Li₂TiO₃ Dopant and Phosphate Coating Improve the Electrochemical Performance of LiCoO₂ at 3.0–4.6 V

Abstract

A sol–gel tandem with a solid-phase modification procedure was developed to synthesize Li₂TiO₃-doped LiCoO₂ together with phosphate coatings (denoted as LCO-Ti/P), which possesses excellent high-voltage performance in the range of 3.0–4.6 V. The characterizations of X-ray diffraction, high-resolution transmission electron microscopy, and X-ray photoelectron spectroscopy illustrated that the modified sample LCO-Ti/P had the dopant of monoclinic Li₂TiO₃ and amorphous Li₃PO₄ coating layers. LCO-Ti/P has an initial discharge capacity of 211.6 mAh/g at 0.1 C and a retention of 85.7% after 100 cycles at 1 C and 25 ± 1 °C between 3.0 and 4.6 V. Nyquist plots reflect that the charge transfer resistance of LCO-Ti/P after 100 cycles at 1 C is much lower than that of the spent LCO, which benefits Li-ion diffusion. Density functional theory calculations disclose the superior lattice-matching property of major crystal planes for Li₂TiO₃ and LiCoO₂, the lower energy barriers for Li-ion diffusion in Li₂TiO₃, and the suppressed oxygen release performance resulting from phosphate adsorption. This work provides useful guidance on the rational design of the high-voltage performance of modified LiCoO₂ materials in terms of lattice-matching properties aside from the phosphate coating to reduce the energy barriers of Li-ion diffusion and enhance cycling stability.

Keywords

LiCoO₂ / High-voltage performance / Li₂TiO₃ / Lattice matching / Li-ion diffusion / Density functional theory calculation

References

[1] Wang K, Wan JJ, Xiang YX, et al. Recent advances and historical developments of high voltage lithium cobalt oxide materials for rechargeable Li-ion batteries. J Power Sources, 2020, 460: 228062.

[2] Lyu YC, Wu X, Wang K, et al. An overview on the advances of LiCoO₂ cathodes for lithium-ion batteries. Adv Energy Mater, 2021, 11(2): 2000982.

[3] Wang LL, Chen BB, Ma J, et al. Reviving lithium cobalt oxide-based lithium secondary batteries-toward a higher energy density. Chem Soc Rev, 2018, 47(17): 6505-6602.

[4] Zt E, Guo HJ, Yan GC, et al. Evolution of the morphology, structural and thermal stability of LiCoO₂ during overcharge. J Energy Chem, 2021, 55: 524-532.

[5] Wan JJ, Zhu JP, Xiang YX, et al. Revealing the correlation between structure evolution and electrochemical performance of high-voltage lithium cobalt oxide. J Energy Chem, 2021, 54: 786-794.

[6] Sharifi-Asl S, Soto FA, Foroozan T, et al. Anti-oxygen leaking LiCoO₂. Adv Funct Mater, 2019, 29(23): 1901110.

[7] Fu A, Zhang ZF, Lin JD, et al. Highly stable operation of LiCoO₂ at cut-off ≥ 4.6 V enabled by synergistic structural and interfacial manipulation. Energy Storage Mater, 2022, 46: 406-416.

[8] Sun LW, Zhang ZS, Hu XF, et al. Realization of Ti doping by electrostatic assembly to improve the stability of LiCoO2 cycled to 4.5 V. J Electrochem Soc, 2019, 166(10): A1793-A1798.

[9] Yu JP, Han ZH, Hu XH, et al. The investigation of Ti-modified LiCoO₂ materials for lithium ion battery. J Power Sources, 2014, 262: 136-139.

[10] Zou MJ, Yoshio M, Gopukumar S, et al. Synthesis and electrochemical performance of high voltage cycling LiM_0.05Co_0.95O₂ as cathode material for lithium rechargeable cells. Electrochem Solid-State Lett, 2004, 7(7): A176.

