Both Resilience and Adhesivity Define Solid Electrolyte Interphases for a High Performance Anode.

Solid electrolyte interphases (SEIs) are sought to protect high-capacity anodes, which suffer from severe volume changes and fast degradations. The previously proposed effective SEIs were of high strength yet abhesive, inducing a yolk-shell structure to decouple the rigid SEI from the anode for accommodating the volume change. Ambivalently, the interfacial void-evolved electro-chemo-mechanical vulnerabilities become inherent defects. Here, we establish a new rationale for SEIs that resilience and adhesivity are both requirements and pioneer a design of a resilient yet adhesive SEI (re-ad-SEI), integrated into a conjugated surface bilayer structure. The re-ad-SEI and its protected particles exhibit excellent stability almost free from the thickening of SEI and the particle pulverization during cycling. More promisingly, the dynamically bonded intact SEI-anode interfaces enable a high-efficiency ion transport and provide a unique mechanical confinement effect for structural integrity of anodes. The high Coulombic efficiency (>99.8%), excellent cycling stability (500 cycles), and superior rate performance have been demonstrated in microsized Si-based anodes.

Fluorinating All Interfaces Enables Super-Stable Solid-State Lithium Batteries by In Situ Conversion of Detrimental Surface Li2CO3.

Li-stuffed battery materials intrinsically have surface impurities, typically Li2CO3, which introduce severe kinetic barriers and electrochemical decay for a cycling battery. For energy-dense solid-state lithium batteries (SSLBs), mitigating detrimental Li2CO3 from both cathode and electrolyte materials is required, while the direct removal approaches hardly avoid Li2CO3 regeneration. Here, a decarbonization-fluorination strategy to construct ultrastable LiF-rich interphases throughout the SSLBs by in situ reacting Li2CO3 with LiPF6 at 60 °C is reported. The fluorination of all interfaces effectively suppresses parasitic reactions while substantially reducing the interface resistance, producing a dendrite-free Li anode with an impressive cycling stability of up to 7000 h. Particularly, transition metal dissolution associated with gas evolution in the cathodes is remarkably reduced, leading to notable improvements in battery rate capability and cyclability at a high voltage of 4.5 V. This all-in-one approach propels the development of SSLBs by overcoming the limitations associated with surface impurities and interfacial challenges.