High energy-density lithium-ion batteries are in demand for portable electronic devices and electrical vehicles. Since the energy density of the batteries relies heavily on the cathode material used, major research efforts have been made to develop alternative cathode materials with a higher degree of lithium utilization and specific energy density. In particular, layered, Ni-rich, lithium transition-metal oxides can deliver higher capacity at lower cost than the conventional LiCoO2 . However, for these Ni-rich compounds there are still several problems associated with their cycle life, thermal stability, and safety. Herein the performance enhancement of Ni-rich cathode materials through structure tuning or interface engineering is summarized. The underlying mechanisms and remaining challenges will also be discussed.

Lithium ion batteries (LIBs) have received worldwide attention as power sources for electric vehicles (EVs) and portable energy storage. [1] However, research to address the limited cycle life, rate capability, energy density, safety concern and cost issue of commercialized LiCoO 2 (LCO), LiNi x Mn y Co z O 2 (NMC), LiNi 0.80 Co 0.15 Al 0.05 O 2 (NCA) and LiFePO 4 (LFP) is still ongoing for their large-scale application in EVs and the electricity grid. [1b] The lithium-and manganese-rich (LMR) layered structure cathode materials xLi 2 MnO 3 ·(1−x)LiMO 2 (M = Ni, Co, Mn or combinations) have entered the spotlight becauseThe lithium-and manganese-rich (LMR) layered structure cathodes exhibit one of the highest specific energies (≈900 W h kg −1 ) among all the cathode materials. However, the practical applications of LMR cathodes are still hindered by several significant challenges, including voltage fade, large initial capacity loss, poor rate capability and limited cycle life. Herein, we review the recent progress and in depth understandings on the application of LMR cathode materials from a practical point of view. Several key parameters of LMR cathodes that affect the LMR/graphite full-cell operation are systematically analyzed. These factors include the first-cycle capacity loss, voltage fade, powder tap density, and electrode density. New approaches to minimize the detrimental effects of these factors are highlighted in this work. We also provide perspectives for the future research on LMR cathode materials, focusing on addressing the fundamental problems of LMR cathodes while keeping practical considerations in mind. Center. Cho' current research is focused on high-energydensity cathode and anode materials and their direct implantation in ful-cell systems, as well as metal-air batteries and redox flow batteries for energy storage.Ji-Guang (Jason) Zhang is a Laboratory Fellow of the Pacific Northwest National Laboratory. He is the group leader for PNNL's efforts in energy storage for transportation applications and has 25-year experience in the development of energy storage devices, including Li-ion batteries, Li-air batteries, Li-metal batteries, Li-S batteries, and thin-film solid-state batteries.

A molecularly-engineered LiFMDFB additive constructs a protective layer for Li-rich cathodes while simultaneously strengthening the interface structure on SGC anodes.

Li-rich layered metal oxides have attracted much attention for their high energy density but still endure severe capacity fading and voltage decay during cycling, especially at elevated temperature. Here, facile surface treatment of Li 1.17 Ni 0.17 Co 0.17 Mn 0.5 O 2 (0.4Li 2 MnO 3 ·0.6LiNi 1/3 Co 1/3 Mn 1/3 O 2 ) spherical cathode material is designed to address these drawbacks by hybrid surface protection layers composed of Mg 2+ pillar and Li-Mg-PO 4 layer. As a result, the surface coated Li-rich cathode material exhibits much enhanced cycling stability at 60 °C, maintaining 72.6% capacity retention (180 mAh g −1 ) between 3.0 and 4.7 V after 250 cycles. More importantly, 88.7% average discharge voltage retention can be obtained after the rigorous cycle test. The strategy developed here with novel hydrid surface protection effect can provide a vital approach to inhibit the undesired side reactions and structural deterioration of Li-rich cathode materials and may also be useful for other layered oxides to increase their cycling stability at elevated temperature.

Li-rich materials are considered the most promising for Li-ion battery cathodes, as high energy densities can be achieved. However, because an activation method is lacking for large particles, small particles must be used with large surface areas, a critical drawback that leads to poor long-term energy retention and low volumetric energy densities. Here we propose a new material engineering concept to overcome these difficulties. Our material is designed with 10 μm-sized secondary particles composed of submicron scaled flake-shaped primary particles that decrease the surface area without sacrificing rate capability. A novel activation method then overcomes the previous limits of Li-rich materials with large particles. As a result, we attained high average voltage and capacity retention in turn yielding excellent energy retention of 93% during 600 cycles. This novel and unique approach may furthermore open the door to new material engineering methods for high-performance cathode materials.