Defects and their interactions in crystalline solids often underpin material properties and functionality 1 as they are decisive for stability 1-5 , result in enhanced diffusion 6 , and act as a reservoir of vacancies 7 . Recently, lithium-rich layered oxides have emerged among the leading candidates for the next-generation energy storage cathode material, delivering 50 % excess capacity over commercially used compounds. Oxygen-redox reactions are believed to be responsible for the excess capacity 8 , however, voltage fading has prevented commercialization of these new materials. Despite extensive research the understanding of the mechanisms underpinning oxygen-redox reactions and voltage fade remain incomplete. Here, using operando three-dimensional Bragg coherent diffractive imaging 2,9 , we directly observe nucleation of a mobile dislocation network in nanoparticles of lithium-rich layered oxide material. Surprisingly, we find that dislocations form more readily in the lithium-rich layered oxide material as compared with a conventional layered oxide material, suggesting a link between the defects and the
Breakthroughs in performance of Li/Cu with Ni-rich cathodes can be achieved via manipulation of anion interfacial chemistry, as uncovered by experiment/modeling.
A combination of cryogenic electron microscopy and cryogenic focused ion beam enabled the characterization of the interface between Li metal and lithium phosphorous oxynitride, one of the well-known interfaces to exhibit exemplary electrochemical stability with a lithium metal anode. The probed structural and chemical information leads to a more comprehensive understanding of the underlying cause for the interfacial stability and its formation mechanism.
Enabling
long cyclability of high-voltage oxide cathodes is a persistent
challenge for all-solid-state batteries, largely because of their
poor interfacial stabilities against sulfide solid electrolytes. While
protective oxide coating layers such as LiNbO3 (LNO) have
been proposed, its precise working mechanisms are still not fully
understood. Existing literature attributes reductions in interfacial
impedance growth to the coating’s ability to prevent interfacial
reactions. However, its true nature is more complex, with cathode
interfacial reactions and electrolyte electrochemical decomposition
occurring simultaneously, making it difficult to decouple each effect.
Herein, we utilized various advanced characterization tools and first-principles
calculations to probe the interfacial phenomenon between solid electrolyte
Li6PS5Cl (LPSCl) and high-voltage cathode LiNi0.85Co0.1Al0.05O2 (NCA). We
segregated the effects of spontaneous reaction between LPSCl and NCA
at the interface and quantified the intrinsic electrochemical decomposition
of LPSCl during cell cycling. Both experimental and computational
results demonstrated improved thermodynamic stability between NCA
and LPSCl after incorporation of the LNO coating. Additionally, we
revealed the in situ passivation effect of LPSCl electrochemical decomposition.
When combined, both these phenomena occurring at the first charge
cycle result in a stabilized interface, enabling long cyclability
of all-solid-state batteries.
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