The trend of being ultra-thin, miniatured, flexible, and highly integrated has been witnessed for electronic devices nowadays in the recent two decades. These advanced devices call for corresponding energy storage modules to meet the requirements for practical applications in communication, mobile health care, and biomedical technologies. However, conventional bulky batteries are unsuitable to be directly made into flexible formats because they may suffer from breakage and cracks within the inner interfaces among functional components upon the frequent deformations during use. Besides, it is also difficult for bulky devices to fit the irregular surfaces such like human body and this will largely decrease the comfort and practicability of related products.