Influence of HDI as a cathode film-forming additive on the performance of LiFe0.2Mn0.8PO4/C cathode

Xu, Xiaoyue; Qin, Yinping; Yang, Wenchao; Sun, Dandan; Liu, Yang; Guo, Bingkun; Wang, Deyu

doi:10.1039/c7ra04979j

Cited by 6 publications

(6 citation statements)

References 21 publications

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“…According to the spectrum mentioned above and literature, , the reaction mechanism is illustrated in Scheme S1. A PC molecule would be oxidized to be a an oxygen free-radical-onium ion on the surface of the cathode during charging, then the polymer A would be formed by the peroxide groups and amide groups which are generated from the dimerization between free radicals and the nucleophilic addition between the charged methines and isocyanate groups of HDI.…”

Section: Resultsmentioning

confidence: 99%

“…In our previous work, a novel strategy was developed to construct a stable interface film by hexamethylene diisocyanate (HDI) and PC via an onium ionization-polymerization. , The amide-based polymer layer, formed by the free-radical-onium ion oxidative intermediate of PC and HDI, could be stable at 5.2 V (vs Li + /Li) and suppress the electrochemical process on the surface of LiNi 1/3 Ni 1/3 Mn 1/3 O 2 in cyclic voltammetry. Compared with other systems containing larger concentrations of the additives, the cell’s performance is obviously improved with 1 mM HDI added, namely the characteristics of polymer membrane is very sensitive to HDI amount.…”

Section: Introductionmentioning

confidence: 99%

“…In our previous work, a novel strategy was developed to construct a stable interface film by hexamethylene diisocyanate (HDI) and PC via an onium ionization-polymerization. 25,26 The amide-based polymer layer, formed by the free-radicalonium ion oxidative intermediate of PC and HDI, could be stable at 5.2 V (vs Li + /Li) and suppress the electrochemical process on the surface of LiNi characteristics of polymer membrane is very sensitive to HDI amount. Therefore, we screen the diisocyanate chemicals to expand the concentration region for the better handling in practical application.…”

Section: ■ Introductionmentioning

confidence: 99%

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Isophorone Diisocyanate: An Effective Additive to Form Cathode-Protective-Interlayer and Its Influence on LiNi_0.5Co_0.2Mn_0.3O₂ at High Potential

Liu

Sun

Zhou

et al. 2018

ACS Appl. Mater. Interfaces

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In this work, we propose a novel electrolyte additive, isophorone diisocyanate (IPDI), to construct the surface protective interlayer. This membrane is produced via nucleophilic addition between the IPDI's diisocyanate groups and the free-radical-onium ion oxidative intermediate of propylene carbonate (PC). In the electrolyte with IPDI added between 10-20 mM, LiNiCoMnO presents the excellent performance, demonstrating the relative wide operational window to form the optimal protective membrane. This protective membrane ameliorates the cyclic stability. Although all systems deliver ∼185 mAh g under 1 C between 2.5-4.6 V (vs Li/Li), the cells in the suitable electrolyte maintain 90.4% in the 50 cycles and 83.2% in the 200 cycles, whereas the control cells are seriously dropped to 73.4% and 69.8%. The cells in the electrolyte with the appropriate IPDI also present the good rate capability, attaining ∼143 mAh g under 5 C, much higher than the cells in the control electrolyte(92.4 mAh g). The additive proposed in this work is helpful to augment the energy density of lithium ion battery and prolong the one-drive distance of electric vehicles.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…In our previous work, a novel strategy was developed to construct a stable interface film by hexamethylene diisocyanate (HDI) and PC via an onium ionization-polymerization. 25,26 The amide-based polymer layer, formed by the free-radicalonium ion oxidative intermediate of PC and HDI, could be stable at 5.2 V (vs Li + /Li) and suppress the electrochemical process on the surface of LiNi characteristics of polymer membrane is very sensitive to HDI amount. Therefore, we screen the diisocyanate chemicals to expand the concentration region for the better handling in practical application.…”

Section: ■ Introductionmentioning

confidence: 99%

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Isophorone Diisocyanate: An Effective Additive to Form Cathode-Protective-Interlayer and Its Influence on LiNi_0.5Co_0.2Mn_0.3O₂ at High Potential

Liu

Sun

Zhou

et al. 2018

ACS Appl. Mater. Interfaces

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“…[35][36][37] Considering the similar molecule structure and decomposition mechanism to PC, 34 the intermediate of FEC at high potential may react with isocyanate through thermodynamics polymerization to produce an amide-based polymer. Due to the relatively low highest occupied molecular orbital (HOMO, ∼ −0.24 a.u.)…”

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“…35 The CEI would be stable at 4.6 V (vs. Li + /Li) on a porous electrode, protect the cathode from the corrosion of electrolyte, suppress the decomposing of solvents at high potential and significantly improve the electrochemical performances of LiNi x Co y Mn 1-x-y O 2 and LiFe 0.2 Mn 0.8 PO 4 /C cathode materials. [35][36][37] Considering the similar molecule structure and decomposition mechanism to PC, 34 the intermediate of FEC at high potential may react with isocyanate through thermodynamics polymerization to produce an amide-based polymer. Due to the relatively low highest occupied molecular orbital (HOMO, ∼ −0.24 a.u.)…”

