Spinel Lithium Manganese Oxide Modification Methods

Haoxuan Xu

School of Energy and Materials, Shanghai Polytechnic University, Shanghai, 201209, China

Keywords: Spinel Lithium Manganese Oxide, Lithium-Ion Battery.

Abstract: Lithium-ion batteries (LIBs) are an excellent new generation of green, environmentally friendly, and

renewable chemical energy sources. The positive electrode material is a crucial component in the production

of LIBs. LiMn

enjoys the benefit of being sourced from plentiful resources, high energy density, affordable

pricing, zero emissions, and superior safety. Spinel lithium manganese oxide belongs to the cubic crystal

system. Thanks to its three-dimensional tunnel structure, lithium ions can deintercalate within the spinel lattice

without inducing structural collapse, allowing for reversible processes. This characteristic makes it one of the

most promising positive electrode materials. LiMn

stands out as a highly promising cathode material for

lithium-ion batteries and finds extensive application in electric vehicles and energy storage devices.

Additionally, the thermal stability and electrochemical performance of LiMn

are excellent, enabling stable

operation under high temperature and high current conditions. Its preparation process is relatively simple and

cost-effective, making it easy to achieve large-scale production. As a highly promising LIBs cathode material,

LiMn

is commonly employed in electric vehicles and energy storage systems. It is expected to further

promote the development and application of lithium-ion battery technology in the future, providing strong

support for achieving greener and more sustainable energy solutions.

1 INTRODUCTION

1.1 Research Background

In the era of the low-carbon economy, LIBs are

gradually most used batteries of the 21st century

owing to their relatively high energy density. As a key

component of LIBs, the efficiency of the positive

electrode material significantly impacts the overall

performance of the battery. Research on positive

electrode materials for LIBs involves multiple

disciplines such as chemistry, physics, materials

science, energy, and electronics. The progress in this

field has attracted great interest from the

electrochemical and chemical power industries. With

the continuous advancement in electrode material

preparation methods, structure determination,

performance improvement, and related theoretical

research, it is expected that finding synthetic methods

with easily controllable preparation conditions,

simple operation, and feasible doping and composite

approaches will strongly promote the research and

application of LIBs. Modification can improve the

electrochemical performance of Mn

, such as

enhancing its electrical conductivity, lithium-ion

diffusion rate, and stability, thereby increasing the

battery's cycle life and energy density. Through

modification, the structural stability of Mn

can be

enhanced, suppressing its volume expansion and

structural damage during charge and discharge

processes, thus improving the battery's cycle life and

safety. Additionally, modification can control the

crystal structure of Mn

such as altering grain size,

morphology, and crystallinity, optimizing its

electrochemical performance, and enhancing the

battery's performance stability and cycle life. Some

modification methods can increase Mn

conductivity, such as conductive additive or

composite materials, thereby reducing internal

resistance and improving charge and discharge

efficiency. Some modification methods can also

reduce production costs, for example, by using

inexpensive materials or simplifying production

processes, making Mn

positive electrode materials

more competitive.

Traditional LIBs positive electrode materials,

such as LiCoO

, NCM, and NCA, though performing

well in battery applications, also have some issues.

The limited availability and high cost of metals such

as cobalt and nickel in traditional positive electrode

materials restrict large-scale commercial

286

Xu, H.

Spinel Lithium Manganese Oxide Modiﬁcation Methods.

DOI: 10.5220/0013922700004914

Paper published under CC license (CC BY-NC-ND 4.0)

In Proceedings of the 2nd International Conference on Renewable Energy and Ecosystem (ICREE 2024), pages 286-291

ISBN: 978-989-758-776-4

applications, leading to high battery costs. Moreover,

safety concerns arise from the cobalt element present

in positive electrode materials like lithium cobalt

oxide, which can lead to thermal runaway reactions

under high temperature or overcharging conditions,

posing safety hazards. Traditional positive electrode

materials also experience capacity decay during long-

term charge and discharge cycles, mainly due to

structural changes in the positive electrode material,

electrolyte decomposition, and solid-liquid interface

reactions. The cycle life of positive electrode

materials is influenced by several factors，including

the structural stability of the material and the stability

of the electrolyte-electrode interface, which can result

in decreased battery performance after prolonged

cycling. Moreover, the specific capacity of traditional

positive electrode materials is generally between 20-

200 mAh/g, which cannot meet the requirements of

high-energy-density batteries, limiting the potential

for performance improvement.

