Just to add a bit:
Yes, the Maxells seem to be the worst of the 1/2 AA lithiums, but the white-and-green ones are also pretty bad. Tadirans (purple and black) usually fail the least catastrophically but given enough time and/or poor storage conditions they too will leak.
If you notice, on the models with the square battery packs with the leads, the wires act as wicks when the batteries leak: the electrolyte travels from the bad battery all the way to the connector where it begins corroding the logic board connector and beyond. It's usually visible as a greenish blue tint on one of the wires at the connector. If the leakage spills beyond the battery pack the velcro usually absorbs a lot of it which thankfully localizes and reduces the damage done.
This mode of failure also happens when PowerBook backup batteries leak. Yes, they will and do leak. The electrolyte will not only leak out of the battery pack and corrode anything around it, but is also wicked to the terminal of the connector where it inflicts damage to the logic board.
If you collect PowerBooks of any vintage, I highly recommend removing the backup batteries from all of them. Some still have replacement battery packs available, if you really need to be able to sleep-swap the main battery. I have yet to see one of the soldered backup batteries from the original 1x0 series cause any problems but it's likely only a matter of time before they do. Also, do not store the PowerBook with its main battery installed. This should be common knowledge but from as many ruined models as I've seen it apparently isn't.