Prof. WU Wei’s Team Won Three Gold Medals at the 8th China International Invention and Innovation Exhibition
At the 8th China (Shanghai) International Invention and Innovation Exhibition, which concluded on 13 June 2025, three postdoctoral researchers from the team of Prof. Wu Wei, Associate Professor at the School of Energy and Environment (SEE), City University of Hong Kong (CityUHK), presented their latest inventions: “High-Density Carnot Battery for Long-Duration Energy Storage,” “Sweating-Inspired Heat Sink for Zero-Energy Thermal Management,” and “Double-Stage Absorption Thermal Battery,” respectively. All three projects received Gold Medals, marking a significant achievement for the team."
The China (Shanghai) International Invention and Innovation Exhibition, organized annually by the Shanghai Invention Association since 2017, covers strategic fields such as digital technology, biomedicine, and green energy. The exhibition provides a platform for global technological exchange through project showcases, roadshows, and contract signings. It features a rigorous award evaluation process with Gold, Silver and Bronze prizes, as well as special competitions. By 2025, the exhibition had grown from 672 entries in its fifth edition to over 1,000 entries this year. The achievement of three Gold Medals is not only a testament to the team’s technological strength, but also highlights CityUHK’s growing global influence in green technology and sustainable development.
Innovation Highlight: High-Density Carnot Battery for Long-Duration Energy Storage
With the continuous development in photovoltaic and wind power, the challenge of accommodating surplus renewable energy imposes higher demands on energy storage technologies. However, existing electricity storage technologies face critical issues such as high cost, short lifespan, flammability/explosiveness, and dependence on specific geographic conditions. To address these limitations, our team has proposed a novel absorption Carnot battery based on thermochemical processes. This system performs a power-thermochemical energy-power cycle, enabling high round-trip efficiency, high energy storage density, and low cost. Due to the thermochemical storage mechanism, the cycle exhibits an extremely low self-discharge rate, making it particularly suitable for long-term energy storage. Compared with conventional Carnot batteries, the absorption Carnot battery offers a comparable round-trip efficiency (30.5%–48.4%) and higher energy storage density (7.6–21.8 kWh/m³). Even after 80 days of standby, the self-discharge rate remains as low as 0.74%, which is substantially lower than that of Rankine-based pumped thermal energy storage. Although the initial capital cost of the absorption Carnot battery is relatively high, its higher energy storage density results in a lower levelized cost of storage, estimated at 0.342 USD/kWh, outperforming Rankine-based pumped thermal energy storage. This technology holds promising potential in various applications, including renewable energy integration and utilization, grid stability and ancillary services, microgrid and off-grid systems, power market optimization, and low-grade waste heat recovery.
Innovation Highlight: Sweating-Inspired Heat Sink for Zero-Energy Thermal Management
With the ever-increasing demands for high-performance electronic and communication technologies, as well as the constant push to reduce the sizes of electronic components, the power density of electronics has continued to rise. Poor thermal management can cause tremendous heat accumulation within electronic devices, resulting in the loss of functionality and, eventually, device failure. It is estimated that the chip performance can degrade by ~10% for every 2°C rise when its operating condition exceeds 70–80 °C. We propose a passive thermal management strategy that relies on moisture desorption of hygroscopic salt solutions through a protective membrane that only allows water vapor to pass through; importantly, it can spontaneously recover cooling capacity during off hours. Experimentally validated results demonstrate that the maximum temperature reduction provided by the strategy can be up to 21°C at a fixed heat flux of 25 kW/m2 when compared with a similarly sized fin heat sink. By employing the strategy in a real computing device (ODROID-XU4), its performance is improved by 32.65% with record-high cost-effectiveness. The strategy can be useful for various applications that need intermittent thermal regulation.
Innovation Highlight: Double-Stage Absorption Thermal Battery
The development and utilization of renewable energy is essential for addressing the global energy crisis and environmental challenges—and is a vital pathway to achieving carbon neutrality. However, the intermittent and unstable nature of renewables often causes mismatches with user demand. Energy storage technologies serve as a critical bridge between energy supply and consumption. Absorption thermal battery (ATB) has garnered attention due to its high energy density and low heat loss, but traditional systems typically require driving temperatures above 80°C, limiting practical applications. To address this issue, our team invented a double-stage ATB device and operational method, which significantly enhances storage capacity under low-temperature heat sources. The system can operate at temperatures as low as 50°C, greatly expanding the application scope of ATES.
Team members (from left): Dr. Yunren Sui, Dr. Zengguang Sui, and Dr. Zhixiong Ding.
Team presenting to the judging panel.
Gold medals and award certificates.