Air pollution is a silent killer that takes the lives of some 7 million people every year through heart disease, stroke, lung cancer, and other respiratory ailments. According to the World Health Organization’s World Ambient Air Quality Database, nine out of 10 people on Earth breathe polluted air, with populations in low-income cities impacted the most. Much of that pollution comes from the exhaust fumes of motor vehicles.

Electric motorcycles and scooters are a key component in air pollution reduction strategies, particularly in cities where the cost of electric cars is unattainable for most people. Improving the range and lifespan of e-scooters takes lightweight, durable, and flame-retardant materials, making DSM’s portfolio of engineering plastics critical to this expanding market.

One particularly challenging component in electric vehicles is the battery. High-capacity batteries help manufacturers extend the range of electric two-wheelers, yet they also need to be rugged to deal with vibrations and impact, and removable so riders can recharge them conveniently. The high voltages produced during charging and discharging of individual cells also creates substantial heat. DSM’s portfolio of materials includes specialized grades that are ready to meet the requirements of this challenging application.

Lithium ion batteries

Used across a wide array of electronics applications – including smartphones and electric vehicles – the latest generation of lithium ion batteries (LiBs) produce much higher outputs and energy density compared with lead-acid batteries.

LiBs are composed of numerous cells connected together. The individual cells each contain electrodes, a separator, and an electrolyte, which conducts the lithium ions from the positive to negative electrodes. The electrolyte used in LiBs is flammable, which poses safety concerns in the event of a short circuit or leakage that could lead to fire or explosion.

To improve the safety of LiBs, dedicated additives are mixed into the electrolyte to improve the specific gravity, charge-discharge efficiency, thermal stability, cycling performance, and overall safety and service life of the battery. DSM is one of the largest global producers of succinonitrile (SN), delivering an additive of the highest purity to improve the safety of LiBs used in electric vehicles, laptops, smartphones, and outdoor equipment.

To avoid electrolyte leakage at the cell contacts, high-performance plastics can be used to seal the prismatic cells. The material used in this application must be highly resistant to chemicals, and provide a very strong bond between metal and plastic. DSM’s  Xytron  polyphenylene sulphide (PPS) materials demonstrates excellent metal-to-plastic bonding based on adhesive-free nanomolding technology.

The individual cells are connected together using busbars safeguarded by fuses, making the stability of the total system essential. If one or more cells become displaced, it places unnecessary electrical and mechanical stresses on the system, potentially leading to failure.

The materials used in this application need to demonstrate high stiffness and dimensional stability, excellent temperature and chemical resistance, intrinsic flame retardance, and high thermal conductivity to move the heat generated within the cells away to the module’s heat sink. Our Xytron TC5070C and TC 5018I grades were designed to meet the specific needs of this application.

DSM has also proposed replacing battery trays made from conventional plastics with trays made from thermally conductive plastics such as Xytron, Arnite PET, or Stanyl PA46. Thermally conductive battery trays would help to avoid local hot spots within the battery and greatly improve the thermal management of the total battery module, with the potential to extend the cycling capacity by 20% or more.

Finally, the total battery module is enclosed within a battery cell housing that ensure that each battery remains in position through the vibrations and harsh conditions the vehicle is exposed to. That material used for the cell housing needs to demonstrate excellent mechanical strength and chemical resistance. DSM’s Akulon polyamide compounds provide the strength and chemical resistance needed, as well as easy processing, and a UL94 V-0 flammability rating.

Talk to us today about the material requirements for your electric two-wheeler batteries.