Ever growth in the energy demand has catapulted us to explore various energies. Henceforth, to meet these ends, among the different cathode active materials, nickel (Ni) rich polycrystalline (PC) cathode materials have been known to serve the purpose aptly. Yet, these PC Ni-rich cathode materials have yielded inferior performances with an increase in voltage and temperature. The absence of grain boundaries in the intrinsic structure, high mechanical strength, high thermal stability, and controllable crystal faucet have made SC cathodes a better prospect. Yet, there are challenges to overcome in the SC cathodes, like larger crystals hindering the Li+ transport, which leads to disappointing electrochemical performance. Through this perspective article, we wish to elucidate the crucial factors that facilitate the growth of SC-NCM cathode, viable dopants, and coating materials that could enhance the performance, future scope, and scalability of SC-NCM at the Industrial level.
The application of Li-rich layered oxides is hindered by their dramatic capacity and voltage decay on cycling. This work comprehensively studies the mechanistic behaviour of cobalt-free Li1.2Ni0.2Mn0.6O2 and demonstrates the positive impact of two-phase Ru doping. A mechanistic transition from the monoclinic to the hexagonal behaviour is found for the structural evolution of Li1.2Ni0.2Mn0.6O2, and the improvement mechanism of Ru doping is understood using the combination of in operando and post-mortem synchrotron analyses. The two-phase Ru doping improves the structural reversibility in the first cycle and restrains structural degradation during cycling by stabilizing oxygen (O2−) redox and reducing Mn reduction, thus enabling high structural stability, an extraordinarily stable voltage (decay rate <0.45 mV per cycle), and a high capacity-retention rate during long-term cycling. The understanding of the structure-function relationship of Li1.2Ni0.2Mn0.6O2 sheds light on the select
The commercialisation of lithium-ion batteries (LIBs) has gradually reformed people's daily life since the 1990s. Compared with other cathode candidates, the Ni-rich ternary cathode materials have been continuously developed due to their high energy density and lower price. However, the fast capacity fading and poor thermal stability still restricted the applications of Ni-rich cathodes. In this regard, a comprehensive understanding of the failure mechanism and corresponding modification strategies need to be raised urgently.
This thesis will firstly introduce the working mechanism of LIBs and different cathode material categories. Secondly, the Li/Ni mixing, which mainly induce the capacity fading of the Ni-rich cathode materials, will be schematically reviewed. The origin of the Li/Ni mixing has been attributed to (i) the similar bonding environments and ionic radius of Ni2+ and Li+, (ii) relieving magnetic frustration, (iii) reducing system entropy and (iv) lower Ni2+ migration