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In this work, the commercial detonation nanodiamonds (DNDs) are introduced to the anodes of lithium ion battery (LIBs) consisting of anatase titanium dioxide (TiO2) and synthesized graphite by a microwave treatment process. The compound TiO2/DND/graphite anodes are favorable for improving the LIB performance, where the LIBs have lithium storage capacities of 540 mA h g−1 at 0.5 C after 100 cycles and 300 mA h g−1 at 5 C after 1000 cycles, which are greatly higher than the theoretical data (168 mA h g−1) from TiO2 anode alone. The high capacity, as well as excellent cycling performance and stability of the LIBs, are attributed to the synergistic effect of DND (larger surface area, low expansion, high lithium adsorption capacity, chemical inertness), TiO2 (high Li+ insertion/extraction voltage, robust structural stability, lower volumetric expansion) and the improved ionic conductivity of the anode with additional fabricated graphitic powders. [ABSTRACT FROM AUTHOR]

Reasonably designing and synthesizing advanced electrode materials is significant to enhance the electrochemical performance of lithium ion batteries (LIBs). Herein, a metal–organic framework (MOF, Mil‐125) was used as a precursor and template to successfully synthesize the porous mooncake‐shaped Li4Ti5O12 (LTO) anode material assembled from nanoparticles. Even more critical, SmF3 was used to modify the prepared porous mooncake‐shaped LTO material. The SmF3‐modified LTO maintained a porous mooncake‐shaped structure with a large specific surface area, and the SmF3 nanoparticles were observed to be attach on the surface of the LTO material. It has been proven that the SmF3 modification can further facilitate the transition from Ti4+ to Ti3+, reduce the polarization of electrode, decrease charge transfer impedance (Rct) and solid electrolyte interface impedance (Rsei), and increase the lithium ion diffusion coefficient (DLi), thereby enhancing the electrochemical performance of LTO. Therefore, the porous mooncake‐shaped LTO modified using 2 wt % SmF3 displays a large specific discharge capacity of 143.8 mAh g−1 with an increment of 79.16 % compared to pure LTO at a high rate of 10 C (1 C=170 mAh g−1), and shows a high retention rate of 96.4 % after 500 cycles at 5 C‐rate. [ABSTRACT FROM AUTHOR]

Due to the large reversible capacity, high operating voltage and low cost, layered ternary oxide cathode materials LiNixCoyAl1−x−yO2(NCA) and LiNixCoyMn1−x−yO2(NCM) are considered as the most potential candidate materials for lithium‐ion batteries (LIBs) used in (hybrid) electric vehicles (EVs). However, next‐generation long‐range EVs require a high specific capacity (around 203 mAh·g–1at 3.7V) at the cathode active material level, which is not provided with current commercially layered ternary oxide cathodes. Increasing the operating voltage is an effective method to improve the specific capacity of the cathode and the energy density of the battery, but the high operating voltage also causes a lot of problems, such as cation mixing and phase transformation, electrolyte decomposition, transition metal dissolution and microcracks. So far, researchers have carried out a lot of works to solve these issues. Surface coating, element doping and the design of electrolytes have been proved to be effective solutions. In this review, the failure mechanisms and modification methods of high‐voltage layered ternary oxide cathode materials are summarized, which could provide valuable information to the research of high‐voltage layered ternary oxide cathode materials in basic science and industrial production. [ABSTRACT FROM AUTHOR]

Accurate and fast prediction of the remaining useful life of lithium (Li) ion batteries is an important requirement for successful electrification of automobiles. Consequently, there is a growing interest in the development of reduced‐order models. The existing reduced‐order electrochemical models can be used to predict battery performance (state of charge [SoC], terminal voltage) when the current through the battery is known a priori. Therefore these models cannot be used for studying the constant voltage (CV) mode of the constant current‐CV (CC‐CV) charging protocol, which is a common battery charging mechanism. In this work, we propose a reduced‐order electrochemical model to estimate the battery SoC under CC‐CV charging conditions, along with an analytical expression to approximate the CV mode charging time. We further propose a framework that accounts for the influence of the battery state of health (SoH) on the battery SoC during an operating cycle and vice‐versa. The proposed framework for estimating the battery SoC and SoH in a coupled manner shows good comparison with a first principles electrochemical model for CC‐CV charging conditions. This model can be used to study battery ageing and it can find applications in real‐time state estimation, charge protocol optimization, and battery design. [ABSTRACT FROM AUTHOR]

