MWCNT/V₂O₅ Core/Shell Sponge for High Areal Capacity and Power Density Li-Ion Cathodes

A multiwall carbon nanotube (MWCNT) sponge network, coated by ALD V(2)O(5), presents the key characteristics needed to serve as a high-performance cathode in Li-ion batteries, exploiting (1) the highly electron-conductive nature of MWCNT, (2) unprecedented uniformity of ALD thin film coatings, and (3) high surface area and porosity of the MWCNT sponge material for ion transport. The core/shell MWCNT/V(2)O(5) sponge delivers a stable high areal capacity of 816 μAh/cm(2) for 2 Li/V(2)O(5) (voltage range 4.0-2.1 V) at 1C rate (1.1 mA/cm(2)), 450 times that of a planar V(2)O(5) thin film cathode. At much higher current (50×), the areal capacity of 155 μAh/cm(2) provides a high power density of 21.7 mW/cm(2). The compressed sponge nanoarchitecture thus demonstrates exceptional robustness and energy-power characteristics for thin film cathode structures for electrochemical energy storage.