I have an old LiPo battery that is nearing the end of its life, how can I dispose of it safely?
First is to discharge the battery to zero volts which can be done by using a LiPo charger or a light bulb. It can then be thrown into a recycle bin, but check with your municipality before doing so as some will not take them. There may be a local or regional centre where they can be dropped off.
It is not advised to use salt water as it takes a long time and its corrosive nature to metals can lead to incomplete discharge.
In the UK, battery retailers and distributors are required to accept waste batteries for disposal if they sell more than 32kg of batteries a year (see https://www.gov.uk/battery-waste-supplier-reponsibilities.)
It is also likely that your local municipal dump will accept batteries for disposal, but you will need to check for your area.