Fan Xinming, Ou Xing, Zhao Wengao, Liu Yun, Zhang Bao, Zhang Jiafeng, Zou Lianfeng, Seidl Lukas, Li Yangzhong, Hu Guorong, Battaglia Corsin, Yang Yong
School of Metallurgy and Environment, Central South University, Changsha, P.R. China.
Empa, Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland.
Nat Commun. 2021 Sep 7;12(1):5320. doi: 10.1038/s41467-021-25611-6.
High nickel content in LiNiCoMnO (NCM, x ≥ 0.8, x + y + z = 1) layered cathode material allows high specific energy density in lithium-ion batteries (LIBs). However, Ni-rich NCM cathodes suffer from performance degradation, mechanical and structural instability upon prolonged cell cycling. Although the use of single-crystal Ni-rich NCM can mitigate these drawbacks, the ion-diffusion in large single-crystal particles hamper its rate capability. Herein, we report a strategy to construct an in situ LiYTi(PO) (LYTP) ion/electron conductive network which interconnects single-crystal LiNiCoMnO (SC-NCM88) particles. The LYTP network facilitates the lithium-ion transport between SC-NCM88 particles, mitigates mechanical instability and prevents detrimental crystalline phase transformation. When used in combination with a Li metal anode, the LYTP-containing SC-NCM88-based cathode enables a coin cell capacity of 130 mAh g after 500 cycles at 5 C rate in the 2.75-4.4 V range at 25 °C. Tests in Li-ion pouch cell configuration (i.e., graphite used as negative electrode active material) demonstrate capacity retention of 85% after 1000 cycles at 0.5 C in the 2.75-4.4 V range at 25 °C for the LYTP-containing SC-NCM88-based positive electrode.
LiNiCoMnO（NCM，x≥0.8，x + y + z = 1）层状正极材料中的高镍含量使得锂离子电池（LIB）具有高比能量密度。然而，富镍NCM正极在长时间电池循环后会出现性能退化、机械和结构不稳定的问题。尽管使用单晶富镍NCM可以减轻这些缺点，但大单晶颗粒中的离子扩散阻碍了其倍率性能。在此，我们报道了一种构建原位LiYTi(PO)（LYTP）离子/电子导电网络的策略，该网络将单晶LiNiCoMnO（SC-NCM88）颗粒相互连接。LYTP网络促进了SC-NCM88颗粒之间的锂离子传输，减轻了机械不稳定性，并防止了有害的晶相转变。当与锂金属负极结合使用时，含LYTP的基于SC-NCM88的正极在25℃下于2.75-4.4V范围内以5C倍率循环500次后，硬币电池容量可达130mAh g。在锂离子软包电池配置（即使用石墨作为负极活性材料）中的测试表明，含LYTP的基于SC-NCM88的正极在25℃下于2.75-4.4V范围内以0.5C倍率循环1000次后，容量保持率为85%。
