Boron in Ni-Rich NCM811 Cathode Material: Impact on Atomic and Microscale Properties

Abstract

Doping of Ni-rich cathode active materials with boron is a promising way to improve their cycling stability and mitigate their degradation, but it is still not understood how this effect is achieved and where the boron is located. To receive deeper insights into the impact of doping on atomic and microscale properties, B-doped Li[Ni 0. 8 Co 0.1 Mn 0 .1 ]O 2 (NCM811) cathode materials were synthesized by a hydroxide coprecipitation as a model compound to verify the presence and location of boron in B-doped, Ni-rich NCM, as well as its impact on the microstructure and electrochemical properties, by a combined experimental and theoretical approach. Besides X-ray diffraction and Rietveld refinement, DFT calculation was used to find the preferred site of boron absorption and its effect on the NCM lattice parameters. It is found that boron shows a trigonal planar and tetrahedral coordination to oxygen in the Ni layers, leading to a slight increase in lattice parameter c through an electrostatic interaction with Li ions. Therefore, B-doping of NCM811 affects the crystal structure and cation disorder and leads to a change in primary particle size and shape. To experimentally prove that the observations are caused by boron incorporated into the NCM lattice, we detected, quantified, and localized boron in 2 mol % Bdoped NCM811 by ion beam analysis and TOF-SIMS. It was possible to quantify boron by NRA with a depth resolution of 2 μm. We found a boron enrichment on the agglomerate surface but also, more importantly, a significant high and constant boron concentration in the interior of the primary particles near the surface, which experimentally verifies that boron is incorporated into the NCM811 lattice.

All-Solid-State Li Batteries with NCM–Garnet-Based Composite Cathodes: The Impact of NCM Composition on Material Compatibility

“…Pristine and B-doped cathode active materials were synthesized by a hydroxide coprecipitation route reported before. 27 The whole synthesis was performed under a replenished argon atmosphere. Aqueous solutions of 2 M NaOH (Sigma-Aldrich, 98%) and 10 M NH 3 (aq) (Alfa Aesar, 28%) (solution 2) were prepared.…”

“…Pristine and B-doped cathode active materials were synthesized by a hydroxide coprecipitation route reported before . The whole synthesis was performed under a replenished argon atmosphere.…”

“…For example, high-capacity Ni-rich NCM cathodes like NCM811 show higher heat release rates as compared to Co- and Mn-rich NCM111 with a lower capacity . Doping with elements like Al, Fe, Sn, W, or B was demonstrated as an effective strategy to optimize Ni-rich NCM for application in conventional LIBs. ,− However, detailed information about the thermal stability of NCM with different compositions and dopants in combination with LLZO is lacking. To close this knowledge gap, we investigated the thermodynamic stability between cubic, Al- and Ta-substituted LLZO (Li 6.45 Al 0.05 La 3 Zr 1.6 Ta 0.4 O 12 ; LLZO:Ta) and two NCM compositions that are of economic importance, namely, NCM111 and Ni-rich NCM811.…”

Scalable Advanced Li(Ni0.8Co0.1Mn0.1)O2 Cathode Materials from a Slug Flow Continuous Process

“…The peak at 3.8/3.72 and 4.22/4.18 V corresponds to the Ni 2+ /Ni 4+ and Co 3+ /Co 4+ , respectively. 55 It is worth mentioning that the transition from H2 to H3, which takes place above the 4.2 V vs Li/Li + , results from the lattice shrinkage in the c direction, leading toward the structural degradation and performance fading. 56 Hence, an operating potential window of 3.0−4.2 V vs Li/ Li + was selected to perform the rest of the electrochemical experiments.…”

Review of Boron Compounds in Lithium Batteries: Electrolyte, Anode, Cathode, Separator, and Battery Thermal Management System (BTMS)

“…This not only improved rate performance and cyclability but also improved structural stability [88]. The mechanism behind the B-doping benefit is not fully understood, but one study suggested that B-doping affected crystal structure and cation disorder [89]. In NMC622, B-doping was found to change the microstructure of primary particles significantly and doping alone provided a marginal benefit to structural and electrochemical stability.…”