Li₂S‐Carbon Sandwiched Electrodes with Superior Performance for Lithium‐Sulfur Batteries

Abstract

As the petroleum resources deplete and the concern on environmental pollution increases, utilization of renewable energies (e.g., solar and wind) and the adoption of electric vehicles are becoming more desirable. However, the development of an electrical energy storage system that can meet the rigorous requirements on the weight and volume for electric vehicles or on the cycle life and cost for stationary storage is a challenge. Li-ion batteries, representing the highest energy density battery chemistry, are believed to be one of the most promising technologies. However, the capacities of the current insertion oxide cathodes (e.g., layered and spinel oxides) have reached their limits of <300 mAh g −1 , [ 1 ] which forces the materials community to develop alternative high-capacity cathode materials that can support multiple electrons per molecule, such as sulfur and oxygen. [ 2 ] Lithium-sulfur (Li-S) batteries, fi rst developed in 1960s, [ 3 ] have attracted much attention in recent years as sulfur offers a high theoretical capacity of 1672 mAh g −1 .[ 4 ] However, the low electronic conductivity of sulfur and its reaction products, along with the dissolution of polysulfi de intermediates into liquid electrolyte and the consequent shuttling effect between the anode and cathode, makes it diffi cult to achieve high capacity and practical cycle life. Signifi cant improvements in the utilization of sulfur and cyclability have been achieved by smartly designed sulfur-carbon nanomaterials, [ 5 ] core-shell structured composites, [ 6 ] and effi cient trapping confi gurations for polysulfi des. [ 7 ] However, although the use of sulfur as the cathode material has many advantages (e.g., low cost, abundance, and high energy), lithium metal or lithiated anodes are required as no lithium is present in the initial stage of the sulfur cathode. Unfortunately, lithium metal anode poses a signifi cant safety hazard and it can react with the polysulfi de ions diffused from the cathode, which limits capacity retention and cycle life. Lithium sulfi de (Li 2 S), the end discharge product of sulfur with a theoretical capacity of 1169 mAh g −1 , is more desirable to be the cathode material than sulfur. Being in the fully lithiated state, Li 2 S cathode will allow the use of lithium-free anodes such as Si, Sn, Sb, or metal oxides. Although a few approaches have been pursued with Li 2 S recently, showing promising results, [ 8,9 ] a more facile and scalable strategy is needed to tap the full potential of the Li 2 S cathode in practical cells.

Durable Carbon-Coated Li2S Core–Shell Spheres for High Performance Lithium/Sulfur Cells

“…Figure 4a shows the discharge capacities of the 2 μm, 1 μm, and 500 nm Li 2 S@C spheres at the 0.5C rate (1C = 1166 mA g −1 Li 2 S). All of the electrodes were first charged to 4.0 V at the 0.05C rate to activate the cathodes 34 and then cycled between 1.5 and 2.8 V at the 0.5C rate. All cells show a high Coulombic efficiency resulting from the small and uniform particle sizes as well as the protection provided by the stable carbon shell of these Li 2 S@C spheres.…”

A chemistry and material perspective on lithium redox flow batteries towards high-density electrical energy storage

“…164, 165 Manthiram and co-workers proposed a compound-sandwiched electrode architecture that includes a bi-functional interlayer on the top, the active material in the middle, and a porous current collector at the bottom. 166 Such a cell configuration showed good electrochemical performance both in polysulfide catholyte and regular sulphur cathode.…”

Kinetically controlled formation of uniform FePO4 shells and their potential for use in high-performance sodium ion batteries

“…Obviously, the introduction of a highly conductive matrix to form a composite material becomes a logical and reasonable approach to achieve higher electron conductivity. [14][15][16][17][18] For example, Liu et al 10 showed that a mixture of single-walled carbon nanotubes and FePO 4 nanoparticles showed much improved battery performance and high cyclability. single-walled carbon nanotubes are a highly connected network that can facilitate the electron transport of embedded FePO 4 particles.…”