High-voltage and stable co-free LiNiO2 positive electrode for sulfide-based all-solid-state batteries

The development of high-voltage LiNiO2 is critical for achieving high-energy-density all-solid-state Lithium-ion batteries. However, their practical application is hindered by structural fatigue and interfacial incompatibility with solid electrolytes. Here, a universal heterophase reconstruction strategy is proposed to engineer a stable LiNiO2-based positive electrode (LiNi0.964Al0.03W0.006O2). In this architecture, high-valence W facilitates the formation of a robust surface spinel phase that exhibits good interfacial compatibility with sulfide electrolytes, while low-valence Al suppresses Li/Ni cation disorder through strong Al–O bonding, stabilizing the layered structure. The synergy of W and Al reinforces a stable layered-spinel framework with enhanced mechanical and chemical integrity, mitigates lattice strain and suppresses the detrimental rock-salt phase and microcracks. Operating up to 4.5 V, LiNi0.964Al0.03W0.006O2 delivers a high capacity of 187.6 mAh g-1 at 0.5 C and maintains 122.1 mAh g-1 even after 720 cycles. This heterophase reconstruction strategy concept is further validated in LiNiO2-based systems (LiNi0.964Al0.03Mo0.006O2, LiNi0.964B0.03W0.006O2, and LiNi0.964B0.03Nb0.006O2), confirming a general, scalable design rule for advancing cobalt-free, high-energy and long-life all-solid-state Lithium-ion batteries. High-voltage Co-free LiNiO2 positive electrode for all-solid-state batteries suffers from structural and interfacial degradation. Here, the authors report a general doping strategy that stabilizes the cathode and enables durable, high-voltage all-solid-state batteries.