Rapid Self-Assembly Spherical Li1.2Mn0.56Ni0.16Co0.08O2 with Improved Performances by Microwave Hydrothermal Method as Cathode for Lithium-Ion Batteries

Limiting voltage and capacity fade of lithium-rich, low cobalt Li1.2Ni0.13Mn0.54Fe0.1Co0.03O2 by controlling the upper cut-off voltage

A new Li1.2Ni0.13Mn0.54Fe0.1Co0.03O2 material with a higher content of Fe and lower content of Co was designed via a simple sol-gel method. Moreover, the effect of upper cut-off voltage on the structural stability, capacity and voltage retention was studied. The Li1.2Ni0.13Mn0.54Fe0.1Co0.03O2 electrode delivers a discharge capacity of 250 mA h g-1 with good capacity retention and coulombic efficiency at 4.6 V cut-off voltage. Importantly, improved voltage retention of 94% was achieved. Ex situ XRD and Raman proved that the electrodes cycled at 4.8 V cut-off voltage showed huge structural conversion from layered-to-spinel explaining the poor capacity and voltage retention at this cut-off voltage. In addition, ex situ FT-IR demonstrates that the upper cut-off voltage of 4.8 V exhibits a higher intensity of SEI-related peaks than 4.6 V, suggesting that reducing the upper cut-off voltage can inhibit the growth of the SEI layer. In addition, when the Li1.2Ni0.13Mn0.54Fe0.1Co0.03O2 cathode was paired with a synthesized phosphorus-doped TiO2 anode (P-doped TiO2) in a complete battery cell, it exhibits good capacity and cycling stability at 1C rate. The material developed in this study represents a promising approach for designing high-performance Li-rich, low cobalt cathodes for next-generation lithium-ion batteries.

Tuning oxygen release of sodium-ion layered oxide cathode through synergistic surface coating and doping

Layered transition metal oxides have the greatest potential for commercial application as cathode materials for sodium-ion batteries. However, transition metal oxides inevitably undergo an irreversible oxygen loss process during cycling, which leads to structural changes in the material and ultimately to severe capacity degradation. In this work, using density function theory (DFT) calculations, the Ni-O bond is revealed to be the weakest of the M-O bonds, which may lead to structural failure. Herein, the synergistic surface CeO2 modification and the trace doping of Ce elements stimulate oxygen redox and improve its reversibility, thus improving the structural stability and electrochemical performance of the material. Theoretical calculations prove that Na0.67Mn0.7Ni0.2Co0.1O2 (MNC) obtains electrons from CeO2, avoiding destruction of the Ni-O bond by over-energy released during the charging process and inhibiting oxygen loss. The capacity retention was 77.37% for 200 cycles at 500 mA g-1, compared to 33.84% for the unmodified Na0.67Mn0.7Ni0.2Co0.1O2. Overall, the present work demonstrates that the synergistic effect of surface coating and doping is an effective strategy for realizing tuning oxygen release and high electrochemical performance.

Microwave hydrothermal renovating and reassembling spent lithium cobalt oxide for lithium-ion battery

With the growing number of lithium-ion batteries (LIBs) that are consumed by worldwide people, recycling is necessary for addressing environmental problems and alleviating energy crisis. Especially, it is meaningful to regenerate LIBs from spent batteries. In this paper, the microwave hydrothermal method is used to replenish lithium, assemble particles and optimize the crystal structure of the spent lithium cobalt oxide. The microwave hydrothermal process can shorten the reaction time, improve the internal structure, and uniformize the particle size distribution of lithium cobalt oxide. It helps to construct a regenerated lithium cobalt oxide (LiCoO₂) battery with high-capacity and high-rate properties (141.7 mAh g^-1 at 5C). The cycle retention rate is 94.5% after 100 cycles, which is far exceeding the original lithium cobalt oxide (89.7%) and LiCoO₂ regenerated by normal hydrothermal method (88.3%). This work demonstrates the feasibility to get lithium cobalt oxide batteries with good structural stability from spent lithium cobalt oxide batteries.

