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The Na-metal-free manufacturing approach can improve both the manufacturing and performance of Na metal solid-state batteries. While significant research has been dedicated to Li-metal-free manufacturing, the exploration of Na-based counterparts remains relatively nascent. Similar to Li-metal-free manufacturing, achieving uniform Na deposition remains a challenge when using a solid-state electrolyte. In this work, we demonstrated the ability to plate a uniform 2.0 mAh cm-2 Na metal anode by the simple placement of an Al foil-based current collector on NASICON solid-state electrolyte. The Na anode uniformity was dramatically improved by functionalizing the Al CC with a ∼96 nm thick layer of Au. It was shown that the in situ plated Na is homogeneous and dense and can be reversibly stripped and plated at a Coulombic efficiency of >90%. Our findings advance the understanding of Na nucleation and growth and offer insights into streamlining manufacturing processes for future all-solid-state Na anodes.

Current methods for bioprinting functional tissue lack appropriate biofabrication techniques to build complex 3D microarchitectures essential for guiding cell growth and promoting tissue maturation1. 3D printing of central nervous system (CNS) structures has not been accomplished, possibly owing to the complexity of CNS architecture. Here, we report the use of a microscale continuous projection printing method (μCPP) to create a complex CNS structure for regenerative medicine applications in the spinal cord. μCPP can print 3D biomimetic hydrogel scaffolds tailored to the dimensions of the rodent spinal cord in 1.6 s and is scalable to human spinal cord sizes and lesion geometries. We tested the ability of µCPP 3D-printed scaffolds loaded with neural progenitor cells (NPCs) to support axon regeneration and form new 'neural relays' across sites of complete spinal cord injury in vivo in rodents1,2. We find that injured host axons regenerate into 3D biomimetic scaffolds and synapse onto NPCs implanted into the device and that implanted NPCs in turn extend axons out of the scaffold and into the host spinal cord below the injury to restore synaptic transmission and significantly improve functional outcomes. Thus, 3D biomimetic scaffolds offer a means of enhancing CNS regeneration through precision medicine.

The goal of this work was to design nerve guidance scaffolds with a unique architecture to maximize the open volume available for nerve growth. Polycaprolactone (PCL) was selected as the scaffold material based on its biocompatibility and month-long degradation. Yet, dense PCL does not exhibit suitable properties such as porosity, stiffness, strength, and cell adhesion to function as an effective nerve guidance scaffold. To address these shortcomings, PCL was processed using a modified salt-leaching technique to create uniquely controlled interconnected porosity. By controlling porosity, we demonstrated that the elastic modulus could be controlled between 2.09 and 182.1 MPa. In addition, introducing porosity and/or coating with fibronectin enhanced the PCL cell attachment properties. To produce PCL scaffolds with maximized open volume, porous PCL microtubes were fabricated and translated into scaffolds with 60 volume percent open volume. The scaffolds were tested in transected rat spinal cords. Linear axon growth within both the microtubes as well as the interstitial space between the tubes was observed, demonstrating that the entire open volume of the scaffold was available for nerve growth. Overall, a novel scaffold architecture and fabrication technique are presented. The scaffolds exhibit significantly higher volume than state-of-the-art scaffolds for promising spinal cord nerve repair.

All solid‐state batteries are desirable for a range of energy storage applications which require high energy density. Achieving a high energy density in a solid‐state battery requires the operation of an energy dense anode with a composite solid‐state cathode. Pores and/or voids within a solid state cathode are ion‐blocking and thus control over the concentration and distribution of pores in the initial electrode and cycled electrode is desirable. This study provides an understanding of the interplay between electrode microstructure and mechanics on active material utilization in solid state cathodes composed of NCM 811 and Li6PS5Cl. Decreasing the solid electrolyte particle size leads to greater active material‐electrolyte contact and less total deformation when exposed to an external load. Composite cathodes with greater compliance can potentially decrease strain between the active material and solid electrolyte, decrease delamination events and result in higher overall active material utilization and high capacity retention. [ABSTRACT FROM AUTHOR]

Anode‐free manufacturing holds promise to enable high energy densities and lower Lithium (Li)‐metal solid‐state batteries (LMSSBs). Nevertheless, in contrast to thick Li foil (>50 µm), the stripping capacity of in situ‐formed Li (10–30 µm) is limited due to diminished creep flow, resulting in reduced accessible capacity. This study explores the correlation between stripping capacity and surface roughness of garnet Li7La3Zr2O12 (LLZO) solid electrolyte. The results reveal that stripping capacity can be enhanced through the surface modification of solid electrolytes. Additionally, this study scrutinizes the stripping behavior of in situ Li under intermittent‐current discharge conditions, which are more relevant to the operational conditions of electric vehicles (EVs). It is demonstrated that, when compared to constant‐current stripping, intermittent‐current stripping effectively suppresses void formation and enhances the stripping capacity of in situ Li by 40%. It is considered that the intermittent current inhibits the accumulation of Li vacancies, thereby delaying the void formation. These findings provide valuable insights into the development of high‐performance anode‐free LMSSBs for EVs. [ABSTRACT FROM AUTHOR]

Alkali metal filament penetration into solid electrolytes causes short circuit induced cell failure, commonly evaluated using the bidirectional critical current density (CCD) test with stepwise increases in current density in alternating directions across symmetric lithium cells. However, the CCD is neither intrinsic to the cell nor to the material but rather depends on various extrinsic factors, such as current profile, transferred charge, pressure, resting intervals, and interface chemistry. The purpose of this study is to disambiguate the interpretation of CCD analyses in the literature and propose alternative approaches to analyze the stability and kinetics of the alkali metal/solid electrolyte interface. Two types of failure modes of electrochemical cells with solid electrolytes are defined: 1) failure of the solid electrolyte by crack formation coupled with or followed by dendrite growth, and 2) failure of the alkali metal electrode by the formation of pores at the interface with the solid electrolyte followed by filament initiation that eventually leads to short‐circuiting. Therefore, the study recommends that CCD tests specify the failure mode. It is demonstrated that unidirectional polarization enablesunambiguous differentiation between failure modes. The proposals for bi‐ and unidirectional testing presented here are expected to provide more reliable and consistent CCD values across the community. [ABSTRACT FROM AUTHOR]