited to applications where safety, flexibility, longevity and environmental compatibility outweigh the need for the highest possible energy density. Potential markets include wearable electronics, medical monitoring devices, smart packaging, distributed sensors, and edge level stationary storage segments that are expanding globally alongside digitalisation, ageing populations, and decentralised energy systems.
Overall, flexible aqueous ion batteries exemplify a broader shift in energy storage research towards application specific, safety driven, and sustainability oriented solutions.
Their future impact will depend not only on scientific advances, but also on manufacturing scalability, cost competitiveness, regulatory acceptance, and ecosystem development.
While challenges remain, these systems highlight how incremental, well-grounded innovation rather than single technology dominance can contribute meaningfully to a resilient and responsible global energy future.
This research is reported in: Pandey et al., Journal of Energy Storage, Elsevier, 2025, Article 117881. https://doi.org/10.1016/j.est.2025.117881.
