Improving electrochemical performance of LiMn0.5Fe0.5PO4 cathode by hybrid coating of Li3VO4 and carbon

Trifunctional Copper-Substitution in LiMn0.6Fe0.4PO4 Nanocrystal for Enhanced Lithium Storage

LiMn0.6Fe0.4PO4 is limited in practical applications due to its low electronic conductivity and slow Li+ diffusion rate. Therefore, Cu doping was applied to modify LiMn0.6Fe0.4PO4, and the mechanism of Cu2+ "three-function" synergistic enhancement of the cathode material performance was explored. Compared to the undoped sample (LMFP), the Cu-doped sample (LMFP-Cu 1%) exhibited significantly improved electronic conductivity and Li+ diffusion coefficient. First-principles calculations also confirmed the high electronic conductivity and low Li+ diffusion barrier of LiMn0.6Fe0.4PO4@C. Additionally, LiMn0.6Fe0.39Cu0.01PO4@C demonstrated excellent rate performance and cycling stability, with discharge capacities of 160.3 mA h g-1 and 121.2 mA h g-1 at 0.1 and 2C rates, respectively. After 200 cycles at 1C rate, the capacity retention was 92.5%. The first principle calculation of DFT can help to show that the introduction of Cu can effectively reduce the diffusion barrier and intrinsic conductivity of Li+, in situ XRD analysis revealed that LiMn0.6Fe0.39Cu0.01PO4@C exhibited good structural stability and reversibility. The incorporation of Cu2+ represents a promising approach to improving the lithium storage capabilities of LiMn0.6Fe0.4PO4 cathode materials.

Study on the Preparation and Electrochemical Properties of LiFe0.4Mn0.6PO4 Coated with Bamboo Shaving-Based Carbon

LiFe1-xMnxPO4 (0 < x < 1) has a high operating voltage range and theoretical energy density, but its actual capacity decreased due to its low electronic conductivity. To overcome this problem, we successfully prepared LiFe0.4Mn0.6PO4/C (LFMP/C) with a uniform carbon coating by a one-step solvothermal method using bamboo shavings as the carbon source. The results showed that heating at a reaction temperature of 180 °C for 18 h was the optimal synthesis condition to obtain LFMP/C. The addition of bamboo shaving-based carbon was effective in inhibiting excessive grain growth and reducing particle size. The disordered carbon layer enhanced the surface conductivity by connecting the surfaces of the particles. The synergistic effect of the nanoparticle size and the pores distributed around the particles increased the specific surface area and thus improved the contact area between the active substance and the electrolyte. Furthermore, there were improvements in electronic conductivity and ionic mobility. LFMP/C-16 showed initial discharge capacities of 150.1 and 143.5 mAh·g-1 at rates of 0.1 and 0.2C, respectively, with a capacity retention rate of 97.73% after 100 cycles, indicating excellent cyclic performance.

LiFe0.3Mn0.7PO4-on-MXene heterostructures as highly reversible cathode materials for Lithium-ion batteries

Two-dimensional (2D) heterostructure materials, incorporating the collective strengths and synergetic properties of individual building blocks, have attracted great interest as a novel paradigm in electrode materials science. The family of 2D transition metal carbides and nitrides (e.g., MXenes) has become an appealing platform for fabricating functional materials with strong application performance. Herein, a 2D LiFe0.3Mn0.7PO4 (LFMP)-on-MXene heterostructure composite is prepared through an electrostatic self-assembly procedure. The functional groups on the surface of MXenes possess highly electronegative properties that facilitate the incorporation of LFMPs into MXenes to construct heterostructure composites. The special heterostructure of nanosized-LiFe0.3Mn0.7PO4 and MXene provides rapid Li+ and electron transport in the cathodes. This LiFe0.3Mn0.7PO4-3.0 wt% MXene composite can exhibit an excellent rate capability of 98.3 mAh g-1 at 50C and a very stable cycling performance with a capacity retention of 94.3 % at 5C after 1000 cycles. Furthermore, NaFe0.3Mn0.7PO4-3.0 wt% MXene with stable cyclability can be obtained by an electrochemical conversion method with LiFe0.3Mn0.7PO4-3.0 wt% MXene. Ex-situ XRD suggests that LiFe0.3Mn0.7PO4-on-MXene achieves a highly reversible structural evolution with a solid solution phase transformation (LFMP→LixFe0.3Mn0.7PO4 (LxFMP), LxFMP→LFMP) and a two-phase reaction (LxFMP←→Fe0.3Mn0.7PO4 (FMP)). This work provides a new direction for the use of MXenes to fabricate 2D heterostructures for lithium-ion batteries.

