Hydrothermal Coating of Patterned Carbon Nanotube Forest for Structured Lithium‐Ion Battery Electrodes

Abstract

Controlling the arrangement and interface of nanoparticles is essential to achieve good transfer of charge, heat, or mechanical load. This is particularly challenging in systems requiring hybrid nanoparticle mixtures such as combinations of organic and inorganic materials. This work presents a process to coat vertically aligned carbon nanotube (CNT) forests with metal oxide nanoparticles using microwave‐assisted hydrothermal synthesis. Hydrothermal processes normally damage delicate CNT forests, which is addressed here by a combination of lithographic patterning, transfer printing, and reduction of the synthesis time. This process is applied for the fabrication of structured Li‐ion battery (LIB) electrodes where the aligned CNTs provide a straight electron transport path through the electrode and the hydrothermal coating process is used to coat the CNTs with conversion anode materials for LIBs. These nanoparticles are anchored on the surface of the CNTs and batteries fabricated following this process show a fourfold longer cyclability. Finally, this process is used to create thick electrodes (350 µm) with a gravimetric capacity of over 900 mAh g−1.

Honeycomb-shaped carbon nanotube supports for BiVO4 based solar water splitting

“…These structures are interesting because they are mechanically robust, allow for a straight forward control of the microscale pore structure (honeycomb cell width), and straight electron transport though the aligned CNTs honeycomb walls which is advantageous in energy storage applications as shown for Li-ion batteries recently. [19] While several CNT honeycomb fabrication and modelling methods have been reported previously [7], [9], [12], [20]- [23], we found that the parameter space that results in defect free large area honeycomb structures is limited. To further understand the relevant factors affecting the honeycomb structure and defects we performed a design of experiment (DoE) analysis of the patterns and heights of CNT forests that result in high quality honeycomb electrodes.…”

Anisotropic Carbon Nanotube Structures with High Aspect Ratio Nanopores for Li-Ion Battery Anodes

“…The colloidal lithography-patterned VACNTs can also survive a microwave-assisted hydrothermal coating method (see Figure S7 ), for which we adapted a protocol reported by Li et al 52 and Jessl et al 53 to coat CNTs with Fe 2 O 3 nanosheets. While this method worked for short structures (as seen in the SEM images in Figure S7 a,b), it is more difficult for higher aspect ratio structures, as the narrow pores tend to close during drying due to capillary forces (as seen in the SEM images in Figure S7 c,d).…”

Fabrication and applications of stimuli‐responsive micro/nanopillar arrays

“…CNT, carbon nanotube; CVD, chemical vapor deposition; RIE, reactive ion etching; PS, polystyrene; Si, silicon to many researchers because of their high electroconductivity and lightweight advantages. 7,[34][35][36][37][38] As shown in Figure 5(C), hexagonally arranged microhole arrays were first prepared by photolithography that patterns positive tone PR resist by developing it with solvents. 34 Then, PVD was introduced to deposit catalyst, Fe/Al 2 O 3 , on the PR master mold.…”

“…For example, molecular assembly can be introduced to grow metal oxide nanopillar arrays with the assistance of a seed layer organized by sputtering 32 or spin-coating. 33 Advancing from that, carbon nanotube (CNT) micro 7,[34][35][36][37] /nanoforests 38 are rendered by bottomup assembly of C x H y molecules on a catalyst patterned by top-down lithography. Highly electroconductive and lightweight CNT micro/nanopillar arrays were obtained with high uniformity and periodicity.…”