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The Li-metal anode plays a critical role in meeting the ever-growing demands for high-energy-density batteries. The rational design of an electrolyte to suppress dendrite formation is of great significance for the practical use of a Li-metal anode in rechargeable Li-metal batteries. In this work, by taking advantage of the lithiophilic polyacenequinone polymer filler, a novel polymer-filler-reinforced gel polymer electrolyte with the merits of high mechanical flexibility, high ionic conductivity, and superior dendrite-Li suppressing ability has been developed. When this gel polymer electrolyte is used in Li symmetrical cells, small and stable Li-plating/stripping overpotentials (∼25 mV) can be maintained over 700 hours. When equipped with a high-voltage cathode of LiNi0.6Co0.2Mn0.2O2 (NCM622) for Li-metal batteries, a high coulombic efficiency of about 99% can be retained after 100 repeated cycles. Such superiority is mainly ascribed to the smart lithiophilic carbonyl groups on the polyacenequinone polymer filler, which can guide uniform Li-ion flux at the Li electrode/electrolyte interface to fundamentally suppress Li dendrite growth during cycling. This work paves a way for designing dendrite-suppressed gel polymer electrolytes for Li-metal batteries and related energy conversion and storage devices. [ABSTRACT FROM AUTHOR]

Lithium–sulfur (Li–S) batteries are of great interest due to their high theoretical energy density and potentially low cost. However, two of the key issues hindering their commercialization are the polysulfide shuttling and Li-dendrite growth, which result in severe capacity decay and serious safety hazards. Herein, liquid-phase delaminated birnessite (HxMnO2+x) nanosheets along with graphene and carbon nanotubes are utilized for the first time to create an "electronegative" coating layer for Li–S batteries to suppress the polysulfide shuttling and Li-dendrite growth. The as-prepared coating layer enables stable cycling of the Li–S battery with a low capacity decay rate of 0.04% per cycle over 1000 cycles at 1C. In addition, a Li-symmetrical cell with the coating layer shows suppressed dendrite growth even after being cycled over 1000 hours at 1 mA cm−2. This excellent performance is ascribed, in part, to the synergistic effect of the chemical and electrostatic interactions among polysulfides, Li ions, and [MnO2+x]x− ions, resulting in a homogeneous Li-ion flux distribution and a mitigated polysulfide shuttling. The proposed concept of an "electronegative" bifunctional coating layer illustrates a simple and effective way to develop highly stable and safe Li–S batteries. [ABSTRACT FROM AUTHOR]

We here demonstrate an unmediated photoelectrochemical oxidation approach to address the overpotential issue of Li–O2 batteries during the charge process. We show that photoexcited holes from the photoelectrode provide a direct oxidation of solid Li2O2, without the use of a redox mediator. The Li–O2 battery composed of carbon nitride on carbon paper as a cathode and also as a photoelectrode exhibits an ultralow charge voltage of 1.96 V resulting in a ‘negative’ overpotential and good cycling performance. These results could represent a new and promising avenue for the future development of photo-charging all-solid-state batteries. [ABSTRACT FROM AUTHOR]

One of the most vexing challenges in Li–S batteries is the polysulfide shuttle. Using a combined theoretical and experimental approach, we show that g-C3N4 coated carbon can provide effective anchoring sites for lithium polysulfides, potentially having implications for the design of electrodes for practical Li–S batteries. [ABSTRACT FROM AUTHOR]