ABSTRACT
Side reactions and dendrite growth on the zinc metal anode surface seriously damage the shelf life and calendar life of Zn-based batteries. Here, an Al-complexed artificial interfacial layer is constructed on the Zn surface (denoted as Al-complex@Zn) by a low-cost, facile, and scalable chemical method. The Al-complex interfacial layer improves the wettability of the electrolyte. Meanwhile, the Al-complex layer not only inhibits the side reaction by a physical barrier on the Zn surface but also regulates the zinc-ion flux to realize the uniform deposition of Zn2+. The Zn//Zn symmetric cell with an Al-complex layer has realized an ultralong cycle life of 2400 h and an extremely low polarization voltage of 20 mV (1 mA cm-2, 0.5 mAh cm-2), surpassing those reported in most literature. Furthermore, when an Al-complex@Zn//NaV3O8·1.5H2O (NVO) full cell is assembled, a high capacity retention of 92.5% is achieved over 1000 cycles at a current density of 4 A g-1. This work provides a facile and low-cost strategy on the modification of zinc anode to realize long-cycled aqueous Zn-ion batteries.
ABSTRACT
The Zn/MnO2 battery is a promising energy storage system, owing to its high energy density and low cost, but due to the dissolution of the cathode material, its cycle life is limited, which hinders its further development. Therefore, we introduced agar as a microskin for a MnO2 electrode to improve its cycle life and optimize other electrochemical properties. The results showed that the agar-coating layer improved the wettability of the electrode material, thereby promoting the diffusion rate of Zn2+ and reducing the interface impedance of the MnO2 electrode material. Therefore, the Zn/MnO2 battery exhibited outstanding rate performance. In addition, the agar-coating layer promoted the reversibility of the MnO2/Mn2+ reaction and acted as a colloidal physical barrier to prevent the dissolution of Mn2+, so that the Zn/MnO2 battery had a high specific capacity and exhibited excellent cycle stability.
ABSTRACT
Rechargeable Li-CO2 batteries as a novel system developed in recent years directly use CO2 as the reactant, which enables deeper penetration of energy storage and CO2 utilization. The Li-CO2 battery system, however, is at an early stage, and many challenges remained to be overcome urgently, especially the problem of high over-potential during the charging process. Here, we report a redox mediator, phenoxathiin, to assist the decomposition of Li2CO3 during the charging process, which effectively reduces the over-potential and improves the cycling performance of the battery. Furthermore, we detect the presence of singlet oxygen during the oxidation of Li2CO3 by phenoxathiin, which reveals more of the underlying science of the reaction mechanism of the Li-CO2 battery.
ABSTRACT
Aqueous rechargeable zinc-metal-based batteries are an attractive alternative to lithium-ion batteries for grid-scale energy-storage systems because of their high specific capacity, low cost, eco-friendliness, and nonflammability. However, uncontrollable zinc dendrite growth limits the cycle life by piercing the separator, resulting in low zinc utilization in both alkaline and mild/neutral electrolytes. Herein, a polyacrylonitrile coating layer on a zinc anode produced by a simple drop coating approach to address the dendrite issue is reported. The coating layer not only improves the hydrophilicity of the zinc anode but also regulates zinc-ion transport, consequently facilitating the uniform deposition of zinc ions to avoid dendrite formation. A symmetrical cell with the polymer-coating-layer-modified Zn anode displays dendrite-free plating/stripping with a long cycle lifespan (>1100 h), much better than that of the bare Zn anode. The modified zinc anode coupled with a Mn-doped V2 O5 cathode forms a stable rechargeable full battery. This method is a facile and feasible way to solve the zinc dendrite problem for rechargeable aqueous zinc-metal batteries, providing a solid basis for application of aqueous rechargeable Zn batteries.
ABSTRACT
Notably, many significant breakthroughs for a new generation of supercapacitors have been reported in recent years, related to theoretical understanding, material synthesis and device designs. Herein, we summarize the state-of-the-art progress toward mechanisms, new materials, and novel device designs for supercapacitors. Firstly, fundamental understanding of the mechanism is mainly focused on the relationship between the structural properties of electrode materials and their electrochemical performances based on some in situ characterization techniques and simulations. Secondly, some emerging electrode materials are discussed, including metal-organic frameworks (MOFs), covalent organic frameworks (COFs), MXenes, metal nitrides, black phosphorus, LaMnO3, and RbAg4I5/graphite. Thirdly, the device innovations for the next generation of supercapacitors are provided successively, mainly emphasizing flow supercapacitors, alternating current (AC) line-filtering supercapacitors, redox electrolyte enhanced supercapacitors, metal ion hybrid supercapacitors, micro-supercapacitors (fiber, plane and three-dimensional) and multifunctional supercapacitors including electrochromic supercapacitors, self-healing supercapacitors, piezoelectric supercapacitors, shape-memory supercapacitors, thermal self-protective supercapacitors, thermal self-charging supercapacitors, and photo self-charging supercapacitors. Finally, the future developments and key technical challenges are highlighted regarding further research in this thriving field.
ABSTRACT
Anode materials with high capacity for aqueous rechargeable lithium batteries (ARLBs) are very rarely reported. Here we found that a dual core-shell structured MWCNTs@S@PPy nanocomposite prepared by us shows excellent electrochemical performance. Its initial discharge capacity in a saturated LiAc aqueous electrolyte is very high, which is up to 481 mA h g-1 based on the weight of the composite and 879 mA h g-1 based on the sulfur content. It shows excellent rate capability. When nanotube LiMn2O4 is used as a cathode, the assembled ARLB can deliver an energy density of 110 Wh kg-1 based on two electrodes and show excellent cycling. These results show great promise for the practical application of ARLBs.