Sustainable Battery Breakthroughs: Soil-Powered Sensors, Sodium-Ion, and Biodegradable Biopower Cells

In this episode, researchers explore novel battery technologies aimed at powering environmental sensors and large-scale energy storage. The discussion covers soil-powered Terracel/ Terrace devices designed for soggy bioswarms in Chicago, a lab on electrode materials and solid-state chemistries, the shift away from lithium reliance through sodium ion options, and biodegradable biopower cells made from waste streams. The show highlights environmental considerations, end-of-life issues, and the push toward greener, scalable energy storage solutions.

Introduction and context

The Conversation Weekly episode surveys a spectrum of efforts to develop sustainable batteries that can power environmental sensing networks and future energy systems without exacerbating e-waste or resource constraints. The discussion threads connect a Chicago-based initiative to embed sensors in green infrastructure with academic research from the UK and the US, and it culminates in a look at pathways toward quieter, more sustainable energy storage solutions while acknowledging policy and deployment considerations.

Terrace: soil-powered sensors for green infrastructure

Bill Yen explains the inspiration from Chicago’s bioswarms and the Array of Things project, which aims to turn the city into a smart, data-driven environment. A central challenge is powering sensors buried in soggy soil where conventional batteries fail. The Terrace device is a soil-powered fuel cell that relies on microbes in the soil to generate power from the organic carbon present in the environment, enabling wireless sensors to monitor parameters such as soil moisture and flood risk. Yen emphasizes the practical constraints of deploying energy harvesting devices in wet, muddy conditions and the need for batteries that can operate in such environments without requiring mined minerals.

"What is the one resource that is present in all these Environments that we can take advantage of to generate power and that is soil because soil is ubiquitous." - Bill Yen

Battery materials: from lithium to diversified chemistries

Lawrence Hardwick of the Stephenson Institute for Renewable Energy gives an accessible primer on how batteries work and what makes a good rechargeable battery. He outlines the move from aqueous to non-aqueous electrolytes in lithium-ion batteries, which unlocked higher cell voltages around 4 volts and enabled scalable energy density. The discussion then shifts to the broader supply chain and the need to diversify beyond lithium, cobalt, and nickel to address resource constraints, volatility in prices, and geopolitical risk. The section underscores the difference between material properties (light elements, high energy density) and real-world deployment challenges, including scale and supply chain considerations for billions of devices and vehicles.

"The breakthrough was in the early 90s was this new type of battery known as a lithium-ion battery and one of the advantages of this was it could operate in a non-aqueous electrolyte that doesn't contain any water and you could get a cell with a potential of 4 volts" - Laurence Hardwick

Diversifying chemistries: the sodium, potassium and nickel debate

Robert Armstrong from the University of St Andrews discusses the volatility of lithium prices and the importance of diversification to alternative chemistries. Sodium and potassium are highlighted as abundant and geographically widespread options with fewer geopolitical constraints. The interview covers the practicalities of sodium-ion batteries, including potential electrolytes and electrode materials designed to avoid cobalt and, where possible, nickel. The section also touches on broader market dynamics, including Chinese manufacturers investing in sodium-ion technology as part of a portfolio to reduce reliance on lithium.

"Sodium and potassium are highly abundant and they're also fairly evenly abundant, so you don't have the sort of supply issues that might plague lithium ion" - Robert Armstrong

Biopower cells: waste-to-energy and biodegradable approaches

Ulugbek Azimov introduces biopower cells, a biodegradable battery derived from waste streams such as coffee and other biomass. The team aims to create a battery that omits rare earth metals and can be recycled into fertiliser at the end of life. They describe their approach as turning a battery into a soil-friendly product rather than adding to e-waste. The discussion highlights the environmental incentives for biodegradable batteries and the potential for large-scale applications in residential and industrial energy storage, with ongoing patent activity and plans to bring a company to market.

"We wanted to make it biodegradable. But during the research stages, we actually found a solution that how we can, instead of making it biodegradable, which also will take a lot of time, and then also if it's compostable, produce CO2, for example, why don't we turn it directly into fertiliser so that you can put it in the soil straight or in the water to grow plants and vegetables." - Ulugbek Azimov

Solid-state and future directions

The episode also surveys solid-state batteries and the prospect of high-energy-density, safer storage using ceramic-based solid electrolytes, with potential advantages in safety, battery-life, and thermal stability. The conversation reflects on the possibility of a future in which multiple device classes require different battery chemistries, from lithium-ion for high-performance needs to sodium-ion or aqueous systems for lower-cost, large-scale storage. The EU battery passport and regulatory framework mentioned at the Dubai event further frame the path toward standardized, traceable battery materials and end-of-life handling across the value chain.

Closing thoughts and next steps

Gemma Ware wraps the episode by highlighting opportunities for early career researchers, the Prototypes for Humanity 2025 program, and ways to engage with the The Conversation’s broader mission of providing trusted STEM content. The show emphasizes the necessity of sustainable batteries that can scale with a growing Internet of Things and grid-storage deployment while addressing environmental and geopolitical concerns.

Applications are open for Prototypes for Humanity 2025 in Dubai and for researchers to submit their projects, with a show note link provided for more information. The episode closes with credits and a reminder of The Conversation’s mission to provide reliable information at no cost to supporters and the public.