LiMn0.8Fe0.2PO4/Carbon Nanospheres@Graphene Nanoribbons Prepared by the Biomineralization Process as the Cathode for Lithium-Ion Batteries

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.

Constructing a 3D Interconnected Carbon Network for Mg-Doped Porous LiMn0.85Fe0.15PO4/C Cathode Materials

Economical and high-safety LiMn0.85Fe0.15PO4/C cathode materials have gained significant attention recently due to their theoretical specific energy advantage of 18% compared to LiFePO4. However, their low electronic conductivity and sluggish diffusion kinetics limit the practical applications of LiMn0.85Fe0.15PO4/C. This paper presents a simple solid-state synthesis of porous LMFM0.01P-2C4P, which is doped with Mg and coated with composite carbon. Mg substitution for Mn shortens the transport path of lithium ions while increasing intrinsic conductivity and structural stability. Additionally, a 3D conductive network structure generated by the composite carbon source (citric acid and polyethylene glycol 400) improves the electronic conductivity and effectively minimizes the internal resistance of the battery. LMFM0.01P-2C4P consists of secondary particles aggregated from primary particles smaller than 100 nm, each of which is coated with a uniform carbon layer. The electronic conductivity and lithium-ion diffusion coefficient greatly exceed those of unmodified LMFP-4C, measuring 7.22 × 10-3 S cm-1 and ∼10-12 cm2 s-1, respectively. Electrochemical studies demonstrate that LMFM0.01P-2C4P delivers a superior specific capacity of 152.1 m Ah g-1 and 124.9 m Ah g-1 at 0.1C and 1C, respectively, along with a capacity retention of 80.8% after 500 cycles at 1C. However, the initial capacity of LMFP-4C is merely 104.1 mAh g-1 at 1C, with a capacity retention of only 65.7% after 500 cycles. This work presents a useful way to enhance the conductivity of phosphate cathode materials for lithium/sodium-ion batteries.

Mn-Rich Induced Alteration on Band Gap and Cycling Stability Properties of LiMnxFe1-xPO4 Cathode Materials

Olivine-type LiMnxFe1-xPO4 (LMFP) has inherited the excellent heat-stable structure of LiFePO4 (LFP) and the high-voltage property of LiMnPO4 (LMP), which shows great promise as a high-safety, high-energy-density cathode material. In order to combine the high energy density and excellent electrochemical performance, it is essential to consider the Mn/Fe ratio. This paper presents a theoretical investigation of the lattice structure parameters, embedded lithium voltage, local electron density, migration barrier, and lithium ion delithiation and lithiation mechanism of different LiMnxFe1-xPO4 (0.5 ≤ x ≤ 0.8) compounds. In situ-coated LiMnxFe1-xPO4 (0.5 ≤ x ≤ 0.8) composite cathode materials with a size of 100-200 nm were prepared by a hydrothermal method to verify the theoretical study. LiMn0.6Fe0.4PO4/C exhibited a specific capacity of 140.2 and 97.58 mA h·g-1 at 1 and 5C, respectively, and a remarkable capacity retention rate of 88.5% after 200 cycles at 1C. When LiMn0.6Fe0.4PO4/C was assembled into a flexible pouch battery and subjected to long cycle tests at different rates and squeeze and extrusion tests, it demonstrated a capacity retention rate of 99.35% for 100 cycles at 0.2C and 93.2% for 200 cycles at 0.5C. Moreover, the structural evolution of LiMn0.6Fe0.4PO4/C were analyzed in situ XRD, indicating a high stability and the resulted as obtine electrochemical performance, paving the way for optimization of high-energy-density LMFP cathode materials.

Bio-inspired carbon electrodes for metal-ion batteries

Carbon has been widely used as an electrode material in commercial metal-ion batteries (MIBs) because of its desirable electrical, mechanical, and physical properties. Still, traditional carbon electrodes suffer from limited mechanical stability and electrochemical performance in MIBs. Drawing inspiration from biological species, the carbon allotropes, such as fullerenes, carbon nanotubes, and graphene, can be engineered into mechanically robust, highly conductive frameworks with enhanced ion storage and transport capabilities for MIBs. Here, we present an assortment of bio-inspired carbon electrodes that have enhanced the cycling stability, capacity retention, and overall performance of MIBs. In addition, mimicking the structure and functionality of biological systems has led to the development of flexible MIBs whose performance does not degrade even when stretched, bent, or twisted. Finite element analysis (FEA) is a useful guide in identifying such bio-inspired carbon frameworks because it can simulate and analyze potential failure scenarios, such as stress build-up or structural collapse in MIBs. This review highlights through several examples that there is much scope for improving carbon-based electrode materials through bio-inspired designs for practical high-performance MIBs.

