Lithium batteries cycle life
Cycle life does not mean a full charge/discharge cycle. It is the actual amount of energy that "passes through" the battery during it's lifetime.
Lithium batteries have the advantage that you can also really use that high cycle life.

For example: let's say we have a battery that you discharge and charge daily and this way it lasts 1 year. ( 1 C /day => 1 year)
If you were to not fully discharge this battery but discharge it until it's half full and then charge to full it would last 2 years ! (0.5 C /day => 2 years)
Likewise at 1/5th discharge per day it would last 5 years.

Note how the amount of displaced energy remains the same:
1 charge per day for 1 year is the same amount of energy as 1/2 charge per day during 2 years.

This is one of the unique properties of Lithium based rechargeable cells.

Lithium cells have no memory effect, the oldfashioned Nickel-Cadmium (NiCd) cells have a memory effect, if you only use 1/2 of their capacity each day they "lose" the unused part of the capacity and they remember (the memory) that you only discharged them 1/2 last times and now they assume that's all you need.

Nickel-MetalHydride (NiMh) cells used to have high self-discharge, they discharge even when you're not using them. Nowadays we have low-self discharge NiMh cells (Sanyo Eneloop, GP ReCyKo) that have fixed this problem.

Lead-Acid batteries (used in cars mainly) are cheaper than Lithium Ion cells but can store less enery per volume.

Lithium cells have the advantage that they can store a high amount of energy in a small space and they are not very heavy.

Lithium cells must be manufactured properly though and also charged properly, mistreating them can result in smoking, fire and even explosion !