An Aqueous Reduction Method To Synthesize Spinel-LiMn₂O₄ Nanoparticles as a Cathode Material for Rechargeable Lithium-Ion Batteries

Abstract

A new synthetic method has been developed and demonstrated for the utilization of commercially cheap MnO 2 for the production of nanoparticles of LiMn 2 O 4 spinel as a cathode material for Li-ion batteries. The process involves the insertion of lithium into electrolytic manganese dioxide (EMD) in an aqueous medium with glucose as a mild reductant in open air. The material resulting from calcination is pure, spinel-structured Li 0.96 Mn 2 O 4 particles of sub-micrometric and nanometric size that exhibit promising electrochemical behavior in nonaqueous Li-salt solutions. Further development of this process may be interesting for the commercial production of LiMn 2 O 4 for Li-ion batteries.

Crystallinity Control of a Nanostructured LiNi0.5Mn1.5O4 Spinel via Polymer‐Assisted Synthesis: A Method for Improving Its Rate Capability and Performance in 5 V Lithium Batteries

“…This procedure has been used to prepare nanometric LiNi 0.5 Mn 1.5 O 4 , which is an attractive spinel on account of its high discharge capacity at potentials close to 5 V. [18][19][20][21] Although it performs acceptably at high discharge rates, its electrochemical response deteriorates markedly at low rates. [22] The rate capability of the nanometric form can be expanded by mixing it with a micrometric spinel of similar composition in a 1:1 ratio. [23] In this work, we used a different approach to obtain nanometric LiNi 0.5 Mn 1.5 O 4 with good electrochemical performance over a wide range of rate capabilities by modifying the experimental synthetic conditions.…”

Effect of reaction temperature on morphology and electrochemical behavior

“…The second red ox pair (4.25 V) is attributed to the intercalation/de-intercalation of lithium into the other half of the tetrahedral sites, where Li + ions do not interact. It is well known that these processes are accompanied by the reversible Mn 3+ /Mn 4+ red ox reactions, and hence the cycling reversibility of LiMn 2 O 4 cathode could be understood [18,37]. It is evident from Fig.…”

“…Also, it is well known that solid-state diffusion of lithium ions, being the rate-determining step of intercalation and deintercalation processes, prefers smaller particle size with shorter diffusion length to aid faster lithium diffusion kinetics [16]. Furthermore, it has been demonstrated [17,18] that the capacity of lithium intercalating oxide electrodes is enhanced by decreasing the average grain size of the oxide. Particularly, even with the same chemical composition and crystal structure, small variations in physical properties of the cathode materials, such as surface morphology and size of the particles, are reported to influence the performance of the battery to a noticeable extent [12].…”

Cathodes for lithium ion batteries: the benefits of using nanostructured materials

“…These conventional solid state methods are not relevant to produce nanosized spinel LiMn 2 O 4 , since repeated heat treatments at high temperatures are necessary, which leads to large particle size, inhomogeneity, irregular morphology and broad particle size distribution. [134][135][136][137] Thus, a sustained effort of many researchers has gone into the development of new synthetic methods to yield nanocrystalline LiMn 2 O 4 particles, such as acetate based chemical solution route, 138 reduction of manganese dioxide by glucose, 139 modified citrate route, 140 ultrasonic spray pyrolysis, 141 sol-gel using citric acid, 142 nitrate based chemical solution route, 143 mechanochemical synthesis, 144 sol-gel method, 27 self-combustion reaction, 145 glycine nitrate combustion process 146 and solid state reaction followed by ball milling. 147 Depending on the synthetic procedure, nanosized LiMn 2 O 4 with different physical and chemical properties, such as crystallinity, amount of combined water, specific surface area, porosity and conductivity were obtained.…”