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Protonic ceramic fuel cells (PCFCs) are attractive next-generation fuel cells working at intermediate temperature (450–700 °C). Currently, the most common method to produce PCFCs is based on co-sintering anode-supported half cells composed of thin BaZr 0.8 Y 0.2 O 3-δ (BZY20) electrolyte layers and thick NiO anode substrates. However, the BZY20 electrolyte reacts with NiO at the high temperature during co-sintering (1400–1600 °C), leading to significant loss of dopants in the electrolyte and thereby degradation in the conductivity. With the aim to improve the chemical compatibility between the BaZrO 3 -based electrolyte and NiO, in this work, we annealed the mixture of NiO and BaZrO 3 doped with different dopants, and found that good compatibility was obtained between NiO and BaZr 0.8 Yb 0.2 O 3-δ or BaZr 0.8 Tm 0.2 O 3-δ at 1500 °C, and NiO and BaZr 0.8 Yb 0.2 O 3-δ at 1350 °C. Furthermore, BaZr 0.8 Y 0.1 Yb 0.1 O 3-δ and BaZr 0.8 Y 0.12 Yb 0.08 O 3-δ also showed good chemical compatibility with NiO at 1350 and 1500 °C. Then, the half cells using the BaZrO 3 electrolyte doped with Y and Yb were fabricated, and the ionic conductivities of the electrolytes implemented into the co-sintered half cells were measured directly in wet hydrogen. The results revealed that BaZr 0.8 Y x Yb 0.2- x O 3-δ (x = 0.10, 0.12, 0.13) showed higher conductivity than that of BaZr 0.8 Y 0.2 O 3-δ , and BaZr 0.8 Y 0.1 Yb 0.1 O 3-δ exhibited the highest conductivity among the three Y and Yb co-doped samples studied in this work. [Display omitted] •Improved phase compatibility with NiO by doping BaZrO 3 with Yb or Tm. • Total doping level in BaZrO 3 keeps at 0.2 by co-doping Y and Yb without dopant loss. • Higher ionic conductivity of BaZrO 3 co-doped with Y and Yb in co-sintered cells. [ABSTRACT FROM AUTHOR]

In this article, an electrolyte flow rate control approach is developed for an all-vanadium redox flow battery (VRB) system based on the linear parameter varying (LPV) framework. The electrolyte flow rate is regulated to provide a trade-off between stack voltage efficiency and pumping energy losses, so as to achieve an energy efficient battery operation. The nonlinear process model is embedded in a linear parameter varying state–space description and a set of state feedback controllers are designed to handle fluctuations in current during both charging and discharging. Simulation studies have been conducted under different operating conditions to demonstrate the performance of the proposed approach. This control approach was further implemented on a laboratory scale VRB system. • A novel electrolyte flow rate control approach is developed for vanadium redox batteries (VRB). • The nonlinear battery system model is embedded into a Linear Parameter Varying (LPV) description. • A computationally efficient controller is designed to optimise the operational efficiency. • The proposed control design is successfully implemented on a lab-scale VRB system. [ABSTRACT FROM AUTHOR]

Mg B 2 superconducting material has a wide range of application prospects for its high transition temperature, favorable structural characteristics and low cost. When using Mg B 2 to produce superconducting energy storage magnets, it is necessary to twist superconducting wires into cables to increase their current carrying capacity. One typical cable is made of 6 Mg B 2 superconducting wires wrapped around 1 central copper wire, forming a (6+1) structure. Mg B 2 coils used for energy storage require solid impregnation and can be cooled by liquid hydrogen or solid nitrogen. Due to the need for fast charging and discharging of energy storage coils and low thermal conductivity of commonly used epoxy resin impregnation and solid nitrogen, it is necessary to consider the temperature variation characteristics caused by AC loss and eddy current loss during operation process. A coil with 8 turns in each layer and 4 layers is simulated using the (6+1)-structure cable. In order to obtain better temperature distribution results while reducing the time required for simulation operation, the simulation time is set to 1 s. The impact of epoxy resin properties and surrounding environments on the coil are then analyzed. The results indicate that increasing the thermal conductivity of epoxy resin can significantly reduce the maximum temperature of the coil, while only changing the cooling method is unhelpful in dealing with the problem of local overheating of the coil. • Epoxy resin affects the position with the highest temperature in a coil. • Cooling effects of static liquid hydrogen and solid nitrogen are almost the same. • Flow rate of liquid hydrogen is not helpful in avoiding coil overheating. [ABSTRACT FROM AUTHOR]