富锂正极材料的衰减机理及循环稳定性提升的研究进展

doi:10.19894/j.issn.1000-0518.210059

摘要/Abstract

摘要：

富锂正极材料xLi₂MnO₃·（1－x）LiMO₂（M＝Ni，Co，Mn等，0<x<1）具有容量高（可达300 mA·h／g以上）、成本低的巨大优势，被誉为是可能的最为重要的下一代锂离子电池正极材料，受到了各国的高度重视和广泛研究。目前，这种材料尚存在初始（首圈）库仑效率低、循环性能差、电压衰减严重等问题，严重阻碍了材料的发展和实际应用进程。为了解决材料存在的这些问题，尤其是其循环稳定性不足及电压衰减的问题，近年来人们在富锂正极材料衰减机理及稳定性提升方面开展了大量的研究工作，并取得了一些重要的进展。本文介绍了富锂正极材料的结构及其工作原理，着重介绍了近年来关于富锂正极材料衰减机理及提升富锂正极材料稳定性方面的研究工作，并对这类材料的发展前景和下一步的研究工作进行了展望。

关键词: 锂离子电池, 富锂正极材料, 衰减机理, 稳定性提升, 体相掺杂, 表面包覆

Abstract:

The lithium-rich cathode material xLi₂MnO₃· (1-x) LiMO₂ (M=Ni, Co, Mn, etc., 0<x<1) has the huge advantages of high capacity (up to 300 mA·h/g or more) and low cost, and is known as probably the most important next-generation cathode material for lithium-ion batteries. It has received great attention and extensive research from various countries. At present, this material still has problems such as low initial (first cycle) Coulomb efficiency, poor cycle performance, and serious voltage attenuation, which all seriously hinder the development and practical application of the material. In order to solve these problems of this material, especially its insufficient cycle stability and voltage attenuation, a lot of research work has been carried out on the degradation mechanism and stability improvement of the lithium-rich cathode material, and some important progresses have been made in recent years. This article introduces the structure and working principle of the lithium-rich cathode material, focusing on the research work in recent years on the degradation mechanism of the lithium-rich cathode material and improving the stability of the lithium-rich cathode material. The further research work has been prospected.

Key words: Lithium-ion battery, Lithium-rich cathode material, Degradation mechanism, Stability improvement, Bulk phase doping, Surface coating

中图分类号:

O646

赵莹, 邵奕嘉, 李罗钱, 任建伟, 廖世军. 富锂正极材料的衰减机理及循环稳定性提升的研究进展[J]. 应用化学, 2022, 39(02): 205-222.

Ying ZHAO, Yi-Jia SHAO, Luo-Qian LI, Jian-Wei REN, Shi-Jun LIAO. Research Progress on the Degradation Mechanism and Cycle Stability Improvement of Lithium-Rich Cathode Materials[J]. Chinese Journal of Applied Chemistry, 2022, 39(02): 205-222.

图/表 15

图1 （a）LiMO2、（b）Li2MnO3和（c）富锂材料的晶体结构示意图［32］

Fig.1 Crystal structure diagram of（a）LiMO2，（b）Li2MnO3and（c）Li-rich materials［32］

图2 高分辨透射电镜（HR-TEM）观察到的Li1.2Co0.1Mn0.55Ni0.15O2的图像［37］

Fig.2 Image of Li1.2Co0.1Mn0.55Ni0.15O2observed by high resolution transmission electron microscope（HR-TEM）［37］

图3 富锂层状正极材料的首次充放电曲线图［45］

Fig.3 The first charge-discharge curves of lithium-rich layered cathode materials［45］

图4 （a）Li1.2Ni0.13Co0.13Mn0.54O2的TM层中的蜂窝型阳离子排列结构；（b）蜂窝结构中的氧由Mn4+和Li+配位；（c）O－／O2－能量与状态密度的示意图［47］

Fig.4 （a）Honeycomb-type cation arrangement in the TM layer of Li1.2Ni0.13Co0.13Mn0.54O2；（b）Oxygen in the honeycomb structure coordinated by Mn4+and Li+；（c）O－／O2－Energy and state density diagram［47］

图5 左图为初始态、充电至4.4 V和充电至4.8 V时对OCV不同状态的PDF谱进行拟合；右图为中心Mn原子周围的局部结构，紫色：Mn，红色：O［49］（注：1?＝0.1 mm）

Fig.5 Figures of the fitting results of PDF spectra at different states of OCV，pristine，charged to 4.4 V，and charged to 4.8 V（left）；Figures of the local structure around the center Mn atom. Purple：Mn，red：O（right）［49］

图6 富锂正极材料的相变序列和结构退化的示意图［53］

Fig.6 Diagram of phase transition sequence and structural degradation of the Li-rich cathode materials［53］

图7 （a）LNCM和LNCM-K的倍率性能；LNCM和LNCM-K在（b）0.5 C，（c）5 C和10 C下的循环性能［59］

Fig.7 （a）Rate performance of LNCM and LNCM-K；Cycling performance of LNCM and LNCM-K at（b）0.5 C，（c）5 C and 10 C［59］

图8 LNCM和LNCM-Pt在（a）0.5 C、（b）1 C和（c）2 C下的循环性能［71］

Fig.8 Cycling performance of LNCM and LNCM-Pt at（a）0.5 C，（b）1 C and（c）2 C［71］

图9 （a）NM-LRM和PD-LRM在0.1 C下首圈充放电性能；（b）NM-LRM和PD-LRM的倍率性能；（c）NM-LRM和PD-LRM在1 C下的循环性能［79］

