Self‐Standing Porous LiCoO2 Nanosheet Arrays as 3D Cathodes for Flexible Li‐Ion Batteries

• Published in: Advanced functional materials Vol. 28; no. 7
• Main Authors: Xue, Liang, Savilov, Serguei V., Lunin, Valery V., Xia, Hui
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc 14.02.2018
• Subjects: 3D nanoarchitectures; Anodes; Arrays; Cathodes; Cobalt oxides; Cycles; Electrode materials; Electrodes; flexible Li‐ion batteries; Gold; LiCoO2; Lithium-ion batteries; Materials science; nanosheet arrays; Nanosheets; Rechargeable batteries; self‐standing cathodes; Stability; Substrates
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.201705836

Self‐standing electrodes are the key to realize flexible Li‐ion batteries. However, fabrication of self‐standing cathodes is still a major challenge. In this work, porous LiCoO2 nanosheet arrays are grown on Au‐coated stainless steel (Au/SS) substrates via a facile “hydrothermal lithiation” method using Co3O4 nanosheet arrays as the template followed by quick annealing in air. The binder‐free and self‐standing LiCoO2 nanosheet arrays represent the 3D cathode and exhibit superior rate capability and cycling stability. In specific, the LiCoO2 nanosheet array electrode can deliver a high reversible capacity of 104.6 mA h g−1 at 10 C rate and achieve a capacity retention of 81.8% at 0.1 C rate after 1000 cycles. By coupling with Li4Ti5O12 nanosheet arrays as anode, an all‐nanosheet array based LiCoO2//Li4Ti5O12 flexible Li‐ion battery is constructed. Benefiting from the 3D nanoarchitectures for both cathode and anode, the flexible LiCoO2//Li4Ti5O12 battery can deliver large specific reversible capacities of 130.7 mA h g−1 at 0.1 C rate and 85.3 mA h g−1 at 10 C rate (based on the weight of cathode material). The full cell device also exhibits good cycling stability with 80.5% capacity retention after 1000 cycles at 0.1 C rate, making it promising for the application in flexible Li‐ion batteries. This work gives a novel approach to fabricate porous LiCoO2 nanosheet arrays on Au‐coated stainless steel substrates. The trivial transformation on crystal structure is the key to build 3D nanoarray electrode. The all‐nanosheet array based LiCoO2//Li4Ti5O12 full cell exhibits outstanding performance and good flexibility.