Search

A microgrid-patterned silicon (MPS) electrode is presented as an electroactive Li host, which enables stepwise sequential Si lithiation/delithiation and Li plating/stripping reactions for a high-energy-density Li–metal full cell.

Enabling reliable operation of energy storage devices over a wide temperature range without safety failures is an urgent prerequisite for extending their applications. Conventional liquid electrolytes in energy storage devices fail to reach this goal due to their limitations in freezing/boiling temperatures and flammability (for organic electrolytes). Here, we demonstrate a new class of aqueous eutectic electrolyte (AEE) based on a colligative property of lithium bis(trifluoromethane sulfonyl)imide (LiTFSI)-water binary mixture. The AEE (5.2 m LiTFSI in water) maximizes effect of freezing-point depression (below −40°C) and shows good electrochemical stability with electrode materials. We identify that a key-underlying mechanism of AEE is coordination of water molecules with Li+ and TFSI-. To explore potential use of AEE, we choose lithium-ion hybrid supercapacitors (HSC) as a model system. The AEE enables the HSC to provide exceptional high-rate cell performance over broad temperature ranges (−40°C ~ 100°C) without incurring fire or explosion.

Electroactive organic-based electrode materials have garnered considerable attention as an emerging candidate to replace inorganic counterparts because of their lightweight, mechanical flexibility, and molecular diversity. Yet, their low energy and power densities associated with poor electronic conductivity and limited ion accessibility often impose a critical impediment for practical applications. Herein, we report that all-fibrous heteromat framework comprising intermingled polyacrylonitrile nanofibers and carbon nanotubes offers three-dimensional bicontinuous electron/ion conductive pathways toward organic-based active materials. At the same time, the framework eliminates heavy metallic current collectors to allow the overall mechanical flexibility of the rechargeable system. Nickel 2,6-naphthalenedicarboxylate (NiNDC) is prepared as a model organic-based anode material for this electrode strategy. Driven by the structural uniqueness, the self-standing heteromat NiNDC anode ultimately affords facile redox kinetics and outstanding electrochemical performance, while surpassing the performance of conventional lithium-ion battery organic-based anodes.

Summary In contrast to enormous progresses in electrode active materials, little attention has been paid to electrode sheets despite their crucial influence on practical battery performances. Here, as a facile strategy to address this issue, we demonstrate nanofibrous conductive electrode binders based on deoxyribonucleic acid (DNA)-wrapped single-walled carbon nanotubes (SWCNT) (denoted as DNA@SWCNT). DNA@SWCNT binder allows the removal of conventional polymeric binders and carbon powder additives in electrodes. As a proof of concept, high-capacity overlithiated layered oxide (OLO) is chosen as a model electrode active material. Driven by nanofibrous structure and DNA-mediated chemical functionalities, the DNA@SWCNT binder enables improvements in the redox reaction kinetics, adhesion with metallic foil current collectors, and chelation of heavy metal ions dissolved from OLO. The resulting OLO cathode exhibits a fast charging capability (relative capacity ratio after 15 min [versus 10 h] of charging = 83%), long cyclability (capacity retention = 98% after 700 cycles), and thermal stability., Graphical Abstract, Highlights • A multifunctional binder based on DNA-wrapped SWCNT is demonstrated • DNA@SWCNT binder shows improved adhesion with metallic foil current collectors • DNA@SWCNT binder enables chelation of heavy metal ions dissolved from cathode materials • DNA@SWCNT binder-containing cathode exhibits fast-charging capability, Nanotechnology; Nanomaterials; Energy Materials

Despite their potential as a next-generation alternative to current state-of-the-art lithium (Li)-ion batteries, rechargeable aqueous zinc (Zn)-ion batteries still lag in practical use due to their low energy density, sluggish redox kinetics, and limited cyclability. In sharp contrast to previous studies that have mostly focused on materials development, herein, a new electrode architecture strategy based on a 3D bicontinuous heterofibrous network scaffold (HNS) is presented. The HNS is an intermingled nanofibrous mixture composed of single-walled carbon nanotubes (SWCNTs, for electron-conduction channels) and hydrophilic cellulose nanofibers (CNFs, for electrolyte accessibility). As proof-of-concept for the HNS electrode, manganese dioxide (MnO2 ) particles, one of the representative Zn-ion cathode active materials, are chosen. The HNS allows uniform dispersion of MnO2 particles and constructs bicontinuous electron/ion conduction pathways over the entire HNS electrode (containing no metallic foil current collectors), thereby facilitating the redox kinetics (in particular, the intercalation/deintercalation of Zn2+ ions) of MnO2 particles. Driven by these advantageous effects, the HNS electrode enables substantial improvements in the rate capability, cyclability (without structural disruption and aggregation of MnO2 ), and electrode sheet-based energy (91 Wh kgelectrode-1 )/power (1848 W kgelectrode-1 ) densities, which lie far beyond those achievable with conventional Zn-ion battery technologies.

The ongoing surge in demand for high-energy/flexible rechargeable batteries relentlessly drives technological innovations in cell architecture as well as electrochemically active materials. Here, a new class of all-nanomat lithium-ion batteries (LIBs) based on 1D building element-interweaved heteronanomat skeletons is demonstrated. Among various electrode materials, silicon (Si, for anode) and overlithiated layered oxide (OLO, for cathode) materials are chosen as model systems to explore feasibility of this new cell architecture and achieve unprecedented cell capacity. Nanomat electrodes, which are completely different from conventional slurry-cast electrodes, are fabricated through concurrent electrospinning (for polymeric nanofibers) and electrospraying (for electrode materials/carbon nanotubes (CNTs)). Si (or rambutan-shaped OLO/CNT composite) powders are compactly embedded in the spatially interweaved polymeric nanofiber/CNT heteromat skeletons that play a crucial role in constructing 3D-bicontinuous ion/electron transport pathways and allow for removal of metallic foil current collectors. The nanomat Si anodes and nanomat OLO cathodes are assembled with nanomat Al2O3 separators, leading to the fabrication of all-nanomat LIB full cells. Driven by the aforementioned structural/chemical uniqueness, the all-nanomat full cell shows exceptional improvement in electrochemical performance (notably, cell-based gravimetric energy density = 479 W h kgCell−1) and also mechanical deformability, which lie far beyond those achievable with conventional LIB technologies.