Fig.9 （a）First charge-discharge characteristics of NM-LRM and PD-LRM at 0.1 C；（b）Rate performance of NM-LRM and PD-LRM；（c）Cycle performance of NM-LRM and PD-LRM at 1 C［79］

图10 （a）LMNC、Na-LMNC、F-LMNC和NaF-LMNC在0.1 C下首圈充放电性能；（b）LMNC、Na-LMNC、F-LMNC和NaF-LMNC的倍率性能；（c）LMNC、Na-LMNC、F-LMNC和NaF-LMNC在1 C下的循环性能；（d）LMNC、Na-LMNC、F-LMNC和NaF-LMNC的电压衰减［86］

Fig.10 （a）First charge-discharge characteristics of LMNC，Na-LMNC，F-LMNC，and NaF-LMNC at 0.1 C；（b）Rate performance of LMNC，Na-LMNC，F-LMNC，and NaF-LMNC；（c）Cycle performance of LMNC，Na-LMNC，F-LMNC，and NaF-LMNC at 1 C；（d）Voltage fading of LMNC，Na-LMNC，F-LMNC，and NaF-LMNC［86］

图11 （a）M0和M1的倍率性能；M0和M1在（b）0.5 C，（c）2 C下的循环性能；（d）M0和M1在1 C下的中值放电电压［89］

Fig.11 （a）Rate performance of M0 and M1；（b）Cycling performance of M0 and M1 at（b）0.5 C，（c）2 C；（d）Discharge median voltage of M0 and M1 at 1 C［89］

图12 （a）改性前后的材料在0.1 C下的首圈充放电性能；（b）改性前后的材料在1 C下的循环性能；（c）改性前后材料的倍率性能［104］

Fig.12 （a）First charge-discharge characteristics of materials before and after modification at 0.1 C；（b）Cycling performance of materials before and after modification at 1 C；（c）Rate performance of materials before and after modification at 0.1 C［104］

图13 （a）LMNCO@RGO和LMNCO NTs在1 C下的循环性能；（b）LMNCO@RGO和LMNCO NTs的倍率性能［114］

Fig.13 （a）Cycling performance of LMNCO@RGO and LMNCO NTs at 1 C；（b）Rate performance of LMNCO@RGO and LMNCO NTs［114］

图14 （a）改性前后的材料在0.1 C下首圈充放电性能；（b）改性前后材料的倍率性能；改性前后的材料在（c）1 C，（d）5 C下的循环性能［120］

Fig.14 （a）First charge-discharge performance of materials before and after modification at 0.1 C；（b）rate performance of materials before and after modification；cycling performance of materials before and after modification at（c）1 C，（d）5 C［120］

图15 （a）LLO@MDZ和LLO在0.1 C下的首圈充放电性能；（b）LLO@MDZ和LLO的倍率性能；（c）LLO@MDZ在1 C的循环性能及库仑效率；（d）LLO在1 C下的循环性能及库伦效率［131］

Fig.15 （a）first charge-discharge performance of LLO@MDZ and LLO at 0.1 C；（b）Rate performance of LLO@MDZ and LLO；（c）Cycling performance and coulombic efficiency of LLO@MDZ at 1 C；（d）Cycling performance and coulombic efficiency of LLO at 1 C［131］

