These two most popular secondary batteries may seem hard to separate when choosing a suitable battery for electronic devices that require a lot of energy in a rechargeable package. But there are some key differences to consider.
Li-ion batteries
Lithium-ion have become the benchmark in rechargeable batteries for electronics which require a lot of power due to their high power density, resistance to ‘the memory effect’ (when batteries progressively take on less charge as time goes by), and their low purchase cost. They also retain charge well when unused, having a fairly low self-discharge rate.
However, they have been dogged by safety issues which were brought into the public’s consciousness with the Samsung Galaxy Note 7 recall due to the phones’ Li-ion batteries catching fire. Li-ion batteries can be prone to catching fire if damaged, incorrectly charged, or stored in the wrong conditions. They are designed in such a way as the positive and negative electrodes cannot come into contact with each other, but if damaged that can change and cause fire.
They also age and slowly retain less overall charge over time, although this is not enough to prevent them from being an effective power source for a number of years for most devices.
Li-po batteries
Lithium-polymer batteries are the ‘newer kid on the block’ and are much loved by manufacturers of premium electronics or devices where space is at a premium as they are thinner and lighter than Li-ion batteries while providing a similar (slightly lower) power capacity.
They do not suffer from the same fragility that Li-ion batteries do, as they don’t use a liquid electrolyte which could leak upon damage. Because they don’t require a rigid shell for protection they’re around 20% lighter and can be formed thinner, too.
What makes them less desirable is their very high purchase cost and shorter lifespan.