In Situ Co–O Bond Reinforcement of the Artificial Cathode Electrolyte Interphase in Highly Delithiated LiCoO₂ for High-Energy-Density Applications

Abstract

Highly delithiated LiCoO 2 has high specific capacity (>200 mAh g −1 ); however, its degradation behavior causes it to have poor electrochemical performance and thermal instability. The degradation of highly delithiated LiCoO 2 is mainly induced by oxygen vacancy migration and weakening of oxygen-related interactions, which result in pitting corrosion and fault formation on the surface. In this research, a coupling agent, namely, 3-aminopropyltriethoxysilane (APTES), was grafted onto the surface of LiCoO 2 to form a cross-linking structure. Through the aza-Michael addition reaction, an oligomer formed from barbituric acid and bisphenol a diglycidyl ether diacrylate were reacted with the cross-linking APTES to form an artificial cathode electrolyte interphase (ACEI). The highly delithiated LiCoO 2 containing the ACEI had considerably less degradation on the surface of the bulk material caused by oxygen release. The formation of the O1 phase was prevented in high delithiation and high-temperature operations. This research revealed that the ACEI reinforced the Co−O bond, which is crucial in preventing gas evolution and O1 phase formation. In addition, the ACEI prevents direct contact between the electrolyte and highly active surface of LiCoO 2 , thereby preventing the formation of a thick and high impedance traditional cathode electrolyte interphase. According to the present results, highly delithiated LiCoO 2 containing the ACEI exhibited outstanding cycle retention and capacity at 55 °C as well as low heat capacity release in the fully delithiated state. The ACEI considerably protected and maintained the electrochemical performance of highly delithiated LiCoO 2 , which is suitable for high-energy-density applications, such as electric vehicles and power tools.

Suppressed Lattice Oxygen Release via Ni/Mn Doping from Spent LiNi0.5Mn0.3Co0.2O2 toward High-Energy Layered-Oxide Cathodes

“…High-resolution transmission electron microscopy (HRTEM) images of the internal regions for the P-LCO and LNCMO-1 samples are presented in Figure d ,h. Unlike the surface region with lattice and structure distortions, the internal region of LNCMO-1 shows a fine layered structure, which is consistent with the XRD profile (Figure S2). The arrangement of atoms formed an alternating pattern of equilateral triangles (Figure j), and for the majority, the distance between nearest-neighbor atoms was measured to be 2.8 Å, which matches perfectly with the simulated Co layer model structure (Figure l) as well as previous reports . Lattice fringes were confirmed with an interplanar spacing of 1.4 Å (Figure k), corresponding to the (110) planes of LNCMO-1.…”

Coating of a Novel Lithium-Containing Hybrid Oligomer Additive on Nickel-Rich LiNi0.8Co0.1Mn0.1O2 Cathode Materials for High-Stability and High-Safety Lithium-Ion Batteries

“…A few recent literature reports exploited similar oligomeric additives for LIB cathodes, prepared through polymerization of BMI or bisphenol A diglycidyl ether diacrylate (EA) with barbituric acid (BTA). − Table summarizes the electrochemical performance of the various cathodes after surface modification. Notably, only the LIB cells incorporating the 1 wt % BTJ-L coated NMC811 cathode exhibited a positive discharge capacity ratio of +1.2% and a significantly lower value of R ct relative to its pristine NCM811 counterpart at 1C for the initial and 100th cycles, respectively.…”

Preventing the Distortion of CoO6 Octahedra of LiCoO2 at High-Voltage Operation of Lithium-Ion Battery: An Organic Surface Reinforcement

“…Figure 6a,b show the K-edge X-ray absorption near edge spectroscopy (XANES) of the pristine and modified electrodes in terms of different states of charge (SOC) in the first charge. According to the literature, the LCO of this work belongs to O3-type material [5]. Figure 6a demonstrates that the pristine LCO electrode has a pre-edge peak around 7710 eV.…”

“…Although the loading density of LCO can be designed up to 4.0 mg cm −2 and used to increase the area capacity, this represents more LCO being needed to maintain the energy density. To solve this problem, several studies have been undertaken, such as increasing the working voltage to more than 4.5 V by doping Al 3+ [4], organic grafting [5], coating metal oxides by atomic layer deposition [6], and adding electrolyte additive [7]. In fact, some of those modified materials have already been commercialized and adopted for the production of batteries, but only with high-voltage maintenance without any guarantee of safety.…”