An expandable cement-induced pseudo-supercapacitor brick for self-energy-storage buildings

Abstract

Buildings profoundly shape human life, yet they account for nearly one-third of global greenhouse gas emissions. As a primary building material, cement is a major contributor to these emissions. Therefore, developing cement-based energy storage devices presents a promising pathway toward low-carbon building solutions. However, due to the inherent electrochemical inertness and lack of energy storage capacity of conventional cement, the performance of such devices remains unsatisfactory for real-world applications. In this study, we introduce a novel strategy by activating the pseudocapacitive behavior of ordinary Portland cement, enabling it to function as a high-performance electrode. Combined with a magnesium cement electrolyte, we fabricate a full-cement supercapacitor that simultaneously provides energy storage and load-bearing functions. Remarkably, this integrated device achieves a record capacitance of 858.1 F, exceeding previously reported cement-based supercapacitors. Furthermore, the device can be directly cast into scalable brick-like modules, allowing seamless assembly into energy-storage walls. Outdoor field tests demonstrate efficient photovoltaic energy capture and delivery to practical electrical loads. Building-scale simulations across various regions in China demonstrate that replacing conventional exterior walls with our energy-storage bricks significantly increases the self-consumption rate by up to 40%, yielding an incremental ∼3000 kWh per building annually and 6000 kWh in high-irradiance regions. This breakthrough offers a transformative solution for developing self-powered buildings and decentralized energy infrastructure with significant carbon reduction potential.