参考文献 131

[1]	CROGUENNEC L, PALACIN M R. Recent achievements on inorganic electrode materials for lithium-ion batteries[J]. J Am Chem Soc, 2015, 137(9):3140-3156.
[2]	ETACHERI V, MAROM R, ELAZARI R, et al. Challenges in the development of advanced Li-ion batteries: a review[J]. Energy Environ Sci, 2011, 4(9):3243-3262.
[3]	NITTA N, WU F, LEE J T, et al. Li-ion battery materials: present and future[J]. Mater Today, 2015, 18(5):252-264.
[4]	DUNN B, KAMATH H, TARASCON J M. Electrical energy storage for the grid: a battery of choices[J]. Science, 2011, 334(6058):928.
[5]	ARMSTRONG A R, LYNESS C, PANCHMATIA P M, et al. The lithium intercalation process in the low-voltage lithium battery anode Li_1+xV_1－xO₂ [J]. Nat Mater, 2011, 10:223.
[6]	HU Y, GAO Y, FAN L, et al. Electrochemical study of poly (2, 6-anthraquinonyl sulfide) as cathode for alkali-metal-ion batteries[J]. Adv Energy Mater, 2020, 10(48):2002780.
[7]	SU C, HAN B, MA J, et al. A novel anthraquinone-containing poly (triphenylamine) derivative: preparation and electrochemical performance as cathode for lithium-ion batteries[J]. Chem Electro Chem, 2020, 7(19):4101-4107.
[8]	KOBAYASHI H, TSUKASAKI T, OGASAWARA Y, et al. Cation-disorder-assisted reversible topotactic phase transition between antifluorite and rocksalt toward high-capacity lithium-ion batteries[J]. ACS Appl Mater Interfaces, 2020, 12(39):43605-43613.
[9]	CHANG Q, LUO Z, FU L, et al. A new cathode material of NiF₂for thermal batteries with high specific power[J]. Electrochim Acta, 2020, 361:137051.
[10]	LUO L W, ZHANG C, XIONG P, et al. A redox-active conjugated microporous polymer cathode for high-performance lithium/potassium-organic batteries[J]. Sci China Chem, 2020, 64(1):72-81.
[11]	YU Z, WANG X, WAN P, et al. Li_1.233Mo_0.467Fe_0.3O₂as an advanced cathode material for high-performance lithium-ion battery[J]. Mater Lett, 2019, 249:45-48.
[12]	SHAO Y, HUANG B, LU Z, et al. High-performance 3D pinecone-like LiNi_1/3Co_1/3Mn_1/3O₂cathode for lithium-ion batteries[J]. Energy Technol, 2019, 7(4):1800769.
[13]	KALLURI S, YOON M, JO M, et al. Surface engineering trategies of layered LiCoO₂cathode material to realize high-energy and high-voltage Li-ion cells[J]. Adv Energy Mater, 2017, 7(1):1601507.
[14]	WEI Y, ZHENG J, CUI S, et al. Kinetics tuning of Li-ion diffusion in layered Li (Ni _x Mn _y Co_z) O₂ [J]. J Am Chem Soc, 2015, 137(26):8364-8367.
[15]	LU Z H, MACNEIL D D, DAHN J R. Layered cathode materials Li Ni _x Li_(1/3-2x/3)Mn_(2/3－x/3)O₂for lithium-ion batteries[J]. Electrochem Solid State Lett, 2001, 4(11):A191-A194.
[16]	LU Z H, BEAULIEU L Y, DONABERGER R A, et al. Synthesis, structure, and electrochemical behavior of Li Ni _x Li_1/3－2x/3Mn_2/3－x/3O₂ [J]. J Electrochem Soc, 2002, 149(6):A778-A791.
[17]	LU Z H, DAHN J R. Understanding the anomalous capacity of Li/Li Ni _x Li_(1/3－2x/3)Mn_(2/3－x/3)O₂cells using in situ X-ray diffraction and electrochemical studies[J]. J Electrochem Soc, 2002, 149(7):A815-A822.
[18]	SHUNMUGASUNDARAM R, SENTHIL ARUMUGAM R, DAHN J R. High capacity Li-rich positive electrode materials with reduced first-cycle irreversible capacity loss[J]. Chem Mater, 2015, 27(3):757-767.
[19]	JOHNSON C S, KIM J S, LEFIEF C, et al. The significance of the Li₂MnO₃component in‘composite’xLi₂MnO₃·(1－x) LiMn_0.5Ni_0.5O₂electrodes[J]. Electrochem Commun, 2004, 6(10):1085-1091.
[20]	KIM J S, JOHNSON C S, VAUGHEY J T, et al. Electrochemical and structural properties of xLi₂M′O₃·(1－x) LiMn_0.5Ni_0.5O₂electrodes for lithium batteries (M′＝Ti, Mn, Zr；0≤x－0.3)[J]. Chem Mater, 2004, 16(10):1996-2006.
[21]	ZHANG M, CHEN M, SHAO Y, et al. Enhanced performance of LiNi_0.03Mo_0.01Mn_1.96O₄cathode materials coated with biomass-derived carbon layer[J]. Ionics, 2018, 25(3):917-925.
[22]	邵奕嘉, 黄斌, 刘全兵, 等. 三元镍钴锰正极材料的制备及改性[J]. 化学进展, 2018, 30(4):410-419.
	SHAO Y J, HUANG B, LIU Q B, et al. Preparation and Modification of Ni-Co-Mn ternary cathode materials[J]. Chem Ind Eng Prog, 2018, 30(4):410-419.
[23]	廖世军, 卲奕嘉, 叶跃坤, 等. 一种溶剂热法制备三元正极材料及其制备方法[P]. 广东:CN107959022A, 2018-04-24.
	LIAO S J, SHAO Y J, YE Y, K, et al. A solvothermal method for preparing ternary cathode material and its preparation method[P]. Guangdong:CN107959022A, 2018-04-24.
[24]	廖世军, 张和, 张梦诗, 等. 一种碳包覆的富锂多元锂离子电池正极材料及其制备方法[P]. 广东:CN107369817A, 2017-11-21.
