Search

Abstract: In this work, a hierarchically porous and ultrathick “breathable” wood‐based cathode for high‐performance Li‐O2 batteries is developed. The 3D carbon matrix obtained from the carbonized and activated wood (denoted as CA‐wood) serves as a superconductive current collector and an ideal porous host for accommodating catalysts. The ruthenium (Ru) nanoparticles are uniformly anchored on the porous wall of the aligned microchannels (denoted as CA‐wood/Ru). The aligned open microchannels inside the carbon matrix contribute to unimpeded oxygen gas diffusion. Moreover, the hierarchical pores on the microchannel walls can be facilely impregnated by electrolyte, forming a continuous supply of electrolyte. As a result, numerous ideal triphase active sites are formed where electrolyte, oxygen, and catalyst accumulate on the porous walls of microchannels. Benefiting from the numerous well‐balanced triple‐phase active sites, the assembled Li‐O2 battery with the CA‐wood/Ru cathode (thickness: ≈700 µm) shows a high specific area capacity of 8.58 mA h cm−2 at 0.1 mA cm−2. Moreover, the areal capacity can be further increased to 56.0 mA h cm−2 by using an ultrathick CA‐wood/Ru cathode with a thickness of ≈3.4 mm. The facile ultrathick wood‐based cathodes can be applied to other cathodes to achieve a super high areal capacity without sacrificing the electrochemical performance. [ABSTRACT FROM AUTHOR]

Lithium–sulfur (Li–S) batteries are one of the most promising next‐generation energy storage systems due to their ultrahigh theoretical specific capacity. However, their practical applications are seriously hindered by some inevitable disadvantages such as the insulative nature of sulfur and Li2S, volume expansion of the cathode, the shuttle effect of polysulfides, and the growth of lithium dendrites on the anode. Of these, the polysulfide shuttle effect is one of the most critical issues causing the irreversible loss of active materials and rapid capacity degradation of batteries. Herein, modified separators with functional coatings inhibiting the migration of polysulfides are enumerated based on three effects toward polysulfides: the adsorption effect, separation effect, and catalytic effect. To solve the shuttle effect problem, researchers have replaced liquid electrolytes with solid‐state electrolytes. In this review, solid‐state electrolytes for lithium–sulfur batteries are grouped into three categories: inorganic solid electrolytes, solid polymer electrolytes, and composite solid electrolytes. Challenges and perspectives regarding the development of an optimized strategy to inhibit the polysulfide shuttle for enhancing cycle stability in lithium–sulfur batteries are also proposed. [ABSTRACT FROM AUTHOR]