Final answer:
Modern batteries are difficult to work on because they are sealed, and their design often makes them single-use or disposable. They contain solids or pastes for improved efficiency, and many types have toxins, requiring specialist knowledge for safe handling.
Step-by-step explanation:
One of the main reasons why modern batteries are difficult to work on compared to older batteries is because they are sealed. Modern batteries, like dry cells, button batteries, and lithium-iodine batteries, use solids or pastes which enable a compact and efficient storage of energy and help maintain a reasonably constant output voltage throughout their discharge process. However, this design also means that once a modern battery is depleted, it cannot be easily opened or serviced, contrary to older batteries such as the standard car battery which use a solution phase chemistry allowing for maintenance like adding distilled water to the cells.
Another factor is that modern batteries are often designed to be disposable, with rechargeable options like nickel-cadmium or lead-acid batteries being the exception. Rechargeable batteries offer economic and environmental advantages due to their ability to be recharged multiple times. However, when they do fail, they typically require a skilled specialist to safely handle the chemicals and components involved in the repair or recycling process.
The presence of toxins in many modern batteries is another reason working on them can be problematic. These toxins can be hazardous to health and the environment if not handled correctly, necessitating careful procedures and expertise for safe disposal or recycling.