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Non-crosslinked poly(ethylene oxide) (PEO) is widely studied for its lithium-ion conductivity and applications as solid polymer electrolytes (SPEs) for lithium-metal-anode batteries (LMBs), but its mechanical softness remains a barrier to roll-to-roll manufacturing. Crosslinking in polymer synthesis can reinforce PEO-based SPEs by linking polymer chains into a three-dimensional network, making them compatible with roll-to-roll processing. Although crosslinking may reduce lithium-ion conductivity by limiting segmental motion, the resulting mechanical enhancement can suppress dendrite growth, improving the reversibility of lithium-metal anodes. Understanding the relationship between the degree of crosslinking, mechanical properties, glass transition temperature, ionic conductivity, and electrochemical reversibility in LMBs is therefore of fundamental importance. Here, we systematically quantify the impact of crosslinking on the ionic, electrochemical, and mechanical properties of PEO. The results indicate that higher crosslinking enhances SPEs’ mechanical strength but reduces ionic conductivity, consistent with the rise in glass transition temperature, supporting the theory that segmental motion governs lithium-ion conduction in PEO. Meanwhile, although crosslinking reduces the limiting current density, whereas the critical current density benefits from mechanical reinforcement of SPEs brought by crosslinking, thereby enhancing the reversibility of lithium-metal anodes. This work provides the opportunity to improve the electro-chemo-mechanical properties of PEO-based SPEs for LMBs. 

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 Lithium‐ and manganese‐rich layered oxides (LMR) stand out as next‐generation lithium‐ion cathode chemistries, which harness both transition‐metal and lattice‐oxygen redox processes to deliver exceptional capacity and energy density. However, their full potential is hindered by intrinsic oxygen instability and structural degradation, resulting in pronounced voltage fade and capacity decay. Here, we present a complex‐concentrated anion‐doping paradigm in which multiple anions, F, Br, and S, are incorporated into the oxygen sublattice to enhance oxygen‐redox and structural stability. X‐ray absorption spectroscopy and aberration‐corrected scanning transmission electron microscopy confirm ultra‐stable local oxygen coordination environments during long‐term cycling, with detrimental phase transformations and oxygen‐loss‐induced cavitation dramatically inhibited. Notably, we show that the characteristic LiTM₆transition metal (TM) honeycomb ordering is preserved even after electrochemical cycling. Concurrently, this strategy yields an unprecedented volume change of only 0.63% upon charging to 4.8 V vs. Li⁺/Li, achieving the first zero‐strain LMR cathode. The resulting LMR cathode delivers ultralow voltage fade (1 mV per cycle during the first 100 cycles and becomes negligible in subsequent cycles) and outstanding energy retention (93% after 200 cycles) in a pouch cell configuration. Our complex‐concentrated anion‐doping concept establishes a broadly applicable strategy for resolving chemo‐mechanical failure mechanisms in ceramic intercalation electrodes for next‐generation energy storage. 

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.