I am currently DMing a campaign where there is a wizard with the Identify spell, the bane of my existence.

Identify allows him to learn the properties of literally every single item the party encounters. I understand that Identify uses resources (either spell slots or time), which is relevant in a dungeon with wandering monsters, but out of perilous situations there are not many drawbacks.

I am going to give the characters a really cool artifact sometime in the future, with a lot of mysterious characteristics that I want them to find out slowly. One action, and all the properties are discovered.

I am creating a shop called Ocean's Potions In which a water genasi wizard creates a whole bunch of random potions in pairs, so the PC's can drink one to find out the characteristics are, and then use the other sister potion when it is relevant in the future. There will be a lot of cool, beneficial, and random potion effects that will effect them when they try them. However, Identify can let them choose the best in one action, and let benefit from the effects twice.

I understand that spells should do what they say they do, but how can I get around this spell ruining everything?

Put a Nondetection effect on the item

The spell Nondetection has the explicit effect that its target becomes unable to be targeted by Divination magic. Identify is a Divination spell. Ergo, an object that has Nondetection cast on it will not be targettable by the Identify spell.

Nondetection

For the duration, you hide a target that you touch from divination magic. The target can be a willing creature or a place or an object no larger than 10 feet in any dimension. The target can't be targeted by any divination magic or perceived through magical scrying sensors.

—Player's Handbook, pg. 263

You will potentially run into the issue that RAW, Nondetection only lasts 8 hours. As DM, however, it's not outside your purview to simply give the object a permanent (maybe dispellable with Dispel Magic or Remove Curse?) version of Nondetection. That way, your players won't be able to short-cut to learning the features of the item with a single spell. And if you do make the Nondetection effect dispellable, then it leaves the door open for your players to feel clever if they do figure out how to remove the Nondetection effect, though it does risk players simply causing the problem you were trying to prevent.

Use the "More Difficult Identification" rules in the Dungeon Master's Guide

In the Dungeon Master's Guide, there are optional rules that you can use to make identifying objects more difficult.

More Difficult Identification

If you prefer magic items to have a greater mystique, consider removing the ability to identify the properties of a magic item during a short rest, and require the identify spell, experimentation, or both to reveal what a magic item does.

—Dungeon Master's Guide, pg. 136

^{Emphasis mine}

If you want to make identification more difficult, you could require that an item require both experimentation and the Identify spell to determine its full properties. Maybe the spell reveals some surface level details and proper experimentation reveals the hidden depths.

Change the rules

Between identify, and the rules for characters figuring out what items do by spending a short rest with them (DMG p. 136), 5e is signalling to us that by design, figuring out what magic items do should not be a challenge. I can see the argument: from a player's standpoint, they might just want to use their treasure and not jump through hoops to do so; they feel like they've already earned it by finding / acquiring it. But as someone who is primarily a DM, I see the other argument too.

Bottom line: decide whether or not you agree with that aspect of 5e. If you do, just let it go, if you don't, change the rules. As-is, it is almost trivial to identify a magic item. You, as the DM, are well within your right to change rules. Doing it mid-game with a precedent already set is another matter. If you wanted to go this route, you could say that those techniques only work on, e.g. uncommon magic items (thereby saving yourself from this issue when the party starts discovering more powerful items). You'll have to make a judgement call regarding what change, if any, is appropriate given the established precedent.