https://wccftech.com/2018-macbook-air-battery-replacement-easier/

Unlike the MacBook models released after 2012, the new 2018 MacBook Air would be a lot easier to repair. For the Genius Bar and Apple Authorized Service Providers, removing the battery and re-installing a new one would be less of a hassle.

Per Apple’s internal Service Readiness Guide, tools will be provided to allow technicians to replace batteries without needing to replace the entire top case enclosure, as was the case before. Even though the battery in the new Retina MacBook Air is still glued to the aluminum enclosure that contains the trackpad and keyboard, placing the notebook in Apple’s iPhone display press tool to activate the new adhesive would be enough to keep the newly installed battery in place.