Highly Reversible Li–Se Batteries with Ultra-Lightweight N,S-Codoped Graphene Blocking Layer

Abstract

The desire for practical utilization of rechargeable lithium batteries with high energy density has motivated attempts to develop new electrode materials and battery systems. Here, without additional binders we present a simple vacuum filtration method to synthesize nitrogen and sulfur codoped graphene (N,S-G) blocking layer, which is ultra-lightweight, conductive, and free standing. When the N,S-G membrane was inserted between the catholyte and separator, the lithium–selenium (Li–Se) batteries exhibited a high reversible discharge capacity of 330.7 mAh g−1 at 1 C (1 C = 675 mA g−1) after 500 cycles and high rate performance (over 310 mAh g−1 at 4 C) even at an active material loading as high as ~ 5 mg cm−2. This excellent performance can be ascribed to homogenous dispersion of the liquid active material in the electrode, good Li+-ion conductivity, fast electronic transport in the conductive graphene framework, and strong chemical confinement of polyselenides by nitrogen and sulfur atoms. More importantly, it is a promising strategy for enhancing the energy density of Li–Se batteries by using the catholyte with a lightweight heteroatom doping carbon matrix. Electronic supplementary materialThe online version of this article (10.1007/s40820-018-0213-5) contains supplementary material, which is available to authorized users.

High-power lithium–selenium batteries enabled by atomic cobalt electrocatalyst in hollow carbon cathode

“…The electrolyte in the cell with cycled bare Se@HC cathode ( Supplementary Fig. 36b, c) changed from colourless to yellow after the first discharge process, implying there was a dissolution of polyselenides in electrolyte 60 . It is clear that by using bare Se@HC cathode without single cobalt catalysts, lithium polyselenides were detached from the cathode and dissolved in the electrolyte, indicating that bare Se@HC cathode owns poor immobilization of polyselenides.…”

State‐Of‐The‐Art and Future Challenges in High Energy Lithium–Selenium Batteries

“…In addition to the efforts on Se cathodes, direct interception of intermediates diffusion, e.g., functionalizing the separator or inserting an interlayer, is also very efficient in suppressing the shuttle effects. [ 203–205 ] Separators and interlayers are usually very thin and light, accounting for negligible volume or mass proportion in the whole cell. Accordingly, high mass loading of active materials or even host‐free cathodes can be realized, which are desirable for high energy LSeBs.…”

“…Similar results were also achieved by using N, S codoped graphene as the interlayer for LSeBs. [ 205 ]…”

The Electrostatic Attraction and Catalytic Effect Enabled by Ionic–Covalent Organic Nanosheets on MXene for Separator Modification of Lithium–Sulfur Batteries

“…The modification of polypropylene (PP) separator is regarded as one complementary countermeasure. [13,14] Various materials, such as carbon nanotubes, [15] graphene oxide, [16] heteroatomdoped carbon, [17] metal oxides, [18] chalcogenides, [19] metalorganic frameworks, and/or their composites, [20] have been utilized as the coating layers of PP separator. It has been proposed that metal-containing coating layers not only alleviate the migration of polysulfides toward the anode through chemical interactions, but also expedite the conversion of the intercepted polysulfides through catalytic effects, [21] thus improving cycling stability to some degree.…”