Liying Liang

Large-scale highly ordered Sb nanorod array anodes with high capacity and rate capability for sodium-ion batteries

Na-ion batteries are a potential substitute to Li-ion batteries for energy storage devices. However, their poor electrochemical performance, especially capacity and rate capability, is the major bottleneck to future development. Here we propose a performance-oriented electrode structure, which is 1D nanostructure arrays with large-scale high ordering, good vertical alignment, and large interval spacing. Benefiting from these structural merits, a great enhancement in electrochemical performance could be achieved. Taking Sb as an example, we firstly report large-scale highly ordered Sb nanorod arrays with uniform large interval spacing (190 nm). In return for this electrode design, high ion accessibility, fast electron transport, and strong electrode integrity are presented here. Used as additive- and binder-free anodes for Na-ion batteries, Sb nanorod arrays showed a high capacity of 620 mA h g−1 at the 100th cycle with a retention of 84% up to 250 cycles at 0.2 A g−1, and a superior rate capability for delivering reversible capacities of 579.7 and 557.7 mA h g−1 at 10 and 20 A g−1, respectively. A full cell coupled by a P2-Na2/3Ni1/3Mn2/3O2 cathode and a Sb nanorod array anode was also constructed, which showed good cycle performance up to 250 cycles, high rate capability up to 20 A g−1, and large energy density up to 130 Wh kg−1. These excellent electrochemical performances shall pave the way for developing more applications of Sb nanorod arrays in energy storage devices.

Extended π-Conjugated System for Fast-Charge and -Discharge Sodium-Ion Batteries

Organic sodium-ion batteries (SIBs) are potential alternatives of current commercial inorganic lithium-ion batteries for portable electronics (especially wearable electronics) because of their low cost and flexibility, making them possible to meet the future flexible and large-scale requirements. However, only a few organic SIBs have been reported so far, and most of them either were tested in a very slow rate or suffered significant performance degradation when cycled under high rate. Here, we are focusing on the molecular design for improving the battery performance and addressing the current challenge of fast-charge and -discharge. Through reasonable molecular design strategy, we demonstrate that the extension of the π-conjugated system is an efficient way to improve the high rate performance, leading to much enhanced capacity and cyclability with full recovery even after cycled under current density as high as 10 A g(-1).

Enhancement of Sodium Ion Battery Performance Enabled by Oxygen Vacancies.

The utilization of oxygen vacancies (OVs) in sodium ion batteries (SIBs) is expected to enhance performance, but as yet it has rarely been reported. Taking the MoO(3-x) nanosheet anode as an example, for the first time we demonstrate the benefits of OVs on SIB performance. Moreover, the benefits at deep-discharge conditions can be further promoted by an ultrathin Al2O3 coating. A series of measurements show that the OVs increase the electric conductivity and Na-ion diffusion coefficient, and the promotion from ultrathin coating lies in the effective reduction of cycling-induced solid-electrolyte interphase. The coated nanosheets exhibited high reversible capacity and great rate capability with the capacities of 283.9 (50 mA g(-1)) and 179.3 mAh g(-1) (1 A g(-1)) after 100 cycles. This work may not only arouse future attention on OVs for sodium energy storage, but also open up new possibilities for designing strategies to utilize defects in other energy storage systems.

Facile synthesis of hierarchical fern leaf-like Sb and its application as an additive-free anode for fast reversible Na-ion storage

Hierarchical Sb was successfully fabricated via a very simple and cost-effective electrochemical deposition method. Morphological and structural characterizations show that the as-prepared Sb has a uniform fern leaf-like structure which is composed of well-crystallized Sb nanoparticles. The formation mechanism of the fern leaf-like Sb was also investigated. The hierarchical Sb exhibits desirable properties for sodium storage, such as high electrical conductivity and large surface area. When used as an additive-free anode for Na-ion batteries, the as-obtained fern leaf-like Sb reveals excellent cycling stability and rate capability. It can afford a high reversible capacity of 589 mA h g−1 over 150 cycles at 0.5 A g−1 and retain a capacity of 498 mA h g−1 at a high rate of 10 A g−1. Furthermore, a full cell constructed using P2-Na2/3Ni1/3Mn2/3O2//fern leaf-like Sb also displays remarkably stable and robust Na-storage performance, which includes a high capacity retention of 70% after 100 cycles at 0.5 A g−1 and a large capacity of 370 mA h g−1 at 10 A g−1. The excellent electrochemical performance of fern leaf-like Sb can be attributed to its morphological and structural features that ensure fast ion and electron transport and a stable electrode structure.

A Selectively Permeable Membrane for Enhancing Cyclability of Organic Sodium‐Ion Batteries

A novel strategy to enhance the cyclability of organic sodium-ion batteries is developed by applying a selectively permeable membrane to allow the passage of Na ions but block the slightly dissolved active molecules and thereby inhibit the further dissolution. After utilization of the membrane, the batteries show highly enhanced cyclability. Such strategy can be potentially extended to many organic materials with low solubilities.

Hierarchical Sb-Ni nanoarrays as robust binder-free anodes for high-performance sodium-ion half and full cells

A novel hierarchical electrode material for Na-ion batteries composed of Sb nanoplates on Ni nanorod arrays is developed to tackle the issues of the rapid capacity fading and poor rate capability of Sb-based materials. The three-dimensional (3D) Sb-Ni nanoarrays as anodes exhibit the synergistic effects of the two-dimensional nanoplates and the open and conductive array structure as well as strong structural integrity. Further, their capacitive behavior is confirmed through a kinetics analysis, which shows that their excellent Na-storage performance is attributable to their unique nanostructure. When used as binder-free sodium-ion battery (SIB) anodes, the nanoarrays exhibit a high capacity retention rate (more than 80% over 200 cycles) at a current density of 0.5 A·g–1 and excellent rate capacity (up to 20 A·g–1), with their capacity being 580 mAh·g–1. Moreover, a P2-Na2/3Ni1/3Mn2/3O2//3D Sb-Ni nanoarrays full cell delivers a highly reversible capacity of 579.8 mAh·g–1 over 200 cycles and an energy density as high as 100 Wh·kg–1. This design strategy for ensuring fast and stable Na storage may work with other electrode materials as well.