Nanomanufacturing - Material specifications - Part 5-2: Nano-enabled electrodes of electrochemical capacitors - Blank detail specification
1Key Takeaways
This standard specifies blank detailed specifications for key control characteristics (KCCs) of nanoelectrodes for electrochemical capacitors, including chemical, physical, structural, and electrochemical properties. This includes nano/nanostructured material electrodes for double-layer capacitors and pseudo-capacitors…
2Expert Interpretation
An in-depth interpretation of IEC TS 62565-5-2, the technical specification for nanoelectrodes, covers the key control characteristics, test methods, and standardization requirements for electrochemical capacitor nanoelectrodes, providing professional guidance for the quality control of new energy storage materials.
IEC TS 62565-5-2 Technical Specification Overview
IEC TS 62565-5-2:2022 is a technical standard for nanofabricated materials published by the International Electrotechnical Commission. It specifically addresses the blank detail specification for nanoelectrodes for electrochemical capacitors. This standard provides a standardized quality control framework for electrochemical capacitor electrode materials used in new energy sectors such as electric vehicles, high-speed trains, and photovoltaic power generation.
Scope of Application and Technical Background
This technical specification applies to electrochemical capacitor electrodes containing nano/nanostructured materials, including electrode materials for electric double-layer capacitors and pseudocapacitors. Specifically, this includes electrode systems constructed with nanomaterials such as nanoporous activated carbon, graphene, carbon nanotubes, carbon black, carbon aerogels, and carbon nanomaterial-coated current collectors.
With the rapid development of new energy technologies, electrochemical capacitors have gained a significant position in the energy storage sector due to their ultra-fast charge and discharge capabilities, long cycle life, and wide operating temperature range. Electrodes, as the bridge between raw materials and devices, directly determine the quality of the entire electrochemical capacitor industry chain.
Key Control Characteristics Classification System
| Characteristic category | Main parameters | Test method | Technical significance |
|---|---|---|---|
| Chemical properties | Moisture content, ash content, magnetic impurities | Karl Fischer method, ICP-MS, TGA | Affects electrode stability and safety |
| Physical properties | Bending strength, peel strength, rebound rate | Coating film cylindrical bending test, peeling method | Determines the mechanical properties of the electrode Energy and processability |
| Structural properties | Thickness, areal density, specific surface area | Micrometer, gravimetric method, BET method | Affect electrode electrochemical performance |
| Electrochemical properties | Specific capacitance, voltage retention, cycle durability | Constant current charge/discharge, constant voltage charge | Directly reflect electrode performance indicators |
In-depth analysis of key chemical control characteristics
Moisture content is a key quality control indicator for electrode materials. Residual moisture can seriously affect electrode resistance as well as device stability and safety. The standard recommends using Karl Fischer coulometric titration for accurate measurement. This method generates iodine through the electrolysis of an iodine-containing reagent. Based on the quantitative reaction of the generated iodine with water, the moisture content in the sample is determined by measuring the amount of electricity required for electrolysis.
The content of magnetic impurities, especially the presence of elements such as Fe, Co, and Ni, will lead to increased self-discharge of electrochemical capacitors. The standard provides three detection methods: ICP-MS, ICP-OES, and AAS, all of which require sample pretreatment by microwave digestion. The ICP-MS method refers to the IEC TS 62607-6-20 standard. Although the standard was originally developed for graphene-based materials, it can be used for other materials covered by this specification after appropriate adjustments.
Standardization of physical property test methods
Bending strength reflects the mechanical strength of the electrode and is measured using a paint film cylindrical bending tester. After cutting the electrode into specific sizes, it is bent in sequence from the largest diameter to the smallest diameter, and the diameter when the electrode cracks is recorded as the bending strength value.
Peel strength is related to various performance characteristics of the electrode, including battery self-discharge, cycle retention, electrode expansion during cycling, etc. The test uses a universal testing machine. The electrode is cut into rectangular pieces, adhered to the electrode surface with double-sided tape, and the other side is adhered to a stainless steel plate. A 180-degree peel test is performed at a specific speed.