The primary substance employed as a the positive

material in LIBs is an intercalation compound formed

by lithium and transition metal oxides，with spinel

lithium manganese oxide being the most common. In

the field of LIBs, spinel lithium manganese oxide is

preferred due to its high energy density and extended

cycle life, and relatively high electrochemical

stability, finding widespread applications in portable

electronic gadgets, electric automobiles, and energy

storage grids, etc. Although commercial LIBs mainly

use lithium cobalt oxide as the positive electrode

material, the development and production of its

utilized as a positive electrode material are of great

significance for cost reduction and fully utilizing

abundant, inexpensive natural resources.

Although spinel lithium manganese oxide has

significant advantages in the realm of lithium-based

batteries, its stability is somewhat lacking.

Unmodified Mn

positive electrode materials in

lithium-ion batteries may encounter some issues: the

relatively low electrical conductivity of pure Mn

results in slow electron transfer rates, limiting the

battery's powering up and draining rates and

performance. The crystal structure of Mn

may

limit the diffusion rate of lithium ions within the

material, resulting in slower reaction rates during

charge and discharge processes, affecting the battery's

power performance. During charge and discharge

cycles, Mn

materials undergo volume expansion

and contraction, which may lead to structural damage

and pulverization, thereby affecting the battery's

cycle life and stability. Mn

materials may

experience capacity decay and structural damage

during long-term cycling, leading to decreased

battery performance and reduced cycle life.

Additionally, the specific capacity of Mn

generally relatively low, unable to meet the

requirements of certain high-energy-density batteries,

limiting the performance development space of

batteries. Therefore, improving its performance

through doping and modification methods is a

feasible direction. If these challenges can be

successfully overcome, spinel lithium manganese

oxide, as an excellent positive electrode material for

LIBs, will demonstrate broad application prospects in

renewable energy, intelligent gadgets, electric cars,

energy storage solutions.

1.2 Energy Storage Principle

As a positive electrode material for LIBs, spinel

lithium manganese oxide, its energy storage

mechanism relies on the diffusion and migration of

lithium ions between the positive and negative

electrodes during the charge and discharge cycles of

the battery. Throughout the charging phase，lithium

ions migrate from the electrolyte to the spinel lithium

manganese oxide lattice structure, leading to an

increase in lithium ion count in the material and an

increase in the battery voltage until it reaches full

charge. During discharge, lithium ions deintercalate

from the spinel lithium manganese oxide structure,

leading to a gradual decrease in battery voltage, while

releasing energy and converting it into electric current

to provide power to the external circuit. When all

lithium-ions are deintercalated from the positive

electrode material, the battery is in an empty state.

The basic principle of energy storage for LiMn

the diffusion and migration of Li movement between

the cathode and anode during the charging and

discharging processes, thereby storing and releasing

electrical energy. It has the advantages of high energy

density, high efficiency, and long cycle life, so it is

widely used in LIBs, energy storage systems, and

other electrochemical fields.

2 CHARACTERISTIC OF

LiMn

2.1 Morphology and Structure of

Spinel LiMn2O4

As a key LIBs cathode material, Spirel-type lithium-

type manganate (LiMn

has a cubic crystal

structure and a space group of Fd-3m (Jian et al.,

2018). The crystal cell parameter is a = 8.142 Å, and

Spinel Lithium Manganese Oxide Modiﬁcation Methods

287

each crystal cell contains 8 Mn

ions and 16 Li

ions.

In the crystal structure, lithium ions and Mn ions

occupy the octahedral and tetrahedral voids

respectively, forming a structure similar to spinel.

Spine-type lithium manganate has a variety of

morphology, and different preparation methods can

control its morphology. Common morphologies

include spherical, rod-shaped, laky and nanowire-

like. The differences in these morphologies are

mainly due to factors such as preparation conditions,

methods, types and proportions of reactants. By

adjusting the morphology of spirel-type lithium

manganate, its electrochemical properties, charge and

discharge characteristics and cyclic stability can be

adjusted (Zhang, 2021).

Spherical spinite-type lithium manganate is often

used in the preparation of composite cathode

materials, possessing a substantial surface area and

outstanding electrochemical characteristics; rod-

shaped spine-type lithium manganate is usually used

in high-power lithium-ion battery cathode materials,

with good electrical conductivity and fast ion

transmission rate; sheet-shaped lithium manganate

can improve electrode filling Charging density, which

enhances the mechanical stability of materials, is

suitable for high-capacity LIBs; nano-wired spinel-

shaped lithium manganate can increase the electrode

surface area and ion transmission rate, improve cycle

performance and stability, and is suitable or lithium-

ion batteries characterized by both high power and

high energy density (Cen et al., 2021).

