Bipolar plates are an important component of polymer electrolyte membrane fuel cell (PEMFC), and their production is crucial for the commercialization of PEMFCs. Therefore, phenolic resin/carbon black/graphite composite bipolar plates were prepared using different molding temperatures (150, 160, 170, 180 °C). The electrical conductivity, mechanical strength, corrosion resistance and mass loss of the composite bipolar plates were measured according to the applicable standards. Among the four composite plates, the composite bipolar plate prepared at 170 °C had a compressive strength of 68 MPa, a flexural strength of 45.3 MPa, an electrical conductivity of 331 S/cm, and the best properties. The electrical conductivity, flexural strength and mass loss of the composite plate prepared at 170 °C after being corroded in acid solution for 20 days are maintained in a relatively stable state.

Bipolar plates are a key part of fuel cells. The optimal hot press temperature, pressure, and time were determined in this study. The press condition can directly affect the relative density, thereby improving the conductivity and mechanical property. Several carbon black doped samples were also successfully prepared on the basis of the optimized preparation method. Results show that carbon black optimized the conductivity due to the “conduction bridge”. The maximum conductivity and bending strength reached 345 S/cm and 32.5 MPa, respectively. Key words: fuel cells; bipolar plate; graphite; composite materials.

The escalating demand for heating and the widespread use of CO2-emitting fossil fuels during cold seasons have imposed significant pressure on our natural resources. As a promising alternative to coal-fired boilers, electrical thermal storage devices (ETSDs) for space heating are gaining popularity. However, designing ETSDs for space heating involves significant challenges, which involve their storage rate and operational stability. In contrast to the research of directly developing mid-temperature ETSDs to manage heat release during long heating hours, this study proposed a new ETSD that uses K2CO3–Na2CO3 for high-temperature storage to match the off-peak hours and thereby gain potential economic benefits. This study used experimental and simulation methods to investigate the ETSD’s temperature distribution. An operational strategy was also proposed to achieve more efficient temperature distribution and higher economic benefits. The ETSD with two steel plates and two insulation layers with a power rating of 1.6 kW was found to be the optimum structure, due to its improved heat storage rate (2.1 °C/min), uniform temperature, and material heat resistance (<750 °C). An energy analysis, economic analysis, and a 7-day cycling operation performance of the device were then conducted by comparing the proposed ETSD with a traditional electric heater. The results revealed that the proposed ETSD released 53.4% of the stored energy in the room, and stored 48.6% of it during valley electric time. The total cost of the proposed ETSD was consistently lower than the traditional electric heater in the second heating season (by the 213th day). The efficiency of its valley heat storage for users was 37.2%. Overall, this study provides valuable insights into the development and practical applications of ETSD systems for space heating.

Reducing costs and improving efficiency are the main challenges in the production of green hydrogen through proton exchange membrane (PEM) electrolyzers. Titanium based components such as bipolar plates (BPP) account for the largest proportion of the cost composition. In this paper, some reported anti-corrosion coating materials based on stainless steel substrate for interface contact resistance are reviewed, and a research work with the best durability at present is mainly introduced. This work proposes the use of stainless-steel bipolar plates coated with Nb and Ti by magnetron sputtering physical vapor deposition (PVD) and vacuum plasma spraying (VPS), respectively. Titanium coating (50 μm) The stainless-steel substrate is protected from corrosion, and the contact resistance is reduced by nearly an order of magnitude with a 50 times thin niobium coating. Niobium/titanium coated stainless steel bipolar plates can operate in the anode environment under standard electrolytic corrosion conditions for more than 1000 h, showing the potential for long-term operation in PEM electrolyzers.

The existing regional integrated energy system with thermal storage electric boiler as the main body cannot solve the cooling problem. In this paper, LiBr refrigerators were added on its basis to realize an energy supply mode that integrates heating and cooling. Established a multi-party win-win mechanism to ensure the minimum risk and obtain the maximum benefit. The results shown that the power grid load reduction ratios in winter and summer were 39% and 31%, respectively. When the subsidy price was 0.1CNY/kWh, the spending gap between sensitive and insensitive users reached 40%. A case of 100 office buildings in Beijing shown that the optimal capacity of phase change heat storage was 80MWh.

Bipolar plates have an important influence on the performance of Proton Exchange Membrane fuel cells (PEMFC). They are the medium to ensure that the reaction medium enters the cell, and the bipolar plate determines the weight of the fuel cell stack to a large extent. Because the weight is directly related to the material cost, the bipolar plate plays a decisive role in the manufacturing cost of fuel cells. In the current fuel cell products, the quality of bipolar plate can be as high as 70%, and accounts for 30% of the cost of the cell. The enhanced composite bipolar plate has unique electrical and mechanical properties. If the technical problems such as agglomeration and compatibility are solved, the performance of bipolar plate can be significantly improved. This review focuses on the current status and research progress on the electrical, mechanical properties of bipolar plates.

Based on the temperature change and thermal storage processes of PCM phase change energy storage unit, the PCM channel number of which is 39, the plate spacing is 0.01 m, the air channel is 40 with its plate spacing of 0.003 m, and the unit length is total of 1.62 m. MATLAB solution about the above PCM energy storage unit was performed according to the model and physical property data, and the numerical simulation was carried out by using Fluent software. The theoretical calculation and numerical simulation were compared and analyzed. It is found that only in the case of smaller or larger flow rate working conditions, the solution results of MATLAB for the increase rate of the average temperature of the phase change material inside the system is quite different from the FLUENT simulation result; the comparison of the phase change process degree of advancement is found that at a higher flow rate, the difference between the two results is small, but the difference is larger when the flow rate is smaller; the comparison result of the PCM liquid rate is different under the small flow rate condition. However, the comparative analysis of heat storage shows that the maximum error does not exceed 10%. It can be seen that the flow rate conditions in the model and working conditions are the obvious factors affecting the two results, but the calculation and simulation results can more accurately describe the heat storage characteristics of the PCM phase change energy storage unit, which was calculated in nearly 90% ranges of working conditions, which can prove that the results of MATLAB and FLUENT are consistent.

Future energy systems face significant challenges in resolving global energy trilemma of clean supply, affordability and security. This calls for high penetration of renewables and electrification of heat and transportation. This paper concerns thermal energy storage (TES), which is expected to play an important role in addressing the energy trilemma. It summarizes our recent work on this area, covering TES materials, modules and applications. Our work on TES materials has been on composite materials, including materials formulation and properties characterization and fabrication. Our work on TES devices is covered the material formulation, exchanger developing and TES system building. The experimental study indicates that the thermal recovery efficiency is from 87∼91% for each TES exchanger. A multistage system with graded use of the thermal energy can enhance the thermal recovery efficiency up to 92%.