Enhanced Cathode Performance: Mixed Al₂O₃ and LiAlO₂ Coating of Li_1.2Ni_0.13Co_0.13Mn_0.54O₂

Abstract

Li-rich, manganese-based cathode materials are attractive candidates for Li-ion batteries because of their excellent capacity, but poor rate and cycle performance have limited their commercial applications. Herein, Li-rich, manganese-based cathode materials were modified with aluminum isopropoxide as an aluminum source modifier using a sol–gel technique followed by a wet chemical method. To investigate the structure, morphology, electronic state, and elemental composition of both pristine- and surface-modified Li1.2Ni0.13Co0.13Mn0.54O2, various characterizations were performed. Based on density functional theory simulations and the results of electrochemical tests, the surface of the modified cathode material was found to contain at least part of the LiAlO2 phase. This was attributed to the aluminum isopropoxide reacting with a Li2CO3/LiOH byproduct on the material surface to form LiAlO2 with a three-dimensional Li-ion channel structure. Electrochemical testing revealed that a 3 wt % aluminum isopropoxide coating of cathode materials exhibited excellent electrochemical performance. Furthermore, the initial Coulombic efficiency and discharge capacity at 0.1 C were up to 88.55% and 272.7 mAh g–1, respectively. A final discharge capacity of 186.4 mAh g–1 was achieved, corresponding to a capacity retention of 83.55% after 300 cycles at 0.5 C. This was attributed to LiAlO2 partially accelerating the diffusion of Li ions and Al2O3 aiding the avoidance of side reactions in the mixed coating layer by partially protecting the structure.

Inhibition of Structural Transformation and Surface Lattice Oxygen Activity for Excellent Stability Li-Rich Mn-Based Layered Oxides

“…The button battery was kept in an air-conditioned space to maintain a constant temperature, but sudden changes in the outside temperature still caused minor variations in the data. This type of variation is typical, and it has also appeared in many reported documents. , Figure b compares the electrochemical capabilities of recently developed LLOs; for details, see Table S6. ,,,− Although the number of cycles is different, the capacity retention rates of materials in these documents are quite excellent. A major obstacle to the commercialization of batteries is the voltage decay of LLOs.…”

“…This type of variation is typical, and it has also appeared in many reported documents. 22,40 Figure 7b compares the electrochemical capabilities of recently developed LLOs; for details, see Table S6. 22,24,46,51−60 Although the number of cycles is different, the capacity retention rates of materials in these documents are quite excellent.…”

“…Both cationic and anionic doping are effective at preventing the change from a layered to a spinel structure. − Surface modification can also successfully address the aforementioned problems since both O 2 release and side reactions take place on the material’s surface. For instance, surface coatingswith materials such as carbon, metal oxides, fluorides, and phosphatesmay reduce the adverse effects. − Ethylene glycol was added in the coprecipitation process to generate a carbon coating and oxygen vacancies (OVs) on the surface of the material in situ . The carbon coating considerably enhances the cycle performance of the material by both reducing the impedance of Li 2 MnO 3 after activation and enhancing the reversibility of anionic redox activity in LLOs.…”

Constructing an Inhomogeneous Surface to Suppress the Capacity Decay of Li-Rich Layered Cathode Materials

“…The intensity ratios of I (003)/ I (104) are also considered as an indication for the degree of Li/Ni cation mixing. It is generally believed that the higher I (003)/ I (104) value means a lower degree of Li/Ni cation mixing, which is beneficial to the cyclic capability. , The I (003)/ I (104) intensity ratios are 2.34, 2.65, and 2.64 for P-LMNO, M-LMNO, and N-LMNO samples, respectively, all of which are much larger than 1.2. This indicates the low cation mixing and highly ordered structure for all samples.…”

Improving the Electrochemical Performance of a Solid-State Battery with a LiFePO4–Garnet-Based Composite Cathode

“…“The Fourteenth Five-Year Plan” advocated for vigorously developing new energy technology, whereby Li-ion batteries as an essential energy storage and conversion device have piqued the interest of researchers. The goals of Li-ion battery research are high energy density, safety, and low cost. − Although the traditional liquid battery has found widespread use, there are still some safety concerns. − Furthermore, all-solid-state batteries use solid-state electrolytes (SSEs) rather than conventional liquid electrolytes, which effectively solve many of the challenges traditional lithium-ion batteries face. − As a result, they offer significant advantages in terms of safety and energy density and are considered promising next-generation rechargeable battery technologies. − At the same time, it opens up the possibility of developing new lithium–air and lithium–sulfur batteries. − …”