Tailoring the Microstructure and Electrochemical Performance of 3D Microbattery Electrodes Based on Carbon Foams

Abstract

Three‐dimensional (3D) carbon electrodes with suitable microstructural features and stable electrochemical performance are required for practical applications in 3D lithium (Li)‐ion batteries. Herein, the optimization of the microstructures and electrochemical performances of carbon electrodes derived from emulsion‐templated polymer foams are dealt with. Exploiting the rheological properties of the emulsion precursors, carbon foams with variable void sizes and specific surface areas are obtained. Carbon foams with an average void size of around 3.8 μm are produced, and improvements are observed both in the coulombic efficiency and the cyclability of the carbon foam electrodes synthesized at 2200 °C. A stable areal capacity of up to 1.22 mAh cm−2 (108 mAh g−1) is achieved at a current density of 50 μA cm−2. In addition, the areal capacity remains almost unaltered, i.e., 1.03 mAh cm−2 (91 mAh g−1), although the cycling current density increases to 500 μA cm−2 indicating that the materials are promising for power demanding applications.

Design Strategies of 3D Carbon‐Based Electrodes for Charge/Ion Transport in Lithium Ion Battery and Sodium Ion Battery

“…To fabricate the 3D foamed electrodes for LIBs and SIBs, two approaches to construct 3D frameworks are usually considered. One is using carbon monolith derived from traditional polymer, [ 18,60–64 ] and the other is based on carbon materials (i.e., graphene, [ 65–67 ] carbon nanotube, [ 68 ] and graphite [ 38 ] ) that are usually combined with the metal foams. Currently, the former fabrication of 3D foamed‐electrode can be optimized by the synthesis condition of polymerization and pyrolysis temperature.…”

“…As shown in Figure a, the foamed carbon electrode derived from high internal phase emulsion (HIPE)‐templated polymer foams with an average void size of around 3.8 µm was prepared by a series of procedures. [ 60 ] The latter method is combining carbon materials on metal foam substrate that can form conductive paths with various scales and ranges.…”

“…a) Illustration showing a series of procedures for preparation the carbon foams derived from HIPE. [ 60 ] b) Illustration for the comparison of the conventional electrode using metal foil and the stretchable electrode based on the PDMS sponge. [ 37 ] c) The photograph of lithium iron phosphate (LFP) on ultrathin graphite foam (UGF), d) SEM image of UGF/LFP, and e) SEM image of UGF.…”

“…[ 38 ] a) Adapted with permission. [ 60 ] Copyright 2019, Wiley‐VCH GmbH, Weinheim. b) Adapted with permission.…”

“…As far as Li + /Na + storage is concerned, it is undesirable for 3D carbon electrode with high surface areas, leading to the lower initial Coulombic efficiency (ICE) caused by the aggravated electrolyte decomposition. [ 60 ] Moreover, the excess of porosity in 3D carbon electrode may limit the ion transport and result in a low volumetric capacity. [ 133 ] Therefore, keeping rational ranges of both the surface area and porosity of 3D carbon electrode is in critical need for achieving an improved electrochemical performance.…”