	LIAO S J, ZHAO H, ZHANG M S, et al. A Carbon-coated lithium-rich multi-element lithium-ion battery cathode material and its preparation method[P]. Guangdong:CN107369817A, 2017-11-21.
[25]	CHEN M, REN W, SHAO Y, et al. Lithium-rich layered nickel-manganese oxides as high-performance cathode materials: the effects of composition and PEG on performance[J]. Ionics, 2016, 22(11):2067-2073.
[26]	鲁志远, 刘燕妮, 廖世军. 锂离子电池富锂锰基层状正极材料的稳定性[J]. 化学进展, 2020, 32(10):1504-1514.
	LU Z Y, LIU Y N, LIAO S J. Enhancing the stability of lithium-rich manganese-based layered cathode materials for Li-ion batteries application[J]. Chem Ind Eng Prog, 2020, 32(10):1504-1514.
[27]	张和, 张梦诗, 廖世军. 富锂三元层状正极材料的研究进展[J]. 应用化学, 2018, 35(11):1277-1288.
	ZHANG H, ZHANG M S, LIAO S J. Research progress of lithium-rich ternary layered cathode materials[J]. Chinese J Appl Chem, 2018, 35(11):1277-1288.
[28]	廖世军, 鲁志远, 赵莹. 一种提升富锂三元材料循环稳定性及容量的方法及其材料[P]. 广东省:CN110518210A, 2019-11-29.
	LIAO S J, LU Z Y, ZHAO Y. A method and material for improving the cycling stability and capacity of lithium-rich ternary materials[P]. Guangdong Province:CN110518210A, 2019-11-29.
[29]	廖世军, 鲁志远, 赵莹. 一种富锂三元正极材料及其绿色制备方法[P]. 广东省:CN109768272A, 2019-05-17.
	LIAO S J, LU Z Y, ZHAO Y. A lithium-rich ternary cathode material and its green preparation method[P]. Guangdong Province:CN109768272A, 2019-05-17.
[30]	ZHENG J, MYEONG S, CHO W, et al. Li-and Mn-rich cathode materials: challenges to commercialization[J]. Adv Energy Mater, 2016, 7(6):1601284.
[31]	LEE W, MUHAMMAD S, SERGEY C, et al. Advances in the cathode materials for lithium rechargeable batteries[J]. Angew Chem Int Ed Engl, 2020, 59(7):2578-2605.
[32]	YU H, ZHOU H. High-energy cathode materials (Li₂MnO₃-LiMO₂) for lithium-ion batteries[J]. J Phys Chem Lett, 2013, 4(8):1268-1280.
[33]	BOULINEAU A, SIMONIN L, COLIN J F, et al. Evolutions of Li_1.2Mn_0.61Ni_0.18Mg_0.01O₂during the initial charge/discharge cycle studied by advanced electron microscopy[J]. Chem Mater, 2012, 24(18):3558-3566.
[34]	YUH, ISHIKAWAR, SOYG, et al. Direct atomic-resolution observation of two phases in the Li_1.2Mn_0.567Ni_0.166Co_0.067O₂cathode material for lithium-ion batteries[J]. Angew Chem Int Ed Engl, 2013, 52(23):5969-5973.
[35]	OHZUKU T, NAGAYAMA M, TSUJI K, et al. High-capacity lithium insertion materials of lithium nickel manganese oxides for advanced lithium-ion batteries: toward rechargeable capacity more than 300 mA·h·g^－1 [J]. J Mater Chem, 2011, 21(27):10179-10188.
[36]	AMMUNDSEN B, PAULSEN J, DAVIDSON I, et al. Local structure and first cycle redox mechanism of layered Li_1.2Cr_0.4Mn_0.4O₂cathode material[J]. J Electrochem Soc, 2002, 149(4):A431-A436.
[37]	MOHANTY D, KALNAUS S, MEISNER R A, et al. Structural transformation of a lithium-rich Li_1.2Co_0.1Mn_0.55Ni_0.15O₂ cathode during high voltage cycling resolved by in situ X-ray diffraction[J]. J Power Sources, 2013, 229:239-248.
[38]	WU Y, MANTHIRAM A. Effect of Al³⁺and F^－doping on the irreversible oxygen loss from layered Li Li_0.17Mn_0.58Ni_0.25O₂ cathodes[J]. Electrochem Solid State Lett, 2007, 10(6):A151-A154.
[39]	WU F, LI W, CHEN L, et al. Renovating the electrode-electrolyte interphase for layered lithium- &manganese-rich oxides[J]. Energy Storage Mater, 2020, 28:383-392.
[40]	ZHAO S, YAN K, ZHANG J, et al. Reaction mechanisms of layered lithium-rich cathode materials for high-energy lithium-ion batteries[J]. Angew Chem Int Ed Engl, 2021, 60(5):2208-2220.
[41]	KONISHI H, HIRANO T, TAKAMATSU D, et al. Electrochemical reaction mechanism of two components in xLi₂MnO_3－(1－x)LiNi_0.5Mn_0.5O₂and effect of x on the electrochemical performance in lithium-ion battery[J]. J Electroanal Chem, 2020, 873:114402.
[42]	ARMSTRONG A R, HOLZAPFEL M, NOVAK P, et al. Demonstrating oxygen loss and associated structural reorganization in the lithium battery cathode LiNi_0.2Li_0.2Mn_0.6O₂ [J]. J Am Chem Soc, 2006, 128(26):8694-8698.
[43]	TANG Z K, XUE Y F, TEOBALDI G, et al. The oxygen vacancy in Li-ion battery cathode materials[J]. Nanoscale Horiz, 2020, 5(11):1453-1466.
[44]	CUI S L, ZHANG X, WU X W, et al. Understanding the structure-performance relationship of lithium-rich cathode materials from an oxygen-vacancy perspective[J]. ACS Appl Mater Interfaces, 2020, 12(42):47655-47666.
