Chemical vapor deposition and filtration are commonly used to fabricate freestanding multiwalled carbon nanotube sheets containing iron(III) oxide (Fe 2 O 3 ) (MWCNT-Fe 2 O 3 sheets). However, the former is relatively expensive, and the latter suffers from poor scalability. Here, the authors develop an inexpensive, scalable, high-throughput, tunable tape-casting method for fabricating flexible, foldable freestanding MWCNT-Fe 2 O 3 sheets. When tested as electrodes in lithium-ion batteries, the sheets perform better than conventional graphite on copper foil (681 mAh g À1 after 20 cycles at 100.5 mA g À1 /0.1 C-rate vs. 72.5 mAh g À1 after 20 cycles at 37.2 mA g À1 /0.1 C-rate). Sheets prepared at Fe 2 O 3 :MWCNT mass ratios ranging from 1/4 to 2/1 are flexible and easy to be separated from the substrate, but a sheet prepared at a 9/1 ratio is not. The ratio can be tuned to suit various applications. Sheets with high (low) Fe 2 O 3 :MWCNT mass ratios has high (low) charge-transfer resistance and are suitable for applications requiring high energy density (high power density). Mechanical compression of the sheets flattens them and increase their density from 0.449 to 0.771 g cm À3 , which in turn increases their electrical conductivity from 3.56 Â 10 3 to 5.73 Â 10 3 S m À1 .