High Rate Micron-Sized Ordered LiNi[sub 0.5]Mn[sub 1.5]O[sub 4]

Ma, Xiaohua; Kang, Byoungwoo; Ceder, Gerbrand

doi:10.1149/1.3439678

Cited by 180 publications

(164 citation statements)

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“…dence on the cation ordering, 11,17 2) the difference in rate capability, 11,18 and 3) the occurrence of reversible phase transitions between ordered and disordered Ni/Mn arrangement during charge/discharge cycling 1,19,20 are debated. Properties such as these provide the foundation for the long-time performance and we cannot rationally design or optimize electrode materials without understanding how the electrochemical signature depends on the structure and chemistry.…”

mentioning

confidence: 99%

Revealing the coupled cation interactions behind the electrochemical profile of LixNi0.5Mn1.5O4

Lee

Persson

2012

Energy Environ. Sci.

114

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We present first-principles energy calculations and a cluster expansion model of the ionic ordering in Li x Ni 0.5 Mn 1.5 O 4 (0 ≤ x ≤ 1), one of the proposed highenergy density next-generation Li-ion cathode materials. The developed model predicts an intricate relationship between the preferred Li-vacancy ordering and the Ni/Mn configuration, which explains the difference in intermediate ground states between ordered (P4 3 32) and disordered (Fd3m) Ni/Mn configuration. The phase sequence as a function of lithiation as well as the voltage profile are well matched with experimental results. Understanding of the inherent chemical interactions and their impact on the performance of an energy storage material is essential when designing and optimizing Li-ion electrode materials.Li-ion batteries are poised to power the new generation of electric vehicles and thereby enable sustainable energy transportation. Among the most promising cathode materials, the lithium manganese spinel, LiMn 2 O 4 , has received attention due to its cheap price, non-toxicity, and good rate capability. 1,2 However, commercialization of LiMn 2 O 4 has been delayed due to capacity fade upon cycling, which has been attributed to the dissolution 3-5 of Mn 3+ produced by the redox process during lithiation/delithiation cycling. 6,7 Furthermore, it has been speculated that the strong Jahn-Teller distortion of the Mn 3+ ion degrades the structural stability of the material and inhibits Li migration. [8][9][10] Previous studies (see for example Ref. 3 and references therein) aimed at improving the cycling performance by substituting other transition metals into LiMn 2 O 4 suggest Li x Ni 0.5 Mn 1.5 O 4 as an attractive material.In Li x Ni 0.5 Mn 1.5 O 4 , the redox process occurs on the Ni site only, which prevents the creation of the Mn 3+ cation and its related problems. 11,12 Furthermore, the reduction of Ni 4+ to Ni 2+ occurs at 4.7 V, 3,11-15 which increases the total energy density of Li x Ni 0.5 Mn 1.5 O 4 as compared to LiMn 2 O 4 from 440 Wh/kg to 686 Wh/kg. 16 Despite the promising qualities of Li x Ni 0.5 Mn 1.5 O 4 for Liion battery applications, some of its fundamental properties have remained unexplained. For example, 1) the origin of the voltage step at Li 0.5 Ni 0.5 Mn 1.5 O 4 and its pronounced depen- * Corresponding author: eunseoklee@lbl.gov dence on the cation ordering, 11,17 2) the difference in rate capability, 11,18 and 3) the occurrence of reversible phase transitions between ordered and disordered Ni/Mn arrangement during charge/discharge cycling 1,19,20 are debated. Properties such as these provide the foundation for the long-time performance and we cannot rationally design or optimize electrode materials without understanding how the electrochemical signature depends on the structure and chemistry. In this communication, we present first-principles energy calculations and a coupled cluster expansion model of the ionic ordering and its effect on the electrochemical behavior of Li x Ni 0.5 Mn 1.5 O 4 . In particular, the mod...

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mentioning

confidence: 99%

Revealing the coupled cation interactions behind the electrochemical profile of LixNi0.5Mn1.5O4

Lee

Persson

2012

Energy Environ. Sci.

