Cho Yoon-Gyo, Jung Seo Hyun, Jeong Jihong, Cha Hyungyeon, Baek Kyungeun, Sung Jaekyung, Kim Minsoo, Lee Hyun Tae, Kong Hoyoul, Cho Jaephil, Kang Seok Ju, Park Jong Mok, Song Hyun-Kon
School of Energy and Chemical Engineering, UNIST, Ulsan 44919, Korea.
Center for Green Fine Chemicals, Korea Research Institute of Chemical Technology, Ulsan 44412, Korea.
ACS Appl Mater Interfaces. 2021 Mar 3;13(8):9965-9974. doi: 10.1021/acsami.0c21164. Epub 2021 Feb 18.
Nickel-rich layered oxides (LiNiCoMnO; (1 - - ) ≥ 0.6), the high-energy-density cathode materials of lithium-ion batteries (LIBs), are seriously unstable at voltages higher than 4.5 V versus Li/Li and temperatures higher than 50 °C. Herein, we demonstrated that the failure mechanism of a nickel-rich layered oxide (LiNiCoMnO) behind the instability was successfully suppressed by employing cyanoethyl poly(vinyl alcohol) having pyrrolidone moieties (Pyrd-PVA-CN) as a metal-ion-chelating gel polymer electrolyte (GPE). The metal-ion-chelating GPE blocked the plating of transition-metal ions dissolved from the cathode by capturing the ions (anode protection). High-concentration metal-ion environments developed around the cathode surface by the GPE suppressed the irreversible phase transition of the cathode material from the layered structure to the rock-salt structure (cathode protection). Resultantly, the capacity retention was significantly improved at a high voltage and a high temperature. Capacity retention and coulombic efficiency of a full-cell configuration of a nickel-rich layered oxide with graphite were significantly improved in the presence of the GPE especially at a high cutoff voltage (4.4 V) and an elevated temperature (55 °C).
富镍层状氧化物（LiNiCoMnO；(1 - - )≥0.6）作为锂离子电池（LIBs）的高能量密度正极材料，在相对于Li/Li的电压高于4.5 V以及温度高于50°C时严重不稳定。在此，我们证明通过使用具有吡咯烷酮基团的氰基乙基聚（乙烯醇）（Pyrd-PVA-CN）作为金属离子螯合凝胶聚合物电解质（GPE），成功抑制了富镍层状氧化物（LiNiCoMnO）不稳定背后的失效机制。金属离子螯合GPE通过捕获离子（阳极保护）阻止了从阴极溶解的过渡金属离子的镀覆。GPE在阴极表面形成的高浓度金属离子环境抑制了阴极材料从层状结构到岩盐结构的不可逆相变（阴极保护）。结果，在高电压和高温下容量保持率显著提高。在GPE存在的情况下，尤其是在高截止电压（4.4 V）和升高温度（55°C）下，富镍层状氧化物与石墨的全电池配置的容量保持率和库仑效率显著提高。
