Hong Liu,Peng Zeng,Yongfang Li,Hao Yu,Manfang Chen,Sidra Jamil,Changqing Miao,Gairong Chen,Qi-Cheng Liu,Zhigao Luo,Xianyou Wang
The merit of high energy density endows the lithium sulfide (Li2S)-based lithium–sulfur batteries (LSBs) as a promising candidate for next-generation energy storage batteries. In this work, Li2S is chemically anchored onto the surface of two-dimensional graphene oxide (GO), which is then tangled and connected by one-dimensional carbon nanotube (CNT) to promote electron transfer, and finally further embedded with PANI-derived carbon (PDC) to suppress a polysulfide shuttle. The deliberately designed carbon matrix offers a fast electron and ion transfer route, suitable surface area, void volume, and pore size for redox reactions and polysulfide confinement. Furthermore, PDC could synergistically immobilize polysulfides inside the cathode by means of chemisorption so as to restrain the shuttle effect in LSBs. Last but not least, PDC with a quinone-based structure could function as a redox mediator (RM) to facilitate Li2S oxidation with minimized polarization. Benefited from the aforementioned advantages, the as-fabricated Li2S-GO/CNT/PDC composite, which is coupled with a lithium metal as the anode, delivers initially a high specific capacity of 925 mAh g–1 at 0.1 C and good retention capability of 550 mAh g–1 after 400 cycles at 2 C. Therefore, the good electrochemical behavior of the Li2S-GO/CNT/PDC composite suggests its promising prospects for the commercial application of LSBs in high-energy storage devices.
He Wang,Hongling Guo,Zihao Huang,Weiliang Liu,Mei Li,Jinshui Yao,Jiaxi Cui,Yuanhao Wang,Manman Ren
The high activity barriers of Li 2 S nucleation and deposition limit the redox reaction kinetics of lithium polysulfides (LiPSs), meanwhile, the significant shuttle effect of LiPSs hampers the advancement of Li-S batteries (LSBs). In this work, a NiSe 2 /CoSe 2 -rGO (NiSe 2 /CoSe 2 -G) sulfur host with bifunctional catalytic activity was prepared through a hard template method. Electrochemical experiment results confirm that the combination of NiSe 2 and CoSe 2 not only facilitates the bidirectional catalytic function during charge and discharge processes, but also increases the active sites toward LiPSs adsorption. Simultaneously, the highly conductive rGO network enhances the electronic conductivity of NiSe 2 /CoSe 2 -G/S and provides convenience for loading NiSe 2 /CoSe 2 catalysts. Benefitting from the exceptional catalytic-adsorption capability of NiSe 2 /CoSe 2 and the presence of rGO, the NiSe 2 /CoSe 2 -G/S electrode exhibits excellent electrochemical properties . At 1C, it demonstrates a low capacity attenuation of 0.087 % per cycle during 500 cycles. The electrode can maintain a discharge capacity of 927 mAh/g at a sulfur loading of 3.3 mg cm −2 . The bidirectional catalytic activity of NiSe 2 /CoSe 2 -G offers a prospective approach to expedite the redox reactions of active S, meanwhile, this work also offers an ideal approach for designing efficient S hosts for LSBs.
Jiongwei Shan,Wei Wang,Bing Zhang,Xinying Wang,Weiliang Zhou,Liguo Yue,Yunyong Li
Designing dense thick sulfur cathodes to gain high-volumetric/areal-capacity lithium–sulfur batteries (LSBs) in lean electrolytes is extremely desired. Nevertheless, the severe Li 2 S clogging and unclear mechanism seriously hinder its development. Herein, an integrated strategy is developed to manipulate Li 2 S redox kinetics of CoP/MXene catalyst via electron-donor Cu doping. Meanwhile a dense S/Cu 0.1 Co 0.9 P/MXene cathode (density = 1.95 g cm −3 ) is constructed, which presents a large volumetric capacity of 1664 Ah L −1 (routine electrolyte) and a high areal capacity of ≈8.3 mAh cm −2 (lean electrolyte of 5.0 µL mg s −1 ) at 0.1 C. Systematical thermodynamics, kinetics, and theoretical simulation confirm that electron-donor Cu doping induces the charge accumulation of Co atoms to form more chemical bonding with polysulfides, whereas weakens Co S bonding energy and generates abundant lattice vacancies and active sites to facilitate the diffusion and catalysis of polysulfides/Li 2 S on electrocatalyst surface, thereby decreasing the diffusion energy barrier and activation energy of Li 2 S nucleation and dissolution, boosting Li 2 S redox kinetics, and inhibiting shuttling in the dense thick sulfur cathode. This work deeply understands the atomic-level manipulation mechanism of Li 2 S redox kinetics and provides dependable principles for designing high-volumetric-energy-density, lean-electrolyte LSBs through integrating bidirectional electro-catalysts with manipulated Li 2 S redox and dense-sulfur engineering.
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