Original publication is here [1].
A commentary in Nature here.

Dockless shared e-scooters are touted as a solution to the last-mile problem, a means to reduce traffic congestion, and an environmentally preferable mode of transportation. While these e-scooters have no tailpipe emissions, full consideration of the life cycle impacts is required to properly understand their environmental impacts.
(…)
Our study differs from previous research by conducting a full LCA to address the environmental impacts associated with the materials, manufacturing, transportation, charging, and end-of-life for shared dockless standing e-scooters.

[1]

Aluminium in the scooter frame and lithium in the battery must be mined, and all the vehicle’s components manufactured. Those steps accounted for about half of the greenhouse gases an e-scooter is responsible for over its lifetime. Almost as significant were the environmental costs of collecting discarded scooters and transporting them to charging stations — a task usually performed by scooter-company employees driving personal vehicles.

Using an e-scooter is more carbon intensive than walking or biking. The scooters are environmentally friendly only when people use them for trips they would otherwise take in cars.

– Nature

[1] Joseph Hollingsworth, Brenna Copeland and Jeremiah X Johnson, Are e-scooters polluters? The environmental impacts of shared dockless electric scooters. Environmental Research Letters, 14, 8 (2019).