Lenovo expands its ThinkPad X1-series with the X1 Titanium Yoga, an expensive business convertible. It is just 11.5 mm thin and also the thinnest ThinkPad so far, but you have to make compromises.
https://www.notebookcheck.net/The-Lenovo-ThinkPad-X1-Titanium-Yoga-is-too-thin.531416.0.html