RESUMO
Zn anode is confronted with serious Zn dendrite growth and water-induced parasitic reactions, which severely hinders the rapid development and practical application of aqueous zinc metal batteries (AZMBs). Herein, inspired by sodium hyaluronate (SH) biomolecules in living organisms featured with the functions of water retention, ion-transport regulation, and film-formation, the SH working as a dynamic and self-adaptive "mask" is proposed to stabilize Zn anode. Benefiting from the abundant functional groups with high hydrophilicity and zincophilicity, SH molecule can constrain active water molecules on the Zn-electrolyte interface and participate in Zn2+ solvation structure to suppress parasitic reactions. Furthermore, the dynamical adsorption of SH with high-density negative charge on the Zn surface could serve as Zn2+ reservoirs to guide uniform Zn deposition. Consequently, stable Zn plating and an ultrahigh cumulative plating capacity (CPC) of 4.8 Ah cm-2 are achieved even at 20 mA cm-2 (20 mAh cm-2 ) in a Zn||Zn symmetric battery, reaching a record level in AZMBs. In addition, the Zn||ß-MnO2 full battery exhibits a substantially improved cycle stability. This work presents a route to realize a highly reversible and stable Zn metal anode by learning from nature.
Assuntos
Compostos de Manganês , Óxidos , Eletrodos , ZincoRESUMO
Uncontrollable growth of lithium (Li) dendrite has severely hindered the development of Li metal anodes, while separator modification is regarded as a simple and effective way to mitigate the growth of Li dendrite. However, the "drop-dregs" phenomenon of coating layer desquamated from polyolefin separator due to their different Young's modulus would induce a nonuniform Li ionic flux, finally resulting in deteriorative electrochemical performance and even thermal runaway of the battery. Herein, we introduce a novel nanopile mechanical interlocking strategy to create delamination-free separator modification, which could stably generate a homogeneous Li ionic flux to guide long-term uniform Li deposition. Both experimental and simulation results demonstrate a strong bonding strength between the coating layer and membrane matrix based on this physical interlocking mechanism. Consequently, with a nearly dendrite-free Li deposition and a largely reduced interface impedance, 1000 h stable cycling of Li/Li half cells enrolled this modified separator is successfully achieved. Also, a significant improvement in Li/LiFePO4 full cells in long-term cycling stability to 500 cycles further indicates its promising practical potential. Moreover, this presented approach without any binding agents or surface activation procedures could be facilely scaled up, providing an applicable and durable separator modification solution toward stable Li metal anodes.
RESUMO
Currently, exploring high-volumetric-capacity electrode materials that allow for reversible (de-)insertion of large-size K+ ions remains challenging. Tellurium (Te) is a promising alternative electrode for storage of K+ ions due to its high volumetric capacity, confirmed in lithium-/sodium-ion batteries, and the intrinsic good electronic conductivity. However, the charge storage capability and mechanism of Te in potassium-ion batteries (KIBs) have not been unveiled until now. Here, a novel K-Te battery is constructed, and the K+ -ion storage mechanism of Te is revealed to be a two-electron conversion-type reaction of 2K + Te â K2 Te, resulting in a high theoretical volumetric capacity of 2619 mAh cm-3 . Consequently, the rationally fabricated tellurium/porous carbon electrodes deliver an ultrahigh reversible volumetric capacity of 2493.13 mAh cm-3 at 0.5 C (based on Te), a high-rate capacity of 783.13 mAh cm-3 at 15 C, and superior long-term cycling stability for 1000 cycles at 5 C. This excellent electrochemical performance proves the feasibility of utilizing Te as a high-volumetric-capacity active material for storage of K+ ions and will advance the practical application of KIBs.
