What should be paid attention to in the application of battery energy storage high temperature adhesive tape?

Matters needing attention in application of high temperature adhesive tape in battery energy storage field

The high-temperature adhesive tape in the field of battery energy storage mainly adapts to the production, assembly and operation and maintenance conditions of lithium batteries and energy storage battery packs, and needs to meet the high-temperature, high-pressure, multi-media and electrical safety requirements of battery cell welding, module packaging, outdoor energy storage and other scenes. The application needs to focus on the core dimensions such as substrate adaptation, process matching, safety protection and operation specification, so as to avoid problems such as poor battery contact, insulation failure and thermal runaway risk caused by improper use of the adhesive tape. The specific precautions are as follows:

Accurately match the high temperature resistance grade of battery working conditions.

It is necessary to select the adhesive tape with corresponding temperature-resistant specifications according to the actual use scenarios, such as short-term high-temperature procedures (above 200℃) such as battery lug welding and bus bar welding, and it is necessary to select polyimide high-temperature adhesive tape with high temperature resistance of 300℃ and above; In low-temperature working conditions (80-150℃) such as battery module packaging and package assembly, PET high-temperature adhesive tape with temperature resistance of 150-200℃ can be selected. It is strictly forbidden to use low-temperature adhesive tape in high-temperature working procedures to prevent battery cell pollution and short circuit caused by tape melting and adhesive layer falling off. At the same time, attention should be paid to the duration of temperature resistance of the tape, and the short-term high temperature and long-term constant temperature conditions should be distinguished to avoid failure due to insufficient temperature resistance.

Confirm the compatibility with the battery substrate to avoid adhesion failure and pollution.

The field of battery energy storage involves aluminum foil/copper foil, tab, plastic shell, lithium battery diaphragm, electrolyte, thermal grease and other substrates and media. Before application, it is necessary to test the compatibility between the adhesive tape and the contact substrate: first, ensure that the adhesive layer is firmly bonded to the metal substrate (aluminum and copper) without warping and degumming, and is suitable for the deformation of the distribution core/module when it expands with heat and contracts with cold; Second, avoid direct contact between the adhesive tape and chemical media such as electrolyte and heat transfer oil, so as to prevent the adhesive layer from being corroded and swollen, which will lead to the decrease of adhesive force or produce harmful substances to pollute the inside of the battery; Third, it is forbidden for the adhesive tape to contact the lithium battery diaphragm, so as to prevent the adhesive layer of the adhesive tape from transferring, and the substrate hardness from being too high to scratch the diaphragm, causing micro-short circuit of the battery cell.

Strictly control the surface treatment of substrate before construction.

Before adhesive tape bonding, it is necessary to thoroughly clean the bonding surfaces such as battery tabs, bus bars and module housings to remove impurities such as oil stains, dust, oxide layers, solder paste residues, electrolyte traces, etc. The adhesive tape can be wiped with special cleaning agents such as anhydrous ethanol and isopropanol, and then applied after the surfaces are completely dried. Oil stain and dust will greatly reduce the adhesive force of the adhesive tape, the oxide layer will lead to uneven adhesion, and the solder paste and electrolyte residue may react with the adhesive layer, which will affect the stability of the adhesive tape and even cause battery safety hazards.

Follow the standard construction to ensure the bonding quality and accuracy.

When pasting, it is necessary to ensure that the adhesive tape is closely attached to the base material, free from bubbles and wrinkles, especially the key parts such as tab wrapping and line insulation, which need to be compacted with tools such as scraper and roller to avoid the gap on the bonding surface caused by bubbles, and the edge will become warped and fall off under high temperature and vibration conditions. When cutting the adhesive tape, the size must be accurate, and the insulation package must be bare and seamless to prevent electrical insulation failure caused by incomplete adhesive tape coverage; For battery pack splicing, sealing and other scenes, the adhesive tape should be kept straight to avoid too large a gap at the splicing place. At the same time, dust-free gloves should be worn during construction to prevent oil stains and sweat from contaminating the adhesive surface of the adhesive tape and the battery substrate.

Strictly control electrical safety and avoid the risk of insulation failure.