2.2 Preparation Method of Lithium

Manganate of Spine

Solid-state reaction method: This method uses solid-

state reactions at high temperatures to generate

spinite-type lithium manganese salts and lithium

salts. It is usually necessary to calcine the reaction

product at high temperature to improve its

crystallinity and purity. Although it requires high

temperature and long-term reaction, it is suitable for

mass production (Guo et al., 2019).

Hydrothermal method: Under high temperature

and high pressure conditions, spine-type lithium

manganate is generated by hydrothermal synthesis.

By adjusting the reaction ratio, reaction time and

reaction temperature and other conditions, the

structural characteristics such as the morphology and

crystal size of the material can be controlled. This

method has high preparation efficiency and

controllability.

Solvent thermal method: This method is to react

manganese salt with lithium salt in an organic solvent

to form a spinerite-type lithium manganate.

Compared with the solid reaction method and the

hydrothermal method, the solvent heat method has a

lower reaction temperature and a shorter reaction

time, and can control the structural characteristics

such as the morphology and crystal size of the

material. This method has high preparation efficiency

and controllability (Guo et al., 2019).

Other methods: There are also other synthesis

methods, such as coprecipitation process, microwave

method, vapor deposition method, etc. These methods

have their scope of application, and appropriate

methods can be selected according to the research

needs.

2.3 Application Prospect of Spinel

Lithium Manganate

As a positive material for lithium-ion batteries, Spire-

type lithium manganate (LiMn

) shows important

application prospects in the fields of wearable

devices, smart homes, electric automobiles and

energy storage solutions.

In the field of electric vehicles, with the increasing

global attention to environmental protection, the

electric vehicle market is developing rapidly. Spine-

type lithium manganate is widely used in the field of

electric vehicles with its high energy density, long

cycle life and cost advantages. At the same time, as

components of the energy storage setup, the spinet-

type lithium manganate is also favored in the fields of

home energy storage infrastructure, photovoltaic

energy storage infrastructure and wind power energy

storage system because of its high discharge voltage

platform, excellent circulation performance and fast

charging and discharge characteristics.

In terms of wearable electronic products, with

people's attention to health and the rapid rise of the

wearable device market, spinel lithium manganate, as

a battery cathode material suitable for small

electronic devices, is favored for its high energy

density and long cycle life. It is widely used in the

field of wearable devices such as smart watches,

smart bracelets and smart glasses (Abaas et al., 2020).

As an excellent lithium-ion battery cathode

material, spine lithium manganate has a wide

application prospect in the future in the fields of

renewable energy, intelligent equipment, electric cars

and energy storage facilities

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3 MODIFICATION METHOD OF

LIMN

3.1 Doping Modification

Doping modification stands in an efficacious manner

approach to enhance the electrochemical behavior of

spinel lithium manganese oxide. Through the

introduction of dopant elements, regulating the

crystal structure and electrochemical traits of spinel

lithium manganese oxide can enhance its lithium-ion

diffusion rate, electrical conductivity, structural

stability, and cycling performance. Doping

modification can introduce dopant elements into the

spinel lattice of manganese oxide, occupying the

octahedral or tetrahedral voids in the crystal structure,

thereby changing the electronic structure and charge

distribution of the material, and optimizing its

electrochemical performance. Commonly used

doping elements include transition metal ions, alkali

metal ions, alkaline earth metal ions, rare earth metal

ions, and non-metallic elements. Doping

modification can increase the electrical conductivity

of spinel lithium manganese oxide, reduce the

diffusion resistance of lithium ions, and improve the

charge and discharge rate and power performance of

the battery. Doping modification can stabilize the

spinel structure of lithium manganese oxide, suppress

its volume expansion and structural damage during

charge and discharge cycles, and improve the cycle

life and stability of the battery. Doping modification

can optimize the crystal structure of lithium

manganese oxide, control the grain size, morphology,

and crystallinity of the material, and improve its

electrochemical performance and energy density.

Doping modification additionally allows for the

adjustment of the redox potential and charge transfer

kinetics of LIBs, optimizing the charge and discharge

voltage platforms, thus enhancing the energy

utilization efficiency and rate performance of the

battery.

