Recent Progress and Perspective of Advanced High‐Energy Co‐Less Ni‐Rich Cathodes for Li‐Ion Batteries: Yesterday, Today, and Tomorrow

Abstract

With the ever‐increasing requirement for high‐energy density lithium‐ion batteries (LIBs) to drive pure/hybrid electric vehicles (EVs), considerable attention has been paid to the development of cathode materials with high energy densities because they ultimately determine the energy density of LIBs. Notably, the cost of cathode materials is still the main obstacle hindering the extensive application of EVs, with the cost accounting for 40% of the total cost of fabricating LIBs. Therefore, enhancing the energy density and simultaneously decreasing the cost of LIBs are essential for the success of EV/hybrid EV industries. Among the existing commercial cathodes, Ni‐rich layered cathodes are widely employed because of their high energy density, relatively good rate capability, and reasonable cycling performance. Ni‐rich layered cathodes containing Co are now being reconsidered due to the increasing price of Co, which is much higher than that of Ni and Mn. In this report, the recent developments and strategies in the improvement of the stabilities of the bulk and surface for Co‐less Ni‐rich layered cathode materials are reviewed.

Dual-anion ionic liquid electrolyte enables stable Ni-rich cathodes in lithium-metal batteries

“…whereas the (104) feature is characteristic of both the layered and rock-salt NiO structure. 33 Moreover, the I 003 /I 104 ratio is a useful indication to evaluate cation mixing in layered oxide materials. For both electrolytes the (003) reflection shifts to slightly lower angles during the charge process from open circuit voltage (OCV) to $ 4.1 V before it dramatically shifts in the reverse direction, i.e., to higher angles in the range of 4.1 $ 4.3 V. This indicates a much narrower interlayer distance, which is caused by the extraction of most of the Li + from the lithium layer.…”

“…compromises structural stability as shown by the decreasing capacities upon longterm cycling (Figure 8A) at the highest upper cut-off voltages. 33 In Table S3 the specific first-charge capacity and the capacity retention upon cycling of Li|ILE|NCM88 cells are summarized for a few selected upper cut-off voltages. The values clearly show the upper cut-off of 4.3 V represents best compromise between energy-storage capacity and cycle life of the cell.…”

Enhanced Li+ Transport in Ionic Liquid‐Based Electrolytes Aided by Fluorinated Ethers for Highly Efficient Lithium Metal Batteries with Improved Rate Capability

“…The relatively lower average CE in Li/NMC cells versus Li/LFP cells demonstrates accelerated side reactions on the cathode/electrolyte interface because of a higher operation potential and NMC's catalytic effect in enhancing the electrolyte decomposition. [57] Considering the anodic stability potential window of the electrolyte and the current per- formance, we can infer that further optimization of the cathode material, for example, the structure, morphology, and surface engineering, [58] as well as the electrolyte, for example, different fluorinated ether, [29,44] and use of additives, is feasible to improve the performance of the Li/NMC cells.…”

Microstructure Engineered Ni‐Rich Layered Cathode for Electric Vehicle Batteries

“…Among the viable cathode materials for LIBs, layered Ni-rich lithium-nickel-cobalt-aluminum oxides, Li[Ni x Co y Al z ]O 2 (NCA), are the most promising materials for EV LIBs owing to their high theoretical capacity (278 mAh g -1 ) and good rate performance. [4,5] Recently, Tesla Motors adopted NCA materials in LIBs to power their Models S, X, and 3, which are capable of operating for 400-550 km per single full charge. However, to compete against internal combustion engine vehicles, EVs should have a driving range exceeding 600 km per single charge, which can be achieved by increasing the energy density of the cathode.…”