<p><span style="font-family:Arial,Helvetica,sans-serif;"><span style="font-size:10.5pt"><span style="font-size:12.0000pt"><span style="background:#ffffff"><span style="color:#333333"><span style="letter-spacing:0.0000pt"><span style="font-weight:normal"><span style="font-style:normal">In the proton exchange membrane fuel cell, the humidified moisture of the anode hydrogen enters the anode flow field plate, the anode diffusion layer and the anode catalytic layer with the hydrogen, and enters the cathode through the membrane, and the water generated by the cathode reaction also enters the cathode catalytic layer, and the cathode diffusion layer reaches the cathode. flow field, and some of the water will be absorbed by the membrane by back-diffusion. Water and ice have densities of 0.9998 and 0.9168 g/cm3 at 0&deg;C, respectively, so a 9% volume expansion occurs when water freezes.When the battery is turned on, the waste heat generated melts the waste heat into water, and the volume shrinks. The volume change caused by repeated water-ice phase transitions can cause negative or even permanent damage to the battery material structure, and even short-circuit battery performance degradation.</span></span></span></span></span></span></span></span></p>

<h1 style="text-align: center;"><span style="font-size:10.5pt"><span style="text-autospace:ideograph-numeric"><span style="line-height:150%"><span style="font-family:Calibri"><span style="font-size:11.0000pt"><span style="background:#ffffff"><span style="font-family:'Microsoft YaHei UI'"><span style="line-height:150%"><span style="color:#222222"><span style="letter-spacing:0.4000pt"><span style="font-style:normal"><font face="Microsoft YaHei UI">The proton exchange membrane is a selectively permeable membrane, which has the dual function of proton channel and hindering the direct reaction of reactants. Accordingly, we should consider the following points when choosing a proton exchange membrane:</font></span></span></span></span></span></span></span></span></span></span></span></h1> <p style="text-align:justify"><span style="font-size:10.5pt"><span style="text-autospace:ideograph-numeric"><span style="line-height:150%"><span style="font-family:Calibri"><span style="font-size:11.0000pt"><span style="background:#ffffff"><span style="font-family:'Microsoft YaHei UI'"><span style="line-height:150%"><span style="color:#222222"><span style="letter-spacing:0.4000pt"><span style="font-style:normal"><font face="Microsoft YaHei UI">①High conductivity of protons to reduce ohmic resistance and improve battery output power;</font></span></span></span></span></span></span></span></span></span></span></span></p> <p style="text-align:justify"><span style="font-size:10.5pt"><span style="text-autospace:ideograph-numeric"><span style="line-height:150%"><span style="font-family:Calibri"><span style="font-size:11.0000pt"><span style="background:#ffffff"><span style="font-family:'Microsoft YaHei UI'"><span style="line-height:150%"><span style="color:#222222"><span style="letter-spacing:0.4000pt"><span style="font-style:normal"><font face="Microsoft YaHei UI">② When DMFC works, keep the membrane structure and resin composition unchanged, so as to maintain excellent chemical and electrochemical stability, and maintain the reliability and durability of the battery;</font></span></span></span></span></span></span></span></span></span></span></span></p> <p style="text-align:justify"><span style="font-size:10.5pt"><span style="text-autospace:ideograph-numeric"><span style="line-height:150%"><span style="font-family:Calibri"><span style="font-size:11.0000pt"><span style="background:#ffffff"><span style="font-family:'Microsoft YaHei UI'"><span style="line-height:150%"><span style="color:#222222"><span style="letter-spacing:0.4000pt"><span style="font-style:normal"><font face="Microsoft YaHei UI">③The membrane should have low reactant permeability coefficients under both dry and wet conditions to reduce the mixing potential and improve the cell Faradaic efficiency;</font></span></span></span></span></span></span></span></span></span></span></span></p> <p style="text-align:justify"><span style="font-size:10.5pt"><span style="text-autospace:ideograph-numeric"><span style="line-height:150%"><span style="font-family:Calibri"><span style="font-size:11.0000pt"><span style="background:#ffffff"><span style="font-family:'Microsoft YaHei UI'"><span style="line-height:150%"><span style="color:#222222"><span style="letter-spacing:0.4000pt"><span style="font-style:normal"><font face="Microsoft YaHei UI">④The surface of the membrane before the decomposition of the membrane resin has a certain viscosity to ensure the good combination of the catalytic layer and the membrane and reduce the contact resistance; </font></span></span></span></span></span></span></span></span></span></span></span></p> <p style="text-align:justify"><span style="font-size:10.5pt"><span style="text-autospace:ideograph-numeric"><span style="line-height:150%"><span style="font-family:Calibri"><span style="font-size:11.0000pt"><span style="background:#ffffff"><span style="font-family:'Microsoft YaHei UI'"><span style="line-height:150%"><span style="color:#222222"><span style="letter-spacing:0.4000pt"><span style="font-style:normal"><font face="Microsoft YaHei UI">⑤The membrane has a certain mechanical strength in the dry and wet state to ensure the preparation and assembly of the membrane electrode assembly; </font></span></span></span></span></span></span></span></span></span></span></span></p> <p style="text-align:justify"><span style="font-size:10.5pt"><span style="text-autospace:ideograph-numeric"><span style="line-height:150%"><span style="font-family:Calibri"><span style="font-size:11.0000pt"><span style="background:#ffffff"><span style="font-family:'Microsoft YaHei UI'"><span style="line-height:150%"><span style="color:#222222"><span style="letter-spacing:0.4000pt"><span style="font-style:normal"><font face="Microsoft YaHei UI">⑥Considering industrialization conditions, membrane material selection should be easy to obtain and low cost.</font></span></span></span></span></span></span></span></span></span></span></span></p>