Proton exchange membrane, English name Proton Exchange Membrane, abbreviated as PEM, also called proton membrane or ion exchange membrane, is a kind of separation function membrane with selective ion transmission.
Proton exchange membrane is one of the key components of a fuel cell. It has the dual functions of transferring protons and separating yin and yang gas. Its performance directly affects the stability and durability of the fuel cell.
At present, only perfluorosulfonic acid proton exchange membranes are used in fuel cells, but their cost occupies the top of the various components of fuel cells.
According to statistics from research and advisory agency TrendBank, it is estimated that by 2025, the capacity of proton exchange membranes in the Chinese market will reach 1.8 million square meters, and the market size will reach 100 billion yuan.
Major domestic enterprises
At present, the proton exchange membrane technology of SDDY New Energy Technology Group is the most mature in China. SDDY is also the only Chinese company that has passed the AFCC technology identification. It is the largest Chinese company in the market after Gore and Como.
SDDY Group Perfluorosulfonic Acid Proton Exchange Membrane
In 2004, SDDY Group and Shanghai Jiaotong University developed a proton exchange membrane. After testing by Toyota Japan and Fuma.Tch, Germany, the performance of proton exchange membranes produced by SDDY is not inferior to similar products.
In 2016, SDDYDF260 has been used in the first batch of fuel cell vehicles produced by Mercedes-Benz and Ford. After that, it has successfully developed three new samples and has entered the batch production trial stage.
In 2014, SDDY Group's proton exchange membrane only had a life of 800 hours; in 2015, the life reached 2000 hours; in 2016, it successfully exceeded 6000 hours.
At present, the thickness of SDDYDF260 film is 15um, in the case of OCV, the durability is more than 600 hours; the film running time reaches 6000 hours; in terms of wet and dry cycles and mechanical stability, the number of cycles has exceeded 20,000 times.
SDDYDF260 membrane technology has matured and has been put into mass production. The second-generation planned production capacity is 200,000 square meters, and SDDY Group has built a perfluorosulfonic acid resin production device required for an annual output of 50 tons of fuel cell ion membranes, which can meet 25,000 electric vehicles. Required for the ionic membrane.
Major foreign companies
Even though SDDY stands out among domestic enterprises, it still has a certain gap compared with foreign advanced enterprises.
According to the United States Department of Energy (DOE), the best proton exchange membrane performance on the market has reached or exceeded the DOE 2020 target in some aspects, mechanical durability reached 23,000 times, chemical durability reached 742 hours, and cost 17 USD / square meter.
At present, the world's most widely used proton exchange membrane is still Gore's select membrane. Domestic Xinyuan Power and Dongfang Electric recently introduced fuel cell stacks using GORE-SELECT® proton exchange membranes from foreign companies.
Note: Gore is the world's leading supplier of proton exchange membrane fuel cell technology. GORE-SELECT® proton exchange membrane has become the standard to meet the demanding applications of automobiles. This proton exchange membrane has been used in other commercial fuel cell vehicles, such as Toyota's MIRAI and Honda's CLARITY FUEL CELL.
DuPont is the world's earliest company to develop and sell proton exchange membranes. Its Nafion membrane is also the most widely used in the world, but it has not introduced new products for use in automotive fuel cells. Gore takes advantage of the excellent properties of its enhanced proton membranes. Quickly occupy and sweep around 85% of the global market.
At present, Gore is a company with more than 25 years of experience in the development and manufacturing of enhanced proton membranes. The ultra-thin and durable GORE-SELECT proton exchange membranes with unique ePTFE material technology cover almost 90% of the world's main OEMs, and dozens of them each year 10,000 square meters of shipments and maintained rapid growth.
However, DuPont did not watch the car proton membrane market slip away from itself. In July 2015, DuPont split, and the separated Chemours Chemical became an independent listed company.
Chemours is a global leader in three business areas, including titanium dioxide technology, fluorine products and special chemicals, and was the earliest developer of Nafion membranes. Currently committed to the development of automotive proton membranes, the new NC700 has been released.
Industrial difficulties
As the most important component of a fuel cell, a proton exchange membrane must have the following six basic properties: proton conductivity, stability, air permeability, water absorption, hydroelectric permeability, and mechanical strength.
At present, the molding processes of perfluorosulfonic acid proton exchange membranes mainly include extrusion molding, solution molding and composite molding.
Extrusion molding processes can be divided into melt extrusion molding and gel extrusion molding. Melt extrusion molding is further divided into melt extrusion cast molding and melt extrusion calendering.
The difficulties of proton exchange membranes are long process cycles, complicated processes, and high cost of film formation.
In addition, the synthesis and sulfonation of perfluorinated substances are very difficult, and the hydrolysis and sulfonation during the film formation process tend to denature and degrade the polymer, making film formation difficult, resulting in higher costs.
According to the data, the price of Proton exchange membrane of Nafion in the United States is 120 USD / kW. For example, a fuel cell car battery stack is 100KW, so the cost of the proton exchange membrane alone is as high as 12,000 USD. This unit price is even higher than the raw material cost of the $ 80 / KWh ternary lithium battery.
At present, the cost of proton exchange membranes still accounts for a large portion of the cost of proton exchange membranes. From the cost structure of proton exchange membranes, it can be seen that the material cost is relatively low. The focus is on technical process costs, which account for more than 80%, which makes proton exchange membranes. There is huge room for future cost reductions.
Therefore, if mass production can be achieved, cost reduction through large-scale production can be achieved.