Project Overview
The MONOLITH project - Micro-solar sensing without Lithium - was supported by Horizon Europe through the BOWI initiative. The goal was to design and develop a solar-powered air temperature and humidity sensor with self-localisation and anti-theft features, capable of continuous operation without lithium-battery energy storage.
The Problem with Lithium
Modern wireless sensor networks typically rely on solar panels combined with rechargeable lithium batteries. Lithium batteries provide a limited number of duty cycles (around 500), which limits device lifespan to 3-5 years. They can only be recharged at temperatures above 0°C - a critical limitation for year-round outdoor deployments. If battery technology didn't have this limitation, we could use at least 10 times smaller energy storage.
Global Impact
Annual worldwide lithium production is approximately 80,000 tonnes. Demand may increase 11x between 2020 and 2030. The global IoT market is projected to reach 27 billion devices in 2025. Assuming supercapacitors replace batteries in just 1 billion IoT devices per year, the material savings and increase in device lifetime would be enormous.
Key Outcomes
- Device lifespan extended to 10-20 years, requiring 6-20 times lower energy storage
- World's first commercially available battery-less and lithium-free sensor network
- Technology transferable to industrial sites, construction sites, and asset trackers