Auto Increment the PersonID field using Invoke-Sqlcmd in Powershell

I have a non Primary Key PersonID in person. How do I auto increment the PersonID field using Invoke-Sqlcmd in Powershell.  

INSERT INTO person (firstname, lastname, title, entityid, workgroupid, supervisorid, did, BirthDate, HireDate, type, site, remote, email, HRID) VALUES ('Trey', 'Songz', 'Manager - Customer Support', '308', '272', '4691', '610-504-6644', '12/12/1977 00:00:00', '04/20/2020 00:00:00', 'Employee', 'Denver, CO', '1', 'trey.songz@verizon.com', '6700');