Enhanced Electrochemical Performance of Ni‐Rich Layered Cathode Materials by using LiPF₆ as a Cathode Additive

Abstract

Residual Li compounds are inevitably present in the form of Li 2 O, LiOH, and Li 2 CO 3 on the surface of layered cathode materials, which not only causes slurry gelation in the cathodecoating process but also degrades liquid electrolyte in the batteries. Owing to their strong alkaline nature, the residual Li compounds can react with acidic LiPF 6 to form Li 3 PO 4 and LiF, two of the main components of robust solid electrolyte interphases. By demonstrating LiNi 0.80 Co 0.10 Mn 0.10 O 2 (NCM811) as an example in this work, we simply dissolved a small amount of LiPF 6 into the cathode-coating slurry, finding that as the amount of LiPF 6 is controlled in the 0.5-1.0 wt % range versus the mass of NCM811, the LiPF 6 additive not only improves the cycling stability but also enhances rate capability of the Li/ NCM811 cells. The former is because the strongly alkaline residual Li compounds react with acidic LiPF 6 to form stable Li 3 PO 4 and LiF. The latter is attributed to a reduction in the surface layer resistance on the cathode, as suggested by the results of surface chemistry and impedance analyses.[a] Dr.

Degradation Mechanisms and Mitigation Strategies of Nickel-Rich NMC-Based Lithium-Ion Batteries

“…Furthermore, Li salts can also be used to improve NMC-based cell performances. For example, LiPF 6 can react with excessive alkaline Li on the surfaces of cathode particles to produce chemically stable Li 3 PO 4 and LiF, and significantly suppress parasitic reactions caused by excessive Li [152]. Surface coating is another commonly used strategy to separate NMC cathode surfaces from electrolytes [15], and atom substitution has also been reported to be effective in enhancing the performance of mitigated Ni-rich NMC-based LIBs.…”

Clean the Ni-Rich Cathode Material Surface With Boric Acid to Improve Its Storage Performance

“…However, although increased nickel content in Ni-rich cathode materials enables them to deliver higher capacity, more residual lithium compounds (RLCs) will be formed on their surface. The RLC mainly contains Li 2 O, Li 2 O 2 , LiOH, LiHCO 3 , and Li 2 CO 3 (Liu et al, 2004;Kim et al, 2006;Bichon et al, 2019;Zhang et al, 2019), which origins from the vestigial of lithium salts and spontaneous reduction reaction of Ni 3+ during the synthesis and storage process (Junhyeok et al, 2018). In detail, excess 5 mol% lithium salts are usually applied to compensate the evaporation loss during high-temperature calcination process (Liang et al, 2017).…”

Hierarchical Lamellar‐Structured MnO2@graphene for High Performance Li, Na and K ion Batteries

“…Because of this, they are known as rocking chair batteries. Lithium ion battery (LIB), with its high energy density, high open circuit voltage and large output power, etc., had been applied commercially for a long time [5,6] . However, nor is LIB without its disadvantages.…”