3D-Printed Graded Electrode with Ultrahigh MnO_2 Loading for Non-Aqueous Electrochemical Energy Storage

摘要

Electrolytic manganese dioxide is one of the promising cathode candidatesfor electrochemical energy storage devices due to its high redoxcapacity and ease of synthesis. Yet, high-loading MnO_2 often suffersfrom sluggish reaction kinetics, especially in non-aqueous electrolytes.The non-uniform deposition of MnO_2 on a porous current collectors alsomakes it difficult to fully utilize the active materials at high mass loading.Here, a 3D printed graded graphene aerogel (3D GA) that containssparsely separated exterior ligaments is developed to create large openchannels for mass transport as well as densely arranged interior ligamentsproviding large ion-accessible active surface. The unique structuraldesign homogenizes the thickness of electro deposited MnO_2 even at anultrahigh mass loading of ≈70 mg cm~(?2). The electrode achieves a remarkablevolumetric capacity of 29.1 mA h cm~(?3) in the non-aqueous electrolyte.A Li-ion hybrid capacitor device assembled with a graded 3D GA/MnO_2cathode and graded 3D GA/VO_x anode exhibits a wide voltage window of0–4 V and a superior volumetric energy density of 20.2 W h L~(?1). The findingsoffer guidance on 3D printed electrode design for supporting ultrahighloading of active materials and developments of high energy densityenergy storage devices.