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introduction：To reduce the cost of all-vanadium redox flow battery, one of the core paths is to increase the current density-the higher the density, the greater the output per unit area and the lower the system cost. However, when the current density goes up, the internal resistance and vanadium ion penetration of the diaphragm will be rapidly amplified, and both energy efficiency and cycle life will be under pressure.

Can domestic PBI film stand firm on this key track? Recently, Japanese customers conducted independent tests on Porimion®PBI flow battery membrane under Zhonghe Energy Storage, and gave clear answers.

01　Low impedance：200mA/cm² energy efficiency  85%

The energy efficiency of Porimion®PBI film reaches 85% when charged and discharged at a current density of 200 Ma/cm.

Energy efficiency is the most direct embodiment of the comprehensive performance of the membrane. The lower the impedance of the membrane, the faster the proton transmembrane speed and the smaller the ohmic loss, and the higher the energy efficiency of the stack, which is the premise of high power density operation.

02 Coulomb efficiency is high: vanadium penetration is effectively suppressed

The coulomb efficiency is high, which indicates that the permeation of vanadium ions across the membrane is very small. Vanadium infiltration is the "invisible killer" of all-vanadium flow battery: it causes self-discharge and capacity attenuation of positive and negative electrodes, and pushes up the cost of electrolyte rebalancing.

PBI membrane permeates and suppresses vanadium, which is equivalent to maintaining the economy of long-term operation-this is more valuable than the temporary efficiency figure.

03　600mA/cm²：Repeated charging and discharging does not degenerate

The test did not stay in the regular interval. Porimion®PBI film did not degrade after long-term repeated charging and discharging at ultra-high current density of 600 Ma/cm.

This means that it is still stable under the harsh working conditions of high power and high current-leaving a solid space for the stack to continue to improve the power density and dilute the unit cost.

Overseas verification is accumulating.

This answer sheet from Japanese customers is not an isolated case. Related reading: The actual measurement of overseas stacks of PBI flow battery membranes: EE 83.74%, CE 99.14%.

At present, many overseas customers of neutralization energy storage PBI membrane have completed the preliminary test, and the feedback is positive, and some of them are pushing the verification to commercial large reactors. From laboratory small reactors to megawatt commercial systems, the reliability of Porimion®PBI membrane is being confirmed step by step.

Is the diaphragm good? Where do you look?

The core difficulty of PBI membrane replacing traditional perfluorinated membrane lies in the balance between "high proton conductivity" and "high vanadium ion barrier".

This independent test by Japanese customers shows that Porimion®PBI membrane has low internal resistance, high selectivity and high power tolerance at the real stack scale. This is a key puzzle on the path of scale verification and cost reduction for all-vanadium redox flow batteries which are in urgent need of cost reductio

Overseas verification is accumulating

This answer sheet from Japanese customers is not an isolated case. Related reading: The actual measurement of overseas stacks of PBI flow battery membranes: EE 83.74%, CE 99.14%.

At present, many overseas customers of neutralization energy storage PBI membrane have completed the preliminary test, and the feedback is positive, and some of them are pushing the verification to commercial large reactors. From laboratory small reactors to megawatt commercial systems, the reliability of Porimion®PBI membrane is being confirmed step by step.

Is the diaphragm good? Where do you look?

The core difficulty of PBI membrane replacing traditional perfluorinated membrane lies in the balance between "high proton conductivity" and "high vanadium ion barrier".

This independent test by Japanese customers shows that Porimion®PBI membrane has low internal resistance, high selectivity and high power tolerance at the real stack scale. This is a key puzzle on the path of scale verification and cost reduction for all-vanadium redox flow batteries which are in urgent need of cost reduction.

Note: The test data in this paper comes from the independent test of neutralization energy storage PBI membrane by Japanese customers, and the test conditions and results are objective records.