Lenovo is well known for their accessories. The W530 is a demanding and power hungry system, but Lenovo has kept the swap-able batteries. Also, they have a neat port underneath many business systems. Under the W530 you can view a port that can be used for connecting the ThinkPad Battery 28++. This is a 9-cell slice that compliments the system. More images and details below.
Top side of the 28++. On the left side it seems like the battery has a dedicated charging port (likely for devices like the Minidock)
Bottom side of the 28++. It has a lock and a release latch.
The slice and W530.
Attaching the battery to the W530. Also, the battery does NOT extend the full length of the W530.
Ensure that you lock the battery.
Rear view of the system with the battery attached.
Slope has increased.
Depending on user preference, some will like the new angle, while others won't. The battery also adds more weight to the already heavy W530.
Lenovo Power Manager can handle both batteries at the same time. The 28++ will extend the total battery life. I have not done proper tests, but it could nearly double the battery life.