Structured Electrode Additive Manufacturing for Lithium-Ion Batteries

As the world increasingly swaps fossil fuels, significant advances in lithium-ion batteries have occurred over the past decade. Though demand for increased energy density with mechanical stability continues to be strong, attempts to use traditional ink-casting to increase electrode thickness or geometric complexity have had limited success. Here, we combined a nanomaterial orientation with 3D printing and developed a dry electrode processing route, structured electrode additive manufacturing (SEAM), to rapidly fabricate thick electrodes with an out-of-plane aligned architecture with low tortuosity and mechanical robustness. SEAM uses a shear flow of molten feedstock to control the orientation of the anisotropic materials across nano to macro scales, favoring Li-ion transport and insertion. These structured electrodes with 1 mm thickness have more than twice the specific capacity at 1 C compared to slurry-cast electrodes and have higher mechanical properties (compressive strength of 0.84 MPa and modulus of 5 MPa) than other reported 3D-printed electrodes

Structured Electrode Additive Manufacturing for Lithium-Ion Batteries

As the world increasingly swaps fossil fuels, significant advances in lithium-ion batteries have occurred over the past decade. Though demand for increased energy density with mechanical stability continues to be strong, attempts to use traditional ink-casting to increase electrode thickness or geometric complexity have had limited success. Here, we combined a nanomaterial orientation with 3D printing and developed a dry electrode processing route, structured electrode additive manufacturing (SEAM), to rapidly fabricate thick electrodes with an out-of-plane aligned architecture with low tortuosity and mechanical robustness. SEAM uses a shear flow of molten feedstock to control the orientation of the anisotropic materials across nano to macro scales, favoring Li-ion transport and insertion. These structured electrodes with 1 mm thickness have more than twice the specific capacity at 1 C compared to slurry-cast electrodes and have higher mechanical properties (compressive strength of 0.84 MPa and modulus of 5 MPa) than other reported 3D-printed electrodes

Equity crowdfunding syndicates and fundraising performance: The effect of human capital and lead investor reputation

Purpose–This paper is about equity crowdfunding syndicates as a form of entrepreneurial finance and looks specifically at the lead investors’ human capital and their ability to raise funds. Design/methodology/approach–The authors develop regressions on a unique hand-collected data set of 178 lead investors taken from the US-based platform AngelList. Findings–Results indicate that lead investors’ specialized human capital has a positive effect on their syndicate fundraising performance. However, it does not find a significant effect of general human capital. It also finds that specialized human capital is mediated by the reputation of the lead investor on the platform. Implications–This study extends human capital theory in the crowdfunding context by providing a more comprehensive portrait of human capital, and in doing so shifts the focus from an entrepreneur to an investor perspective, an approach much neglected in the crowdfunding literature. Originality–This study advances the current knowledge on crowdfunding as it is one of the first to understand syndicate investment as an innovative and alternative platform-based financial channel. It also contributes to the current debate on the role of human capital in crowdfunding and more generally to entrepreneurial finance

The effect of lead investor’s human capital on funding performance: the moderating role of investment ambition

We seek to determine the correlation between the human capital of lead investors and their funding performance within equity crowdfunding syndicates. We posit that the multi-faceted human capital of lead investors conveys their credibility and project quality. Using data derived from a sample of 157 individual lead investors on AngelList, we find that lead investors with higher levels of investment experience and entrepreneurial experience display improved funding performance. The research also highlights that lead investors’ investment ambitions moderate the effects of work experience and managerial experience on their funding performance. However, educational level and Ivy League education do not lead to significant effects on lead investors’ funding performance. This article contributes to the ongoing discussion on the role of human capital in crowdfunding by offering a multi-faceted view from an investor’s perspective.</p

Garnet Solid Electrolyte Protected Li-Metal Batteries

Garnet-type solid state electrolyte (SSE) is a promising candidate for high performance lithium (Li)-metal batteries due to its good stability and high ionic conductivity. One of the main challenges for garnet solid state batteries is the poor solid–solid contact between the garnet and electrodes, which results in high interfacial resistance, large polarizations, and low efficiencies in batteries. To address this challenge, in this work gel electrolyte is used as an interlayer between solid electrolyte and solid electrodes to improve their contact and reduce their interfacial resistance. The gel electrolyte has a soft structure, high ionic conductivity, and good wettability. Through construction of the garnet/gel interlayer/electrode structure, the interfacial resistance of the garnet significantly decreased from 6.5 × 10⁴ to 248 Ω cm² for the cathode and from 1.4 × 10³ to 214 Ω cm² for the Li-metal anode, successfully demonstrating a full cell with high capacity (140 mAh/g for LiFePO₄ cathode) over 70 stable cycles in room temperature. This work provides a binary electrolyte consisting of gel electrolyte and solid electrolyte to address the interfacial challenge of solid electrolyte and electrodes and the demonstrated hybrid battery presents a promising future for battery development with high energy and good safety

Rapid, in Situ Synthesis of High Capacity Battery Anodes through High Temperature Radiation-Based Thermal Shock

