Fa fa faaaa...foul! CAPITAL NO!! Every electronic gadget has a potential risk of explosion. Especially if used inappropriately.

However,
1) Branded products tend to come with a reliable manufacturing guaranty
2) Some like HetoGrow solar power banks - https://www.hetogrowshop.com/shop - tend to have double overcharge and discharge protection. This further reduces the risk of explosion due to volatility of current; and keeps battery charge for longer.
3) Branded power banks also come with detailed product spec and user manual which you must read to understand the limits of the product.

5 Reasons a Power Bank/Smartphone can Explode
1) Composition of the internal control circuit (ICC). It should be well fitted to prevent short circuit (ie, prevent sparks caused by loose wires that touch). It should control temperature and be able to shut down if a set level is exceeded, and to start working again when temperature declines back to as safe level. A key function is also to prevent overcharging and undercharging. 
2) Faulty, wrong type, poor quality or recycled batteries
3) Use of improper or... https:///xi0H2J

When gadgets explode the impact can be very devastating. Authentic gadgets tend to have a Caution Section in the user manual. Here’s HetoGrow’s safety tips to note in using your power bank - https://www.hetogrowshop.com/manual

1) Do not drop, knock, disassemble or attempt to repair the product by yourself. I suppose unless if out of warranty & you’re an expert.
2) Avoid USB charge or use of the product in a moist area or wet condition.  
3) Do not expose the product to a damaging heat source. 
4) Do not throw into water or fire.  
5) Keep away from explosive or flammable conditions or substances.
6) Keep away from children. Warranty does not cover wrong usage, human error or damage.  
7) If USB charging where current is volatile, keep safe and avoid direct body contact.  
8') Keep in normal room temperature. The standard operating temperature is 0°c - 45°c.  
9) Keep product safe. As with mobile electronic products, do not abuse or use inappropriately.  

For the best chance of avoiding an explosion you are better off with a top brand. See more pics and additional info https://hetogrow..com/2017/10/is-it-true-that-branded-power-bank-wont-explode.html