Highly reversible Li-ion full batteries using a Mg-doped Li-rich Li1.2Ni0.28Mn0.468Mg0.052O2 cathode and carbon-decorated Mn3O4 anode with hierarchical microsphere structures

Microsphere structured Mg-doped Li-rich Li1.2Ni0.28Mn0.468Mg0.052O2 cathode and carbon-decorated Mn3O4 anode materials were prepared for application to lithium-ion full batteries. As-assembled lithium-ion full batteries exhibited enhanced electrochemical performances like high charge/discharge capacity, and long-term capacity retention.

C/Sn deposition on a helical carbon nanofiber matrix as a high performance anode for lithium-ion batteries

C/Sn/HCNF composites were successfully prepared by solution phase synthesis and carbon thermal reduction. Within the hybrid composite, the HCNFs, Sn and carbon layer show a synergistic effect in improving coulombic efficiency and electrical capacity.

Simple Glycerol-Assisted and Morphology-Controllable Solvothermal Synthesis of Lithium-Ion Battery-Layered Li1.2Mn0.54Ni0.13Co0.13O2 Cathode Materials

High-performance lithium-rich-layered oxide is regarded as a promising candidate for lithium-ion battery (LIB) cathode materials because of its outstanding high specific capacity. Despite in-depth research over the past decade, there are still a number of serious problems limiting its commercialization. Here, we report a simple morphological design and size-controllable material preparation strategy to enhance the electrochemical performance of LIB cathode materials. We use a simple solvothermal method to obtain a carbonate precursor material with different morphologies by adjusting the solvent ratio of the system, which will be conveniently formed into Li_1.2Mn_0.54Ni_0.13Co_0.13O₂ by calcination. Moreover, further relation between the morphology and electrochemical performance of cathode materials is systematically investigated. The microsphere cathode material with suitable size exhibits superior electrochemical performances among all samples in terms of initial reversible capacity (280.4 mA h g^-1 at 0.1 C) and cycle performance (87.67% retention after 200 cycles at 1 C). Even at 5 C, a high discharge capacity of 150.8 mA h g^-1 can be obtained. In addition, this work provides a feasible and effective approach to controllable synthesis of stable structures and high-performance oxide electrode materials for LIBs.

Impact of surface coating on electrochemical and thermal behaviors of a Li-rich Li1.2Ni0.16Mn0.56Co0.08O2 cathode

Lithium-rich layered oxide materials are considered as potential cathode materials for future high-performance lithium-ion batteries (LIBs) owing to their high operating voltage and relatively high specific capacity. However, perceptible issues such as poor rate performance, poor capacity retention, and voltage degradation during cycling need to be improved before the successful commercialization of the material. In this report, zirconia coated Li1.2Ni0.16Mn0.56Co0.08O2 (NMC) (where ZrO2 = 1.0, 1.5 and 2.0 wt%) materials are synthesized using a sol-gel assisted ball milling approach. A comparison of structural, morphological and electrochemical properties is examined to elucidate the promising role of ZrO2 coating on the performance of the NMC cathode. A uniform and homogeneous ZrO2 coating is observed on the surface of NMC particles as evident by TEM elemental mapping images. The ZrO2 coated NMCs exhibit significantly improved electrochemical performance at a higher C-rate as compared to pristine material. 1.5% ZrO2 coated NMC demonstrates better cycling stability (95% capacity retention) than pristine NMC (77% capacity retention) after 50 cycles. All ZrO2 coated NMC materials demonstrated improved thermal stability compared to pristine material. The difference in onset temperature of 2 wt% ZrO2 coated and pristine NMC is 20 °C. The improved electrochemical performance of ZrO2 coated NMC can be attributed to the stabilization of its surface structure due to the presence of ZrO2.

Hierarchical Li-rich oxide microspheres assembled from {010} exposed primary grains for high-rate lithium-ion batteries

The wide particle size distribution of LLO microspheres assembled from {010} exposed primary grains is proposed to improve their Li⁺ kinetics and tap-density.

