Have you seen this Haribo power bank? It's cute! It's also become a sensation on social media because it offers one of the best power-to-weight ratios on the market, with a capacity of 20,000 mAh at just 286 grams. We CT scanned one and found something alarming inside... 🧵

The power bank's enclosure contains two lithium-ion pouch cells. In this @lumafield CT scan we can strip away the lower-density plastic shell and isolate the bank's electronics and side-by-side battery cells.

We can section in from the side to see a cross-section of the battery cells.

Here's a detailed look at the top of those battery cells. Lithium-ion pouch cells are made by coating a thin foil with anode and cathode materials, then winding them up into an oblong "jelly roll". Controlling this winding process is extremely important; uneven winding leads to unpredictable current distribution, which causes lithium plating, dendrite growth, and possibly shorts and thermal runaway, which can cause fires. This cell has very poor anode-cathode overhang consistency!

Here's a cross-section of a high-quality cylindrical cell to give you an idea of the consistent anode-cathode overhang we'd expect to see in a good battery. If you want to learn more about lithium-ion battery quality, check out this thread:

The bottom of the Haribo power bank is even worse; in some spots there's practically zero anode-cathode overhang!

Hong Kong DC Global offers two versions of these wireless Haribo-branded earbuds under license from the gummy bear producer, priced at just $11.19 for the basic model and $19.20 for a model with a small touchscreen on the case that supports fun wallpapers.