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Hermetically Coated and Well‐Separated Co 3 O 4 Nanophase within Porous Graphitic Carbon Nanosheets: Synthesis, Confinement Effect, and Improved Lithium‐Storage Capacity and Durability
Author(s) -
Zhang Jingfei,
Ren Wangyu,
Zhou Yunyun,
Li Pei,
Xu Lin,
Sun Dongmei,
Wu Ping,
Zhou Yiming,
Tang Yawen
Publication year - 2016
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201600573
Subject(s) - anode , materials science , chemical engineering , porosity , crystallinity , nanoparticle , nanotechnology , lithium (medication) , carbon fibers , current density , electrode , composite number , composite material , chemistry , medicine , physics , quantum mechanics , endocrinology , engineering
Considerable lithium‐driven volume changes and loss of crystallinity on cycling have impeded the sustainable use of transition metal oxides (MOs) as attractive anode materials for advanced lithium‐ion batteries that have almost six times the capacity of carbon per unit volume. Herein, Co 3 O 4 was used as a model MO in a facile process involving two pyrolysis steps for in situ encapsulation of nanosized MO in porous two‐dimensional graphitic carbon nanosheets (2D‐GCNs) with high surface areas and abundant active sites to overcome the above‐mentioned problems. The proposed method is inexpensive, industrially scalable, and easy to operate with a high yield. TEM revealed that the encaged Co 3 O 4 is well separated and uniformly dispersed with surrounding onionlike graphitic layers. By taking advantage of the high electronic conductivity and confinement effect of the surrounding 2D‐GCNs, a hierarchical GCNs‐coated Co 3 O 4 (Co 3 O 4 @GCNs) anode with 43.5 wt % entrapped active nanoparticles delivered a remarkable initial specific capacity of 1816 mAh g −1 at a current density of 100 mA g −1 . After 50 cycles, the retained capacity is as high as 987 mAh g −1 . When the current density was increased to 1000 mA g −1 , the anode showed a capacity retention of 416 mAh g −1 . Enhanced reversible rate capability and prolonged cycling stability were found for Co 3 O 4 @GCN compared to pure GCNs and Co 3 O 4 . The Co 3 O 4 @GCNs hybrid holds promise as an efficient candidate material for anodes due to its low cost, environmentally friendly nature, high capacity, and stability.