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Amine‐ and Amide‐Functionalized Mesoporous Carbons: A Strategy for Improving Sulfur/Host Interactions in Li–S Batteries
Batteries & Supercaps ( IF 5.1 ) Pub Date : 2020-03-12 , DOI: 10.1002/batt.202000027 Samuel J. Fretz 1 , Marco Agostini 2 , Piotr Jankowski 2, 3 , Patrik Johansson 2 , Aleksandar Matic 2 , Anders E. C. Palmqvist 1
Batteries & Supercaps ( IF 5.1 ) Pub Date : 2020-03-12 , DOI: 10.1002/batt.202000027 Samuel J. Fretz 1 , Marco Agostini 2 , Piotr Jankowski 2, 3 , Patrik Johansson 2 , Aleksandar Matic 2 , Anders E. C. Palmqvist 1
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Lithium–sulfur (Li–S) batteries are of great interest due to their potentially high energy density, but the low electronic conductivity of both the sulfur (S8) cathode active material and the final discharge product lithium sulfide (Li2S) require the use of a conductive host. Usually made of relatively hydrophobic carbon, such hosts are typically ill‐suited to retain polar discharge products such as the intermediate lithium polysulfides (LiPs) and the final Li2S. Herein, we propose a route to increase the sulfur utilization by functionalizing the surface of ordered mesoporous carbon CMK3 with polar groups. These derivatized CMK3 materials are made using a simple two‐step procedure of bromomethylation and subsequent nucleophilic substitution with amine or amide nucleophiles. We demonstrate that, compared to the unfunctionalized control, these modified CMK3 surfaces have considerably larger binding energies with LiPs and Li2S, which are proposed to aid the electrochemical conversion between S8 and Li2S by keeping the LiPs species in close proximity to the carbon surface during Li–S battery cycling. As a result, the functionalized cathodes exhibit significantly improved specific capacities relative to their unmodified precursor.
中文翻译：
胺和酰胺功能化介孔碳：改善Li-S电池中硫/主体相互作用的策略
锂硫（Li–S）电池由于其潜在的高能量密度而备受关注，但是硫（S 8）正极活性物质和最终放电产物硫化锂（Li 2 S）的电子传导率都较低使用导电主体。通常由相对疏水的碳制成，此类主体通常不适合保留极性放电产物，例如中间的多硫化锂（LiPs）和最终的Li 2S.在此，我们提出了一种通过用极性基团官能化有序介孔碳CMK3的表面来提高硫利用率的途径。这些衍生的CMK3材料是通过简单的两步溴甲基化步骤制成的，随后通过胺或酰胺亲核试剂进行亲核取代。我们证明，与未官能化的对照物相比，这些修饰的CMK3表面与LiPs和Li 2 S具有更大的结合能，这被提议用于辅助S 8和Li 2之间的电化学转化。通过在Li–S电池循环期间将LiPs物种保持在碳表面附近来实现S。结果，相对于其未改性的前体，官能化的阴极表现出显着改善的比容量。
更新日期：2020-03-12
中文翻译：
胺和酰胺功能化介孔碳：改善Li-S电池中硫/主体相互作用的策略
锂硫（Li–S）电池由于其潜在的高能量密度而备受关注，但是硫（S 8）正极活性物质和最终放电产物硫化锂（Li 2 S）的电子传导率都较低使用导电主体。通常由相对疏水的碳制成，此类主体通常不适合保留极性放电产物，例如中间的多硫化锂（LiPs）和最终的Li 2S.在此，我们提出了一种通过用极性基团官能化有序介孔碳CMK3的表面来提高硫利用率的途径。这些衍生的CMK3材料是通过简单的两步溴甲基化步骤制成的，随后通过胺或酰胺亲核试剂进行亲核取代。我们证明，与未官能化的对照物相比，这些修饰的CMK3表面与LiPs和Li 2 S具有更大的结合能，这被提议用于辅助S 8和Li 2之间的电化学转化。通过在Li–S电池循环期间将LiPs物种保持在碳表面附近来实现S。结果，相对于其未改性的前体，官能化的阴极表现出显着改善的比容量。
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