RESUMEN
Developing insertion-type anode is key to advancing "rocking chair" zinc-ion batteries, though there are few reported insertion-type anodes. Herein, the Bi2O2CO3 is a high-potential anode, with a special layered structure. A one-step hydrothermal method was used to prepare Ni-doped Bi2O2CO3 nanosheet, and also a free-standing electrode consisting of Ni-Bi2O2CO3 and CNTs was designed. Both cross-linked CNTs conductive networks and Ni doping improve charge transfer. Ex situ tests (XRD, XPS, TEM, etc.) reveal the H+/Zn2+ co-insertion mechanism of Bi2O2CO3 and that Ni doping improves its electrochemical reversibility and structural stability. Therefore, this optimized electrode offers a high specific capacity of 159 mAh g-1 at 100 mA g-1, a suitable average discharge voltage of ≈0.400 V, and a long-term cycling stability of 2200 cycles at 700 mA g-1. Besides, the Ni-Bi2O2CO3//MnO2 "rocking chair" zinc-ion battery (based on the total mass of cathode and anode) delivers a high capacity of ≈100 mAh g-1 at 50.0 mA g-1. This work provides a reference for designing high-performance anode in zinc-ion batteries.
RESUMEN
Increasing insertion host materials are developed as high-performance anodes of "rocking-chair" zinc ion batteries. However, most of them show unsatisfactory rate capabilities. Herein, layered BiOIO3 is reported as an excellent insertion host and a zinc ion conductor, i.e., Zn3(PO4)2·4H2O (ZPO), is introduced to construct a BiOIO3@ZPO heterojunction with a built-in electric field (BEF). Both ZPO and a BEF obviously enhance Zn2+ transfer and storage, which is proven by theoretical calculations and experimental studies. The conversion-type mechanism of BiOIO3 is revealed through ex situ characterizations. The optimized electrode exhibits a high reversible capacity of 130 mAh g-1 at 0.1 A g-1, a low average discharge voltage of 0.58 V, an ultrahigh rate performance with 68 mAh g-1 at 5 A g-1 (52% of capacity at 0.1 A g-1), and an ultralong cyclic life of 6000 cycles at 5 A g-1. Significantly, the BiOIO3@ZPO//Mn3O4 full cell shows a good cyclic life of 67 mAh g-1 over 1000 cycles at 0.1 A g-1. This work provides a new insight into the design of anodes with excellent rate capability.
RESUMEN
The graphitic carbon nitride is considered as the promising anode of lithium ion battery due to its high theoretical capacity (>1000 mAh g-1) and easy synthesis method. But the electrochemical inactivity and the structural collapse during cycles lead to its poor electrochemical performance in practice. Here, an interesting molten salt method is used to obtain the KCl-preintercalated carbon nitride nanosheets with abundant N vacancies and pyridinic-N. The KCl as a prop enhances the interlayer distance and the structural stability. And the N vacancy and the pyridinic-N increase the conductivity, the active sites and the reversibility of Li+ storage. Thus, the optimized electrode shows a higher specific discharge capacity (389 mAh g-1 at 0.1 A g-1) and a longer cyclic life (66% capacity retention after 10 K cycles at 3.0 A g-1) compared to those of bulk g-C3N4.
RESUMEN
The obtainment of low-cost, easily prepared and high-powered LiMn2O4 is the key to achieve its wide application in various electronic devices. In this work, a mild and easily scaled molten salt method (KCl@LiCl) is utilized to convert commercial MnO2 to the high-performance LiMn2O4. At the same reaction temperature, the molten salt method leads to the formation of K+-doped LiMn2O4 with higher crystallinity compared to the conventional solid state method, which contributes to the improved inner charge transfer. The Li3PO4 protective layer is coated on the surface of K+-doped LiMn2O4 to elevate the interfacial stability and the Li+ transfer on interface. Thus, the optimized electrode shows a higher specific discharge capacity (103/60 mAh g-1 at 0.02/2 A g-1) and a longer cyclic life (80 mAh g-1 after 500 cycles at 0.5 A g-1) compared to those of LiMn2O4 by solid state method (49/2 mAh g-1 at 0.02/2 A g-1 and 20 mAh g-1 after 500 cycles at 0.5 A g-1).