Metal and non-metal doping is a prevalent tactic

aimed at enhancing the galvanic process

characteristics of LiMn

cathode materials. These

doped elements include metal elements such as cobalt

(Co), nickel (Ni), copper (Cu), and non-metallic

elements such as fluorine (F), phosphorus (P) and

silicon (Si). Through doping, the crystal and

electronic structure of lithium manganate can be

changed, thus improving its electrochemical

properties (Li, 2022). In addition to the physical and

chemical properties of the material itself, the

preparation process is also a key factor, which can be

used to improve the stability and capacity decay rate

of the material. Research shows that the prepared

material has the advantages of uniform particle size,

high crystallinity and large specific surface area,

which can effectively improve its electrochemical

activity. Therefore, while adopting the element

doping strategy, it is usually necessary to optimize the

synthesis method and process.

The solid-phase method conducted at elevated

temperatures involves the preparation of spinel-type

lithium manganate cathode materials after mixing

raw materials in a certain proportion and after many

high-temperature calcination and grinding processes.

The sol-gel method typically employs citric acid as a

complexing agent to prepare materials through

stirring., dissolving, drying and curing, grinding into

powder, calcination heat treatment and other steps. In

contrast to the thermal solid-state processing

approach., the wet chemical method of sol-gel

synthesis offers advantages such as lower solution

viscosity, improved uniformity, and enhanced

quantification and the preparation conditions are

relatively mild (Cen et al., 2021).

Using Li

, Mn

and SiO

as raw materials,

a series of Si-doped LiMn

-xSi

(x=0,0.005,0.010,0.020) positive electrode materials

were synthesized using the high-temperature solid-

state approach. The research the outcomes

demonstrate that Si

的、doping has no effect on the

initial spine composition of the sample, but the lattice

constant increases along with the rise of silicon

doping, optimizing the crystal structure. The charge

and discharge performance test shows that Si

doping effectively improves the initial discharge ratio

capacity of lithium manganate. At room temperature

and 0.2 C, along with the rise of silicon doping, the

initial discharge ratio capacity of the sample is

increased from 122.5 mAh/g to 127.7mAh/g. It shows

the best cycle stability at x=0.010. The capacity

retention rate post 100 cycles under ambient

conditions and 1C is 94.30%, and the retention of

capacity post 50 cycles at high temperature 55℃ and

1C is as high as 89.08% (Lu et al., 2023).

The sol-gel method is used to analyze lithium

dihydrate acetate and manganese tetrahydrate acete as

lithium and manganese sources, and ethyl silicate as

silicon sources to prepare spinite-type lithium

manganese cathode materials. XRD and XPS spectra

show that Si

has successfully replaced part of the

in the lattice, resulting in a slight contraction of

the lattice and producing a small amount of impurity

peaks, indicating that the silicon element has not been

completely doped and Li

SiO

has been generated. At

10mA/g current density and 1.5-4.8V voltage, the

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289

initial discharge ratio capacity of the sample is

147mAh/g, and the capacity retention rate is 60%

after 51 cycles (Lu et al., 2023).

The template orientation method is used to modify

the silicon ions mixed in the microsphere nickel-

doped lithium manganate (LiNi

0.5

1.5

). EDX

analysis shows that silicon ions are successfully

incorporated into the lattice of lithium manganate, but

a small amount of salt phase impurities appear in the

XRD spectrum. SEM characterization shows that the

microspheres doped with silicon ions are uniform in

size and about 15mm in diameter. Compared with

undoped samples, the capacity retention rate

increased from 93.1% to 99.4% after 100 cycles at 1

In the process of single silicon element doping

modified spinite-type lithium manganate, TEOS is

often used as a silicon source. The particle size

obtained after doping is evenly distributed, the shape

is regular, and the edges and corners are clear. Si

mainly replaces Mn

at the octahedron 16d position

in lithium manganate crystal cells, thus obtaining a

high first discharge ratio capacity. The primary

synthesis approaches employed include the high-

temperature solid-phase method and the sol-gel

method. Both methods have an optimized effect in

micro-particle morphology control, but the synthesis

conditions are relatively strict, such as high

temperature (450-800 ℃ ), long-term (roaking time

takes 10-25 hours), and cumbersome operation (long-

term stirring). Mixing and grinding multiple times)

and the stoichiometric ratio is difficult to control (Lu

et al., 2023).