Self-Thermal Management in Filtered Selenium-Terminated MXene Films for Flexible Safe Batteries

Li-ion batteries with superior interior thermal management are crucial to prevent thermal runaway and ensure safe, long-lasting operation at high temperatures or during rapid discharging and charging. Typically, such thermal management is achieved by focusing on the separator and electrolyte. Here, the study introduces a Se-terminated MXene free-standing electrode with exceptional electrical conductivity and low infrared emissivity, synergistically combining high-rate capacity with reduced heat radiation for safe, large, and fast Li+ storage. This is achieved through a one-step organic Lewis acid-assisted gas-phase reaction and vacuum filtration. The Se-terminated Nb2Se2C outperformed conventional disordered O/OH/F-terminated materials, enhancing Li+-storage capacity by ≈1.5 times in the fifth cycle (221 mAh·g-1 at 1 A·g-1) and improving mid-infrared adsorption with low thermal radiation. These benefits result from its superior electrical conductivity, excellent structural stability, and high permittivity in the infrared region. Calculations further reveal that increased permittivity and conductivity along the z-direction can reduce heat radiation from electrodes. This work highlights the potential of surface groups-terminated layered material-based free-standing flexible electrodes with self-thermal management ability for safe, fast energy storage.

Enhancement of Li2ZrO3 Modification of the Cycle Life of N/S-Doped LiMn0.5Fe0.5PO4/C Composite Cathodes for Lithium Ion Batteries

LiMn_0.5Fe_0.5PO₄ cathodes have a high energy density but a poor rate and poor cycling performance. To this end, a series of N/S-doped LiMn_0.5Fe_0.5PO₄/C composite cathodes modified with different contents of Li₂ZrO₃ were prepared by a solvothermal synthesis combined with calcination. The microstructure, chemical composition, and electrochemical properties are analyzed. Li₂ZrO₃ adsorbed on the LiMn_0.5Fe_0.5PO₄ primary particles' surface in an amorphous state and on spherical particles (5-10 nm). The cycling life and rate performance of the cathodes are improved by the modification of a moderate amount of Li₂ZrO₃. The LMFP/NS-C/LZO1 shows available capacities of 166.8 and 118.9 mAh·g^-1 at 0.1 and 5 C, respectively. The LMFP/NS-C/LZO1 shows no capacity loss after 100 cycles of charging/discharging (1 C), and still has a high capacity retention of 92.0% after 1000 cycles of charging/discharging (5 C). The excellent cycling performance of the LMFP/NS-C/LZO1 can be attributed to the improvement of the cathode microstructure and the electrochemical kinetics and the inhibition of Mn²⁺ dissolution by the moderate Li₂ZrO₃ modification.

Boron-Catalyzed Graphitization Carbon Layer Enabling LiMn0.8 Fe0.2 PO4 Cathode Superior Kinetics and Li-Storage Properties

The poor electrode kinetics and low conductivity of the LiMn_0.8 Fe_0.2 PO₄ cathode seriously impede its practical application. Here, an effective strategy of boron-catalyzed graphitization carbon coating layer is proposed to stabilize the nanostructure and improve the kinetic properties and Li-storage capability of LiMn_0.8 Fe_0.2 PO₄ nanocrystals for rechargeable lithium-ion batteries. The graphite-like BC₃ is derived from B-catalyzed graphitization coating layers, which can not only effectively maintain the dynamic stability of the LiMn_0.8 Fe_0.2 PO₄ nanostructure during cycling, but also plays an important role in enhancing the conductivity and Li⁺ migration kinetics of LiMn_0.8 Fe_0.2 PO₄ @B-C. The optimized LiMn_0.8 Fe_0.2 PO₄ @B-C exhibits the fastest intercalation/deintercalation kinetics, highest electrical conductivity (8.41 × 10^-2 S cm^-1 ), Li⁺ diffusion coefficient (6.17 × 10^-12 cm² s^-1 ), and Li-storage performance among three comparison samples (B-C0, B-C6, and B-C9). The highly reversible properties and structural stability of LiMn_0.8 Fe_0.2 PO₄ @B-C are further proved by operando XRD analysis. The B-catalyzed graphitization carbon coating strategy is expected to be an effective pathway to overcome the inherent drawbacks of the high-energy density LiMn_0.8 Fe_0.2 PO₄ cathode and to improve other cathode materials with low-conductivity and poor electrode kinetics for rechargeable second batteries.

Recent Advances on Materials for Lithium-Ion Batteries

Environmental issues related to energy consumption are mainly associated with the strong dependence on fossil fuels. To solve these issues, renewable energy sources systems have been developed as well as advanced energy storage systems. Batteries are the main storage system related to mobility, and they are applied in devices such as laptops, cell phones, and electric vehicles. Lithium-ion batteries (LIBs) are the most used battery system based on their high specific capacity, long cycle life, and no memory effects. This rapidly evolving field urges for a systematic comparative compilation of the most recent developments on battery technology in order to keep up with the growing number of materials, strategies, and battery performance data, allowing the design of future developments in the field. Thus, this review focuses on the different materials recently developed for the different battery components—anode, cathode, and separator/electrolyte—in order to further improve LIB systems. Moreover, solid polymer electrolytes (SPE) for LIBs are also highlighted. Together with the study of new advanced materials, materials modification by doping or synthesis, the combination of different materials, fillers addition, size manipulation, or the use of high ionic conductor materials are also presented as effective methods to enhance the electrochemical properties of LIBs. Finally, it is also shown that the development of advanced materials is not only focused on improving efficiency but also on the application of more environmentally friendly materials.