Lenovo ThinkPad X220 really does get 20+ hours of battery life (sort of) - Liliputing
Amazon.com: Lenovo 0A36307 ThinkPad 9 Cell Extended Life Battery 44++ for Lenovo ThinkPad X220, X230 Models Only. (Caution: Not for X220 Tablet, X230 Tablet Models) : Electronics
Amazon.com: Lenovo ThinkPad 9 Cell Lithium Ion Battery 44++ ( Manufacturers P/N; 0A36307 ) 94Wh Extended Life System Battery For X220 And X230 Laptops Only : Electronics
29++ 9 Cell Battery for Lenovo ThinkPad X220 X220i
Lenovo ThinkPad X220 Review - StorageReview.com
Lenovo X220 X220i Tablet Battery
Amazon.com: Lenovo ThinkPad 9 Cell Lithium Ion Battery 44++ ( Manufacturers P/N; 0A36307 ) 94Wh Extended Life System Battery For X220 And X230 Laptops Only : Electronics