Fabrication of an LiMn₂O₄@LiMnPO₄ composite cathode for improved cycling performance at high temperatures

Abstract

The cyclability of LiMn 2 O 4 (LMO), a spinel cathode used in Li-ion batteries (LIBs), at high temperatures (>50°C) should be improved. In this study, we use an olivine-type LiMnPO 4 (LMP) cathode with a composite structure as the surface material to improve the cyclability of LMO. The fabrication strategy includes mechanical coating of the LMO core with shell precursor particles and their subsequent transformation into LMP rod particles via hydrothermal vapor conversion. The core-shell precursor particles (composing NH 4 MnPO 4 •H 2 O (AmMP) plates) are successfully converted into LMO@LMP composite particles with a rod-like surface layer. The composite cathode fabricated with 7 mass% AmMP exhibits improved capacity retention of 72% after 30 cycles at 60°C, while that of the uncoated LMO cathode decreases to 63%. Further structural arrangement of the surface particles can lead to the development of a suitable cathode material for large-scale applications of LIBs.

LiMn0.8Fe0.2PO4@C cathode prepared via a novel hydrated MnHPO4 intermediate for high performance lithium-ion batteries

“…According to the standard data of the PDF card (JCPDS no. 50-0554), the impurity of NH 4 MnPO 4 ·H 2 O incompletely decomposed, 39 marked with “*”, while a small amount of the impurity NH 4 H 2 PO 4 also formed (marked with “•”). 40 The impurity NH 4 MnPO 4 ·H 2 O is generated in the sol–gel reaction and easily decomposed to form MnHPO 4 and NH 3 .…”

Regulation of surface oxygen activity in Li-rich layered cathodes using band alignment of vanadium phosphate surface coatings

“…This would correspond to a stable Mn 2+ surface state with a reversible Mn 2+/3+ redox couple. 85,86 Interestingly, at 100–250 cycles, LVP–LLO exhibits an increase in both Mn 2+ and Co 2+ states at the Mn and Co L edges; evidence for surface transformation from a spinel-type to a Fm 3̄ m rock-salt coordination structure (Ni 2+ , Mn 2+ , Co 2+ ). 87 In contrast, bulk TFY Mn L edge measurements do not display a similar shift to a lower energy.…”

Smart Powder Processing for Excellent Advanced Materials and Its Applications

“…The flake-like LCP cathode exhibited a charge/ discharge plateau at ~4.8 V and a better discharge capacity of 109 mAh/g because of the high specific surface area and small platelet thickness (Kozawa et al, 2021a). Other applications of the wet mechanical processing including the synthesis of Sr 3 Al 2 (OH) 12 hydrogarnet , and the fabrication of composite cathode of LiMn 2 O 4 coated by LiMnPO 4 (Kozawa et al, 2020) have been investigated.…”