The Renaissance of High-Capacity Cathode Materials for Lithium Ion Cells

Synthesis and Electrochemical Characterization of a Li-Rich Li1.17Ni0.34Mn0.5O2Cathode Material for Lithium-Ion Cells

“…Among the various lithium-rich cathode materials, Li 1.2 Ni 0.2 Mn 0.6 O 2 and Li­[Li 0.2 Ni 0.13 Co 0.13 Mn 0.54 ]­O 2 are the two main compositions that are extensively studied owing to their high initial discharge capacity. However, lithium-rich cathode materials suffer from serious issues including low initial coulombic efficiency, poor cycling stability, and rate performances. − These thorny issues mainly arise because of the transformation of the layered rock-salt structure to the spinel structure and the poor electronic conductivity of these materials. , Moreover, decomposition of electrolyte takes place at the highly delithiated state near the upper voltage limit of 4.8 V. These problems seriously restrict the commercial application of lithium-rich cathode materials. , Nowadays, surface modification and elemental doping have been proposed as efficient strategies to suppress structural transformation of Li-rich cathodes. Surface modifications with oxides such as Al 2 O 3 , TiO 2 , ZrO 2 , and phosphates (e.g., FePO 4 ) and fluorides (e.g., AlF 3 ) as a protective layer have been considered as the most efficient strategies to boost the electrochemical performance of lithium-rich cathodes, including coulombic efficiency, specific capacity, cyclability, and rate capability. − However, most of the coating materials are electrical insulators and will increase the electrical resistance on the surface and finally cause a negative impact on the electrochemical performance.…”

“…3−5 These thorny issues mainly arise because of the transformation of the layered rock-salt structure to the spinel structure and the poor electronic conductivity of these materials. 6,7 Moreover, decomposition of electrolyte takes place at the highly delithiated state near the upper voltage limit of 4.8 V. These problems seriously restrict the commercial application of lithium-rich cathode materials. 8,9 Nowadays, surface modification and elemental doping have been proposed as efficient strategies to suppress structural transformation of Lirich cathodes.…”

Surface Modification on Nickel Rich Cathode Materials for Lithium‐Ion Cells: A Mini Review

“…Ni-rich NCM materials, where x > y and z and both di-and trivalent nickel are present, have attracted a lot of interest recently due to their superior specific capacity and energy density along with their low Co content, which is a comparatively scarce metal. [20][21][22][23] In NCMs, a higher Ni content favours a higher capacity compared to one electron Co 3 + /4 + redox couple and the electrochemically inactive Mn 4 + ions since nickel offers a two-electron Ni 2 + /4 + redox process (Figure 2). [24] Therefore, increasing the Ni content, which offers a greater degree of lithium utilization and enhances energy density, is a commonly employed strategy to get the most out of the energy content of the NCM cathode.…”

Lithium-Rich Li1.17Ni0.17Co0.17Mn0.5O2 Cathode Material for Lithium-Ion Cells: Effect of Calcination Temperature on Electrochemical Performance

“…Thus, one of the hottest areas in materials research over the past several years has been the hunt for safe and high-performance cathode materials for high-energy-density LIBs. – In this regard, layered lithium-rich (Li-rich) oxides with the general formula x Li 2 MnO 3 ·(1– x )­LiMO 2 (M = Mn, Co, Ni, etc.) have recently received significant attention among battery researchers owing to their high specific capacity between 2.0 and 4.8 V. – An electrochemical reaction that involves the electrochemical activation of Li 2 MnO 3 and the transfer of multiple lithium ions is the cause of their extraordinary capacity. Li + and O 2– ions are simultaneously removed from the Li 2 MnO 3 lattice during the activation process, offering a high capacity of more than 250 mAhg –1 . , Li-rich layered oxides have other numerous benefits, including low toxicity, low cost, and high safety on overcharging; however, several major issues need to be solved before their commercial application.…”

“…Li + and O 2– ions are simultaneously removed from the Li 2 MnO 3 lattice during the activation process, offering a high capacity of more than 250 mAhg –1 . , Li-rich layered oxides have other numerous benefits, including low toxicity, low cost, and high safety on overcharging; however, several major issues need to be solved before their commercial application. These include a significant irreversible capacity loss during the first cycle, inferior rate performance, and severe capacity and voltage fading during extended cycling. – In addition to this, Li-rich layered oxides undergo severe surface deterioration due to the decomposition of electrolytes and also due to the Jahn–Teller effect in a highly delithiated state, particularly up to 4.8 V . To boost the electrochemical performance of these layered Li-rich oxide cathode materials, a number of strategies have been employed, which include surface modification, – partial substitution of Ni and Mn by other elements, , and optimization of preparation methods .…”