Development of Real-Time Estimation of Thermal and Internal Resistance for Reused Lithium-Ion Batteries Targeted at Carbon-Neutral Greenhouse Conditions

Abstract

The transition toward renewable-powered greenhouse agriculture offers opportunities for reducing operational costs and environmental impacts, yet challenges remain in managing fluctuating energy loads and optimizing agricultural inputs. While second-life lithium-ion batteries provide a cost-effective energy storage option, their thermal and electrical characteristics under real-world greenhouse conditions are poorly documented. Similarly, although plasma-activated water (PAW) shows potential to reduce chemical fertilizer usage, its integration with renewable-powered systems requires further investigation. This study develops an adaptive monitoring and modeling framework to estimate the thermal resistances (R-u, R-c) and internal resistance (R-int) of second-life lithium-ion batteries using operational data from greenhouse applications, alongside a field trial assessing PAW effects on beefsteak tomato cultivation. The adaptive control algorithm accurately estimated surface temperature (T-s) and core temperature (T-c), achieving a root mean square error (RMSE) of 0.31 degrees C, a mean absolute error (MAE) of 0.25 degrees C, and a percentage error of 0.31%. Thermal resistance values stabilized at R-u approximate to 3.00 degrees C/W (surface to ambient) and R-c approximate to 2.00 degrees C/W (core to surface), indicating stable thermal regulation under load variations. Internal resistance (R-int) maintained a baseline of similar to 1.0-1.2 Omega, with peaks up to 12 Omega during load transitions, confirming the importance of continuous monitoring for performance and degradation prevention in second-life applications. The PAW treatment reduced chemical nitrogen fertilizer use by 31.2% without decreasing total nitrogen availability (69.5 mg/L). The NO3--N concentration in PAW reached 134 mg/L, with an initial pH of 3.04 neutralized before application, ensuring no adverse effects on germination or growth. Leaf nutrient analysis showed lower nitrogen (1.83% vs. 2.28%) and potassium (1.66% vs. 2.17%) compared to the control, but higher magnesium content (0.59% vs. 0.37%), meeting Japanese adequacy standards. The total yield was 7.8 kg/m(2), with fruit quality comparable between the PAW and control groups. The integration of adaptive battery monitoring with PAW irrigation demonstrates a practical pathway toward energy efficient and sustainable greenhouse operations.