[45]	DING X, LI Y X, WANG S, et al. Towards improved structural stability and electrochemical properties of a Li-rich material by a strategy of double gradient surface modification[J]. Nano Energy, 2019, 61:411-419.
[46]	MUHAMMAD S, KIM H, KIM Y, et al. Evidence of reversible oxygen participation in anomalously high capacity Li-and Mn-rich cathodes for Li-ion batteries[J]. Nano Energy, 2016, 21:172-184.
[47]	LUO K, ROBERTS M R, HAO R, et al. Charge-compensation in 3D-transition-metal-oxide intercalation cathodes through the generation of localized electron holes on oxygen[J]. Nat Chem, 2016, 8(7):684-691.
[48]	NAKAYAMA K, ISHIKAWA R, KOBAYASHI S, et al. Dislocation and oxygen-release driven delithiation in Li₂MnO₃ [J]. Nat Commun, 2020, 11(1):4452.
[49]	WANG L, DAI A, XU W, et al. Structural distortion induced by manganese activation in a lithium-rich layered cathode[J]. J Am Chem Soc, 2020, 142(35):14966-14973.
[50]	HONG J, LIM H D, LEE M, et al. Critical role of oxygen evolved from layered Li-excess metal oxides in lithium rechargeable batteries[J]. Chem Mater, 2012, 24(14):2692-2697.
[51]	YU X Y, YU L, LOU X W. Metal sulfide hollow nanostructures for electrochemical energy storage[J]. Adv Energy Mater, 2016, 6(3):1501333.
[52]	SINGER A, ZHANG M, HY S, et al. Nucleation of dislocations and their dynamics in layered oxide cathode materials during battery charging[J]. Nat Energy, 2018, 3(8):641-647.
[53]	LIU H, HARRIS K J, JIANG M, et al. Unraveling the rapid performance decay of layered high-energy cathodes: from nanoscale degradation to drastic bulk evolution[J]. ACS Nano, 2018, 12(3):2708-2718.
[54]	DING X, LI Y X, DENG M M, et al. Cesium doping to improve the electrochemical performance of layered Li_1.2Ni_0.13Co_0.13Mn_0.54O₂cathode material[J]. J Alloys Compd, 2019, 791:100-108.
[55]	ZHANG K, SHENG H, WU X, et al. Improving electrochemical properties by Sodium doping for lithium-rich layered oxides[J]. ACS Appl Energ Mater, 2020, 3(9):8953-8959.
[56]	CHEN B, ZHAO B, ZHOU J, et al. Enhanced electrochemical performance of Li_1.2Ni_0.2Mn_0.6O₂cathode materials through facile layered/spinel phase tuning[J]. J Solid State Electrochem, 2018, 22(8):2587-2596.
[57]	LIU Y, LIU D, WU H H, et al. Improved cycling stability of Na-doped cathode materials Li_1.2Ni_0.2Mn_0.6O₂ via a facile synthesis[J]. ACS Sustainable Chem Eng, 2018, 6(10):13045-13055.
[58]	XUE Z, QI X, LI L, et al. Sodium doping to enhance electrochemical performance of overlithiated oxide cathode materials for Li-ion batteries via Li/Na ion-exchange method[J]. ACS Appl Mater Interfaces, 2018, 10(32):27141-27149.
[59]	LIU Z, ZHANG Z, LIU Y, et al. Facile and scalable fabrication of K⁺-doped Li_1.2Ni_0.2Co_0.08Mn_0.52O₂cathode with ultra high capacity and enhanced cycling stability for lithium-ion batteries[J]. Solid State Ion, 2019, 332:47-54.
[60]	YANG M, HU B, GENG F, et al. Mitigating voltage decay in high-capacity Li_1.2Ni_0.2Mn_0.6O₂cathode material by surface K⁺doping[J]. Electrochim Acta, 2018, 291:278-286.
[61]	JIN Y, XU Y, REN F, et al. Mg-doped Li_1.133Ni_0.2Co_0.2Mn_0.467O₂in Li site as high-performance cathode material for Li-ion batteries[J]. Solid State Ion, 2019, 336:87-94.
[62]	MENG F, GUO H, WANG Z, et al. Magnesium-doped Li[Li_0.2Mn_0.54Ni_0.13Co_0.13]O₂cathode with high rate capability and improved cyclic stability[J]. Ionics, 2018, 25(5):1967-1977.
[63]	LOU M, FAN S S, YU H T, et al. Mg-doped Li_1.2Mn_0.54Ni_0.13Co_0.13O₂nano flakes with improved electrochemical performance for lithium-ion battery application[J]. J Alloys Compd, 2018, 739:607-615.
[64]	XU G, XUE Q, LI J, et al. Understanding the enhanced electrochemical performance of Samarium substituted Li[Li_0.2Mn_0.54－xSm _x Co_0.13Ni_0.13]O₂cathode material for lithium ion batteries[J]. Solid State Ion, 2016, 293:7-12.
[65]	ETEFAGH R, ROZATI S M, ARABI H. Al-doped Li_1.21[Mn_0.54Ni_0.125Co_0.125]O₂cathode material with enhanced electrochemical properties for lithium-ion battery[J]. Appl Phys A, 2020, 126(10):814.
[66]	SETENIB, RAPULENYANEN, NGILAJC, et al. Structural and electrochemical behavior of Li_1.2Mn_0.54Ni_0.13Co_0.13－xAl _x O₂(x＝0.05) positive electrode material for lithium-ion battery[J]. Mater Today: Proc, 2018, 5(4):10479-10487.
