I have mouse that take two AAA batteris, so it take 3V.
Is it OK put one 10440 of 3.7V and one spacer instead?
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While a fresh alkaline cell would typically have an open circuit reading of a little more than 1.5v leading to a series pair producing more than 3v, this would never be as high as 3.7v in practice.
You'll also find that your 3.7v cell is actually closer to 4.2v when fully charged.
Although it's possible that the designers of your mouse used ICs with a wide voltage range, it's very unlikely as this would probably be more expensive.
As such you'll probably find that your mouse's max operating voltage is 3.3v and might survive a short term peak of up to 3.6v.
So your 3.7v nominal (4.2v peak) lithium cell is very likely to do some damage - don't do it.