High capacity battery electrodes require nanosized components to avoid pulverization associated with volume changes during the charge–discharge process. Additionally, these nanosized electrodes need an electronically conductive matrix to facilitate electron transport. Here, for the first time, we report a rapid thermal shock process using high-temperature radiative heating to fabricate a conductive reduced graphene oxide (RGO) composite with silicon nanoparticles. Silicon (Si) particles on the order of a few micrometers are initially embedded in the RGO host and in situ transformed into 10–15 nm nanoparticles in less than a minute through radiative heating. The as-prepared composites of ultrafine Si nanoparticles embedded in a RGO matrix show great performance as a Li-ion battery (LIB) anode. The in situ nanoparticle synthesis method can also be adopted for other high capacity battery anode materials including tin (Sn) and aluminum (Al). This method for synthesizing high capacity anodes in a RGO matrix can be envisioned for roll-to-roll nanomanufacturing due to the ease and scalability of this high-temperature radiative heating process

Chemically Crushed Wood Cellulose Fiber towards High-Performance Sodium-Ion Batteries

Carbon materials have attracted great interest as an anode for sodium-ion batteries (SIBs) due to their high performance and low cost. Here, we studied natural wood fiber derived hard carbon anodes for SIBs considering the abundance and low cost of wood. We discovered that a thermal carbonization of wood fiber led to a porous carbon with a high specific surface area of 586 m² g^–1, while a pretreatment with 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) could effectively decrease it to 126 m² g^–1. When evaluating them as anodes for SIBs, we observed that the low surface area carbon resulted in a high initial Coulombic efficiency of 72% compared to 25% of the high surface area carbon. More importantly, the low surface area carbon exhibits an excellent cycling stability that a desodiation capacity of 196 mAh g^–1 can be delivered over 200 cycles at a current density of 100 mA g^–1, indicating a promising anode for low-cost SIBs

A Thermally Conductive Separator for Stable Li Metal Anodes

Li metal anodes have attracted considerable research interest due to their low redox potential (−3.04 V vs standard hydrogen electrode) and high theoretical gravimetric capacity of 3861 mAh/g. Battery technologies using Li metal anodes have shown much higher energy density than current Li-ion batteries (LIBs) such as Li–O₂ and Li–S systems. However, issues related to dendritic Li formation and low Coulombic efficiency have prevented the use of Li metal anode technology in many practical applications. In this paper, a thermally conductive separator coated with boron-nitride (BN) nanosheets has been developed to improve the stability of the Li metal anodes. It is found that using the BN-coated separator in a conventional organic carbonate-based electrolyte results in the Coulombic efficiency stabilizing at 92% over 100 cycles at a current rate of 0.5 mA/cm² and 88% at 1.0 mA/cm². The improved Coulombic efficiency and reliability of the Li metal anodes is due to the more homogeneous thermal distribution resulting from the thermally conductive BN coating and to the smaller surface area of initial Li deposition

Conformal, Nanoscale ZnO Surface Modification of Garnet-Based Solid-State Electrolyte for Lithium Metal Anodes

Solid-state electrolytes are known for nonflammability, dendrite blocking, and stability over large potential windows. Garnet-based solid-state electrolytes have attracted much attention for their high ionic conductivities and stability with lithium metal anodes. However, high-interface resistance with lithium anodes hinders their application to lithium metal batteries. Here, we demonstrate an ultrathin, conformal ZnO surface coating by atomic layer deposition for improved wettability of garnet solid-state electrolytes to molten lithium that significantly decreases the interface resistance to as low as ∼20 Ω·cm². The ZnO coating demonstrates a high reactivity with lithium metal, which is systematically characterized. As a proof-of-concept, we successfully infiltrated lithium metal into porous garnet electrolyte, which can potentially serve as a self-supported lithium metal composite anode having both high ionic and electrical conductivity for solid-state lithium metal batteries. The facile surface treatment method offers a simple strategy to solve the interface problem in solid-state lithium metal batteries with garnet solid electrolytes

Three-Dimensional Printed Thermal Regulation Textiles

Space cooling is a predominant part of energy consumption in people’s daily life. Although cooling the whole building is an effective way to provide personal comfort in hot weather, it is energy-consuming and high-cost. Personal cooling technology, being able to provide personal thermal comfort by directing local heat to the thermally regulated environment, has been regarded as one of the most promising technologies for cooling energy and cost savings. Here, we demonstrate a personal thermal regulated textile using thermally conductive and highly aligned boron nitride (BN)/poly­(vinyl alcohol) (PVA) composite (denoted as a-BN/PVA) fibers to improve the thermal transport properties of textiles for personal cooling. The a-BN/PVA composite fibers are fabricated through a fast and scalable three-dimensional (3D) printing method. Uniform dispersion and high alignment of BN nanosheets (BNNSs) can be achieved during the processing of fiber fabrication, leading to a combination of high mechanical strength (355 MPa) and favorable heat dispersion. Due to the improved thermal transport property imparted by the thermally conductive and highly aligned BNNSs, better cooling effect (55% improvement over the commercial cotton fiber) can be realized in the a-BN/PVA textile. The wearable a-BN/PVA textiles containing the 3D-printed a-BN/PVA fibers offer a promising selection for meeting the personal cooling requirement, which can significantly reduce the energy consumption and cost for cooling the whole building