Five-volt-class high-capacity all-solid-state lithium batteries

Abstract

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–4Li2TiF6 (1.7 × 10−5 S cm−1 at 30 °C). LiCl–4Li2TiF6 shields high-voltage spinel oxide cathodes, achieving 106 mAh g−1 at 2C with 75.2% retention over 500 cycles for LiNi0.5Mn1.5O4, sharply contrasting with the conventional LiNbO3 counterpart, which decomposes and fails to prevent detrimental interfacial degradation. The efficacy of LiCl–4Li2TiF6 is validated across various systems, including LiCoMnO4, LiFe0.5Mn1.5O4 and pouch-type LiNi0.5Mn1.5O4||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.