@EdS
in my last toot I talked about temperature gradients inside a pack. Here it is different, it is inside each cell, but it is also true. Temperature gradients inside a single cell lead to non uniform (and faster) ageing.

@EdS
The problem is when ageing is not the same in all cells, if one cell is at 8Ah but all other it is 9, your pack capacity is the minimum, that is 8Ah... Temperature gradients in a pack lead to non uniform ageing.

@EdS
a battery is a series/parallel association of cells. In series you are adding voltages, and in parallel you are adding capacities (Amp-hours). For example, if you put in series 80 3.7V 10Ah cells you get a 300V 10Ah pack that is 3kWh . The pack capacity is equal to the capacity of the smallest cell (when fresh, they all are 10 Ah)...

@EdS as a widely spread rule, 10°C of difference would change the battery lifetime in a factor of two (x2), that is, if you keep your battery 10°C colder it will last 2 times more.
This rule is not always true, but it could be considered here as an illustration.
In fact this is true when battery is at rest (not used). For example, when charging a battery, excessive cold temperatures can damage a battery (under 15°C).

@EdS the inner temperature of a battery cell is very important in battery degradation. Depending of the cooling design and current flow on the battery temperature may vary in a very significant way and then battery degradation (because it is directly related to temperature)...

@thardin The main difference between batteries and supercacitors is in power and energy densities. Supercapacitors are very powerful, that is, they can deliver all their energy in a very short time, but compared to batteries the total stored energy (per kg) is very low: they have high power density but poor energy density.
Inversely, (lithium-ion) batteries can store a big amount of energy but they can not be charged/discharged very quickly.
The applications of both devices are different.