[67]	LIU S, LIU Z, SHEN X, et al. Surface doping to enhance structural integrity and performance of Li-rich layered oxide[J]. Adv Energy Mater, 2018, 8(31):1802105.
[68]	LI H, JIAN Z, YANG P, et al. Niobium doping of Li_1.2Mn_0.54Ni_0.13Co_0.13O₂cathode materials with enhanced sructural stability and electrochemical performance[J]. Ceram Int, 2020, 46(15):23773-23779.
[69]	BAO L, YANG Z, CHEN L, et al. The effects of trace Yb doping on the electrochemical performance of Li-rich layered oxides[J]. ChemSusChem, 2019, 12(10):2294-2301.
[70]	CHEN J, ZOU G, DENG W, et al. Pseudo-bonding and electric-field harmony for Li-rich Mn-based oxide cathode[J]. Adv Funct Mater, 2020, 30(46):2004302.
[71]	LIU Y, LI J, YANG Z, et al. Suppressing the voltage decay of lithium-rich cathode for Li-ion batteries via Pt nanoparticles surface modification[J]. Ceram Int, 2020, 46(17):26564-26571.
[72]	SORBONI Y G, ARABI H, KOMPANY A. Effect of Cu doping on the structural and electrochemical properties of lithium-rich Li_1.25Mn_0.50Ni_0.125Co_0.125O₂nanopowders as a cathode material[J]. Ceram Int, 2019, 45(2):2139-2145.
[73]	WANG Y, GU H T, SONG J H, et al. Suppressing Mn reduction of Li-rich Mn-based cathodes by F-doping for advanced lithium-ion batteries[J]. J Phys Chem C, 2018, 122(49):27836-27842.
[74]	TENG R, YU H T, GUO C F, et al. Effect of F dopant on the structural stability, redox mechanism, and electrochemical performance of Li₂MoO₃cathode materials[J]. Adv Sustainable Syst, 2020, 4(12):2000104.
[75]	LIUT, ZHAOSX, GOULL, et al. Electrochemical performance of Li-rich cathode material, 0.3Li₂MnO₃-0.7LiMn_1/3Ni_1/3Co_1/3O₂microspheres with F-doping[J]. Rare Met, 2018, 38(3):189-198.
[76]	RICHARDS W D, DACEK S T, Kitchaev D A, et al. Fluorination of lithium-excess transition metal oxide cathode materials[J]. Adv Energy Mater, 2018, 8(5):1701533.
[77]	LUN Z, OUYANG B, KITCHAEV D A, et al. Improved cycling performance of Li-excess cation-disordered cathode materials upon fluorine e substitution[J]. Adv Energy Mater, 2019, 9(2):1802959.
[78]	KAPYLOU A, SONG J H, MISSIUL A, et al. Improved thermal stability of lithium-rich layered oxides by fluorine doping[J]. Chemphyschem, 2018, 19(1):116-122.
[79]	WANG M J, YU F D, SUN G, et al. Co-regulating the surface and bulk structure of Li-rich layered oxides by a phosphor doping strategy for high-energy Li-ion batteries[J]. J Mater Chem A, 2019, 7(14):8302-8314.
[80]	LIU D, FAN X, LI Z, et al. A cation/anion co-soped Li_1.12Na_0.08Ni_0.2Mn_0.6O_1.95F_0.05cathode for lithium-ion batteries[J]. Nano Energy, 2019, 58:786-796.
[81]	PENG Z, MU K, CAO Y, et al. Enhanced electrochemical performance of layered Li-rich cathode materials for lithium-ion batteries via aluminum and boron dual-doping[J]. Ceram Int, 2019, 45(4):4184-4192.
[82]	SUN Y, WU Q, ZHAO L. A new doping element to improve the electrochemical performance of Li_1.2Mn_0.54Ni_0.13Co_0.13O₂ materials for Li-ion batteries[J]. Ceram Int, 2019, 45(1):1339-1347.
[83]	VANAPHUTI P, BAI J, MA L, et al. Unraveling Na and F coupling effects in stabilizing Li, Mn-rich layered oxide cathodes via local ordering modification[J]. Energy Storage Mater, 2020, 31:459-469.
[84]	LI M, WANG H, ZHAO L, et al. Improving the electrochemical performance of lithium-rich oxide layer material with Mg and La co-doping[J]. J Alloys Compd, 2019, 782:451-460.
[85]	HU K, LV G, ZHANG J, et al. Na₂S Treatment and coherent interface modification of the Li-rich cathode to address capacity and voltage decay[J]. ACS Appl Mater Interfaces, 2020, 12(38):42660-42668.
[86]	ZHANG P, ZHAI X, HUANG H, et al. Synergistic Na⁺and F^－co-doping modification strategy to improve the electrochemical performance of Li-rich Li_1.20Mn_0.54Ni_0.13Co_0.13O₂cathode[J]. Ceram Int, 2020, 46(15):24723-24736.
[87]	LIM SN, SEOJY, JUNGDS, et al. The crystal structure and electrochemical performance of Li_1.167Mn_0.548Ni_0.18Co_0.105O₂composite cathodes doped and co-doped with Mg and F[J]. J Electroanal Chem, 2015, 740:88-94.
[88]	ZENG Z, GAO D, YANG G, et al. Ultrathin interfacial modification of lithium-rich layered oxide electrode/sulfide solid electrolyte via atomic layer deposition for high electrochemical performance batteries[J]. Nanotechnology, 2020, 31(45):454001.
