Strategies toward High‐Loading Lithium–Sulfur Battery

Abstract

despite all these promises, three intrinsic drawbacks need to be resolved before fulfilling the promise of the market potential.First, the most stable but electronically insulating S 8 (≈10 −14 S cm −2 ) with cyclic configuration is used as the starting material in Li-S cathode, significantly limiting the full utilization of the active materials to reach the theoretical capacity. Therefore, it is the first priority to design the cathode that ensures the maximum usage of the starting materials, which sets the upper limit of the capacity performance. Second, the muti-step reduction process releases highly soluble lithium polysulfides (LiPSs) intermediates (Li 2 S x , where x = 4-8) into the organic electrolyte. [6] Unlike the batteries based on ion-insertion mechanism, [7,8] Li-S battery possesses unique and complex electrochemical/chemical processes during operation. During galvanostatic discharge process, two distinct plateaus can be verified at about 2.4 and 2.1 V in the voltage profile, corresponding to the reduction of sulfur into long-chain polysulfides and subsequent reaction from short-chain polysulfides to Li 2 S, respectively. [9] Further investigations about the reaction mechanism of Li-S battery based on experimental and theoretical studies reveal that the existence of various intermediates during electrochemical processes, indicating much more complex battery chemistry compared to the simple stepwise reaction model. [10,11] As a result, the soluble intermediates can diffuse through the polymeric separator to the anode surface, causing the loss of active materials and degradation of anode. Third, the density difference between the starting material (sulfur, 2.07 g cm −3 ) and discharge product (Li 2 S, 1.66 g cm −3 ) causes significant volumetric change during continuous cycling, damaging the integrity of the cathode structure and leading to serious capacity fading. [12] Besides above problems concerning the cathode side of the Li-S battery, other issues arose on the anode side, such as the unstable solid-electrolyte interphase (SEI), surface passivation, and uncontrolled lithium dendrite growth. [13][14][15] Stemmed from the basic problems mentioned above from the very beginning of the designed Li-S battery systems, various derivative problems were gradually unraveled during persistent efforts for improving the battery performance to approach the ultimate goal for commercialization. In the past decade, fundamental studies about Li-S battery were carried in laboratories all over the world, and it gradually put the puzzle together while brought promising performance improvement. [11,[16][17][18][19][20] However, to date, most of the lab-scale progresses have been based on batteries with sulfur loading lower than 2 mg cm −2 , Lithium-sulfur (Li-S) batteries, due to the high theoretical energy density, are regarded as one of the most promising candidates for breaking the limitations of energy-storage system based on Li-ion batteries. Tremendous efforts have been made to meet the challenge of high-performan...

Comparative life cycle assessment of high performance lithium-sulfur battery cathodes

“…The goal of this research is to compare the associated environmental impacts during the manufacturing process of 5 Li–S batteries. Those Li–S batteries were selected because they rely on different strategies to achieve high sulfur loadings which afford large energy densities; a paramount aspect towards practical implementation ( Hu et al., 2020 ). Moreover, all the selected batteries present acceptable cycle stability which reduces their associated environmental burdens ( Peters et al., 2016 ).…”

Optimizing Redox Reactions in Aprotic Lithium–Sulfur Batteries

“…[ 188 ] Such increased thickness can cause the issues including poor electrical contact between active materials and current collectors as well as severe cracking of cathode coating, which lead to poor structural stability, increased internal resistance, and slow electronic transfer. [ 11 ] Current collectors featuring unique 3D structure were designed effectively to utilize the solid–liquid–solid transition in redox reactions of Li–S battery. [ 30 ] To date, various 3D current collectors, including porous current collector, sandwich‐type current collector, multilayered current collector, have been designed.…”

“…Moreover, as the increase of the viscosity of electrolyte, the charge transfer resistance increases. In the liquid‐to‐solid transition process, a dip‐in voltage profile at the start of the transition is formed by the nucleation barrier of solid Li 2 S 2 /Li 2 S. [ 11 ] The converse transition of solid Li 2 S to dissolved LiPSs also needs to overcome additional activation energy due to the aggregation of Li 2 S produced. [ 12 ] These processes collectively slow the overall reaction reactions and lead to a reduced energy efficiency in Li–S batteries.…”

Metal–organic framework based bifunctional oxygen electrocatalysts for rechargeable zinc–air batteries: current progress and prospects

“…Lithium-sulfur batteries with a higher energy density also face the issue of poor stability and safety. 3,[7][8][9][10] In this regard, metalair batteries especially Zn-air batteries have received great attention due to their unique advantages: (i) high energy density: the energy density of ZABs (1086 and 1370 W h kg À1 , including oxygen and excluding oxygen) is several times higher than that of lithium-ion batteries; 7,[10][11][12][13] (ii) suitable working voltage and intrinsic safety: the working voltage of ZABs is appropriately high and will not cause the decomposition of water in the electrolyte; 7,10,14 (iii) low cost ($$100 kW À1 h À1 ) and a stable discharge prole.…”