Electrode Materials with a Crater-Type Morphology Prepared by Electrospraying for High-Performance Lithium-Ion Batteries

Rechargeable lithium-ion batteries with good electrochemical properties require nanostructured electrode materials, which are usually prepared through complex synthesis processes. Herein, a new facile method is reported for the synthesis of high-performance electrode materials with a crater-like morphology through repulsion between positive charges. The produced electrode material does not possess a nanostructure. However, it is capable of rapidly transferring lithium ions and electrons owing to the large contact area with electrolyte and the high concentration sp² -hybridized carbon coating. LiFePO₄ and LiNi_1/3 Co_1/3 Mn_1/3 O₂ electrodes prepared by this process achieved high discharge capacities of 165.7 and 199.9 mAh g^-1 at 0.1 C, with excellent rate capability of 127.5 and 162.6 mAh g^-1 at 10 C, respectively. Although the crater-type materials might decrease the electrode tap density, they facilitate better electrochemical properties such as high capacity, high power, and fast charging. Furthermore, this new method can be applied trough a sol-gel process for the synthesis of electrode materials to improve their electrochemical characteristics.

Polyvinylpyrrolidone-Induced Uniform Surface-Conductive Polymer Coating Endows Ni-Rich LiNi0.8Co0.1Mn0.1O2 with Enhanced Cyclability for Lithium-Ion Batteries

The Ni-rich LiNi_0.8Co_0.1Mn_0.1O₂ (NCM₈₁₁) cathode has attracted great interest owing to its low cost, high capacity, and energy density. Nevertheless, rapid capacity fading is a critical problem because of direct contact of NCM₈₁₁ with electrolytes and hence restrains its wide applications. To prevent the direct contact, the surface inert layer coating becomes a feasible strategy to tackle this problem. However, to achieve a homogeneous surface coating is very challenging. Considering the bonding effect between NCM₈₁₁, polyvinylpyrrolidone (PVP), and polyaniline (PANI), in this work, we use PVP as an inductive agent to controllably coat a uniform conductive PANI layer on NCM₈₁₁ (NCM₈₁₁@PANI-PVP). The coated PANI layer not only serves as a rapid channel for electron conduction, but also prohibits direct contact of the electrode with the electrolyte to effectively hinder side reaction. NCM₈₁₁@PANI-PVP thus exhibits excellent cyclability (88.7% after 100 cycles at 200 mA g^-1) and great rate performance (152 mA h g^-1 at 1000 mA g^-1). In situ X-ray diffraction and in situ Raman are performed to investigate the charge-discharge mechanism and the cyclability of NCM₈₁₁@PANI-PVP upon electrochemical reaction. This surfactant-modulated surface uniform coating strategy offers a new modification approach to stabilize Ni-rich cathode materials for lithium-ion batteries.

Organic carbon gel assisted-synthesis of Li1.2Mn0.6Ni0.2O2 for a high-performance cathode material for Li-ion batteries

Li_1.2Ni_0.2Mn_0.6O₂ with a stable network flake structure shows excellent rate capacities and cycling stability as a Li-ion battery cathode.

The effect of cation mixing controlled by thermal treatment duration on the electrochemical stability of lithium transition-metal oxides

An optimal degree of Ni²⁺occupancy in the lithium layer as “pillaring” that enhances the electrochemical performance of NMC materials.

Li-rich layered Li1.2Mn0.54Ni0.13Co0.13O2 derived from transition metal carbonate with a micro–nanostructure as a cathode material for high-performance Li-ion batteries

Li_1.2Mn_0.54Ni_0.13Co_0.13O₂, created from designed carbonates with a micro–nanostructure, exhibits an improved tap density and delivers outstanding electrochemical performances for LIBs.

Hollow Li1.2Mn0.54Ni0.13Co0.13O2 micro-spheres synthesized by a co-precipitation method as a high-performance cathode material for Li-ion batteries

Hollow Li_1.2Mn_0.54Ni_0.13Co_0.13O₂ micro-spheres were successfully synthesized by a co-precipitation method.