A Long-Life and Safe Ni-Rich Cathode Material for Lithium Batteries

초록

High-energy Ni-rich (≥90%) cathodes are inherently unstable during cycling, exhibit extensive gassing, and have poor thermal safety, limiting their use in long-life battery applications. Addressing these issues not only requires developing an innovative cathode design, but also implementing an electrolyte tailored for cathode/electrolyte compatibility. Herein, we introduce the use of Li[Ni0.902Co0.081Al0.010B0.007]O2 as a structurally and chemically redesigned cathode material, in combination with 1:9 fluoroethylene carbonate:ethyl methyl carbonate, as a cathode-customized ethylene carbonate-free electrolyte that addresses the aforementioned issues. This cathode/electrolyte system breaks away from the conventional degradation mechanisms reported in Ni-rich cathodes. The developed cathode exhibited an excellent cycle life (10 000 cycles) and suppressed gas evolution even when its particles are extensively cracked, with its performance validated under practically relevant conditions, including a high electrode density (3.2 g cm−3) and capacity (700 mAh). In contrast to a conventional Ni-rich cathode that experiences exacerbated thermal safety issues when cycled, the configuration reported herein maintained its thermal stability even after long-term cycles. Collectively, the developed Ni-rich-cathode/electrolyte system transcends the traditional limitations of Ni-rich cathodes and provides opportunities for redefining the practical limits of high-energy, long-life, and safe batteries.

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