Tailored Electrolytes Enabling Practical Lithium–Sulfur Full Batteries via Interfacial Protection

Abstract

The electroactivity of the sulfur composite cathode generally studied requires high electrode porosity, which brings many constraints to the design of lithium–sulfur (Li–S) batteries (e.g., electrolyte quantity and energy density). Here, we focus on electrolyte engineering for highly stable covalent-type sulfurized polyacrylonitrile (SPAN) to realize practical Li–S full batteries with jointly improved volumetric energy density (E v) and cyclability. The conformal polycarbonate cathode-electrolyte interphase (CEI) derived by cyclic carbonate is determined to play a fundamental role in eliminating the fatal shuttle effect, thereby safeguarding the “solid-phase” mechanism of SPAN. The tailored electrolyte also induces a bilayered solid electrolyte interphase (SEI) with enhanced Li+ transport and mechanical strength, which unlocks the compatibility of an ultrathin Li anode. Practical Li-SPAN pouch cells, composed of high-capacity SPAN cathodes (4.08 mAh cm–2) and 1.2× excess Li anodes, can achieve an E v of 615 Wh L–1 and show a cycle life at least 7 times that of the conventional carbonate-based electrolyte.

Locally Concentrated Ionic Liquid Electrolyte with Partially Solvating Diluent for Lithium/Sulfurized Polyacrylonitrile Batteries

“…[4][5][6] Besides the strong interaction between sulfur fragments and dehydrocyclized polyacrylontrile skeletons, [7,8] the remarkable electrochemical properties are also closely related to the formation of protective, polycarbonate-based cathode/ electrolyte interphases (CEIs) in carbonate-based electrolytes. [9,10] In fact, dissolution of polysulfide and fast capacity decay are still observed when ether-based electrolytes are employed. [9,11] Unfortunately, the conventional carbonate-based electrolytes for commercial lithium-ion batteries are incompatible with lithium-metal anodes (LMAs).…”

Geometrical engineering of a SPAN–graphene composite cathode for practical Li–S batteries

“…In the C 1s spectra for the SPAN cathode, both electrolytes showed the presence of organic polycarbonate compounds (i.e., poly(CO 3 )) due to the decomposition of EC or FEC solvent molecules. From the previous studies by Shen et al, 70 notably, it was known that the formation of those amorphous organics on the SPAN surface can effectively prevent the shuttle issue in SPAN-based Li-S batteries. A Li-S battery featuring a 2D-SPAN/G cathode, with a relatively low sulfur loading of 5 mg cm À2 , and modied electrolyte also delivers high areal capacity and demonstrates long-term cycling stability over 500 cycles (Fig.…”

Thiophilic–Lithiophilic Hierarchically Porous Membrane-Enabled Full Lithium–Sulfur Battery with a Low N/P Ratio

“…However, many factors influence the commercialization of LSBs, for example, the growth of lithium dendrites, shuttle effect of LiPSs, and large volume expansion. Because of the active chemical nature of lithium, it reacts with the electrolyte to form a solid electrolyte interface (SEI), which can prevent other Li from continuing to react with the electrolyte; thus, Li + will unevenly deposit on the SEI surface in the reaction . During cycling, irregularly deposited lithium aggregates and results in the lithium dendrites. , Sulfur is insulated/nonconductive and has poor activity when used as an electrode alone.…”