Fuel Cell (FC) Technology in Toyota's New Mirai

～ from the Proceedings of the 2021 JSAE Annual Congress (Spring) Technical Sessions ～

2021/09/01

Summary
Overview of the FC system on the all-new Mirai
FC unit
FC stacks and cells
High pressure hydrogen storage system
High pressure hydrogen tank

Summary

There were 4,035 attendees at the 2021 Society of Automotive Engineers of Japan (JSAE) Annual Congress (Spring) that was held online from May 26 to 28, 2021. This is more than the 3,408 attendees at the 2020 JSAE Congress (Autumn), which was held online due to the COVID-19 pandemic.

Toyota Motor Corporation (Toyota) gave a number of presentations on the fuel cell vehicle (FCV) system installed on the all-new Mirai, and introduced the development contents of various elemental technologies. This report will introduce some of them.

The all-new Mirai, launched by Toyota in December 2020, has a smaller stack which fits under the hood, three high-pressure hydrogen tanks including in the center tunnel to increase the amount of hydrogen loaded, and improved fuel efficiency to increase the cruising range by 30%, from 650km to 850km.
The components of the FC (fuel cell) unit, even the auxiliary components such as the hydrogen mixing pipe, have been optimized using simulations to reduce the operating noise of the main shutoff valve, pump, compressor, and other components, and improve the quietness of the system, thereby reducing the size and cost as well as improving the merchantability.
The stack case, which protects the cell layers in the FC stacks, has been downsized by revising the structure and construction method. The cells have improved power generation by improving the physical properties of the electrode materials and reduced cost by reducing the amount of precious metal used, while the cell structure has been revised to improve manufacturability.
The high-pressure valves, high-pressure pressure reducing valves, high-pressure temperature sensors, and other components which make up the high-pressure hydrogen storage system are also downsized reducing the mass and cost.
The high-pressure hydrogen tank uses high-strength, high-elasticity carbon fiber to reduce the number of CFRP layers by 7%, increasing the volume and reducing the weight of the tank, while increasing productivity by speeding up the winding process and automating tank quality measurements. The mass efficiency of the high-pressure hydrogen tank has been improved by 5% to achieve 6.0wt%.


All-new Mirai launched in December 2020	FC system of the all-new Mirai

(Source: Toyota)

References

The reference numbers, titles, and names of speakers of the presentations referred to in this report are as follows. (All speakers belong to Toyota Motor Corporation.)

20215124 “Development of the High-Performance Fuel Cell Electrode for New FCV, Establishment of High Performance and Durability”, Kenji Tsubosaka
20215125 “Fuel Cell Channel Design using 3D Numerical Model”, Daisuke Hayashi
20215126 “Design of Fuel Cell that Enable High-Speed Production for New FCV”, Taiki Kuwahara
20215127 “Structure and Equipping of FC Stack for New FCV”, Yuma Takabatake
20215128 “Development of Physical Model of Fuel Cell System and Application for Control Design”, Nobukazu Mizuno
20215130 “Development of Hydrogen Mixing Pipe for New FCV by using Two-Phase Flow Simulation”, Hideyuki Arai
20215131 “Development of Noise Reduction for the New Type FCV”, by Ryota Akaboshi
20215133 “Development of High-Pressure Hydrogen Tank for New FCV”, Sogo Goto
20215134 “Development of the Hydrogen Pressure Vessel's Fatigue Failure Model Considering CFRP Failure Modes”, Tsuyoshi Nishihara
20215135 “Development of the High-Pressure Hydrogen Storage System Parts for New FCV”, by Koji Kida

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