Search for: All records

Abstract Lithium metal (Li⁰) solid‐state batteries encounter implementation challenges due to dendrite formation, side reactions, and movement of the electrode–electrolyte interface in cycling. Notably, voids and cracks formed during battery fabrication/operation are hot spots for failure. Here, a self‐healing, flowable yet solid electrolyte composed of mobile ceramic crystals embedded in a reconfigurable polymer network is reported. This electrolyte can auto‐repair voids and cracks through a two‐step self‐healing process that occurs at a fast rate of 5.6 µm h⁻¹. A dynamical phase diagram is generated, showing the material can switch between liquid and solid forms in response to external strain rates. The flowability of the electrolyte allows it to accommodate the electrode volume change during Li⁰stripping. Simultaneously, the electrolyte maintains a solid form with high tensile strength (0.28 MPa), facilitating the regulation of mossy Li⁰deposition. The chemistries and kinetics are studied by operando synchrotron X‐ray and in situ transmission electron microscopy (TEM). Solid‐state NMR reveals a dual‐phase ion conduction pathway and rapid Li⁺diffusion through the stable polymer‐ceramic interphase. This designed electrolyte exhibits extended cycling life in Li⁰–Li⁰cells, reaching 12 000 h at 0.2 mA cm⁻²and 5000 h at 0.5 mA cm⁻². Furthermore, owing to its high critical current density of 9 mA cm⁻², the Li⁰–LiNi_0.8Mn_0.1Co_0.1O₂(NMC811) full cell demonstrates stable cycling at 5 mA cm⁻²for 1100 cycles, retaining 88% of its capacity, even under near‐zero stack pressure conditions. 

Abstract Oxide ceramic electrolytes (OCEs) have great potential for solid-state lithium metal (Li⁰) battery applications because, in theory, their high elastic modulus provides better resistance to Li⁰dendrite growth. However, in practice, OCEs can hardly survive critical current densities higher than 1 mA/cm². Key issues that contribute to the breakdown of OCEs include Li⁰penetration promoted by grain boundaries (GBs), uncontrolled side reactions at electrode-OCE interfaces, and, equally importantly, defects evolution (e.g., void growth and crack propagation) that leads to local current concentration and mechanical failure inside and on OCEs. Here, taking advantage of a dynamically crosslinked aprotic polymer with non-covalent –CH₃⋯CF₃bonds, we developed a plastic ceramic electrolyte (PCE) by hybridizing the polymer framework with ionically conductive ceramics. Using in-situ synchrotron X-ray technique and Cryogenic transmission electron microscopy (Cryo-TEM), we uncover that the PCE exhibits self-healing/repairing capability through a two-step dynamic defects removal mechanism. This significantly suppresses the generation of hotspots for Li⁰penetration and chemomechanical degradations, resulting in durability beyond 2000 hours in Li⁰-Li⁰cells at 1 mA/cm². Furthermore, by introducing a polyacrylate buffer layer between PCE and Li⁰-anode, long cycle life >3600 cycles was achieved when paired with a 4.2 V zero-strain cathode, all under near-zero stack pressure. 

Abstract Designing stable Li metal and supporting solid structures (SSS) is of fundamental importance in rechargeable Li‐metal batteries. Yet, the stripping kinetics of Li metal and its mechanical effect on the supporting solids (including solid electrolyte interface) remain mysterious to date. Here, through nanoscale in situ observations of a solid‐state Li‐metal battery in an electron microscope, two distinct cavitation‐mediated Li stripping modes controlled by the ratio of the SSS thickness (t) to the Li deposit's radius (r) are discovered. A quantitative criterion is established to understand the damage tolerance of SSS on the Li‐metal stripping pathways. For mechanically unstable SSS (t/r < 0.21), the stripping proceeds via tension‐induced multisite cavitation accompanied by severe SSS buckling and necking, ultimately leading to Li “trapping” or “dead Li” formation; for mechanically stable SSS (t/r > 0.21), the Li metal undergoes nearly planar stripping from the root via single cavitation, showing negligible buckling. This work proves the existence of an electronically conductive precursor film coated on the interior of solid electrolytes that however can be mechanically damaged, and it is of potential importance to the design of delicate Li‐metal supporting structures to high‐performance solid‐state Li‐metal batteries.