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2.
ACS Appl Mater Interfaces ; 11(32): 28774-28780, 2019 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-31314493

RESUMO

Safety is critical to developing next-generation batteries with high-energy density. Polyether-based electrolytes, such as poly(ethylene oxide) and poly(ethylene glycol) (PEG), are attractive alternatives to the current flammable liquid organic electrolyte, since they are much more thermally stable and compatible with high-capacity lithium anode. Unfortunately, they are not stable with 4 V Li(NixMnyCo1-x-y)O2 (NMC) cathodes, hindering them from application in batteries with high-energy density. Here, we report that the compatibility between PEG electrolyte and NMC cathodes can be significantly improved by forming a 2 nm Al2O3 coating on the NMC surface. This nanoscale coating dramatically changes the composition of the cathode electrolyte interphase and thus stabilizes the PEG electrolyte with the NMC cathode. With Al2O3, the capacity remains at 84.7% after 80 cycles and 70.3% after 180 cycles. In contrast, the capacity fades to less than 50% after only 20 cycles in bare NMC electrodes. This study opens a new opportunity to develop safe electrolyte for lithium batteries with high-energy density.

3.
ACS Appl Mater Interfaces ; 11(19): 17333-17340, 2019 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-31013429

RESUMO

Rechargeable metallic lithium batteries are considered as promising candidates for next-generation energy storage due to their high energy densities. However, safety concerns associated with electrolyte flammability and dendrite growth hinder their practical applications. Nonflammable liquid electrolytes have attracted significant attention recently, but they are mainly based on expensive ionic liquids, fluorinated solvents, or with highly concentrated salt. Here we design a novel trisalt electrolyte composed of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI)-lithium bis(oxalato)borate (LiBOB)-LiPF6 in EC/PC solvent, which is not flammable even in contact with fire. Moreover, it creates unique protection of solid electrolyte interphase (SEI) film on lithium metal anode that allows 400 cycles of Li/Li(NiMnCo)1/3O2 cells with a capacity retention of 97.0% at 0.83 mA cm-2. This work illustrates that low-cost fluorine-free carbonate solvents can also realize nonflammable electrolyte with high performance, which opens new opportunities to promote safety and energy density of rechargeable lithium batteries simultaneously.

4.
ACS Appl Mater Interfaces ; 11(12): 11292-11297, 2019 Mar 27.
Artigo em Inglês | MEDLINE | ID: mdl-30883077

RESUMO

Developing novel energy storage materials is critical to many renewable energy technologies. In this work, we report on the synthesis and electrochemical properties of materials composed of porous cobalt selenide microspheres prepared from molecular cluster precursors. The cobalt selenide microspheres excel as Na+ ion battery electrode materials, with a specific capacity of ∼550 mA h/g and excellent cycling stability of 85% over 100 cycles, and perform equally well as Li+ ion battery electrodes with a specific capacity of ∼600 mA h/g and cycling stability of 80% over 100 cycles. Materials which reversibly store large amounts of Na+ ions are uncommon, and these performances represent significant advances in the field. More broadly, this work establishes metal chalcogenide molecular clusters as valuable precursors for creating new, tunable energy storage materials.

5.
Angew Chem Int Ed Engl ; 58(17): 5557-5561, 2019 Apr 16.
Artigo em Inglês | MEDLINE | ID: mdl-30779275

RESUMO

The lithium-sulfur battery is an attractive option for next-generation energy storage owing to its much higher theoretical energy density than state-of-the-art lithium-ion batteries. However, the massive volume changes of the sulfur cathode and the uncontrollable deposition of Li2 S2 /Li2 S significantly deteriorate cycling life and increase voltage polarization. To address these challenges, we develop an ϵ-caprolactam/acetamide based eutectic-solvent electrolyte, which can dissolve all lithium polysulfides and lithium sulfide (Li2 S8 -Li2 S). With this new electrolyte, high specific capacity (1360 mAh g-1 ) and reasonable cycling stability are achieved. Moreover, in contrast to conventional ether electrolyte with a low flash point (ca. 2 °C), such low-cost eutectic-solvent-based electrolyte is difficult to ignite, and thus can dramatically enhance battery safety. This research provides a new approach to improving lithium-sulfur batteries in aspects of both safety and performance.

6.
Adv Mater ; 30(12): e1704947, 2018 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-29383759

RESUMO

The rapid development of flexible and wearable electronics proposes the persistent requirements of high-performance flexible batteries. Much progress has been achieved recently, but how to obtain remarkable flexibility and high energy density simultaneously remains a great challenge. Here, a facile and scalable approach to fabricate spine-like flexible lithium-ion batteries is reported. A thick, rigid segment to store energy through winding the electrodes corresponds to the vertebra of animals, while a thin, unwound, and flexible part acts as marrow to interconnect all vertebra-like stacks together, providing excellent flexibility for the whole battery. As the volume of the rigid electrode part is significantly larger than the flexible interconnection, the energy density of such a flexible battery can be over 85% of that in conventional packing. A nonoptimized flexible cell with an energy density of 242 Wh L-1 is demonstrated with packaging considered, which is 86.1% of a standard prismatic cell using the same components. The cell also successfully survives a harsh dynamic mechanical load test due to this rational bioinspired design. Mechanical simulation results uncover the underlying mechanism: the maximum strain in the reported design (≈0.08%) is markedly smaller than traditional stacked cells (≈1.1%). This new approach offers great promise for applications in flexible devices.

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