1. Battery research

2. Issues around battery disposal & recycling
Batteries contain selected heavy metals, such as lead and mercury, which are toxic to our body. They cause kidney diseases and dysfunctions of various systems, e. g. gastrointestinal and nervous systems. For this reason, it is important to ensure that this waste is properly protected and eliminated from the environment. 

3. Methods of battery recycling
Depending on the type of waste (cells of one type or mixture of cells), three basic types of battery recycling processes are used in the battery recycling process: mechanical, hydrometallurgical and thermal. 

4. Mechanical processes:          the batteries are shredded and separated into different fractions: 
Ferromagnetics - steel and other metals, 
Diamagnetics - paper and plastics, 
paramagnetics - other impurities.
Hydrometallurgical method:         involves the recovery of materials by dissolving waste in acids or bases. 

5. C. Thermal method:        involves the recovery of materials by melting metal in furnaces at a temperature of approx. 1400°C. Due to the possibility of toxic substances being released from the waste, the process is carried out in such a way as to exclude direct contact with the skin, respiratory tract and mucous membranes. 

6. We are currently using electrodes:
Lead-acid battery (Planty battery) - the electrode (-) is made of lead (with additives) and the electrode (+) is made of lead oxide (IV) - such batteries are widely used in cars;
 Lithium-ion battery (Li-ion) - one of the electrodes is made of porous carbon and the other of metal oxides;
Lithium-polymer battery (Li-Po) - a variant of Li-ion batteries in which a liquid electrolyte is replaced by a solid polymer electrolyte; 
Nickel-cadmium battery (Ni-Cd), also called secondary alkaline battery - the electrodes are made of nickel hydroxide and cadmium hydroxide; 

7. How different material changes under charging and discharging conditions
Lead-acid battery:
The charging process is based on connecting the battery to the appropriate terminals of a DC source and takes about 10 hours; 
The state of complete discharge of the battery consists in the complete conversion of both electrodes into solid lead sulphate and is reversible. However, after some time lead sulphate becomes crystalline, causing a decrease in battery capacity. In this case, the battery cannot be recharged;
Lithium-ion battery:
Batteries must be charged in 2 phases: 
direct current charging at the value appropriate for the cell until the cell reaches 4.20 volts; 
DC charging at 4.20 V until the current drops to 50 mA;

8. 3. Lithium-polymer battery:
a)  These cells are not even resistant to small overloads and are easy to damage, which is why the electronic systems controlling the charging process are very complex. 
   ~ These batteries with a capacity of up to 5000 mAh are used in mobile devices: mobile phones, digital cameras, electronic cigarettes and others. 
4.  Nickel-cadmium battery:
a)  These batteries are characterized by quite high current efficiency. They should be discharged and charged in full cycles. The battery should be charged immediately, not leaving it for longer in the discharged state. This battery can withstand about 1000 charging and discharging cycles. 
~ Charging such cells is not easy, because during charging the voltage on the cell practically does not increase.

9. Why segregate batteries?
The answer to this question is trivially simple …
One watch battery can contaminate up to 50,000 litres of water and one finger battery permanently contaminates a cubic metre of earth. 
        So ...
Non-recycled batteries are deadly!