Energy Storage and Distributed Resources Division, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.
Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States.
ACS Appl Mater Interfaces. 2016 Nov 23;8(46):31677-31683. doi: 10.1021/acsami.6b11111. Epub 2016 Nov 15.
The phase transition, charge compensation, and local chemical environment of Ni in LiNiO were investigated to understand the degradation mechanism. The electrode was subjected to a variety of bulk and surface-sensitive characterization techniques under different charge-discharge cycling conditions. We observed the phase transition from the original hexagonal H1 phase to another two hexagonal phases (H2 and H3) upon Li deintercalation. Moreover, the gradual loss of H3-phase features was revealed during the repeated charges. The reduction in Ni redox activity occurred at both the charge and the discharge states, and it appeared both in the bulk and at the surface over the extended cycles. The degradation of crystal structure significantly contributes to the reduction of Ni redox activity, which in turn causes the cycling performance decay of LiNiO.
研究了 LiNiO 中 Ni 的相转变、电荷补偿和局部化学环境，以了解其降解机制。在不同的充放电循环条件下，对电极进行了多种体相和表面敏感的表征技术。我们观察到在 Li 脱嵌过程中，原始的六方 H1 相转变为另外两种六方相（H2 和 H3）。此外，在反复充电过程中，H3 相特征逐渐消失。在充电和放电状态下，Ni 的氧化还原活性都发生了降低，并且在扩展循环中，无论是在体相还是在表面都出现了这种情况。晶体结构的降解显著导致 Ni 氧化还原活性的降低，从而导致 LiNiO 的循环性能下降。
