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 (LiNi_0.964Al_0.03W_0.006O₂). 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, LiNi_0.964Al_0.03W_0.006O₂ 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 (LiNi_0.964Al_0.03Mo_0.006O₂, LiNi_0.964B_0.03W_0.006O₂, and LiNi_0.964B_0.03Nb_0.006O₂), confirming a general, scalable design rule for advancing cobalt-free, high-energy and long-life all-solid-state Lithium-ion batteries.