[11] Xu LM, Wang K, Gu F, et al. Determining the intrinsic role of Mg doping in LiCoO₂. Mater Lett, 2020, 277: 128407.

[12] Madhavi S, Subba Rao GV, Chowdari BVR, et al. Effect of Cr dopant on the cathodic behavior of LiCoO₂. Electrochim Acta, 2002, 48(3): 219-226.

[13] Wang FQ, Jiang Y, Lin SL, et al. High-voltage performance of LiCoO₂ cathode studied by single particle microelectrodes-influence of surface modification with TiO₂. Electrochim Acta, 2019, 295: 1017-1026.

[14] Zhou AJ, Lu YT, Wang QJ, et al. Sputtering TiO₂ on LiCoO₂ composite electrodes as a simple and effective coating to enhance high-voltage cathode performance. J Power Sources, 2017, 346: 24-30.

[15] Jayasree SS, Nair S, Santhanagopalan D Ultrathin TiO₂ coating on LiCoO₂ for improved electrochemical performance as Li-ion battery cathode. ChemistrySelect, 2018, 3(10): 2763-2766.

[16] Cho J, Kim YJ, Park B Novel LiCoO₂ cathode material with Al₂O₃ coating for a Li ion Cell. Chem Mater, 2000, 12(12): 3788-3791.

[17] Scott ID, Jung YS, Cavanagh AS, et al. Ultrathin coatings on nano-LiCoO₂ for Li-ion vehicular applications. Nano Lett, 2011, 11(2): 414-418.

[18] Zhou AJ, Liu Q, Wang Y, et al. Al₂O₃ surface coating on LiCoO₂ through a facile and scalable wet-chemical method towards high-energy cathode materials withstanding high cutoff voltages. J Mater Chem A, 2017, 5(46): 24361-24370.

[19] Shim JH, Lee SH, Park SS Effects of MgO coating on the structural and electrochemical characteristics of LiCoO₂ as cathode materials for lithium ion battery. Chem Mater, 2014, 26(8): 2537-2543.

[20] Cho J, Kim YJ, Kim TJ, et al. Zero-strain intercalation cathode for rechargeable Li-ion cell. AngewChemInt Ed Engl, 2001, 40(18): 3367-3369.

[21] Kim YJ, Cho J, Kim TJ, et al. Suppression of cobalt dissolution from the LiCoO₂ cathodes with various metal-oxide coatings. J Electrochem Soc, 2003, 150(12): A1723.

[22] Cho J, Kim TG, Kim C, et al. Comparison of Al₂O₃- and AlPO₄-coated LiCoO₂ cathode materials for a Li-ion cell. J Power Sources, 2005, 146(1–2): 58-64.

[23] Appapillai AT, Mansour AN, Cho J, et al. Microstructure of LiCoO₂ with and without “AlPO₄” nanoparticle coating: combined STEM and XPS studies. Chem Mater, 2007, 19(23): 5748-5757.

[24] Zhou AJ, Xu J, Dai XY, et al. Improved high-voltage and high-temperature electrochemical performances of LiCoO₂ cathode by electrode sputter-coating with Li₃PO₄. J Power Sources, 2016, 322: 10-16.

[25] Wang CW, Zhou Y, You JH, et al. High-voltage LiCoO₂material encapsulated in a Li₄Ti₅O₁₂ ultrathin layer by high-speed solid-phase coating process. ACS Appl Energy Mater, 2020, 3(3): 2593-2603.

[26] Lu J, Peng Q, Wang WY, et al. Nanoscale coating of LiMO2 (M = Ni Co, Mn) nanobelts with Li+-conductive Li2TiO3: toward better rate capabilities for Li-ion batteries. J Am Chem Soc, 2013, 135(5): 1649-1652.