114

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“…2 Appropriate ratios of Li 2 CO 3 , MnO 2 and NiCO 3 were ball-milled in acetone at 12 h. Li-doped samples had a Li:Ni:Mn ratio of 1.1:0.45:1.5. Dried mixture powders were pelletized and then calcined at 900°C for 12 h in air.…”

Section: Materials Synthesismentioning

confidence: 99%

“…For this purpose, high-voltage spinel LiNi 0.5 Mn 1.5 O 4 is a promising cathode material for LIBs [1][2][3] because it has a high redox potential of about 4.7 V, which makes its energy density (650 W h kg − 1 ) 20% higher than that of the conventional LiCoO 2 . However, the electrochemical properties of LNMO spinel depend on several factors, such as its structure, 3,4 the quantity of Mn 3+ ions, 5,6 the particle size 2,7 and the morphology of particles. 8 Among these factors, the structure of the spinel has a critical influence on its electrochemical performance.…”

Section: Introductionmentioning

confidence: 99%

High electrochemical performance of high-voltage LiNi0.5Mn1.5O4 by decoupling the Ni/Mn disordering from the presence of Mn3+ ions

Lee¹,

Kim²,

Kang³

2015

NPG Asia Mater

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Electrochemical activity in high-voltage spinel LiNi 0.5 Mn 1.5 O 4 (LNMO) is strongly affected by the disordering of Ni/Mn and the presence of Mn 3+ ions. However, understanding the effect of the Ni/Mn disordering or the presence of Mn 3+ ions on electrochemical properties is not trivial because disordering is typically coupled with the presence of Mn 3+ ions. Here, we demonstrate for the first time that the doping of Li instead of Ni increases Ni/Mn disordering, which is decoupled from the presence of Mn 3+ ions. The resultant material has a particle size of~1-2 μm and can achieve 120 mAh g − 1 at 10 C for 50 cycles and further deliver about 60 mAh g − 1 even at a rate of~60 C (1 min discharge). Superior electrochemical performance is achieved by increased solid-solution phase transition behavior, which is caused by increased Ni/Mn disordering during delithiation. By decoupling, we find that the electrochemical properties in LNMO strongly depend on the phase transformation behavior and that the Ni/Mn disordering, rather than Mn 3+ ions, affects the phase transformation by increasing the solid-solution reaction. The fundamental understanding gained from this work could be applied to the development of other phase-separating compounds to improve their electrochemical performance. INTRODUCTIONFor a lithium-ion battery, a high energy density is an essential requirement for novel applications such as plug-in hybrid electric vehicles and electric vehicles. Increasing the redox potential of cathode materials is an effective way to achieve high energy density in the cell. For this purpose, high-voltage spinel LiNi 0.5 Mn 1.5 O 4 is a promising cathode material for LIBs 1-3 because it has a high redox potential of about 4.7 V, which makes its energy density (650 W h kg − 1 ) 20% higher than that of the conventional LiCoO 2 . However, the electrochemical properties of LNMO spinel depend on several factors, such as its structure, 3,4 the quantity of Mn 3+ ions, 5,6 the particle size 2,7 and the morphology of particles. 8 Among these factors, the structure of the spinel has a critical influence on its electrochemical performance. 9-11 The LNMO structure is dictated by the ordering of Ni and Mn at two octahedral sites, which results in two spinel forms: disordered and ordered. The Ni and Mn in the ordered spinel are well ordered in two distinct octahedral sites, 4b sites for Ni and 12d sites for Mn, whereas the Ni and Mn in the disordered spinel are randomly distributed in 16d octahedral sites. 1,12 In the ordered spinel, the ordering of Ni/Mn exists without Mn 3+ ions because a second annealing process at o700°C simultaneously leads to the ordering of Ni/Mn on two distinct octahedral sites and the oxidation of Mn 3+ ions into Mn 4+ ions. However, the disordered spinel shows both the disordering of Ni/Mn and the presence of Mn 3+ ions. The correlation

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“…Ban et al [16] CNT network, which served as the superhighway for the electron and Li ion migration. Thang et al [18] successfully functionalized CNTs by a mixture of H 2 SO 4 /HNO 3 , and the CNTs were used as conducting addition to prepare LiMn 2 O 4 /CNT and LNMO/CNT. The nanocomposites cathodes displayed good capability when the content of CNT was 10%.…”

