One of the consequences of not understanding our conscious nature is the idea that we are fragile bubbles of energy and that we need to protect our energy from the negative energy or attacks of others.
Protection is a somewhat misguided notion. Real protection comes from wisdom, not from the energetic or physical. It's our understanding or wisdom-mind that manages our energy and body system. If we think of our total system as a pyramid with layers, most people have their emotions and their energy at the top, thinking that this is their real self and should dictate what they do. The proper position is for the conscious intellect to be at the top, from which place its wisdom dictates the lower levels.
If I'm in a city and I see someone yelling angrily across the street about a parking dispute, I do not need to worry about how to protect my energy system from his negative energy.
As long as my understanding of the situation is in place, then my mind remains clear and at peace despite his rage. On a physical level nothing is ever guaranteed but, insofar as possible, I am protected by my understanding that angry people can be dangerous and that I should therefore completely avoid the situation. If I am very concerned for the safety of others around, I might call the police.
Emotionally and energetically, when we are around toxic, negative emotions it does not feel pleasant. For example, it can make us feel more tired and frustrated if we spend a whole week with angry or depressed people.
Once you are in the presence of very negative energy, you cannot entirely avoid feeling it. The lesson is to gain the clarity to avoid such situations in the first place.
Your partner wants to know if you want to go on vacation with another couple, one of whom is highly negative? Say no thanks, that's not how I want to spend my time. Don't rationalize to yourself why you should just go along for the ride and put up with it. Unless there is a very good reason to tolerate it, such as a rare family duty to perform, say no to being around people who have a heavy, negative mind.
Keep your energy clean and positive by gaining wisdom and positive habits, and avoiding negativity as much as possible. Your No to negativity is a Yes to the positive. That also means saying no to useless amounts of talking, debating, discussing and negotiating.
In this world, it's not possible to entirely evade contact with negative people or emotions. But you don't need to resort to magical ideas for how to protect your energy. You just need wisdom.