The latest report projects that the power bank market will be worth US$29.5 billion in the next 5 years. It indicates that the growth in demand for devices such as smartphones drive this industry. In addition, it is possible that different forms of energy storage (such as hydrogen as opposed to lithium-ion batteries) may influence this market in the near future.
https://www.notebookcheck.net/The-power-bank-market-may-be-worth-nearly-US-30-billion-in-2024.427000.0.html