[27] Shim JH, Lee J, Han SY, et al. Synergistic effects of coating and doping for lithium ion battery cathode materials: synthesis and characterization of lithium titanate-coated LiCoO₂ with Mg doping. Electrochim Acta, 2015, 186: 201-208.

[28] Cui ZZ, Wang ZY, Zhai YW, et al. Improving cycling stability and rate capability of high-voltage LiCoO₂ through an integration of lattice doping and nanoscale coating. J Nanosci Nanotechnol, 2020, 20(4): 2473-2481.

[29] Zhu J, Li YJ, Xue LL, et al. Enhanced electrochemical performance of Li₃PO₄ modified Li[Ni_0.8Co_0.1Mn_0.1]O₂ cathode material via lithium-reactive coating. J Alloys Compd, 2019, 773: 112-120.

[30] Zhao ZK, Chen S, Mu DB, et al. Understanding the surface decoration on primary particles of nickel-rich layered LiNi_0.6Co_0.2Mn_0.2O₂ cathode material with lithium phosphate. J Power Sources, 2019, 431: 84-92.

[31] Wang X, Wu Q, Li SY, et al. Lithium-Aluminum-Phosphate coating enables stable 4.6 V cycling performance of LiCoO₂ at room temperature and beyond. Energy Storage Mater, 2021, 37: 67-76.

[32] Gu R, Cheng T, Ma ZT, et al. Enhanced cycling stability of high voltage LiCoO₂ by surface phosphorylation. J Alloys Compd, 2019, 803: 348-353.

[33] Kresse G, Furthmüller J Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set. Phys Rev B Condens Matter, 1996, 54(16): 11169-11186.

[34] Perdew JP, Burke K, Ernzerhof M Generalized gradient approximation made simple. Phys Rev Lett, 1996, 77(18): 3865-3868.

[35] Zhang JN, Li QH, Ouyang CY, et al. Trace doping of multiple elements enables stable battery cycling of LiCoO2 at 4.6 V. Nat Energy, 2019, 4(7): 594-603.

[36] Monkhorst HJ, Pack JD Special points for Brillouin-zone integrations. Phys Rev B, 1976, 13(12): 5188-5192.

[37] Henkelman G, Uberuaga BP, Jónsson H A climbing image nudged elastic band method for finding saddle points and minimum energy paths. J Chem Phys, 2000, 113(22): 9901-9904.

[38] Zhang ZJ, Hu GR, Cao YB, et al. Enhanced electrochemical performance of nano LiMnPO₄ with multifunctional surface co-coating of Li₂TiO₃ and carbon. Solid State Ion, 2015, 283: 115-122.

[39] Wang Y, Zhang QH, Xue ZC, et al. An in situ formed surface coating layer enabling LiCoO2 with stable 4.6 V high-voltage cycle performances. Adv Energy Mater, 2020, 10(28): 2001413.

[40] Gu R, Qian RC, Lyu YC, et al. One-step integrated comodification to improve the electrochemical performances of high-voltage LiCoO₂ for lithium-ion batteries. ACS Sustain Chem Eng, 2020, 8(25): 9346-9355.

[41] Yang XR, Lin M, Zheng GR, et al. Enabling stable high-voltage LiCoO₂ operation by using synergetic interfacial modification strategy. Adv Funct Mater, 2020, 30(43): 2004664.

[42] Nie KH, Sun XR, Wang JY, et al. Realizing long-term cycling stability and superior rate performance of 4.5 V-LiCoO2 by aluminum doped zinc oxide coating achieved by a simple wet-mixing method. J Power Sources, 2020, 470: 228423.

[43] Zhou MJ, Cai LL, Bajdich M, et al. Enhancing catalytic CO oxidation over Co₃O₄ nanowires by substituting Co²⁺ with Cu²⁺. ACS Catal, 2015, 5(8): 4485-4491.

[44] Sathiyamoorthi R, Chandrasekaran R, Gopalan A, et al. Synthesis and electrochemical performance of high voltage cycling LiCo_0.8M_0.2O₂ (M = Mg, Ca, Ba) as cathode material. Mater Res Bull, 2008, 43(6): 1401-1411.

