We have a complicated energy ecosystem in the modern world. We have primary consumption devices that we see all the time like your phone or your computer. We have devices that store power for those devices in the form of portable battery systems (e.g. power banks) that can extend their charge when needed. We may even have additional layers (power banks for home redundancy or use on the move) before we are plugging into infrastructure-provided power at your home, office, or wherever you may find yourself. We probably all inherently know that not all power provided is of the same quality. That 12-volt power adapter you picked up at the convenience store for $1.99 just does not charge as well as that sleek adapter that is branded with your matching phone manufacturer of choice. This is true of all the links in your power chain. That charging wire that always seems to run hotter than anything else you plug into your devices may be telling you something. The batteries (and their management systems) in many of our devices are carefully crafted and incredibly made power storage marvels. It is often easy to forget that we can cause damage that both decreases their usable life and may make them prone to failures because the links in our power chain may not be up to the job of safely charging our most treasured electronic devices. The next time you notice that slower than normal charge, that ragged connection patched with electrical tape, or the poor cord that always ends up smashed into a wad at that bottom of your travel bag, I encourage you to cut out that weak link in your power chain.
If you want to learn more about the continual improvements in cable standards, please see the USB Implementers Forum.