Enhancing the Electrochemical Properties of Nickel-Rich Cathode by Surface Coating with Defect-Rich Strontium Titanate

Abstract

Ni-rich layered ternary cathodes (i.e., LiNi x Co y M z O 2 , M = Mn or Al, x + y + z = 1 and x ≥ 0.8) are promising candidates for the power supply of portable electronic devices and electric vehicles. However, the relatively high content of Ni 4+ in the charged state shortens their lifespan due to inevitable capacity and voltage deteriorations during cycling. Therefore, the dilemma between high output energy and long cycle life needs to be addressed to facilitate more widespread commercialization of Ni-rich cathodes in modern lithium-ion batteries (LIBs). This work presents a facile surface modification approach with defect-rich strontium titanate (SrTiO 3−x ) coating on a typical Ni-rich cathode: LiNi 0.8 Co 0.15 Al 0.05 O 2 (NCA). The defect-rich SrTiO 3−xmodified NCA exhibits enhanced electrochemical performance compared to its pristine counterpart. In particular, the optimized sample delivers a high discharge capacity of ∼170 mA h/g after 200 cycles under 1C with capacity retention over 81.1%. The postmortem analysis provides new insight into the improved electrochemical properties which are ascribed to the SrTiO 3−x coating layer. This layer appears to not only alleviate the internal resistance growth, from uncontrollable cathode−electrolyte interface evolution, but also acts as a lithium diffusion channel during prolonged cycling. Therefore, this work offers a feasible strategy to improve the electrochemical performance of layered cathodes with high nickel content for nextgeneration LIBs.

Stabilizing High-Voltage Performance of Nickel-Rich Cathodes via Facile Solvothermally Synthesized Niobium-Doped Strontium Titanate

“…Accordingly, the prominent peak of lattice oxygen is located at ∼529.4 eV, originating from the Sr–O and Ti–O bonds in the perovskite structures of STO . Besides, the peak located at ∼531.5 eV is the oxygen vacancy peak, as confirmed by our previous work . Furthermore, a peak was generated at ∼532 eV index to the Nb–O bond after Nb replaced the Ti position .…”

“…Figure (a) compares the XRD patterns of NCM811, STO-811-600, and 1% Nb-STO-811 cathodes before and after 100 charge–discharge cycles under high voltage. The rhombic marking reflects those new appeared peaks, which should be attributed to the CEI generation . In addition, the CEI generation in bare NCM811 is more pronounced compared with those coated after high-voltage cycling.…”

“…30 The 32 Besides, the peak located at ∼531.5 eV is the oxygen vacancy peak, as confirmed by our previous work. 33 Furthermore, a peak was generated at ∼532 eV index to the Nb−O bond after Nb replaced the Ti position. 34 It is also worth mentioning that no peak shifts were observed during the XPS measurement, as indicated by the dashed line in each elemental profile.…”

“…Postmortem analysis was conducted to validate the effects of (Nb-)STO modification on the Ni-rich cathode structure after cycling at 3.0−4.5 V. XRD is first employed to confirm the CEI generation and cathode The rhombic marking reflects those new appeared peaks, which should be attributed to the CEI generation. 33 In addition, the CEI generation in bare NCM811 is more pronounced compared with those coated after high-voltage cycling. As can be seen from Figure 8(b), the (003) peak of bare NCM811 shifts to lower 2θ values by approximately 0.11°a fter 100 cycles, reflecting increased lattice parameters.…”

Rechargeable Zn−MnO2 Batteries: Progress, Challenges, Rational Design, and Perspectives

“…[1] Over the past few years, the desire for safe batteries has dramatically risen since fires have occurred occasionally within different electronic appliances employing lithium-ion batteries (LIBs). [2] The leading cause of such fires is the highly flammable electrolyte, and avoiding such accidents requires using a non-flammable electrolyte. Recently, zinc-ion batteries (ZIBs) have been regarded as one of the most viable options to substitute LIBs without the risk of explosion.…”