No abstract

Engineered polycrystalline electrodes are critical to the cycling stability and safety of lithium-ion batteries, yet it is challenging to construct high-quality coatings at both the primary-and secondaryparticle levels. Here, we present a room-temperature synthesis route to achieve full surface coverage of secondary particles and facile infusion into grain boundaries, thus offering a complete "coatingplus-infusion" strategy. Cobalt boride metallic glass is successfully applied to Ni-rich layered cathode LiNi 0.8 Co 0.1 Mn 0.1 O 2 . It dramatically improves the rate capability and cycling stability, including under high-discharge-rate and elevated-temperature conditions and in pouch full cells.The superior performance originates from simultaneous suppression of microstructural degradation of intergranular cracking and side reactions with electrolyte. Atomistic simulations identified the critical role of strong selective interfacial bonding, which offers not only a large chemical driving force to ensure uniform reactive wetting and facile infusion but also lowered the surface/interface 2 oxygen activity, contributing to the exceptional mechanical and electrochemical stabilities of the infused electrode.

The kinetics of mass transport is central to ceramic processing and device stability. In this work, the effect of electrical and hydrogen reduction on the grain growth behavior of doped zirconia and ceria has been investigated. Faster grain growth has been observed under reducing conditions in all cases. The results firmly establish that a depressed local oxygen potential can enhance cation kinetics in fluorite‐structured oxide ceramics. Meanwhile, a large electrical current can generate a sharp, spatially varied oxygen potential profile, creating a graded microstructure with a dramatic grain size transition across the length of the sample.

Protonic ceramic electrochemical cells hold the promise to be operated below 600 o C 1,2 . Although the high proton conductivity of the bulk electrolyte has been demonstrated, it cannot be fully utilized in electrochemical full cells due to unknown causes 3 . Here we showed that it all comes from poor contacts between the low-temperature processed oxygen electrode-electrolyte interface.We demonstrated that a simple acid treatment can effectively rejuvenate the high-temperature annealed electrolyte surface, resulting in reactive bonding between the oxygen electrode and the electrolyte and improved electrochemical performance and stability. This enables exceptional protonic ceramic fuel-cell performance down to 350 o C, with peak power densities of 1.6 W cm −2 at 600 o C, 650 mW cm −2 at 450 o C, and 300 mW cm −2 at 350 o C, as well as stable electrolysis operations with current densities above 3.9 A cm −2 at 1.4 V and 600 o C. Our work highlights the critical role of interfacial engineering in ceramic electrochemical devices and offers new understanding and practices towards sustainable energy infrastructure.

An integral LiMn1.5Ni0.5O4 shell completely wets ∼10 μm LiCoO2 single crystals to cut off global oxygen migration and enables >4.6 V cycling.