The battery energy storage tape mostly bears the role of insulation and isolation, so attention should be paid in application: First, the tape with corresponding insulation strength should be selected according to the battery voltage grade, and the high-voltage energy storage battery pack should be selected with special insulation high-temperature tape with breakdown voltage ≥10kV, and it is forbidden to replace it with ordinary high-temperature tape; Second, when the adhesive tape is wrapped in layers, the overlapping width of the layers should not be less than 5mm to prevent the gaps at the layers from causing weak insulation; Third, avoid the use of the adhesive tape in the bending and stretching state, which will lead to the cracking of the adhesive tape substrate and the separation of the adhesive layer and reduce the insulation performance; Fourth, it is forbidden to cover the safety components such as the temperature sensor, pressure relief valve and explosion-proof sheet of the battery with adhesive tape to prevent the temperature monitoring and pressure relief and explosion-proof functions of the battery from being affected.

Adapt to the subsequent operation requirements of battery technology

If the tape needs to go through subsequent processes such as battery injection, aging, hot pressing, baking, etc. after use, it is necessary to confirm in advance whether the tape is suitable for the corresponding process: the tape pasted before the injection process must have the characteristics of electrolyte resistance and moisture resistance, and there is no residual adhesive layer after peeling, so as to avoid polluting the injection system; In the aging and baking process (60-85℃), the adhesive tape with stable adhesion should be selected to prevent the adhesive layer from softening and shifting after high temperature baking; The adhesive tape removed after battery cell welding needs to ensure that there is no residual glue and substrate residue, which will affect the subsequent packaging and bonding process of the battery and even lead to poor battery cell contact.

Control the storage and construction environment to avoid premature failure of the adhesive tape.

Unused high-temperature adhesive tapes should be stored in a cool, dry, ventilated and dark environment, with the temperature controlled at 5-25℃ and the relative humidity ≤60%, away from fire sources, heat sources, electrolytes, organic solvents, etc., to prevent the aging of the adhesive tape substrate and the adhesive layer from becoming sticky. It is forbidden to use expired adhesive tapes during the storage period. The construction environment should be kept dust-free and dry, and the adhesive tape should not be pasted in the environment with high humidity (> 70%), high dust and corrosive gas. High humidity will cause water vapor on the adhesive surface of the adhesive tape, which will reduce the adhesive force, and the corrosive gas will corrode the adhesive tape substrate and adhesive layer.

Pay attention to the sample test before batch application.

Under the new batch of adhesive tapes and new application scenarios (such as new battery base materials and new process conditions), it is necessary to carry out small sample test first to simulate the actual working conditions such as high temperature, vibration, chemical contact, cold and hot cycle, test whether the adhesive force, temperature resistance, insulation and compatibility of the adhesive tapes meet the standards, and then carry out batch construction after confirming that there is no failure, pollution and potential safety hazard, so as to avoid the quality problems of batch products caused by improper tape selection or mismatched working conditions.

Standardize repair and disposal to avoid secondary risks.

When repairing the battery, peeling off the failed adhesive tape should be done gently with special tools to avoid scratching the battery substrate, tab or diaphragm; After repair, the adhesive surface needs to be cleaned again, and after removing the residual adhesive layer, a new adhesive tape is applied. Waste high-temperature adhesive tapes (including adhesive layer and base material) should be collected separately to avoid mixing with electrolyte and battery waste, and to prevent the organic components in the adhesive layer from reacting with electrolyte. At the same time, it is strictly forbidden to throw them away at will, and they should be treated according to the relevant standards of industrial solid waste.

Follow the product instructions and match the industry standards.

The selection, construction and storage shall be carried out in strict accordance with the product instructions of the tape manufacturer, and the use mode (such as over-temperature, over-pressure, out-of-range use) shall not be changed at will. At the same time, the high-temperature adhesive tape for battery energy storage should meet the relevant standards of new energy battery industry (such as GB 31241, UL 94, etc.) and have the characteristics of flame retardant, halogen-free and low smoke, especially in outdoor and large-capacity scenes such as energy storage battery packs. It is necessary to use V0-grade flame retardant high-temperature adhesive tape to reduce fire hazards, and it is strictly forbidden to use non-certified and non-dedicated high-temperature adhesive tape.