Folding insensitive, high energy density lithium-ion battery featuring carbon nanotube current collectors

Here we report a fully foldable lithium-ion battery (LIB) with high energy density using Li4Ti5O12 (LTO) as the anode and LiCoO2 (LCO) as the cathode with free standing carbon nanotube (CNT) Macro-Films (CMF) as the current collectors. The CMFs were produced using a scalable Floating Catalyst Chemical Vapor Deposition method. The highly flexible CMFs could be folded multiple times without plastic deformation. Importantly the active material (LTO in case of the anode or LCO in case of the cathode) infiltrates into the pores of the CMF forming a strong interface that is resistant to delamination even when the battery is folded repeatedly. Not only does the CMF impart shape conformality it also significantly boosts the energy density of the device. This is because the CMF is significantly lighter than conventional metal current collectors. We show that the energy density of the fully foldable battery with CMF current collectors can be up to ∼2-fold higher than conventional LIBs at realistic mass loading (∼5 mg cm−2) of the electrode materials.