“Anode-free” solid-state batteries (SSBs), which have no active material at the anode and undergo in situ lithium plating during the first charge, can exhibit extremely high energy density (~1500 Wh L-1). However, there is a lack of understanding of lithium plating/stripping mechanisms at bare solid-state electrolyte (SSE) interfaces since excess lithium is often used. Here, we demonstrate that commercially relevant quantities of lithium (> 5 mAh cm-2) can be reliably plated at relatively high current densities (1 mA cm-2) using the sulfide SSE Li6PS5Cl. Investigations of lithium plating/stripping mechanisms, in conjunction with cryo-focused ion beam (FIB) and ex situ synchrotron tomography, reveal that the cycling stability of these cells is intrinsically limited by spatially uneven plating/stripping. Local lithium depletion toward the end of stripping decreases electrochemically active area, which results in high local current densities and void formation, accelerating subsequent filament growth and short circuiting compared to lithium-excess cells. Despite this governing degradation mode, we show that anode-free cells exhibit comparable Coulombic efficiencies to lithium-excess cells before short circuiting, and improved resistance to short-circuiting is achieved by avoiding local lithium depletion through retention of lithium at the interface. These new insights provide a foundation for engineering future high-energy anode-free SSBs.

“Anode-free” solid-state batteries feature high energy density since there is no anode active material upon assembly. While beneficial effects of interfacial layers at the anode-solid electrolyte interface have previously been demonstrated, the mechanisms through which they influence lithium plating/stripping are unclear. Here, we reveal the evolution of 100-nm silver and gold interfacial layers during anode-free lithium plating/stripping using electrochemical methods, electron microscopy, synchrotron micro x-ray computed tomography, and modeling. The alloy layers significantly improve Coulombic efficiency and resistance to short circuiting, even though the alloys form solute regions or particulates that detach from the current collector as lithium grows. In-situ electrochemical impedance spectroscopy shows that the alloy layers return to the interface and mitigate contact loss at the end of stripping, avoiding a critical vulnerability of anode-free cells. The enhanced contact retention is driven by uniform Li thickness that promotes spatially uniform stripping, as well as local alloy delithiation in response to current concentrations to homogenize current and diminish voiding.

This paper introduces Starsaber, a new conceptual launch vehicle design. Starsaber is a twostage-to-orbit (TSTO) vehicle capable of putting a 300 lb. class payload into low Earth orbit (LEO). The vehicle is composed of a reusable winged booster, powered by two hydrocarbon fueled ejector ramjet (ERJ) engines, and a LOX/RP-1 expendable upper stage. The vehicle utilizes advanced structural and thermal protection system (TPS) materials, as well as advanced subsystems.

No abstract

“Anode-free” solid-state batteries feature high energy density since there is no anode active material upon assembly. While beneficial effects of interfacial layers have previously been demonstrated, the mechanisms through which they influence lithium plating/stripping are unclear. Here, we reveal the evolution of 100-nm silver and gold interfacial layers during anode-free lithium plating/stripping using electrochemical methods, electron microscopy, and modeling. The alloy layers significantly improve Coulombic efficiency and resistance to short circuiting, even though the alloys form solute regions or particulates that detach from the current collector as lithium grows. In-situ electrochemical impedance spectroscopy shows that the alloy layers return to the interface and mitigate contact loss at the end of stripping, avoiding a critical vulnerability of anode-free cells. The enhanced contact retention is driven by increased Li uniformity that promotes spatially even stripping, as well as local alloy delithiation in response to current concentrations to homogenize current and diminish voiding.