[89]	MENG F, GUO H, WANG Z, et al. Modification of Li[Li_0.2Mn_0.54Ni_0.13Co_0.13]O₂cathode with α-MoO₃ via a simple wet chemical coating process[J]. Appl Surf Sci, 2019, 479:1277-1286.
[90]	ZHANG C, FENG Y, WEI B, et al. Heteroepitaxial oxygen-buffering interface enables a highly stable cobalt-free Li-rich layered oxide cathode[J]. Nano Energy, 2020, 75:104995.
[91]	HUANG Z, CAI M, SONG Z, et al. Surface modification of hierarchical Li_1.2Mn_0.56Ni_0.16Co_0.08O₂with melting impregnation method for lithium-ion batteries[J]. J Alloys Compd, 2020, 840:155678.
[92]	JAMES ABRAHAM J, NISAR U, MONAWWAR H, et al. Improved electrochemical performance of SiO₂-coated lithium-rich layered oxides-Li_1.2Ni_0.13Mn_0.54Co_0.13O₂ [J]. J Mater Sci-Mater El, 2020, 31(21):19475-19486.
[93]	WANX, CHEW, ZHANGD, et al. Improved electrochemical behavior of Li-rich cathode Li_1.4Mn_0.61Ni_0.18Co_0.18Al_0.03O_2.4 via Y₂O₃surface coating[J]. Mater Charact, 2020, 169:110602.
[94]	LI Y, HUANG H, YU J, et al. Improved high rate capability of Li[Li_0.2Mn_0.534Co_0.133Ni_0.133]O₂cathode material by surface modification with Co₃O₄ [J]. J Alloys Compd, 2019, 783:349-356.
[95]	WANG C C, LIN J W, YU Y H, et al. Nanolaminated ZnO-TiO₂coated lithium-rich layered oxide cathodes by atomic layer deposition for enhanced electrochemical performances[J]. J Alloys Compd, 2020, 842:155845.
[96]	RAN X, TAO J, CHEN Z, et al. Surface heterostructure induced by TiO₂modification in Li-rich cathode materials for enhanced electrochemical performances[J]. Electrochim Acta, 2020, 353:135959.
[97]	VIVEKANANTHA M, PARTHEEBAN T, KESAVAN T, et al. Alleviating the initial coulombic efficiency loss and enhancing the electrochemical performance of Li_1.2Mn_0.54Ni_0.13Co_0.13O₂using β-MnO₂ [J]. Appl Surf Sci, 2019, 489:336-345.
[98]	WEN X, LIANG K, TIAN L, et al. Al₂O₃coating on Li_1.256Ni_0.198Co_0.082Mn_0.689O_2.25with spinel-structure interface layer for superior performance lithium-ion batteries[J]. Electrochim Acta, 2018, 260:549-556.
[99]	ZUO Y, HUANG B, JIAO C, et al. Enhanced electrochemical properties of Li[Li_0.2Mn_0.54Ni_0.13Co_0.13]O₂with ZrF₄ surface modification as cathode for Li-ion batteries[J]. J Mater Sci-Mater Electron, 2017, 29(1):524-534.
[100]	LI C D, YAO Z L, XU J, et al. Surface-modified Li[Li_0.2Mn_0.54Ni_0.13Co_0.13]O₂nanoparticles with LaF₃as cathode for Li-ion battery[J]. Ionics, 2016, 23(3):549-558.
[101]	ZHU W, CHONG S, SUN J, et al. The enhanced electrochemical performance of Li_1.2Ni_0.2Mn_0.6O₂through coating MnF₂ nano protective layer[J]. Energy Technol, 2019, 7(10):1900443.
[102]	LIU B, ZHANG Z, WAN J, et al. Improved electrochemical properties of YF₃-coated Li_1.2Mn_0.54Ni_0.13Co_0.13O₂as cathode for Li-ion batteries[J]. Ionics, 2017, 23(6):1365-1374.
[103]	ZHAO S, SUN B, YAN K, et al. Aegis of lithium-rich cathode material via heterostructured LiAlF₄coating for high-performance lithium-ion batteries[J]. ACS Appl Mater Interfaces, 2018, 10(39):33260-33268.
[104]	JIANG B, LUO B, LI J, et al. Electrochemical effect of graphite fluoride modification on Li-rich cathode material in lithium-ion batteries[J]. Ceram Int, 2019, 45(1):160-167.
[105]	WU F, XUE Q, LI L, et al. The positive role of (NH₄)₃AlF₆coating on Li[Li_0.2Ni_0.2Mn_0.6]O₂oxide as the cathode material for lithium-ion batteries[J]. RSC Adv, 2017, 7(2):1191-1199.
[106]	LEE H, LIM S B, KIM J Y, et al. Characterization and control of irreversible reaction in Li-rich cathode during the initial charge process[J]. ACS Appl Mater Interfaces, 2018, 10(13):10804-10818.
[107]	YU Z. Electrochemical performances of carbon-coated Li[Li_0.29Mn_0.57Co_0.14]O₂cathode caterials for lithium-ion batteries[J]. Int J Electrochem Sci, 2019:4216-4225.
[108]	LEE S J, KIM S J, SON J T. Evaluations of discharge capacity and cycle stability for a graphene-added Li_1.9Ni_0.35Mn_0.65O₂cathode fabricated by using carbonate co-precipitation[J]. J Korean Phys Soc, 2020, 77(11):1035-1039.
[109]	PANG S, ZHU M, XU K, et al. The glucose-based treatment: a green and cost-efficient lithium-rich layered oxide modification strategy[J]. Ceram Int, 2019, 45(15):19268-19274.
[110]	LI X, ZHENG L, ZANG Z, et al. Multiply depolarized composite cathode of Li_1.2Mn_0.54Ni_0.13Co_0.13O₂embedded in a combinatory conductive network for lithium-ion battery with superior overall performances[J]. J Alloys Compd, 2018, 744:41-50.