We investigated the applicability of an ionic liquid electrolyte to a phosphorus‐doped Si (P‐doped Si) electrode to improve the performance and safety of the lithium‐ion battery. The electrode exhibited excellent cycling performance with a discharge capacity of 1000 mA h g−1 over 1400 cycles in the ionic liquid electrolyte, whereas the capacity decayed at the 170th cycle in the organic electrolyte. The lithiation/delithiation reaction of P‐doped Si occurred a localized region in the organic electrolyte, which generated a high stress and large strain. The strain accumulated under repeated charge‐discharge cycling, leading to severe electrode disintegration. In contrast, the reaction of P‐doped Si proceeded uniformly in the ionic liquid electrolyte, which suppressed the electrode disintegration. The P‐doped Si electrode also showed good rate performance in the ionic liquid electrolyte; a discharge capacity of 1000 mA h g−1 was retained at 10 C. A P‐doped Si electrode exhibited excellent cycling performance with a discharge capacity of 1000 mA h g−1 over 1400 cycles in an ionic liquid electrolyte, whereas the capacity decayed at approximately the 170th cycle in an organic electrolyte. It is concluded that the ionic liquid electrolytes could be successfully applied to a P‐doped Si electrode and that they represent one type of promising electrolyte for next‐generation LIBs with this electrode. [ABSTRACT FROM AUTHOR]

Lithium chromium pyrophosphate (LiCrP2O7) and carbon-coated LiCrP2O7 (LiCrP2O7/C) were synthesized by solid-state and sol-gel routes, respectively. The materials were characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and conductivity measurements. LiCrP2O7 powder has a conductivity of ∼ 10−8 S cm−1, ∼ 104 times smaller than LiCrP2O7/C (∼ 10−4 S cm−1). LiCrP2O7/C is electrochemically active, mainly between 1.8 and 2.2 V versus Li+/Li (Cr3+/Cr2+ redox couple), whereas LiCrP2O7 has limited electrochemical activity. LiCrP2O7/C delivers a reversible specific charge up to ∼ 105 mAh g−1 after 100 cycles, close to the theoretical limit of 115 mAh g−1. Operando XRD experiments show slight peak shifts between 2.2 and 4.8 V versus Li+/Li, and a reversible amorphization between 1.8 and 2.2 V versus Li+/Li, suggesting an insertion reaction mechanism. [ABSTRACT FROM AUTHOR]

In this study, Li3V2(1-x)Fe3x(PO4)3 (0 ≤ x ≤ 0.09) powders are prepared via a solution method and heattreated at 700 °C for 8 hours. The chemical composition, morphology, crystalline structure, and valence of iron in the prepared samples were investigated with ICP, SEM, XRD, and EXAFS. The effects of Fe-substitution for vanadium sites on the electrochemical properties as cathode materials for lithium ion batteries are studied with capacity retention study and incremental capacity analysis. In addition to the monoclinic Li3V2(PO4)3 phase, olivine LiFePO4 is also observed when x ≥ 0.03. The valence of iron in the prepared powders is predominately 3+ at low substitution level (x ≤ 0.05), while the ratio of the Fe2+ to Fe3+ increases abruptly when the substitution level is higher than x = 0.07. Among the prepared samples, Li3V1.86Fe0.21(PO4)3 shows the best cycling performance at rates higher than 1C. It demonstrates discharge capacities of 141.2 mAh/g for second cycle and 126 mAh/g after 30 cycles at 5C rate. [ABSTRACT FROM AUTHOR]

The high capacity cathode materials with charge voltage above 4.5 V are widely being developed. To reduce surface reactivity at high voltage, Al2O3 and pullulan are used for coating on the Li(Li0.08Ni0.34Co0.08Mn0.5)O2 surface and are characterized by electrochemical analysis. Charge/discharge and electrochemical results reveal that the organic coating sustains in high voltage cycles. Ionic conductivity of surface coating plays a key role in the battery performance. [ABSTRACT FROM AUTHOR]