Standards Development

Scope

This document establishes the general requirements and test methods for vanadium flow battery stacks. The test items mainly include appearance, internal leakage, external leakage, insulation resistance, characteristic charging curve, characteristic discharging curve, rated power, rated energy efficiency, high temperature storage performance, low temperature storage performance, heat shock strength, vibration, collision impact, external short-circuit. The general requirements includes the working environment, equipment accuracy, warning and caution signs, inspection rules(routine test and type test), packaging, transport, and storage of the stacks.

This standard is applicable to stacks of vanadium flow batteries.

Purpose

Due to the accelerated expansion of renewable energies worldwide, the demand for stationary electrochemical energy storage systems, long duration energy storage in particular, is increasing. One of the most important technologies is flow batteries, which have seen an accelerated expansion of systems with installed capacities of up to more than 2 GWh, especially in the last three years. Today, the vanadium flow battery (VFB) is the most important representative with the largest number of commercial and demonstration installations. Now VFB has been developed to numerous MWh-100MWh class energy storage demonstrations.

As a result, companies are now spread all over the world and are mainly located in China, Germany, Austria, Japan, USA, Canada, Spain, Italy, Australia, India, Korea, South Africa and other Countries. Due to the rapidly increasing demand for VFBs and thus the increasing demand for the core component - stack, which is the power unit of the flow batteries. The stack offers the electrochemical reaction site during charging/discharging, which ultimately determines the stack’s performance, e.g. the power, the energy efficiency and reliability. The characteristics (e.g.charge-discharge performance, safety, enironmental adaptation, reliability) of stacks correlate closely to the quality of flow battery system (FBS) and flow battery energy system (FBES). The stack is independent of the electrolyte, and now can be expressed solely as standard products for the system assembly. Thus, a large number of stack production plants with over GW/ year was installed, and more than 10GW capacity production line are currently under construction or in planning all over the world.

Standardised stacks lead to a standardization of production results, higher availability and better quality, as well as increased trust in stack producers and battery manufacturers and thus bring about reduced cost and higher reliability for the FBS and FBES. In this context, the three standards IEC 62932-1:2020, IEC-62932- 2-1:2020 and IEC 62932-2-2:2020 have already been developed and published, covering general aspects, test methods and safety aspects of FBES. Although some items on stacks have been involved in the issued standards: IEC-62932-2-1:2020 offered the determination of input/output power (chapter 6.2 and 6.3) and energy efficiency (chapter 6.4) for the FBS or FBES, while not for the stacks which don’t have BSS, BMS or fluid circulation system; IEC-62932-2-2:2020 offered the determination of external short-circuit, heat shock strength and leakage for the stacks (Annex B), there is still large deficiency for efficiently specifying the qualification of stacks during circulation. As the physical property: appearance, insulation resistance; fundamental property: charge-discharge performance, rated power, energy efficiency; enironmental adaptation: high and low temperature storage performance; trasporting aspects: vibration, collision impact; and other aspects: signs, storage, packaging of a product, are missing in the issued IEC 62932 series standards.

Therefore, the standard of VFB stack shall include not only the above aspects, but also require a more comprehensive and exclusive consideration, is urgently needed for the high-quality circulation of stacks and hence widely application of VFB systems. This standard shall match with IEC 62932 or reference the related items at the greatest extent.

In opinion of the National Energy Administration, National Standardization Technical Committee for Fuel Cells and Flow Batteries (NEA, SAC/TC23), a standard regarding ‘General requirements and test methods of vanadium flow battery stack’ is therefore necessary due to the importance of the topic and the reasons mentioned above.