[111]	PARK K, KIM J, PARK J H, et al. Synchronous phase transition and carbon coating on the surface of Li-rich layered oxide cathode materials for rechargeable Li-ion batteries[J]. J Power Sources, 2018, 408:105-110.
[112]	LIU D, WANG F, WANG G, et al. Well-wrapped Li-rich layered cathodes by reduced graphene oxide towards high-performance Li-ion batteries[J]. Molecules, 2019, 24(9):1680.
[113]	CHEN J J, LI Z D, XIANG H F, et al. Bifunctional effects of carbon coating on high-capacity Li_1.2Ni_0.13Co_0.13Mn_0.54O₂ cathode for lithium-ion batteries[J]. J Solid State Electrochem, 2014, 19(4):1027-1035.
[114]	MA D, LI Y, WU M, et al. Enhanced cycling stability of Li-rich nanotube cathodes by 3D graphene gierarchical architectures for Li-ion batteries[J]. Acta Mater, 2016, 112:11-19.
[115]	DING F, LI J, DENG F, et al. Surface heterostructure induced by PrPO₄modification in Li_1.2[Mn_0.54Ni_0.13Co_0.13]O₂ cathode material for high-performance lithium-ion batteries with mitigating voltage decay[J]. ACS Appl Mater Interfaces, 2017, 9(33):27936-27945.
[116]	ZHOU L, YIN Z, TIAN H, et al. Spinel-embedded and Li₃PO₄modified Li[Li_0.2Mn_0.54Ni_0.13Co_0.13]O₂cathode materials for high-performance Li-ion battries[J]. Appl Surf Sci, 2018, 456:763-770.
[117]	XIAO B, WANG B, LIU J, et al. Highly stable Li_1.2Mn_0.54Co_0.13Ni_0.13O₂enabled by novel atomic layer deposited AlPO₄ coating[J]. Nano Energy, 2017, 34:120-130.
[118]	LIU Y, FAN X, HUANG X, et al. Electrochemical performance of Li_1.2Ni_0.2Mn_0.6O₂coated with a facilely synthesized Li_1.3Al_0.3Ti_1.7(PO₄)₃ [J]. J Power Sources, 2018, 403:27-37.
[119]	CHEN D, ZHENG F, LI L, et al. Effect of Li₃PO₄coating of layered lithium-rich oxide on electrochemical performance[J]. J Power Sources, 2017, 341:147-155.
[120]	HE L, XU J, HAN T, et al. SmPO₄-coated Li_1.2Mn_0.54Ni_0.13Co_0.13O₂as a cathode material with enhanced cycling stability for lithium-ion batteries[J]. Ceram Int, 2017, 43(6):5267-5273.
[121]	SONG J, WANG Y, FENG Z, et al. Investigation on the electrochemical properties and stabilized surface/interface of nano-AlPO₄-coated Li_1.15Ni_0.17Co_0.11Mn_0.57O₂as the cathode for lithium-ion batteries[J]. ACS Appl Mater Interfaces, 2018, 10(32):27326-27332.
[122]	ZHANG X, HAO J, WU L, et al. Enhanced electrochemical performance of perovskite LaNiO₃coating on Li_1.2Mn_0.54Ni_0.13Co_0.13O₂as cathode materials for Li-ion batteries[J]. Electrochim Acta, 2018, 283:1203-1212.
[123]	WU F, LI Q, BAO L, et al. Role of LaNiO₃in suppressing voltage decay of layered lithium-rich cathode materials[J]. Electrochim Acta, 2018, 260:986-993.
[124]	XU Z, CI L, YUAN Y, et al. Potassium prussian blue-coated Li-rich cathode with enhanced lithium-ion storage property[J]. Nano Energy, 2020, 75:104942.
[125]	LUO S, GUO H, FENG S, et al. Clearing surficial charge-transport obstacles to boost the performance of lithium-rich layered oxides[J]. Chem Eng J, 2020, 399:125142.
[126]	WANG E, ZHAO Y, XIAO D, et al. Composite nanostructure construction on the grain surface of Li-rich layered oxides[J]. Adv Mater, 2020:e1906070.
[127]	WANG D, ZHANG X, XIAO R, et al. Electrochemical performance of Li-rich Li[Li_0.2Mn_0.56Ni_0.17Co_0.07]O₂cathode stabilized by metastable Li₂SiO₃surface modification for advanced Li-ion batteries[J]. Electrochim Acta, 2018, 265:244-253.
[128]	ZHANG M, LI Z, YU L, et al. Enhanced long-term cyclability in Li-rich layered oxides by electrochemically constructing a Li _x TM_3－xO₄-type spinel shell[J]. Nano Energy, 2020, 77:105188.
[129]	SHEVTSOV A, HAN H, MOROZOV A, et al. Protective spinel coating for Li_1.17Ni_0.17Mn_0.50Co_0.17O₂cathode for Li-ion batteries through sngle-source precursor approach[J]. Nanomaterials, 2020, 10(9):1870.
[130]	TANG W, CHEN Z, HUANG H, et al. PVP-bridged γ-LiAlO₂nanolayer on Li_1.2Ni_0.182Co_0.08Mn_0.538O₂cathode materials for improving the rate capability and cycling stability[J]. Chem Eng Sci, 2021, 229:116126.
[131]	XIEY, CHENS, LINZ, et al. Enhanced electrochemical performance of Li-rich layered oxide, Li_1.2Mn_0.54Co_0.13Ni_0.13O₂, by surface modification derived from a MOF-assisted treatment[J]. Electrochem Commun, 2019, 99:65-70.