3.2 Surface Modification

Surface modification is another effective method to

enhance the electrochemical performance of spinel

lithium manganese oxide the electrochemical

performance of LiMn

. Through the introduction

of surface functional groups or coating layers, the

surface properties and electrochemical reactivity of

LiMn

can be regulated to improve its lithium-ion

diffusion rate, surface wettability, interfacial

compatibility, and structural stability. Surface

modification can introduce surface functional groups

such as hydroxyl groups, carboxyl groups, amino

groups, sulfhydryl groups, and phosphonate groups

onto the surface of lithium manganese oxide, thereby

changing its surface chemical composition and

surface energy, and optimizing its surface

electrochemical performance. Surface modification

can also deposit coating layers such as carbon, metal

oxides, conductive polymers, and ceramic materials

onto the surface of lithium manganese oxide, forming

a surface protective layer or conductive network,

improving its surface structural stability and

electrochemical activity, and enhancing its cycle life

and rate performance. Surface modification can

regulate the surface morphology and roughness of

lithium manganese oxide, control the particle size,

shape, and distribution, and optimize its surface

reactivity and interfacial compatibility. Surface

modification can also enhance the surface adsorption

capacity and catalytic activity of lithium manganese

oxide, promote the formation of solid-electrolyte

interface (SEI) films, and improve the stability and

safety of the battery. Surface modification can

improve the surface charge transfer kinetics and

electrochemical reaction kinetics of LiMn

, reduce

the charge transfer resistance and polarization of the

battery, and improve its energy efficiency and power

density.

3.3 Composite Modification

Composite modification is a comprehensive method

to improve the electrochemical properties of

LiMn

. By combining LiMn

with other

functional materials, the composite material's overall

electrochemical performance can be synergistically

improved, achieving complementary advantages and

overcoming individual shortcomings. Composite

modification can combine spinel lithium manganese

oxide with carbonaceous materials like graphene,

carbon nanotubes, carbon black, and carbon fibers to

form a conductive network, improving the electrical

conductivity and charge transfer rate of the composite

material, and enhancing its rate performance and

power density. Composite modification can combine

spinel lithium manganese oxide with metal oxides

such as titanium dioxide, iron oxide, cobalt oxide, and

nickel oxide to form a heterojunction structure,

improving the electrochemical activity and redox

reaction kinetics of the composite material, and

enhancing its capacity and energy density. Composite

modification can combine spinel lithium manganese

oxide with conductive polymers such as polyaniline,

polypyrrole, polythiophene, and polyacetylene to

form a hybrid material, improving the

electrochemical stability and structural flexibility of

the composite material, and enhancing its cycle life

and mechanical properties. Composite modification

can combine LiMn

with ceramic materials

materials like aluminum oxide, silicon dioxide,

zirconium dioxide, and boron nitride to form a

protective layer or skeleton structure, improving the

structural stability and thermal conductivity of the

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composite material, and enhancing its safety and

reliability. Composite modification can also combine

spinel lithium manganese oxide with nanostructured

materials such as nanoparticles, nanowires,

nanosheets, and nanopores to form a nanostructured

architecture, improving the surface area and reaction

activity of the composite material, and enhancing its

specific capacity and energy density.

4 CONCLUSION

Spine-type lithium manganate is considered one of

the most potential cathode materials of LIBs at

present due to its significant advantages in

performance and application range. In the realm of

LIBs, it is crucial to develop high-performance

positive materials suitable for large-scale commercial

applications, essential for advancements of lithium-

ion battery technology. Compared with other cathode

materials such as LiFePO

, LiCoO

, LiNiO

and

ternary NCM, lithium spinite manganate has the

benefits of affordability and environmental

friendliness, environmental protection, strong

stability, simple preparation and excellent

performance, so it has attracted much attention. It is

an excellent cathode material for LIBs due to its high

energy density, long cycle life, and high

electrochemical stability. However, unmodified

positive electrode materials may encounter

some problems in LIBs, for example low electrical

conductivity, slow lithium ion diffusion rate, poor

structural stability, and limited specific capacity.

Modification methods such as doping modification,

surface modification, and composite modification can

effectively enhance the electrochemical behavior of

LiMn

, optimize its crystal structure and surface

properties, and enhance its charge and discharge rate,

cycle life, and safety performance. The research and

development of modified spinel lithium manganese

oxide positive electrode materials are of great

significance to the progression of LIBs technology

and the advancement of new energy applications.

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