High‐Capacity Layered‐Spinel Cathodes for Li‐Ion Batteries

Abstract

Li and Mn-rich layered oxides with the general structure x Li2 MnO3 ⋅(1-x) LiMO2 (M=Ni, Mn, Co) are promising cathode materials for Li-ion batteries because of their high specific capacity, which may be greater than 250 mA h g(-1) . However, these materials suffer from high first-cycle irreversible capacity, gradual capacity fading, limited rate capability and discharge voltage decay upon cycling, which prevent their commercialization. The decrease in average discharge voltage is a major issue, which is ascribed to a structural layered-to-spinel transformation upon cycling of these oxide cathodes in wide potential ranges with an upper limit higher than 4.5 V and a lower limit below 3 V versus Li. By using four elements systems (Li, Mn, Ni, O) with appropriate stoichiometry, it is possible to prepare high capacity composite cathode materials that contain LiMn1.5 Ni0.5 O4 and Lix Mny Niz O2 components. The Li and Mn-rich layered-spinel cathode materials studied herein exhibit a high specific capacity (≥200 mA h g(-1) ) with good capacity retention upon cycling in a wide potential domain (2.4-4.9 V). The effect of constituent phases on their electrochemical performance, such as specific capacity, cycling stability, average discharge voltage, and rate capability, are explored here. This family of materials can provide high specific capacity, high rate capability, and promising cycle life. Using Co-free cathode materials is also an obvious advantage of these systems.

Investigation of Li1.17Ni0.20Mn0.53Co0.10O2 as an Interesting Li‐ and Mn‐Rich Layered Oxide Cathode Material through Electrochemistry, Microscopy, and In Situ Electrochemical Dilatometry

“…During initial cycling in the wide potential range the monoclinic Li 2 MnO 3 phase disappears. In parallel, we detect a continuous phase transition from a layered to spinel structure . Clear evidences for that are accumulated from Raman spectroscopy and electron diffraction data collected in post mortem analyses of these cathodes after cycling .…”

“…In parallel, we detect a continuous phase transition from a layered to spinel structure . Clear evidences for that are accumulated from Raman spectroscopy and electron diffraction data collected in post mortem analyses of these cathodes after cycling . The formation of a spinel Li−Mn−O phase leads to the famous voltage fading of these cathodes, namely, the average voltage becomes lower upon cycling,due to a major redox activity of this phase around 3 V .…”

“…Clear evidences for that are accumulated from Raman spectroscopy and electron diffraction data collected in post mortem analyses of these cathodes after cycling . The formation of a spinel Li−Mn−O phase leads to the famous voltage fading of these cathodes, namely, the average voltage becomes lower upon cycling,due to a major redox activity of this phase around 3 V . In order to mitigate the capacity fading and discharge voltage decay upon cycling of these HENCM cathodes, researchers have adopted various ways such as surface coating, surface modification and doping with cations such as Mg, Al, Sn.…”

Solid‐State Lithium Conductors for Lithium Metal Batteries Based on Electrospun Nanofiber/Plastic Crystal Composites

“…AB ruker AVANCE III 500 MHz wide bore solid-state spectrometer equipped with a4mm magic angle spinning (MAS) probe was used to collect static 1 H, 7 Li, 19 FNMR spectra for pure [C 2 mpyr][FSI], [C 2 mpyr][FSI] containing 50 mol %L iFSI, and the composite membranes. Spectra were acquired at selected points from À50 8Ct o 150 8Ca fter equilibrating for 120 sa te ach point.…”

Review on Challenges and Recent Advances in the Electrochemical Performance of High Capacity Li‐ and Mn‐Rich Cathode Materials for Li‐Ion Batteries

“…On the other hand, the presence of high amounts of Li 2 MnO 3 results in a lowering of the average discharge voltage upon cycling. [86] Chemical treatment of spinel LiMn 2 O 4 and Li[Li 1/3 Mn 5/3 ]O 4 by ammonia has yielded oxygen deficient spinel materials with enhanced capacity and stability. [87] Treatment of Li-, Mn-rich materials by ammonium carbonate at high temperatures, which decomposes to NH 3 , H 2 O, and CO 2 , yielded O 2− deficient material with higher discharge capacity and rate capabilities, though this was attributed to the formation of CO 2 instead of reaction with the NH 3 .…”