Synthesis of Well‐Crystallized, High‐Performance LiNi_0.5Mn_1.5O₄ Octahedra as Lithium‐Ion‐Battery Electrode Promoted by Metal Manganese Powders

Abstract

Metal Mn powders instead of conventional Mn salts were used for the first time tried as a Mn source to synthesize high‐performance LiNi0.5Mn1.5O4 (M‐LNMO) using a sol–gel method. Mn powders promote the formation of well‐crystallized octahedra with the Fd3m spinel structure. M‐LNMO has a lower stress, a slightly smaller lattice constant, which arises from the lower amount of Mn3+ because of the lower oxygen deficiency, a higher cation ordering, and longer Li−O and shorter Mn (Ni)−O bonds than LiNi0.5Mn1.5O4 synthesized from manganese acetate (MA‐LNMO). The well‐crystallized octahedra, the low stress, the low amount of Mn3+, and the long Li−O and short Mn (Ni)−O bonds for M‐LNMO result in its excellent performance such as a discharge capacity of 68 mAh g−1 at 50 C and a capacity retention of 90 % after 600 cycles at 10 C. This study raises the possibility to promote the synthesis of high‐performance LiNi0.5Mn1.5O4 for mass production by using cheap and simple Mn sources such as Mn powders.

Recent advances on low-Co and Co-free high entropy layered oxide cathodes for lithium-ion batteries

“…The electrode materials prepared by solid state method often have irregular particle shape and poor stoichiometric control. The solution-gel synthesis method can make the reagent mix evenly in the solution, and the final product has a narrow particle size distribution, good crystallinity and better uniformity [66,67,86].…”

Study on annealing treatment of spinel LiNi 0 . 5 Mn 1 . 5 O 4 as cathode materials for high‐voltage lithium‐ion batteries

“…The preparation methods of LiNi 0.5 Mn 1.5 O 4 include high‐temperature solid‐phase synthesis method 59 ; sol and gel method 60 ; hydrothermal method 61 ; co‐precipitation method, 62 spray drying method, 63 etc. Among these methods, the high‐temperature solid‐phase method is the most applicable to industrial production because of its simple preparation process, high controllability, and low price.…”

HEPES-Assisted Co-Precipitation Synthesis of LiNi0.5Mn1.5O4: Tuning the Mn3+ Content and Electrochemical Properties by pH Values

“…However, the disordered Fd 3m structure is composed of Mn 3+ and Mn 4+ , and Mn 3+ is generated by the loss of oxygen at elevated temperatures (>700 °C), and can't be replaced by inhalation at the cooling stage (LiMn 1.5 Ni 0.5 O 4 → α Li y Ni 1−y O + β LiMn 1.5+x Ni 0.5−x O 4 + γ O 2 ). 16,17 The Mn 3+ ions in the disordered LNMO can help to improve the electrochemical activity. 18 The redoxactive Mn 3+ improves the spinel electronic conductivity, which shows a short discharging plateau at ca.…”

“…39,57,58 Consequently, the excellent cycling performance of the LNMO-7.5 electrode may be facilitated by the low surface film resistance, the better rate capability may be promoted by the low charge transfer resistance and high Li + diffusion coefficient. 17…”