Xinming Fan¹, Xing Ou^1*, Wengao Zhao^2,3*, Yun Liu¹, Bao Zhang¹, Jiafeng Zhang¹, Lianfeng Zou⁴, Lukas Seidl², Yangzhong Li⁵, Guorong Hu¹, Corsin Battaglia², Yong Yang^3*

1 School of Metallurgy and Environment, Central South University, Changsha 410083, P.R. China

2 Empa, Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland

3 School of Energy Research, Xiamen University, Xiamen, Fujian 361005, P.R. China

4 Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington 99354, United States

5 High Performance Computing Department, National Supercomputing Center in Shenzhen, Shenzhen, Guangdong 518055, China

* Corresponding authors emails: ouxing@csu.edu.cn, wengao.zhao@empa.ch, yyang@xmu.edu.cn

DOI10.24435/materialscloud:ga-f0 [version v1]

Publication date: Jul 21, 2021

How to cite this record

Xinming Fan, Xing Ou, Wengao Zhao, Yun Liu, Bao Zhang, Jiafeng Zhang, Lianfeng Zou, Lukas Seidl, Yangzhong Li, Guorong Hu, Corsin Battaglia, Yong Yang, In situ inorganic conductive network enables superior high-voltage operation of single-crystal Ni-rich cathode, Materials Cloud Archive 2021.116 (2021), doi: 10.24435/materialscloud:ga-f0.

Description

High nickel content in LiNixCoyMnzO2 (NCM, x ≥ 0.8, x + y + z = 1) layered cathode material allows high energy density in lithium-ion batteries (LIBs). However, Ni-rich NCM cathodes suffer from performance degradation, mechanical and structural instability upon prolonged cell cycling. Although the use of single-crystal Ni-rich NCM can mitigate these drawbacks, the ion-diffusion in large single-crystal particles hamper its rate capability. Herein, we report a strategy to construct an in situ Li1.4Y0.4Ti1.6(PO4)3 (LYTP) ion/electron conductive network which interconnects single-crystal LiNi0.88Co0.09Mn0.03O2 (SC-NCM88) particles. The LYTP network facilitates the lithium-ion transport between SC-NCM88 particles, mitigates mechanical instability and prevents detrimental crystalline phase transformation. When used in combination with a Li metal anode, the LYTP-containing SC-NCM88-based cathode enables a coin cell capacity of 130 mAh g-1 after 500 cycles at 5 C rate in the 2.75-4.4 V range at 25 °C. Tests in Li-ion pouch cell configuration (i.e., graphite used as negative electrode active material) demonstrate capacity retention of 85% after 1000 cycles at 0.5 C in the 2.75-4.4 V range at 25 °C for the LYTP-containing SC-NCM88-based positive electrode.

Materials Cloud sections using this data

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File name	Size	Description
Figure 1.png MD5md5:23c39d7abd4661567c958179590533aa	1.5 MiB	Figure 1. LYTP@SC-NCM88 preparation process. Schematic illustration of the synthesis method for LYTP modified SC-NCM88 cathode.
Figure 2.png MD5md5:2b6b1d3324efccaec69827f3e8ce0a57	344.4 KiB	Figure 2. Representative morphology images of LYTP@SC-NCM88. (a) Overall and (b) cross-sectional morphologies derived from SEM images. (c) Cross-section EPMA image of 1% LYTP@SC-NCM88 with the corresponding selected area LYTP mapping results of Ni, Co, Mn, Ti, and P elements. (d) TEM, (e) HRTEM, and (f) STEM elemental mappings of Ni, Co, Mn, Y, and Ti for 1% LYTP@SC-NCM88.
Figure 3.xlsx MD5md5:0861947ae32d47451ca938628f09bb1a	829.1 KiB	Figure 3. Raw data of conductivity and structure characterization of LYTP@SC-NCM88. The comparison of (a) electron conductivity and (b) Li-ion conductivity between pristine SC-NCM88 and 1% LYTP@SC-NCM88. (c) The XRD Rietveld refinement of 1% LYTP@SC-NCM88.
Figure 4.xlsx MD5md5:18c57a27372f573405be1cdf1a5358cd	2.4 MiB	Figure 4. Raw data of electrochemical performance for coin-type half cells. Cycling stability of pristine SC-NCM88 and 1% LYTP@SC-NCM88 against a lithium metal anode at 0.5 C under testing temperature of (a) 25 oC and (b) 55 oC. Charge/discharge curves for (c) SC-NCM88 and (d) 1% LYTP@SC-NCM88 from 1st to 100th cycle at 55 oC. (e) Cycling capability at various current densities and (f) long-term cycling stability at 5C for SC-NCM88 and 1% LYTP@SC-NCM88. All cells were cycled in 2.75-4.4V.
Figure 5.xlsx MD5md5:a92e413901278173cbad120637143668	95.2 KiB	Figure 5. Raw data of electrochemical evaluation for pouch-type full cells. (a) Cycling performances and (b, c) corresponding dQ/dV curves of the pristine SC-NCM88 and the 1% LYTP@SC-NCM88 against a graphite anode from the 1st cycle to the 1000th cycle. (d) Cycling performance and (e) energy density for the pristine SC-NCM88 and the 1% LYTP@SC-NCM88 at an elevated temperature of 45 oC. All cells were cycled in the voltage range of 2.75-4.4 V.
Figure 6.xlsx MD5md5:383ff725236fa464e329a410d94d4575	2.9 MiB	Figure 6. Raw data of phase transitions Investigation during cycling. Operando XRD characterization of the full contour plots and selected line patterns for (a, c) SC-NCM88 and (b, d) 1% LYTP@SC-NCM88 cathodes during the initial cycle in the voltage range of 2.75-4.6 V. (e) The variation of the c-axis parameter during charging for pristine SC-NCM88 and 1% LYTP@SC-NCM88.
Figure 7.xlsx MD5md5:2eceda7cd5c5579cc1b789635d4f9eec	504.8 KiB	Figure 7. Density functional theory calculation. Raw data of the total and partial density of states plots for (a) pristine SC-NCM88 and (b) 1% LYTP@SC-NCM88.
Figure 8.xlsx MD5md5:013adbef6f974d5a4952c1edd8a2906d	348.9 KiB	Figure 8. Raw data of surface chemistry compositions of cycled cathodes. TOF-SIMS depth profiles of the near-surface chemical composition for (a) C2HO-, (b) POF2-, (c) C2F-, (d) PO3-, (e) NiF3-, (f) CoF3-, (g) MnF3- and (h) 6LiF2-. XPS spectra of (i) C 1s, (j) O 1s, (k) F 1s and (l) P 2p elements for the pristine SC-NCM88 and 1% LYTP@SC-NCM88 cathodes after 200 cycles from 2.7V to 4.4 V.
Figure 9.png MD5md5:e3dafdee822e1c16ac74a4c7e1855f19	622.6 KiB	Figure 9. Intraparticle structural evolution after long-term cycling. Post-mortem HRTEM and magnified HRTEM at selected area images for (a, a1, a2) pristine SC-NCM88 and (b, b1, b2) 1% LYTP@SC-NCM88 after 200 cycles. Cross-sectional SEM images of (c) pristine SC-NCM88 and (g) 1% LYTP@SC-NCM88. Low-magnification HAADF-STEM image of FIB-cross section for the surface region and magnified HAADF-STEM images taken from the corresponding surface areas for (d-f) pristine SC-NCM88 and (h-j) 1%LYTP@SC-NCM

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Keywords

single-crystal Ni-rich NCM In situ conductive network lithium-ion transport crystalline phase transformation Experimental