ABSTRACT
The modification of metallic Zn anode contributes to solving the cycling issue of Zn-ion batteries (ZIBs) by restraining the dendrite growth and side reactions. In this regard, modulating (002) Zn is an effective way to prolong the lifespan of ZIBs with a parallel arrangement of Zn deposition. Herein, the authors propose to add trace amounts of Zn(BF4 )2 additive in 3 M ZnSO4 to promote in-plane Zn deposition by forming a BF4 - -[Zn(H2 O)6 ]2+ -[Zn(BF4 )3 ]- transfer process and specifically functioning on (002) facets. In this way, the optimized electrolyte highly boosts the cycling stability of Zn anodes with a long lifespan at 34.2% Zn utilization (500 h/10 mA cm-2 ) and 51.3% Zn utilization (360 h/10 mA cm-2 ; 834 h/1 mA cm-2 ). Moreover, the electroplated Zn on Cu substrate exhibits a competitive cumulative plating capacity (CPC) of 2.87 Ah cm-2 under harsh conditions. The assembled Zn|(NH4 )2 V6 O16 ·3H2 O full cells with a high cathode loading of 29.12 mg cm-2 also realizes almost no capacity degradation even after 2000 cycles at 2 A g-1 . With this cost-effective strategy, it is promising to push the development of aqueous ZIBs as well as provide inspiration for metal anode optimization in other energy storage systems.
Subject(s)
Electric Power Supplies , Zinc , Ions , ElectrodesABSTRACT
Two-dimensional (2D) oxides have unique electrical, optical, magnetic, and catalytic properties, which are promising for a wide range of applications in different fields. However, it is difficult to fabricate most oxides as 2D materials unless they have a layered structure. Here, we present a facile strategy for the synthesis of ultrathin oxide nanosheets using a self-formed sacrificial template of carbon layers by taking advantage of the Maillard reaction and violent redox reaction between glucose and ammonium nitrate. To date, 36 large-area ultrathin oxides (with thickness ranging from ~1.5 to ~4 nm) have been fabricated using this method, including rare-earth oxides, transition metal oxides, III-main group oxides, II-main group oxides, complex perovskite oxides, and high-entropy oxides. In particular, the as-obtained perovskite oxides exhibit great electrocatalytic activity for oxygen evolution reaction in an alkaline solution. This facile, universal, and scalable strategy provides opportunities to study the properties and applications of atomically thin oxide nanomaterials.
ABSTRACT
Zero liquid discharge (ZLD), which maximizes water recovery and eliminates environmental impact, is an urgent wastewater management strategy for alleviating freshwater shortage. However, because of the high concentration of salts and broad-spectrum foulants in wastewater, a huge challenge for ZLD is lack of a robust membrane-based desalination technology that enables direct wastewater recovery without costly pretreatment processes. Here, a paradigm-shift membrane distillation (MD) strategy is presented, wherein the traditional hydrophobic porous membrane is replaced with a hydrophilic nonporous charge-gradient hydrogel (CGH) membrane that possesses hypersaline tolerance, fouling/scaling-free properties, and negligible vapor transfer resistance inside the membrane, simultaneously. Therefore, the CGH-based MD with high water flux enables direct desalination of hypersaline wastewater (130 g L-1 ) containing broad-spectrum foulants (500 mg L-1 ) during continuous long-term operation (200 h), and this technology paves a promising way to direct ZLD for wastewater management.
ABSTRACT
Low-grade heat (below 373 kelvin) is abundant and ubiquitous but is mostly wasted because present recovery technologies are not cost-effective. The liquid-state thermocell (LTC), an inexpensive and scalable thermoelectric device, may be commercially viable for harvesting low-grade heat energy if its Carnot-relative efficiency (ηr) reaches ~5%, which is a challenging metric to achieve experimentally. We used a thermosensitive crystallization and dissolution process to induce a persistent concentration gradient of redox ions, a highly enhanced Seebeck coefficient (~3.73 millivolts per kelvin), and suppressed thermal conductivity in LTCs. As a result, we achieved a high ηr of 11.1% for LTCs near room temperature. Our device demonstration offers promise for cost-effective low-grade heat harvesting.
