Something to test out(SyncToy.ps1):
$BitLockerPass="fjuksAS1337"
$SecureString = ConvertTo-SecureString $BitLockerPass -AsPlainText -Force
Unlock-BitLocker -MountPoint "E:" -Password $SecureString
"C:\Program Files\SyncToy 2.1\SyncToyCmd.exe" -R "PowerShell Projects"
Note: you should store the encrypted password somewhere other than your script for production use.
Reference:
SyncToy
Unlock-BitLocker