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Forming a Stable CEI Layer on LiNi_0.5Mn_1.5O₄Cathode by the Synergy Effect of FEC and HDI

Sun

Wang

Zhou

et al. 2018

J. Electrochem. Soc.

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As a promising additive for film forming on anodes, fluoroethylene carbonate (FEC) has been applied widely in commercial lithium ion batteries (LIBs). However, the influence of FEC in high-voltage Li + energy storage systems are still under disputing for the negative effects on cathodes. Considering a FEC molecule would be electro-oxidized to a radical onium ion, we investigate hexamethylene diisocyanate (HDI) as the additive which can react with the intermediate to form an amide-based polymer via thermodynamic processes. The polymer would be stable at high potential. In the FEC-containing electrolyte with HDI added, a surface layer is formed on the LiNi 0.5 Mn 1.5 O 4 cathode, which would protect the compounds from decomposing and improve the performances of the batteries. The capacity retention of Li/LiNi 0.5 Mn 1.5 O 4 cells cycled between 3.5-4.9 V (vs. Li + /Li) is significantly increased from 59.1% to 76.1% in 200 cycles, and the rate capability is also improved compared with the ones without HDI. The electrolyte system also shows a good compatibility with graphite, presenting a promising prospect for the practical application of high-voltage LIBs. In the development of LIBs, the building of solid electrolyte interphase (SEI) is an important milestone, for which passes Li + cations but blocks the solvent molecules from continual decomposing and/or co-intercalating into anodes, making the "rocking chair" batteries workable. 26 reveals that FEC molecule would be defluorinated and decarboxylated on anodes, then produce a highly cross-linked elastic polymer network, which meets the require of the failure strain in anodes' charging-discharging processes. FEC can also enhance the ionic conductivity of the interphase, 27 widen the operating temperature 17,27,28 and improve the safety 29 of batteries. Thus FEC is widely used as an important multifunctional additive in state-of-the-art LIBs.On the other hand, in order to meet the increasing demand of high energy density, high-voltage cathodes have been proposed for next generation LIBs. 30 However, the effects of the SEI formation additives on cathodes are still under discussing. 31 In the comprehensive considering, the additives for LIBs should improve the performances of both anode and cathode. 32 Unfortunately, as an important additive for SEI forming, FEC exhibited negative effects on LiNi 0.5 Mn 1.5 O 4 cathode even the concentration of the additive is benefit for the anodes. 33 The calculation shows a FEC molecule would be oxidized to a radical cation, and a thick layer on the cathode is formed while the concentration of the additive is 5 wt%, which is not preferential for the electrochemical performance of high-voltage LIBs in the tests. 33,34We have previously reported an onium ionization-polymerized cathode electrolyte interphase (CEI) film formed by HDI and propylene carbonate (PC). A PC molecule would be oxidized to be a free radical-onium ion at high potential (>4.3 V vs. Li + /Li, Reaction 1). The free radical of the intermediate would auto polymerize...

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Impedance studies of LiMn0.8Fe0.2PO4/C cathodes for lithium-ion batteries

Zhang

Wang

Zhuang

et al. 2021

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Influence of HDI as a cathode film-forming additive on the performance of LiFe_0.2Mn_0.8PO₄/C cathode

Cited by 6 publications

References 21 publications

Isophorone Diisocyanate: An Effective Additive to Form Cathode-Protective-Interlayer and Its Influence on LiNi_0.5Co_0.2Mn_0.3O₂ at High Potential

Isophorone Diisocyanate: An Effective Additive to Form Cathode-Protective-Interlayer and Its Influence on LiNi_0.5Co_0.2Mn_0.3O₂ at High Potential

Forming a Stable CEI Layer on LiNi_0.5Mn_1.5O₄Cathode by the Synergy Effect of FEC and HDI

Impedance studies of LiMn0.8Fe0.2PO4/C cathodes for lithium-ion batteries

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Influence of HDI as a cathode film-forming additive on the performance of LiFe0.2Mn0.8PO4/C cathode

Cited by 6 publications

References 21 publications

Isophorone Diisocyanate: An Effective Additive to Form Cathode-Protective-Interlayer and Its Influence on LiNi0.5Co0.2Mn0.3O2 at High Potential

Isophorone Diisocyanate: An Effective Additive to Form Cathode-Protective-Interlayer and Its Influence on LiNi0.5Co0.2Mn0.3O2 at High Potential

Forming a Stable CEI Layer on LiNi0.5Mn1.5O4Cathode by the Synergy Effect of FEC and HDI

Impedance studies of LiMn0.8Fe0.2PO4/C cathodes for lithium-ion batteries

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Influence of HDI as a cathode film-forming additive on the performance of LiFe_0.2Mn_0.8PO₄/C cathode

Isophorone Diisocyanate: An Effective Additive to Form Cathode-Protective-Interlayer and Its Influence on LiNi_0.5Co_0.2Mn_0.3O₂ at High Potential

Isophorone Diisocyanate: An Effective Additive to Form Cathode-Protective-Interlayer and Its Influence on LiNi_0.5Co_0.2Mn_0.3O₂ at High Potential

Forming a Stable CEI Layer on LiNi_0.5Mn_1.5O₄Cathode by the Synergy Effect of FEC and HDI