Enhanced Cycle Life and Rate Capability of Single-Crystal, Ni-Rich LiNi 0.9 Co 0.05 Mn 0.05 O 2 Enabled by 1,2,4-1 H -Triazole Additive

Ternary LiNi x Co y Mn z O 2 oxides with extremely high nickel (Ni) contents ( x ≥ 0.9) are promising cathode candidates developed for higher-energy-density lithium-ion batteries, with an aim to relieve mileage anxiety. However, the structural and interfacial instability still restrict their application in electric vehicles. In this work, a novel electrolyte additive 1,2,4-1 H -Triazole (HTZ) is introduced to improve the interfacial stability of LiNi 0.9 Co 0.05 Mn 0.05 O 2 (NCM90), promoting cycle life both at 30 °C and a harsh condition of 60 °C, as well as rate capability. The NCM90||Li cells with 0.3% HTZ-added electrolyte retain 86.6% of their original capacity after 150 cycles at 1C and 30 °C, well exceeding 74.8% obtained with the baseline electrolyte. It is revealed that the additive HTZ could inhibit the thermal decomposition of LiPF 6 salt and suppress the generation of HF acidic species. More importantly, additive HTZ is preferentially oxidized to construct a compact and dense cathode electrolyte interphase (CEI) layer, which is beneficial for stabilizing the electrode/electrolyte interface and suppressing unwanted side reactions.