Section: Introductionmentioning

confidence: 99%

“…can afford a high energy density of 658 W h kg −1 , which is higher than the traditional LiCoO 2 (620 W h kg −1 ) and LiFePO 4 (591 W h kg −1 ) cathode materials [3]. However, some drawbacks such as the fast capacity fading at high voltage [4] and the appearance of rock-salt phase at high temperature [5] limit the commercialization of LNMO.…”

mentioning

confidence: 99%

Hollow spherical LiNi0.5Mn1.5O4 built from polyhedra with high-rate performance via carbon nanotube modification

Wang

Zhao

et al. 2016

Sci. China Mater.

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can afford a high energy density of 658 W h kg −1 , which is higher than the traditional LiCoO 2 (620 W h kg −1 ) and LiFePO 4 (591 W h kg −1 ) cathode materials [3]. However, some drawbacks such as the fast capacity fading at high voltage [4] and the appearance of rock-salt phase at high temperature [5] limit the commercialization of LNMO.It has been widely acknowledged that the electrochemical property of electrode materials is strongly related to the particle size, crystallinity and morphology [6]. To improve the performance, a wide variety of nanostructured electrodes, such as nanorods [7], porous structures [8], hollow microcubes and microspheres [9], and core-shell microspheres [10], have been designed and utilized in LIBs. Among these nanostructures, the porous and hollow structures can increase the contact area between the electrode and electrolyte, which is beneficial to reduce the transport path of lithium ions. Zhu et al. [11] reported the synthesis of LNMO microspheres with larger pores, which exhibited excellent performance. Luo et al. [12] synthesized LNMO hollow microspheres with excellent cycling stability and rate capability, which was attributed to the short electronic/ionic diffusion distance and accommodated volume change derived from the hollow structure. Li et al. [13] designed uniform LiNi 1/3 Mn 1/3 Co 1/3 O 2 hollow microspheres with improved performance by using porous Mn 1.5 Co 1.5 O 4 microspheres as the template. All these literatures demonstrate that the rational structural design can significantly improve the electrochemical performance.The cycling performance and high-rate capability are highly dependent on the conductivity of electrode materials [14]. Surface modification has been proved to be an efficient strategy to enhance electronic conductivity [15]. Among all modifying materials, carbon nanotube (CNT) is an ideal high electronic conducting material. It can efficiently improve the sluggish electron transportation and ABSTACT Lithium nickel manganese oxide spinel (LiNi0.5-Mn1.5O4, LNMO) has attracted much attention as the cathode material for rechargeable lithium-ion batteries due to its high energy density and low cost. However, the short cycle life and poor high-rate capability hinder its commercialization. In this study, we synthesized hollow spherical LNMO built from polyhedral particles. The LNMO hollow structure guarantees sufficient contact with electrolyte and rapid diffusion of lithium ions. To enhance the conductivity, we use carbon nanotubes (CNTs) to modify the surface of the cathode. After CNT modification, the LNMO hollow structure manifests outstanding cycling stability and high-rate capability. It delivers a discharge capacity of 127 mA h g −1 at 5 C, maintaining 104 mA h g −1 after 500 cycles. Even at a high rate of 20 C, a capacity of 121 mA h g −1 can be obtained. The excellent electrochemical performance is ascribed to the unique structure and the enhanced conductivity through CNT modification. It is demonstrated that the CNTmodified hollow spherical LNMO...

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High Rate Micron-Sized Ordered LiNi[sub 0.5]Mn[sub 1.5]O[sub 4]

Cited by 180 publications

References 42 publications

Revealing the coupled cation interactions behind the electrochemical profile of LixNi0.5Mn1.5O4

Revealing the coupled cation interactions behind the electrochemical profile of LixNi0.5Mn1.5O4

High electrochemical performance of high-voltage LiNi0.5Mn1.5O4 by decoupling the Ni/Mn disordering from the presence of Mn3+ ions

Hollow spherical LiNi0.5Mn1.5O4 built from polyhedra with high-rate performance via carbon nanotube modification

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