I have a spare laptop battery which was never used, and when I tried to use it after taking it out of storage, I found that it had died.
Do laptop batteries die out at after a certian time ( 2 years?) regardless of whether they was used or not?
Different answers for Li-ion and Ni-cad?
TIA all replies. 
Yes, they do. All batteries die eventually and dry-cell batteries go more quickly than wet cells. Lithium ion batteries generally have a longer shelf-life than Nickel-Cadmium and rechargeable batteries that are used regularly last longer than batteries which are never used at all. If you have a spare battery it is a good idea to switch them out regularly. Ni-cads also have a ‘memory’ so you need to discharge them fully between chargings.
You can extend the life of your non-rechargeable dry-cell batteries if you store them in the freezer.
Welcome to the board!
Yes, all batteries die, but that sounds a bit extreme. Is it completely dead? If if’ts just mostly dead, it may recover (at least partially) after a few cycles.
While that’s not exactly false, what most people call memory effect is most often a voltage depression caused by over charging the cells. For more info, look here
That’s what I’ve always done too, but it might not be so usefull anymore. it this thread samclem noted that consumer report couldn’t find any significant difference when storing batteries in the fridge/freezer. In some batteries it can even be harmfull, in that the electrolyte might freeze, which I guess could be bad…
Batteries are made up of cells. (Hence it is a D-cell, not a D-battery.) In the cells of a battery, not all are equal and one may be weaker than the others. It can self-discharge faster than the other. Then when you go to charge it, the other cells charge (somewhat) normally but the weak one won’t. (The charged cells limit the current to the uncharged one.)
One solution is to open the battery and charge the weak one individually. But: 1. That is not standard consumer do-it-your-self stuff. 2. You still have a weak cell so it’s a temporary fix.
Note that a Ni-Cd cell completely discharging Is Not A Good Thing (as the first link given by Popup points out).
Recommending that a Ni-Cd be fully discharged, as tcburnett suggests, is also Not A Good Thing.
There are significant differences in how Ni-Cd and NiMh batteries should be treated, again see Popup’s link.