Practical Application Case: Electrode Resistivity Test
Resistivity reflects the conductivity of the electrode and is related to the composition, structure, and uniformity of the electrode material. Since the electrode is prepared by coating the electrode slurry on a highly conductive current collector, the current collector can significantly affect the determination of the electrode resistivity. Therefore, the standard requires the measurement of coating resistivity and contact resistivity. When preparing the sample, the electrode slurry needs to be coated on an insulating substrate rather than a current collector.
Correlation Analysis of Structural Characteristics and Electrochemical Performance
Specific surface area is measured using the Brunauer-Emmett-Teller method using a suitable nitrogen adsorption apparatus according to ISO 9277. The pore volume of an electrode includes pores within the mesopores and macropores of the electrode material, as well as the inter- and intra-particle porosity of the electrode material, and reflects the electrode's ability to absorb electrolyte.
Surface density and rolling density are measured gravimetrically. The electrode and current collector are punched into several small discs, and the mass of each disc is weighed and recorded using an electric balance. Surface density is equal to the average mass of the electrode minus the average mass of the current collector. Rolling density is calculated by dividing the surface density by the difference between the electrode and current collector thicknesses.
Standardized Electrochemical Performance Testing Procedure
To understand the performance potential of nanoelectrode materials, it is common practice to assemble and characterize complete devices using these materials. Therefore, reproducible device assembly is crucial for measuring capacitor-related KCC in BDS.
Specific capacitance measurement procedure: The device assembled with the electrodes is charged to a rated voltage using CCC, then discharged using CVC for a specific time, and finally discharged using CCD to a specific voltage. The voltage across the capacitor terminals is recorded over time throughout the measurement. The device capacitance is calculated based on the voltage and charging time, and the specific capacitance is obtained by normalizing the capacitance to the mass of the electrodes in the device.
| Test Items | Test Conditions | Evaluation Indicators | Industry Standard Values |
|---|---|---|---|
| Cycle Durability | Constant Current Charge and Discharge Cycles | Capacity Retention ≥80% | 10,000 Cycles |
| Temperature Durability | High Temperature Constant Voltage Hold | Internal Resistance Change Rate ≤ 20% | 85°C/500 hours |
| Voltage Holding Rate | Open Circuit Voltage Decay | Voltage Holding Rate ≥ 90% | 72 Hour Test |
Analysis of the Degree of Standardization of Measurement Methods
The standard divides the availability of measurement methods into four situations: Case 1) No standardized measurement method has been established, but the technical community has reached a consensus on the necessity of specifying a KCC; Case 2) No standardized measurement method has been established, but good practice guidelines developed by stakeholder groups or alliances can serve as the basis for measurement; Case 3) A standardized measurement method exists that is applicable to other use cases but can be adjusted for the required use case; Case 4) A standardized measurement method exists that is fully applicable to the use case under consideration.
Currently, the measurement methods for several key parameters are still in Case 1 status, requiring suppliers and customers to negotiate and determine specific measurement procedures. This reflects that nanoelectrode technology is still in a rapid development stage, and standardization work still needs to be continuously improved.
Standard Implementation Recommendations and Industry Impact
For material suppliers, this specification provides necessary feedback from manufacturers to guide the design and production of raw materials; for end-product manufacturers, it provides a toolbox for assessing product quality in order to manage and improve process control and product yield; for commercialization and trade, it provides guidance on reference test methods for electrode classification.
Implementation recommendations include: establishing a complete quality management system to ensure full process control from raw materials to finished products; strengthening communication and collaboration between suppliers and users to jointly determine parameter requirements for specific application scenarios; and continuously paying attention to standard updates and promptly adopting the latest test methods and requirements.
The release of this technical specification will strengthen the connection between material manufacturing and downstream users, promote the standardization and industrialization of nanoelectrode materials, and provide solid technical support for the development of new energy storage technologies.