Yue Peng,Hongxin Liu,Yunfeng Li,Yan Song,Chengwei Zhang,Gongkai Wang
Lithium-ion hybrid capacitors (LICs) have gained increasing focus owing to their high energy/power densities. The development of anodes with superior rate capability is an effective way to surmount the kinetic mismatch between anodes and cathodes, and thus, enhancing the energy/power densities. Herein, Co 3 O 4 nanoparticles embedded in three-dimensionally (3D) ordered macro-/mesoporous TiO 2 (Co 3 O 4 @TiO 2 ) are synthesized through an in situ method from dual templates. Differing from the composite prepared by loading active nanoparticles on support, Co 3 O 4 nanoparticles are embedded in TiO 2 framework, which can improve the stability of the electrode. Furthermore, the hierarchically porous structure of TiO 2 is in favor of the rapid diffusion of ions and electrolyte. As a result, The Co 3 O 4 @TiO 2 -2 composite with an optimized Co 3 O 4 content (~25 wt%) delivers a high capacity of 944.1 mAh g −1 after 100 cycles at 0.1 A g −1 and high-rate capability (405.7 mAh g −1 after 1000 cycles at 5 A g −1 ). The LIC assembled with Co 3 O 4 @TiO 2 -2 anode and activated carbon (AC) cathode delivers high energy/power densities (maximum, 87.9 Wh kg −1 /10208.9 W kg −1 ) and great cycle stability (88.1%, 6000 cycles, 0.5 A g −1 ).
This work introduces an effective, inexpensive and large-scale production route to the fabrication of a novel honeycomb-spherical Co 3 O 4 -TiO 2 nanocomposite anode material for use in rechargeable lithium ion batteries. The microstructure and phase composition of the Co 3 O 4 -TiO 2 product were characterized systematically. The Co 3 O 4 -TiO 2 nanocomposite electrode yielded fairly high reversible capacity of ∼1000 mAh/g at 200 mA/g after 100 cycles. Moreover, the electrode exhibited extraordinary rate ability and could regain its original specific capaities as reversing to the low current densities. Meanwhile, when being applied as anode material in full cells, it still achieved remarkably improved electrochemical performance compared with traditional graphite material. Noticeably, in-situ XRD measurement verified the conversion mechanism for the Co 3 O 4 -TiO 2 electrode. The likely contributing factors to these outstanding electrochemical properties of the Co 3 O 4 -TiO 2 nanocomposite could be related to the distinctive morphology including interlaced Co 3 O 4 nanoflakes (NFs) and the TiO 2 nanoparticles (NPs), which contains superior structural stability and allows more channels for the Li + insertion/extraction reaction. This research shows that the as-prepared Co 3 O 4 -TiO 2 nanocomposite could be suitable for use as a favorable cycle performance anode material for lithium ion batteries.
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