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초록

Advances in battery technology have been impeded by the voltage constraints of electrolytes. Here we present a high-energy all-solid-state battery design featuring >5 V operation and an ultrahigh areal capacity of 35.3 mAh cm−2; these attributes were enabled by a highly conductive and ultrahigh-voltage stable fluoride solid electrolyte, LiCl–4Li<inf>2</inf>TiF<inf>6</inf> (1.7 × 10−5 S cm−1 at 30 °C). LiCl–4Li<inf>2</inf>TiF<inf>6</inf> shields high-voltage spinel oxide cathodes, achieving 106 mAh g−1 at 2C with 75.2% retention over 500 cycles for LiNi<inf>0.5</inf>Mn<inf>1.5</inf>O<inf>4</inf>, sharply contrasting with the conventional LiNbO<inf>3</inf> counterpart, which decomposes and fails to prevent detrimental interfacial degradation. The efficacy of LiCl–4Li<inf>2</inf>TiF<inf>6</inf> is validated across various systems, including LiCoMnO<inf>4</inf>, LiFe<inf>0.5</inf>Mn<inf>1.5</inf>O<inf>4</inf> and pouch-type LiNi<inf>0.5</inf>Mn<inf>1.5</inf>O<inf>4</inf>||Li (or Ag–C) all-solid-state batteries, and further demonstrated by operability down to 2.3 V with 258 mAh g−1 and ultrathick 1.8-mm electrodes. This shielding layer with >5 V stability introduces a transformative design paradigm by revisiting the previously forbidden high-voltage cathodes. © 2025 Elsevier B.V., All rights reserved.

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