How fuel cells beat lithium batteries

Yixing Electric's China Blue-G New Energy Technology Group Co., Ltd. and Canadian Hydrogenics signed a $50 million purchase license agreement. The agreement stipulates that Hydrogenics will deploy a system for 1,000 zero-emission hydrogen fuel cell buses in China.

Coincidentally, Beijing Hydrogen Power Creation Technology Co., Ltd. and Guoda Hydrogen Energy Technology Co., Ltd. signed an order for 500 sets of 30KW fuel cell electric reactors worth 120 million yuan, and delivered them one after another before the end of 2017.

Behind the flood of fuel cell orders, on the one hand, was a new subsidy policy introduced late last year by four ministries that made it clear that fuel cell car subsidies would not go downhill. At present, fuel cells are subsidized based on models, which is four times as strong as in the United States and Japan. On the other hand, fuel cells do have an incomparable high energy density and high power density for lithium batteries.

Although the embedded reaction principle adopted by lithium-ion batteries is groundbreaking compared to the heterogeneous redox reaction mechanism of conventional secondary batteries, breaking the traditional idea that the negative electrode must be a lithium source, and achieving high voltage and high specific energy The secondary battery system has made great achievements in social commerce. However, based on the unique heterogeneous electro catalysis and open working principle, the fuel cell is a relatively advanced development level of the secondary battery in terms of the electrochemical device.

Why are fuel cells a more advanced level of development than secondary cells?

1, working methods

First of all, in terms of working methods, lithium batteries can not have an excessive energy density. Because the secondary battery is a sealed operation, it must also be developed into a fully sealed system and strive to achieve non-maintenance. This is particularly important for lithium power. It is precisely this point that determines that the energy density of lithium batteries must be limited, and It can not be too high. Otherwise closed + high energy = bomb.

But car development requires higher energy densities, and it is bound to use open working principles, such as lithium air batteries. Lithium air cells are also a semi-fuel cell to some extent, but due to some basic technical constraints, their large-scale application is impossible. Therefore, from the perspective of the fundamental need to pursue energy density, the open working mode of fuel cells is a higher level of development than secondary batteries.

2, working principles

Secondly, from the working principle of the fuel cell, whether it is the oxidation of hydrogen or the reduction of oxygen, a high exchange current density can be obtained on the surface of the Pt/C Catalyst, which makes the hydrogen fuel cell have a very high power; The energy density of hydrogen fuel cells depends on the hydrogen storage system, which can increase the battery energy density by simply increasing the volume or number of hydrogen storage tanks. In other words, fuel cells have both high energy density and high power density.

In fact, no secondary battery system has so far been comparable to PEMFC in terms of energy density and power density. It is worth noting that endurance and power are precisely the most basic technical requirements of modern cars. Of course, safety is the higher priority requirement, but regardless of how you look at it, the safety of fuel cells is above secondary batteries. Therefore, from the perspective of electrochemical devices, fuel cells have a higher level of development than secondary cells.

3, the nature of work

Finally, in essence, the secondary battery is an energy storage device that stores and releases electrical energy through reversible electrochemical reactions. The fuel cell is an electrical energy production device. It converts the chemical energy in the fuel into electrical energy through an electro catalytic reaction. The working method is similar to that of an internal combustion engine.

In other words, the energy of a lithium battery is converted into electricity to chemical energy and then to electrical energy, while a fuel cell converts chemical energy directly into electrical energy. From the perspective of energy conversion, fuel cells are undoubtedly a more advanced level of development than secondary batteries.

summary

Even if the hydrogen fuel cell is a system that has a higher level than the lithium battery, it is realistic that the current industrial and technical maturity of the lithium battery is much higher than that of the fuel cell. At present, the development of hydrogen fuel cells faces four major difficulties: 1. The cost and service life of hydrogen fuel cell electric reactors; 2, hydrogen mass production, transportation and filling(hydrogen station) process combined cost is higher; 3, the construction of terminal hydrogenation stations is a problem at the government level; 4, in the long run depends on the large-scale cheap preparation of hydrogen.

Although Toyota and Honda have released fuel cell cars in 2015 and 2016, and the mass-produced fuel cell cars have actually detonated the entire industry, the difficulties faced by hydrogen fuel cells have not been solved. Fuel cell cars are difficult to solve. For the current research and industrialization of hydrogen fuel cells, it will take at least 5-10 years before large-scale commercialization of fuel cells is possible.

The page contains the contents of the machine translation.