Lithium coin cells are very small and very light, great for small, low-power devices. They're also fairly safe, have a long shelf life and fairly inexpensive per unit. However, they are not rechargeable and have high internal resistance (which is what makes them fairly safe if there's only one or two in use) so they can't provide a lot of continuous current: 0.005Cis about as high as you can go before the capacity is seriously degraded. However, they can provide higher current as long as its 'pulsed' (usually about 10% rate).
Pros: Light, high-density, small, inexpensive, high cell voltage, easy to stack for higher voltages, long shelf-life.
Cons: Non-reusable, low current draw capability, needs a special holder.
Lithium coin cells were originally developed in the 1970’s as a 3 volt miniature power source for low drain and battery backup applications. Their high energy density and long shelf life made them well suited for these applications. Lithium coin cells are available in a wide range of sizes and capacities.
As electronics have evolved over the decades, device designers have found lithium coin cells to be a useful power source for their size and capacity.
Many of these newer applications have low background drains and utilize very fast high rate pulses (for example sensors). When design engineers select a battery power source, it is important that all of the battery characteristics be considered including battery internal resistance, capacity, voltage, size, etc.