A half millimeter thick coplanar flexible battery with wireless recharging capability.
Most of the existing flexible lithium ion batteries (LIBs) adopt the conventional cofacial cell configuration where anode, separator, and cathode are sequentially stacked and so have difficulty in the integration with emerging thin LIB applications, such as smart cards and medical patches. In order to overcome this shortcoming, herein, we report a coplanar cell structure in which anodes and cathodes are interdigitatedly positioned on the same plane. The coplanar electrode design brings advantages of enhanced bending tolerance and capability of increasing the cell voltage by in series-connection of multiple single-cells in addition to its suitability for the thickness reduction. On the basis of these structural benefits, we develop a coplanar flexible LIB that delivers 7.4 V with an entire cell thickness below 0.5 mm while preserving stable electrochemical performance throughout 5000 (un)bending cycles (bending radius = 5 mm). Also, even the pouch case serves as barriers between anodes and cathodes to prevent Li dendrite growth and short-circuit formation while saving the thickness. Furthermore, for convenient practical use wireless charging via inductive electromagnetic energy transfer and solar cell integration is demonstrated.
Joo-Seong
JS
Kim
Dongah
D
Ko
Dong-Joo
DJ
Yoo
Dae Soo
DS
Jung
Cafer T
CT
Yavuz
Nam-In
NI
Kim
⊥High Temperature Energy Materials Research Center, Korea Institute of Science and Technology (KIST), 5, Hwarang-ro 14-gil, Seongbuk-gu, Seoul 136-791, Republic of Korea.
In-Suk
IS
Choi
#Center for Nanomaterials Characterization, Korea Research Institute of Standards and Science (KRISS), 267 Gajeong-ro, Yuseong-gu, Daejeon 305-340, Republic of Korea.
Jae Yong
JY
Song
Jang Wook
JW
Choi
Coplanar structure; flexible battery; interelectrode barrier; lithium ion battery; wireless charging