Micropatterned arrays of vertically-aligned CNTs grown on aluminum as a new cathode platform for LiFePO 4 integration in lithium-ion batteries

The conventional lithium-ion battery fabrication process involves mixing of the active cathode material with additives and tape casting on metallic current collectors. The thickness of this layer limits the performance of the cathode. In this work, a novel cathode platform is presented consisting of a micropatterned array of vertically aligned carbon nanotubes (CNTs) on aluminum (Al) foil that serves as host for active cathode powders. This highly conductive three-dimensional structure provides a high specific surface area to support greater mass loading capable of achieving high energy and power densities. The feasibility of this structure was demonstrated by using commercially available lithium iron phosphate (LFP) powder which was processed and dispersed using two different techniques—vibration-assisted drip-coating and electrophoretic deposition. A high specific capacity of 143 mAh/g at 3.4 V was achieved at C/20 rate for the novel cathode fabricated using electrophoretic deposition, which seemed superior to vibration-assisted drip coating with its easier application, more uniform particle coating, stronger particle attachment to the CNTs, and better electrochemical performance. In addition, CNT array on Al has been demonstrated to be a viable candidate for fabricating cathodes for energy storage applications without the need for any additives and/or binders.