Two-dimensional materials for miniaturized energy storage devices: from individual devices to smart integrated systems

Abstract

Nowadays, the increasing requirements of portable, implantable, and wearable electronics have greatly stimulated the development of miniaturized energy storage devices (MESDs). Electrochemically active materials and microfabrication techniques are two indispensable parts in MESDs. Particularly, the architecture design of microelectrode arrays is beneficial to the accessibility of two-dimensional (2D) active materials. Therefore, this study reviews the recent advancements in microbatteries and microsupercapacitors based on electrochemically active 2D materials. Emerging microfabrication strategies enable the precise control over the thickness, homogeneity, structure, and dimension in miniaturized devices, which offer tremendous opportunities for achieving both high energy and power densities. Furthermore, smart functions and integrated systems are discussed in detail in light of the emergence of intelligent and interactive modes. Finally, future developments, opportunities, and urgent challenges related to 2D materials, device fabrications, smart responsive designs, and microdevice integrations are provided.

3D Interdigitated Microsupercapacitors with Record Areal Cell Capacitance

“…The increasing need for onboard energy supply/storage in wearable electronics, wireless sensor networks, and the upcoming Internet of Things has pushed for the miniaturization of a variety of technologies. In this context, the appeal to include an energy storage unit directly onto microchip is high and great efforts have been recently devoted to integrating energy harvesting and storage elements directly in microscale devices, with the objective of achieving energy self‐sufficiency of embedded electronics.…”

All‐Solid‐State Planar Sodium‐Ion Microcapacitors with Multidirectional Fast Ion Diffusion Pathways

“…2019, 6,1902147 and LSV curves at 2 mV s −1 under a cell architecture of stainless steel/ ionogel electrolyte/sodium plate were recorded by electrochemical workstation (CHI760E). Sci.…”

“…2019, 6,1902147 Remarkably, NTO//AGNIMCs80 also disclosed a considerable capacitance retention of 75% and a high Coulombic efficiency of >95% after 1500 cycles at 1.5 mA cm −2 (Figure 5c). Sci.…”

“…[18][19][20] In contrast, MSCs can fully reversibly adsorb/desorb electrolyte ions or perform fast faradaic reaction at the interface of electrode and electrolyte, affording high power density of up to 1000 W cm −3 , fast charge and discharge rate, and longevity, [21][22][23] while they suffer from low energy density, usually less than 5 mWh cm −3 . [1][2][3][4][5][6][7][8] In principle, Herein, the first prototype planar sodium-ion microcapacitors (NIMCs) are constructed based on the interdigital microelectrodes of urchin-like sodium titanate as faradaic anode and nanoporous activated graphene as non-faradaic cathode along with high-voltage ionogel electrolyte on a single flexible substrate.…”

“…[48] In summary, we have constructed allsolidstate planar NTO//AGNIMCs with the unique merit of multidirectional fast ion diffusion pathways, showing high volumetric perfor mance, remarkable mechanical flexibility, and hightemper ature stability due to the use of nonflammable highvoltage ionogel electrolyte and the advance of inplane separator free geometry. 2019, 6,1902147 As a result, NTO//AGNIMCs exhibited a high volumetric energy density Adv.…”