The Road Towards Planar Microbatteries and Micro‐Supercapacitors: From 2D to 3D Device Geometries

Abstract

The rapid development and further modularization of miniaturized and self‐powered electronic systems have substantially stimulated the urgent demand for microscale electrochemical energy storage devices, e.g., microbatteries (MBs) and micro‐supercapacitors (MSCs). Recently, planar MBs and MSCs, composed of isolated thin‐film microelectrodes with extremely short ionic diffusion path and free of separator on a single substrate, have become particularly attractive because they can be directly integrated with microelectronic devices on the same side of one single substrate to act as a standalone microsized power source or complement miniaturized energy‐harvesting units. The development of and recent advances in planar MBs and MSCs from the fundamentals and design principle to the fabrication methods of 2D and 3D planar microdevices in both in‐plane and stacked geometries are highlighted. Additonally, a comprehensive analysis of the primary aspects that eventually affect the performance metrics of microscale energy storage devices, such as electrode materials, electrolyte, device architecture, and microfabrication techniques are presented. The technical challenges and prospective solutions for high‐energy‐density planar MBs and MSCs with multifunctionalities are proposed.

Hierarchical Ordered Dual‐Mesoporous Polypyrrole/Graphene Nanosheets as Bi‐Functional Active Materials for High‐Performance Planar Integrated System of Micro‐Supercapacitor and Gas Sensor

“…The rapid progress in portable, wearable, and implantable electronics has intensively spurred micro‐electrochemical energy storage devices and their integrated systems. [ 1–3 ] As one competitive miniaturized energy storage unit, micro‐supercapacitors (MSCs) constructed on a planar substrate exhibit significant advantages such as separator‐free architecture, high power density, fast charge/discharge rate, outstanding cycling stability, and favorable safety. [ 4,5 ] They can be directly integrated with energy harvesters (e.g., solar cell and nanogenerator) and energy consumption units (e.g., digital display and sensor) to realize a self‐powered standalone system.…”

Zinc based micro‐electrochemical energy storage devices: Present status and future perspective

“…The booming development of microelectrochemical energy storage devices (MESDs) is driven by the smart, wearable, and flexible microelectronics applied in microrobots, wireless self‐powered systems, patient tracking and location, implantable medical sensors, and internet of things 1‐3 . However, current power sources with heavy mass, undesired big volume, and inferior flexibility cannot satisfy the demand of MESDs with the compatible advantages of light weight, miniaturization, tunable thinness, and mechanical flexibility 4 .…”

“…In principle, the total areal size of MESDs could be in the millimeter or even in the centimeter scale with different configurations 5 . To date, lithium‐based MESDs, especially for lithium thin‐film microbatteries (MBs) (<1 mm in thickness), 3,6‐8 have been extensively developed in commercial application for wearable and card‐type devices. Nevertheless, these lithium thin‐film MBs exhibit low volumetric energy densities (<200 Wh/L), comparing with conventional sandwich lithium‐ion batteries (<650 Wh/L) 9 .…”

“…As is well‐known, zinc ion MBs (ZIMBs) and zinc ion microsupercapacitors (ZIMSCs) are the two main zinc‐based MESDs as power supplies coupled with various microelectronics 20‐23 . As a rule, ZIMBs display high energy density through slow redox reactions, for example, ion insertion/extraction and conversion reaction in the internal electrode, while ZIMSCs through rapid Faradic reaction at the interface between the electrode and electrolyte or the fast adsorption/desorption of electrolyte ions, equipped with high power density 3,24‐26 . Compared with ZIMBs, ZIMSCs have come into their renaissance owing to long service life and high power density 5 .…”

Miniaturized Energy Storage Devices Based on Two‐Dimensional Materials

“…As shown in Figure 1, the configuration of microelectronic devices has developed from linear,p lanar shapes to 3D architectures. [10] At the same time, many materials, such as variouse lementary substances, [11,12] oxides, [13][14][15] sulfides, [16][17][18] hydroxides, [19,20] and organic compounds, [21][22][23] with forms ranging from 0D to 3D, [24][25][26] have been investigatedf or both MB and MSC electrode purposes. Amongt hese, 2D materials attract considerable attention due to their uniquee lectrochemical and mechanical properties when applied in energy storage.…”