Suppressing Fe–Li, Ni–Li Antisite Defects in LiFePO₄ and LiNi_1/3Co_1/3Mn_1/3O₂ by Optimized Synthesis Methods

Abstract

Antisite defects in LiFePO 4 and LiNi 1/3 Co 1/3 Mn 1/3 O 2 cathode materials will severely decrease Li + diffusion ability and the cell capacity. However, the mechanism of constraining antisite defects during the hydrothermal route is not fully understood. Herein, the Fe−Li, Ni−Li antisite defects in LiFePO 4 and LiNi 1/3 Co 1/3 Mn 1/3 O 2 cathode materials are successfully suppressed by optimized synthesis methods. As a result, their discharge capacity and rate performance at room and low temperature are significantly enhanced owing to smaller potential difference, less charge transfer resistance, reduced polarization, and enhanced Li + diffusion coefficient. The comprehensive investigation of synthesis parameters indicates that high attraction and less repulsion force governed by the zeta potential is crucial for making ideal cathode materials by facilitating coalescence, providing the sufficient cations occupation needed, and constructing uniform layer-by-layer surroundings for the precursors.

Revealing the Ultrahigh Rate Performance of the La and Ce Co-doping LiFePO4 Composite

“…Furthermore, the enlarged interplanar spacing facilitates the transport of Li + for less diffusion resistance. The modification of LC-LFP by adding La and Ce favors the construction of a regular crystal with less Fe–Li anti-site defects as shown in FTIR spectroscopy (Figure e) due to a closer wavenumber of LC-LFP (957.7 cm –1 ) to the Fe–Li defect-free theoretical value (957.0 cm –1 ) . As a result, the prepared LC-LFP would obtain an enhanced electrochemical performance.…”

“…The LiFePO 4 cathode (LFP) exhibiting favorable electrochemical potential, cost saving, and high stability has been widely employed in lithium-ion batteries (LIBs) for large-scale energy backup systems and electric vehicles (EVs). − Unfortunately, its poor electrical conductivity (10 –9 –10 –10 S cm –1 ) and sluggish lithium ion diffusion kinetics (∼10 –14 cm 2 s –1 ) deriving from the covalent character of polyanion frameworks are inhibiting the raise of charging/discharging rates in LiFePO 4 -based LIBs . To address these issues, two promising approaches, reducing particle size to a nanoscale and carbon coating on the active particles, are usually adopted to enhance the electrochemical performance. , Nevertheless, these strategies are still not satisfying the requirement of the application on the ultra-high rate (>50 C) and larger power density due to the limited improvement of Li + deintercalation kinetics …”

Chemomechanics of Rechargeable Batteries: Status, Theories, and Perspectives

“…Antisite defects can directly change the chemical environment of the defective region, impeding ion diffusion and deteriorating battery performance in most cases. ,− The impeded ion diffusion can be attributed to two reasons: (1) antisite defects act as obstructions along the ion diffusion pathways; (2) antisite defects cause lattice shrinkage and thus increase ionic diffusion energy barriers . OVs are intrinsic defects in many battery materials, and their presence can dramatically alter the chemical and mechanical stability of battery materials.…”

Correlation Between Li‐Fe Anti‐Site and Memory Effect of LiFePO4 in Li‐Ion Batteries

“…[9,[25][26][27] Previous studies indicated that LiFePO 4 synthesized at a low temperature has about 5~10 % LiÀ Fe anti-sites, which will decrease after high-temperature treatment. [28] Various methods have been used to reduce the defect concentration, such as lithium-excess, [9] enlarging exposure face, [29] suppressing the prior occupancy of Fe ion, [30] controlling the nucleation and evolution, [31] regulating pH values, [32] reducing the particle size, [16] etc. Whether there is any correlation between the LiÀ Fe anti-site and the memory effect of LiFePO 4 ?…”