Depending on how the electricity is generated, electric vehicles promise much more sustainable transport with lower CO2, NOx and particulate emissions. Although EVs are still a small percentage of new-vehicle sales, the share of cars containing an electric engine is expected to rise to 50% by 2030.
Electric and hybrid vehicles are equipped with regenerative braking. This means that the electric motor acts as a generator when braking which charges the battery. Conventional brakes are much less used so drivers need replace brake pads only rarely, even for city driving. Brake pad wear for autonomous driving cars is even lower because of better prediction of emergencies. McKinsey predicts that fully autonomous driving with human override (level 4 autonomy) could account for 60-70% of all miles driven in the US before 2030. Brake pads for those cars could last the whole life of the car. All this will also greatly reduce the brake aftermarket.
Corrosion, wear and noise
Longer brake pad life brings its own problem, though, since corrosion on rarely used brake pads and rotors can affect brake performance. This should be addressed within a couple of years with corrosion-resistant friction materials and rotors.
Quiet operation is particularly important for electric vehicles because of their virtually silent running. Noise (including high-frequency squealing), Vibration and Harshness all become unacceptable in terms of driver and passenger comfort. Currently brake pads on EVs have to be much larger than on conventional cars due to the additional weight of the car caused by the batteries.
So, although electric vehicles promise a breakthrough solution to urban pollution from traffic congestion, brake wear and the resultant emissions must fall, too. There is talk of zero-emissions cities in the future. Safe driving will then above all need advanced design and highly consistent, quality-controlled production of the brake pad materials.
Brake compounders and raw materials suppliers have to work together closely to improve the brake friction, lubrication and wear (tribology).