title: Encapsulation of redox polysulphides via chemical interaction with nitrogen atoms in the organic linkers of metal-organic framework nanocrystals.
abstract: Lithium polysulphides generated during discharge in the cathode of a lithium-sulphur redox cell are important, but their dissolution into the electrolyte from the cathode during each redox cycle leads to a shortened cycle life. Herein, we use in situ spectroelectrochemical measurements to demonstrate that sp(2) nitrogen atoms in the organic linkers of nanocrystalline metal-organic framework-867 (nMOF-867) are able to encapsulate lithium polysulphides inside the microcages of nMOF-867, thus helping to prevent their dissolution into the electrolyte during discharge/charge cycles. This encapsulation mechanism of lithiated/delithiated polysulphides was further confirmed by observations of shifted FTIR spectra for the C = N and C-N bonds, the XPS spectra for the Li-N bonds from nMOF-867, and a visualization method, demonstrating that nMOF-867 prevents lithium polysulphides from being dissolved in the electrolyte. Indeed, a cathode fabricated using nMOF-867 exhibited excellent capacity retention over a long cycle life of 500 discharge/charge cycles, with a capacity loss of approximately 0.027% per cycle from a discharge capacity of 788 mAh/g at a high current rate of 835 mA/g.
authors.affiliation: Department of Materials Science and Engineering, Advanced Institute of Science and Technology Korea 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea.
authors.forename: Jung Hyo
authors.initials: JH
authors.lastname: Park
authors.affiliation: Department of Materials Science and Engineering, Advanced Institute of Science and Technology Korea 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea.|Department of Chemical and Biological Engineering, Sookmyung Women's University Cheonpa-ro 47-gil 100, Yongsan-gu, Seoul 04310, Republic of Korea.
authors.forename: Kyung Min
authors.initials: KM
authors.lastname: Choi
authors.affiliation: Department of Materials Science and Engineering, Advanced Institute of Science and Technology Korea 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea.
authors.forename: Dong Ki
authors.initials: DK
authors.lastname: Lee
authors.affiliation: Graduate School of EEWS (Energy, Environment, Water, and Sustainability) Korea Advanced Institute of Science and Technology 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea.
authors.forename: Byeong Cheul
authors.initials: BC
authors.lastname: Moon
authors.affiliation: Department of Materials Science and Engineering, Advanced Institute of Science and Technology Korea 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea.
authors.forename: Sang Rim
authors.initials: SR
authors.lastname: Shin
authors.affiliation: School of Mechanical and Materials Engineering, Washington State University Pullman, Washington 99164-2920, USA.
authors.forename: Min-Kyu
authors.initials: MK
authors.lastname: Song
authors.affiliation: Department of Materials Science and Engineering, Advanced Institute of Science and Technology Korea 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea.|Graduate School of EEWS (Energy, Environment, Water, and Sustainability) Korea Advanced Institute of Science and Technology 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Republic of Korea.
authors.forename: Jeung Ku
authors.initials: JK
authors.lastname: Kang