Nitrogen-doped porous carbon sponge-confined ZnO quantum dots for metal it collector-free lithium ion battery

ZnO is one of the promising anode materials for lithium ion batteries (LIBs) due to its high theoretical capacity (978 mAh g(-1)) and abundant geology reserves. However, the volume variation (about 221%) during de/lithiation and poor conductivity restrict its development. To relieve the volume variation, we build a flexible sponge film, which is composed of single-walled carbon nanotubes (SWCNT) and N-doped porous carbon (NPC) anchored by similar to 3 nm ZnO quantum dots (ZnO-QDs), namely ZnO@NPCF. The ZnO-QDs is derived from zeolitic imidazolate framework (ZIF-8) in situ. To improve the electronic conductivity, a 3D conductive network is constructed through the pyrolysis treatment. In addition, the robust SWCNT network enables the formation of self-supporting electrodes without binder and metal collector for lithium ion battery. Taking advantages of this unique structure, the ZnO@NPCF-20 exhibits a stable cycling performance over 1000 cycles at a current density of 1A g(-1) with a small decay of 0.0217% per cycle. Moreover, the ZnO@NPCF-20 electrode with a high mass loading of 2.2 mg cm(-2) can maintain a stable areal capacity of about 1 mAh cm(-2) after 350 cycles at a current density of 400 mA g(-1), which demonstrates the promising potential for LIBs electrode.