We used to know how to make batteries that didn't leak - 1980's RadioShack's helishly expensive premium series of batteries were nearly bulletproof. I wish I still had a choice between cheap shit and spending a bit more for batteries that don't destroy my gear.
That's why mercury was added to batteries, it was a leakage protection barrier, but of course now it's banned.
That is what I was going to suggest but you beat me to it. Before the tiny amount of mercury was removed from alkaline batteries, I do not remember them ever leaking.
Ahh so the added mercury stopped gas build-up.
"Gas can form in all of these [alkaline] batteries due to the corrosion of zinc. Zinc in the battery gets corroded into the electrolyte as the battery is used. This corrosion can cause electrolysis and can cause the generation of hydrogen gas in the canister. Build-up of hydrogen gas can cause the battery to leak, limiting the ability of the battery to function. Mercury suppresses this zinc corrosion, which is why it is added..."
I'd like to believe the mercury environmental bans made Duracell batteries crap, but other brands aren't leaking. I can still buy Dick Smith AA batteries, 12 year supply stockpiled... and years old already but not leaking lol.
You need a seal that can "burp" or permit gas to pass, but not electrolyte.