[45] Ahamed P, Yousuf MA A novel solid state reaction route to the preparation of LiCoO₂ using micro porous filter paper as scaffolds. Mater Res Express, 2020, 7(6): 065506.

[46] Bian XF, Fu Q, Bie XF, et al. Improved electrochemical performance and thermal stability of Li-excess Li_1.18Co_0.15Ni_0.15Mn_0.52O₂ cathode material by Li₃PO₄ surface coating. Electrochim Acta, 2015, 174: 875-884.

[47] Wang MJ, Yu FD, 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 Mater Chem A, 2019, 7(14): 8302-8314.

[48] Huang YY, Zhu YC, Fu HY, et al. Mg-pillared LiCoO2: towards stable cycling at 4.6 V. Angew Chem Int Ed Engl, 2021, 60(9): 4682-4688.

[49] Wang YT, Cheng T, Yu ZE, et al. Study on the effect of Ni and Mn doping on the structural evolution of LiCoO2 under 4.6 V high-voltage cycling. J Alloys Compd, 2020, 842: 155827.

[50] Wang LL, Ma J, Wang C, et al. A novel bifunctional self-stabilized strategy enabling 4.6 V LiCoO2 with excellent long-term cyclability and high-rate capability. Adv Sci (Weinh), 2019, 6(12): 1900355.

[51] Zhang W, Wu YL, Xu ZM, et al. Rationally designed sodium chromium vanadium phosphate cathodes with multi-electron reaction for fast-charging sodium-ion batteries. Adv Energy Mater, 2022, 12(25): 2201065.

[52] Li HX, Xu M, Gao CH, et al. Highly efficient, fast and reversible multi-electron reaction of Na₃MnTi(PO₄)₃ cathode for sodium-ion batteries. Energy Storage Mater, 2020, 26: 325-333.

[53] Yang W, Bai CJ, Xiang W, et al. Dual-modified compact layer and superficial Ti doping for reinforced structural integrity and thermal stability of Ni-rich cathodes. ACS Appl Mater Interfaces, 2021, 13(46): 54997-55006.

[54] Zhang P, Xie C, Han G, et al. Stable cycling of LiCoO2 at 4.55 V enabled by combined Mg doping and surface coating of NASICON-type electrolyte. Mater Today Nano, 2021, 15: 100122.

[55] Wang M, Zhang R, Gong YQ, et al. Improved electrochemical performance of the LiNi_0.8Co_0.1Mn_0.1O₂ material with lithium-ion conductor coating for lithium-ion batteries. Solid State Ion, 2017, 312: 53-60.

[56] Lee SW, Kim MS, Jeong JH, et al. Li₃PO₄ surface coating on Ni-rich LiNi_0.6Co_0.2Mn_0.2O₂by a citric acid assisted Sol-gel method: improved thermal stability and high-voltage performance. J Power Sources, 2017, 360: 206-214.

[57] Yoon M, Dong YH, Yoo Y, et al. Unveiling nickel chemistry in stabilizing high-voltage cobalt-rich cathodes for lithium-ion batteries. AdvFunct Mater, 2020, 30(6): 1907903.

[58] Zhu Z, Wang H, Li Y, et al. A surface Se-substituted LiCo[O₂–δSeδ] cathode with ultrastable high-voltage cycling in pouch full-cells. Adv Mater, 2020, 32(50): 2005182.

[59] van der Ven A Lithium diffusion in layered Li _xCoO₂. Electrochem Solid-State Lett, 1999, 3(7): 301.

[60] Wei Y, Zheng JX, Cui SH, et al. Kinetics tuning of Li-ion diffusion in layered Li(Ni _xMn _yCo _z)O₂. J Am ChemSoc, 2015, 137(26): 8364-8367.