Synergistical Stabilization of Li Metal Anodes and LiCoO₂ Cathodes in High-Voltage Li∥LiCoO₂ Batteries by Potassium Selenocyanate (KSeCN) Additive

Abstract

Dramatic growth of lithium (Li) dendrite and structural deterioration of LiCoO2 (LCO) lead to rapid failure of a high-voltage Li∥LCO battery. The nitrile group (−CN) is beneficial to maintain the integrity of the LCO lattice due to its strong affiliation to Co ions, whereas the −CN bond is incompatible with the Li metal anode, leading to form a deleterious solid electrolyte interphase (SEI) film. Herein, a dual-functional electrolyte additive potassium selenocyanate (KSeCN) is introduced to construct stable and dense SEI/cathode electrolyte interphase (CEI) films by synergistic effects with −Se and −CN groups, resulting in uniform Li deposition and a stabilized LCO lattice during cycling. With a trace amount of KSeCN (0.1 wt %) in conventional carbonated electrolyte, the Li∥LCO battery exhibits promoted cycling performance at high charge cutoff 4.6 V. This work provides a strategic guidance for rational design of electrolyte to construct stable SEI and CEI films, to achieve a high-energy-density Li∥LCO battery with great performance.

Rationally Designed Fluorinated Amide Additive Enables the Stable Operation of Lithium Metal Batteries by Regulating the Interfacial Chemistry

“…Some other additives are designed with a higher intrinsic reduction potential compared with carbonate solvent molecules. However, they exhibit inferior affinity with Li + and thus cannot effectively migrate with Li + and be reduced under an electric field, which significantly decreases their effect. , Therefore, it is highly desirable to seek additives that are compatible with carbonate-based electrolytes and exhibit both high affinity with Li + and high reduction potential simultaneously so as to effectively regulate the interfacial chemistry.…”

Constructing a Stabilized Cathode Electrolyte Interphase for High-Voltage LiCoO2 Batteries via the Phenylmaleic Anhydride Additive

“…Huang et al revealed that Mg-pillared LiCoO 2 , substituting the Octa-3a site in the Li slab by Mg 2+ , benefited to eliminate CEI overgrowth and enhance cycling stability within the voltage window of 3.0–4.6 V . Besides, the design of the functional electrolyte with appropriate additives is convenient and cost-effective, which holds great potential for commercial applications without a large-scale change of production conditions. ,− Electrolyte additives with specially designed functional groups could approach the inner Helmholtz layer and in situ participate in forming a uniform and stabilized CEI film on the surface of LCO, which blocks the reactions at the electrode/electrolyte interface. ,− For instance, Ruan et al adopted 5-acetylthiophene-2-carbonitrile (ATCN) to in situ construct a stable CEI film with low impedance, increasing the capacity retention of Li||LCO batteries from 53 to 91% after 200 cycles at a charge cutoff of 4.5 V . Anhydride-type additives have also been widely concerned and applied in LIBs, such as Li||LiNi 0.9 Co 0.05 Mn 0.05 O 2 and Li||LiNi 0.5 Mn 1.5 O 4 batteries (as summarized in Table S1), which however have rarely been well-investigated for LCO batteries at a high charge cutoff voltage of, e.g., 4.65 V until now.…”

Strengthening the Interfacial Stability of the Silicon-Based Electrode via an Electrolyte Additive─Allyl Phenyl Sulfone

“…By optimizing the electrolyte components, the property and stability of the electrode-electrolyte interface can be manipulated. In particular, designing electrolyte additives is considered one of the most economical, feasible, and scalable approaches to improve the electrochemical performance of batteries with the silicon-based anode. − …”