Engineering Crystal Orientation of Cathode for Advanced Lithium-ion Batteries: A Minireview

Engineering crystal orientation has attracted widespread attention since it is related to the cyclability and rate performance of cathode materials for lithium-ion batteries (LIBs). Regulating the crystal directional growth with optimal exposed crystal facets is an effective strategy to improve the performance of cathode materials, but still lacks sufficient attention in research field. Herein, we briefly introduce the characterization techniques and identification methods for crystal facets, then summarize and illuminate the major methods for regulating crystal orientation and their internal mechanism. Furthermore, the optimization strategies for layered-, spinel-, and olivine-structure cathodes are discussed based on the characteristic of crystal structure, and the relationship between exposure of special crystal facets and lithium storage performance is deeply analyzed, which could guide the rational design of cathodes for LIBs.

New Insights Into Microbial Induced Calcium Carbonate Precipitation Using Saccharomyces cerevisiae

Saccharomyces cerevisiae plays an important role in the mineralization of many metal ions, but it is unclear whether this fungus is involved in the mineralization of calcium carbonate. In this study, S. cerevisiae was cultured under various conditions to explore its ability to perform microbially induced calcium carbonate precipitation (MICP). Organic acids, yeast extract, and low-carbon conditions were the factors influencing the biomineralization of calcium carbonate caused by S. cerevisiae, and biomolecules secreted by the fungus under different conditions could change the morphology, size, and crystal form of the biosynthesized mineral. In addition, transcriptome analysis showed that the oxidation of organic acids enhanced the respiration process of yeast. This implied that S. cerevisiae played a role in the formation of calcium carbonate through the mechanism of creating an alkaline environment by the respiratory metabolism of organic acids, which could provide sufficient dissolved inorganic carbon for calcium carbonate formation. These results provide new insights into the role of S. cerevisiae in biomineralization and extend the potential applications of this fungus in the future.

Calcium-Based Biomineralization: A Smart Approach for the Design of Novel Multifunctional Hybrid Materials

Biomineralization consists of a complex cascade of phenomena generating hybrid nano-structured materials based on organic (e.g., polymer) and inorganic (e.g., hydroxyapatite) components. Biomineralization is a biomimetic process useful to produce highly biomimetic and biocompatible materials resembling natural hard tissues such as bones and teeth. In detail, biomimetic materials, composed of hydroxyapatite nanoparticles (HA) nucleated on an organic matrix, show extremely versatile chemical compositions and physical properties, which can be controlled to address specific challenges. Indeed, different parameters, including (i) the partial substitution of mimetic doping ions within the HA lattice, (ii) the use of different organic matrices, and (iii) the choice of cross-linking processes, can be finely tuned. In the present review, we mainly focused on calcium biomineralization. Besides regenerative medicine, these multifunctional materials have been largely exploited for other applications including 3D printable materials and in vitro three-dimensional (3D) models for cancer studies and for drug testing. Additionally, biomineralized multifunctional nano-particles can be involved in applications ranging from nanomedicine as fully bioresorbable drug delivery systems to the development of innovative and eco-sustainable UV physical filters for skin protection from solar radiations.

Zero Lithium Miscibility Gap Enables High-Rate Equimolar Li(Mn,Fe)PO4 Solid Solution

Forming olivine-structured Li(Mn,Fe)PO₄ solid solution is theoretically a feasible way to improve the energy density of the solid solutions for lithium ion batteries. However, the Jahn-Teller active Mn³⁺ in the solid solution restricts their energy density and rate performance. Here, as demonstrated by operando X-ray diffraction, we show that equimolar LiMn_0.5Fe_0.5PO₄ solid solution nanocrystals undergo a single-phase transition during the whole (de)lithiation process, with a feature of zero lithium miscibility gap, which endows the nanocrystals with excellent electrochemical properties. Specifically, the energy density of LiMn_0.5Fe_0.5PO₄ reaches 625 Wh kg^-1, which is 16% higher than that of LiFePO₄. Moreover, the high-performance LiMn_0.5Fe_0.5PO₄ nanocrystals are prepared by a microwave-assisted hydrothermal synthesis in pure water.

Biomineralization Forming Process and Bio-inspired Nanomaterials for Biomedical Application: A Review

Biomineralization is a process in which organic matter and inorganic matter combine with each other under the regulation of living organisms. Because of the biomineralization-induced super survivability and retentivity, biomineralization has attracted special attention from biologists, archaeologists, chemists, and materials scientists for its tracer and transformation effect in rock evolution study and nanomaterials synthesis. However, controlling the biomineralization process in vitro as precisely as intricate biology systems still remains a challenge. In this review, the regulating roles of temperature, pH, and organics in biominerals forming process were reviewed. The artificially introducing and utilization of biomineralization, the bio-inspired synthesis of nanomaterials, in biomedical fields was further discussed, mainly in five potential fields: drug and cell-therapy engineering, cancer/tumor target engineering, bone tissue engineering, and other advanced biomedical engineering. This review might help other interdisciplinary researchers to bionic-manufacture biominerals in molecular-level for developing more applications of biomineralization.