Internal structure of portable energy storage

Which two-dimensional materials are used in energy storage devices?

Two-dimensional materials such as layered transition-metal dichalcogenides, carbides, nitrides, oxides and graphene-based materials have enabled very thin active electrodes with high energy density and excellent cyclability for flexible energy-storage devices.

Why do we need flexible energy storage devices?

To achieve complete and independent wearable devices, it is vital to develop flexible energy storage devices. New-generation flexible electronic devices require flexible and reliable power sources with high energy density, long cycle life, excellent rate capability, and compatible electrolytes and separators.

How to fulfill flexible energy-storage devices?

To fulfill flexible energy-storage devices, much effort has been devoted to the design of structures and materials with mechanical characteristics.

What is a hybrid energy storage device?

Hybrid devices, which take advantage of both battery-type materials and capacitive materials, aim to simultaneously produce high energy density and high power density, striking a balance between both 60, 61, 62, 63, 64. Developing flexible or even stretchable energy-storage devices is particularly important for wearable devices (Fig. 2e).

What are compatible energy storage devices?

Compatible energy storage devices that are able to withstand various mechanical deformations, while delivering their intended functions, are required in flexible/wearable electronics. This imposes constraints on the structural designs, materials selection, and miniaturization of the cells.

What is the mechanical reliability of flexible energy storage devices?

As usual, the mechanical reliability of flexible energy storage devices includes electrical performance retention and deformation endurance. As a flexible electrode, it should possess favorable mechanical strength and large specific capacity. And the electrodes need to preserve efficient ionic and electronic conductivity during cycling.