High‐Performance All‐Solid‐State Lithium–Sulfur Batteries Enabled by Amorphous Sulfur‐Coated Reduced Graphene Oxide Cathodes

Abstract

suffer from safety problems arising from lithium anode and fast capacity fading due to the insulating nature of sulfur, the dissolution-induced polysulfide shuttle reaction, and large volume changes. [4][5][6] To address these issues, carbonaceous material [7,8] and conducting polymers [9] have been used to trap the high-order polysulfides in the cathodes; protective layers and electrolyte additives are employed for protection of metallic-lithium anodes from reactions with polysulfide. [10,11] However, the shuttle reaction still exists, and the safety issue induced by lithium dendrite is still a great challenge.All-solid-state Li-S batteries can completely inhibit the dissolution of polysulfide, eliminate the polysulfide shuttle, and avoid lithium dendrite formation. [12][13][14][15][16][17][18][19] However, the use of rigid solid electrolytes in all-solid-state Li-S batteries also increases the stress/strain and interface resistance and reduce the reaction kinetics. [20][21][22] The key challenge is to minimize stress/strain and to construct a robust electronic and ionic pathway in the sulfur cathode, due to the electronic/ionic insulting nature of sulfur. For enhancing the electronic conductivity and reducing the electronic contact resistance, Kobayashi et al. synthesized a sulfur and acetylene black (AB) nanocomposite cathode using a gas-phase mixing method, and reported a reversible capacity of 900 mA h g −1 at a current density of 0.013 mA cm −2 in all-solid-state batteries. [23] The sulfur and carbon-nanofibers composite cathode also shows a high capacity in the all-solid-state Li-S batteries. [24] To ensure high ionic conduction in the sulfur cathode, Lin et al. synthesized core-shell structured lithium-sulfide nanoparticles with an Li 3 PS 4 electrolyte as shell, showing six orders of magnitude higher in ionic conductivity than that of bulk lithiumsulfide. Excellent cyclic performance was demonstrated for allsolid-state Li-S batteries at 60 °C. [13] By incorporation of five sulfur atoms in the Li 3 PS 4 electrolyte, the Li 3 PS 4+5 cathode with loading density of 0.25-0.6 mg cm −2 exhibits excellent cycling stability for all-solid-state Li-S batteries. [14] These studies demonstrate that a close contact of the nanosulfur, either to carbon or to electrolytes, and uniformly distributing these composites into an ionic/electronic conducting matrix, can significantly improve the electrochemical performances of solid-state Li-S cell because the nano-sulfur contacts both the highly ionic and Safety and the polysulfide shuttle reaction are two major challenges for liquid electrolyte lithium-sulfur (Li-S) batteries. Although use of solid-state electrolytes can overcome these two challenges, it also brings new challenges by increasing the interface resistance and stress/strain. In this work, the interface resistance and stress/strain of sulfur cathodes are significantly reduced by conformal coating ≈2 nm sulfur (S) onto reduced graphene oxide (rGO). An Li-S full cell consisting of an rGO@S-Li 10 GeP 2 S 12 -acetyle...

Sulfur Redox Reactions at Working Interfaces in Lithium–Sulfur Batteries: A Perspective

“…Considering the ultimate particle size at the range of micrometer obtained through strong ball‐milling, the mixed‐conductive networks in cathode composites can be further strengthened by constructing the intimate nanosized triple‐phase contact. Recently, Xu and co‐workers described a unique nanosized cathode with high electronic/ionic conduction by the deposition of sulfur nanoparticles on conductive reduced graphene oxide and then uniformly mixing with LGPS electrolyte and conductive carbon . Wang and co‐workers demonstrated a novel bottom‐up approach to obtain a mixed ion/electron conductive Li 2 S nanocomposite, in which the active Li 2 S and solid electrolyte with several nanometer size were in situ embedded on the conductive carbon matrix ( Figure a) .…”

Recent Developments of All‐Solid‐State Lithium Secondary Batteries with Sulfide Inorganic Electrolytes

“…Because the contact at the interface in ASSLSBs is solid‐to‐solid, the volume change during cycling easily leads to poor contact, resulting in fast capacity deterioration. Recently, Yao et al . reported a unique sulfur cathode fabricated by deposition on reduced graphene oxide (rGO) to improve the electronic conduction and reduce the stress/strain from volume change.…”

“…(c) Cycling performances of rGO@S‐40 composites at 1.0 C and corresponding Coulombic efficiencies at 60 °C. Photograph of the Li−S full cells (d) before and (e) after 750 cycles at 1.0 C and 60 °C …”

Structural Design of Lithium–Sulfur Batteries: From Fundamental Research to Practical Application

“…Another paper recent reported by Wang and Xu developed S-rGO-Li 10 GeP 2 S 12 composites with a similar structure to improve both the ionic and electronic conductivity of the cathode material. This study also introduced an attractive bi-layer sulfide electrolyte to improve the stability with reduced side reactions in Li-S batteries [379]. These studies give new insights into interface design and provide examples of how to reduce the interface resistance between sulfur/SSEs, creating a balance of ionic and electronic conductivity.…”