Solid State Batteries

Five-Volt-Class High-Capacity All-Solid-State Lithium Batteries Strategy and performance: Achieved 5 V operability and ultrahigh areal capacity 35.3 mAh cm−2) in ASSBs using a fluoride solid electrolyte, LiCl–4LTF, with high Li+ conductivity 1.7 10−5 S cm−1). Mechanistic insight: Synchrotron X-ray analyses and theory reveal that the 100x Li+ conductivity enhancement over Li2TiF6 arises from increased Li+ concentration and interfacial Cl substitution, predominantly at surface/interface regions. Interfacial stability: As a 5 V–stable shielding layer, LiCl–4LTF enables excellent rate and cycling performance of spinel cathodes (e.g., 106 mAh g−1 at 2C with 75.2% retention after 200 cycles), outperforming unstable LNbO coatings.

Arrhenius plots of Li+ conductivities and crystal structures of Li2TiF6 with TiF6

Electrochemical stability windows

Versatility: Effectiveness is validated across high-voltage spinels LNMO, LCMO, LFMO, low-voltage extended operation 258 mAh g−1), and pouch-type full cells.

Comparison of cycling performance with LNMO electrodes in ASSBs

By combining exceptional 5 V oxidative stability with fast Li+ transport, LiCl–4LTF enables record-high areal capacity and stable high-voltage operation across multiple ASSB architectures, establishing a broadly applicable interfacial design paradigm.

Source: Son et al., Nature Energy, 2025

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