Additive Manufacturing: Rethinking Battery Design

Abstract

T wo major trends are changing the way batteries are designed. First, small portable electronic devices have steadily evolved toward compact and thin form factors while retaining high levels of device functionality. As a result of this trend, batteries have become an everincreasing fraction of the total device volume, as shown in Fig. 1. Second, the advent of truly manufacturable and scalable flexible electronics has lifted the dimensional limitations of device design. However, this has in turn introduced new design complexities for integration, processing, and reliability. Connecting and integrating a battery, which oftentimes is the largest component in an electronic device, poses complex manufacturing, cost, and reliability issues. These technology progressions have motivated a shift in energy storage design and manufacturing to accommodate novel materials, new device geometries, and non-traditional fabrication methods. Additive manufacturing (AM) is a suite of manufacturing processes that is currently changing the way we design and manufacture products.1 AM technology will lead to a revolution in the way energy storage components are designed, integrated, and utilized in electronic devices. In this article we focus on recent advances in additive manufacturing for batteries and highlight current and future research directions for battery design, manufacturing, and integration for small, portable, and wearable electronics. Conventional Large-scale Battery ManufacturingAdvances in batteries are following typical process scale and efficiency trajectories. Batteries, such as the lithium-ion (Li-ion) cells found in smartphones, typically contain four main elements: a positive electrode, a negative electrode, a liquid electrolyte, and polymer-based separators. Focusing on the anode and cathode, traditional fabrication methods use ink-like materials (referred to as slurries) to form the electrode films. The slurries are formed by mixing electrode materials and conductive additives with binders for adhesion. This slurry is then spread onto a foil in a slot die or blade coating machine.Slot die or blade coating is the standard method for depositing battery electrodes in industry. In this process, a slot die head or blade is set a fixed distance from a current collector substrate. In large-scale production, the substrate moves, the head/ blade is fixed, and material is continuously injected onto the moving foil and is evenly distributed over the current collector. The head/blade typically resides about 5-200 µm above the current collector substrate where smaller gap distances may result in imperfect applied films after drying, and larger operating gaps may result in uneven surfaces. The final thickness of the dried electrode depends on the concentration, morphology, viscosity, and surface chemistry of the ink or slurry. This coating process has been used successfully at scale for many years to fabricate battery electrodes, however, there is no inherent capability to pattern shapes or nonrectilinear features into this e...

Supercapacitors on demand: all-printed energy storage devices with adaptable design

“…A metal blade (stencil printing) or a rubber squeegee (screen printing) forces and transfers the ink (possessing appropriate viscosity, wetting, etc properties) through the mesh or mask pattern onto the substrate underneath. (10) Registration or alignment markings allows multiple and sequential layers of printing possible, with a high level of accuracy that is crucial in producing printed electronic components or devices. Various levels of automation are possible by using advanced printing machines, such as in-line registration, up/downloading, ink curing and more.…”

Fabrication and Characterization of 3D-Printed Highly-Porous 3D LiFePO4 Electrodes by Low Temperature Direct Writing Process

“…In a 3D lithium-ion battery, energy density can be improved by increasing the electrode height to accommodate more active materials while maintaining the Li-ion diffusion length constant. Therefore, the energy density can be enhanced without sacrificing power density [ 19 , 20 , 21 ].…”

Additive Manufacturing of Electrochemical Energy Storage Systems Electrodes

“…[5] Consequently, the blade distributes the slurry material evenly on the current collector at the adjusted thicknesstypically 5-200 μm. [6] This method, with its relatively simple working principle, allows relatively good thickness control and scalability. Yet, the produced thin films may present agglomeration of conducting or binding agents, thereby preventing the active material from being accessible for ion or electronic transport and decreasing the electrochemical performance.…”

“…[20] As shown in Figure 1b, research on additive manufacturing techniques (AMTs) is gaining traction along with research on EES devices. As a consequence, nowadays the challenge is the manufacturing of EES electrodes with controllable micro-and nanomorphologies through a scalable technique toward higher energy and power densities, lightweight, low volume, [6] and flexible of EES devices. Considering the advantages and potential of AM (Figure 1c), this work first presents a concise description of the main 3D printing techniques for researchers with general interest in AM.…”