Some household batteries contain chemicals like lead, mercury or cadmium. If batteries are thrown into your normal rubbish bin, they are likely to end up in landfill. Once buried, the batteries start to break down and can leak some of these chemicals into the ground. This can cause soil and water pollution, which may be a health risk for humans.
Recycling stops batteries going to landfill and helps recover thousands of tonnes of metals, including valuable metals like nickel, cobalt and silver. This reduces the need to mine new materials, cutting CO2 emissions and saving resources.
from the Gov web site