I do business in Shenzhen China and know quite a lot about trade in mobile phone battery's.
Certain buyers insist on the lowest price around $1.5 US and some company's are willing to supply anything you ask for. Battery's come with certain built in safety devices in the form of 2 integrated circuits. These are supplied as 1 IC or 2 IC one regulates the charge the other detects short circuits and overheating the cost is very low just a few cents. Problem is they take up room in the tiny battery so if you leave them out you can put more chemical in giving the battery a longer life or use chemical of lower quality and cost. Any damage or leakage exits from the weakest point in the battery the end at the convectors. This is a real problem the fluid being a conductor the battery then shorts out and you hope pray its a 2 IC model. Having the pallets sit on the ground in Dubai 40 degrees and then exposed to lower pressure is a disaster waiting to happen.There is no way to determine the quality of a battery without actually destroying it, unless you have your own QC people in the factory, assuming they are not bribed. Labels and boxes mean nothing in China which ever brand would you like is possible.
Its really bad news Phone battery's do not belong in aircraft unless you are 100% sure of the supply chain and fire systems on the aircraft are in place.
The risk of fire is so great I will not deal in battery's.
Last week an electric car in Shenzhen was hit in an accident and burst into flames killing all 3 in the car. There is no petrol in an electric car, the cause of the fire is currently being investigated.