Graphitic Nanocarbon–Selenium Cathode with Favorable Rate Capability for Li–Se Batteries

Zhao

et al. 2020

Energy Tech

Selenium (Se) has received extensive attention as the most competitive cathode material for next generation high‐energy batteries. However, the shuttle effect of polyselenide and volume change lead to inferior electrochemical properties. To solve these issues, a porous bamboo‐derived carbon (PBC) with abundant meso/micropores is prepared as a framework to effectively encapsulate elemental selenium. For Li–Se batteries, Se/PBC electrode delivers an outstanding capacity of 509 mAh g−1 after 200 cycles at 0.2 C (1 C = 675 mA g−1) with a low capacity fade of 0.036% per cycle. The Se/PBC composite also reveals a satisfied electrochemical performance for Na–Se batteries with an excellent capacity of 409 mAh g−1 after 200 cycles at 0.2 C. Moreover, Se/PBC electrode also presents excellent long‐term cycle performance and rate performance at 15 C for Li–Se batteries and 10 C for Na–Se batteries. The outstanding properties are attributed to the specific 3D structure and high conductivity of PBC, which significantly inhibits the shuttle effect and enhances the reaction kinetics. Herein, not only the great application potential of bamboo in energy storage systems is demonstrated, but also an effective approach and low‐cost strategy for improving the performance of lithium/sodium–selenium batteries is offered.

Section: Resultsmentioning

confidence: 99%

Porous Bamboo‐Derived Carbon as Selenium Host for Advanced Lithium/Sodium–Selenium Batteries

Zhao

et al. 2020

Energy Tech

“…ZIF‐8 loaded with DOX and VER (DOX‐VER/ZIF‐8) is further modified with poly(ethylene glycol)‐folate (PEG‐FA) to obtain better stability and active targeting ability. As a result, the multifunctional nanoplatform of PEG‐FA/DOX‐VER/ZIF‐8 could efficiently overcome the multidrug resistance in in vitro studies for cancer treatment …”

Section: Mofs For Drug Delivery and Chemotherapymentioning

confidence: 99%

Metal‐Organic Framework Mediated Multifunctional Nanoplatforms for Cancer Therapy

Zeng

Song

et al. 2018

Advanced Therapeutics

“…[ 11 ] Inspired by this work, various carbon hosts have also been demonstrated for Li–Se batteries. Compared to the mesoporous carbon/Se (MeC/Se) [ 12–14 ] and hierarchical porous carbon/Se cathodes, [ 15–17 ] the MiC/Se cathodes such as metal‐organic framework‐derived MiC, [ 18–20 ] graphitic MiC sheets [ 21 ] and MiC sphere [ 22,23 ] shows obviously higher specific capacity, better cycling stability, along with better rate capability. However, the chain‐like Se molecules can be formed in pores which are usually not larger than 5 nm.…”

Section: Introductionmentioning

confidence: 99%

New Insight into the Confinement Effect of Microporous Carbon in Li/Se Battery Chemistry: A Cathode with Enhanced Conductivity

Tan

Liu

et al. 2020

Small

increasing requirement of energy density. Among these alternatives to the conventional lithium-ion batteries, lithium-sulfur (Li-S) batteries are of particular interest due to their high theoretical gravimetric energy density (2500 Wh kg −1 ) and natural abundance of sulfur. [1] Selenium (Se), as an element that also belongs to the chalcogen group in periodic table, has been recently proposed as a promising cathode material. [2][3][4][5] In spite of the lower theoretical gravimetric capacity of Se (675 mAh g −1 ), the volumetric capacity of Se (3253 mAh cm −3 ) is comparable to that of S (3467 mAh cm −3 ). Moreover, Se possesses an electronic conductivity that is ≈20 orders of magnitude higher than S, which enables a higher utilization rate, better kinetics and higher loading of active materials in electrode. These advantages make Se a promising candidate of cathode materials for high energy lithium battery.The Li-Se electrochemistry highly depends on the organic electrolyte. In ether-based electrolytes, the Se cathode operated via solidliquid-solid mechanism suffers from the dissolution of reaction intermediates-lithium polyselenide, resulting in the continuous leakage of active materials and shuttle reaction between cathode and anode. [4][5][6] Using the carbonate-based electrolytes that seldom dissolve lithium polyselenide intermediates is a potential strategy to address this problem occurred in Li-Se batteries. [7] However, because of the irreversible reactions between the nucleophilic long-chain polysulfide anions (Se 2− or Se 2− ) and carbonate molecules, the bulk Se cathode even prepared with nanostructured Se active materials is incompatible with these electrolytes. [5,8,9] Recently, it was found that the Se confined in CMK-3 matrix can perform well with carbonate electrolytes. [2] By forming the space-confined Se chains in pores of carbon hosts, the Se molecules can are directly converted to Li 2 Se without the lithium polyselenide intermediates. [10] Moreover, the terminal Se molecules in helical Se x are preferentially attacked by Li + , enabling a higher electrochemical activity than the ring structure. [11] Inspired by this work, various carbon hosts have also been demonstrated for Li-Se batteries. Compared to the mesoporous carbon/Se (MeC/Se) [12][13][14] and hierarchical porous carbon/Se cathodes, [15][16][17] the MiC/Se cathodes such as metal-organic framework-derived MiC, [18][19][20] graphitic MiC Embedding the fragmented selenium into the micropores of carbon host has been regarded as an effective strategy to change the Li-Se chemistry by a solid-solid mechanism, thereby enabling an excellent cycling stability in Li-Se batteries using carbonate electrolyte. However, the effect of spatial confinement by micropores in the electrochemical behavior of carbon/selenium materials remains ambiguous. A comparative study of using both microporous (MiC) and mesoporous carbons (MeC) with narrow pore size distribution as selenium hosts is herein reported. Systematic investigations reveal that the high Se ut...