Lead-acid batteries
The old workhorse of car starters, UPS units and home inverters.
Storage · Electrochemical · No. 72
- Storage
- Duration: Hours
The battery under your car bonnet has the best recycling loop of any battery, yet careless recycling poisons children.
Chart: Illustration: Lead-acid batteries
Where it comes from
Chart: Map of where it comes from
Two plates of lead and lead dioxide sit in sulphuric acid and turn into lead sulphate as they discharge; the EU will require 85% recycled lead from 2031.
Three things to know
- Lead-acid stores only 25 to 50 Wh/kg, against 150 to 300 for lithium-ion, so it is heavy for its energy.
- Up to half of lead-acid batteries in poorer countries are recycled informally, spreading a neurotoxin into soil, air and blood.
- Its water-based acid cannot burn, so US fire rules only apply above about 70 kWh, against 20 kWh for lithium-ion.
The journey
- 1 Lead and acidMostly recycled lead, dilute sulphuric acid
- 2 PlatesLead dioxide and spongy lead plates
- 3 DischargeBoth plates turn into lead sulphate
- 4 Backup dutyCar starters, UPS, telecom, home inverters
- 5 RecyclingSmelted again, safely or informally