Polyimide gel polymer electrolyte-nanoencapsulated LiCoO2 cathode materials for high-voltage Li-ion batteries

We demonstrate a novel and facile approach to surface modification of high-voltage charged LiCoO₂, which is based on encapsulating LiCoO₂ by a polyimide (PI) gel polymer electrolyte layer. The PI is introduced onto the LiCoO₂ by thermally curing 4-component (pyromellitic dianhydride/biphenyl dianhydride/phenylenediamine/oxydianiline) polyamic acid. The PI nanoencapsulating layer features the high surface coverage, nanometer thickness, and facile ion transport. These unique characteristics are expected to enable the PI coating layer to effectively suppress the undesirable interfacial reaction of the LiCoO₂ with liquid electrolyte, which plays a key role in noticeably improving the 4.4 V cycle performance and mitigating the vigorous exothermic reaction between the charged LiCoO₂ and liquid electrolyte.     

Ultrafast auto flame synthesis for the mass production of LiCoO2 as a cathode material for Li-ion batteries

Journal of Solid State Electrochemistry - This article reports for the first time ultrafast automatic flame synthesis of high-quality LiCoO2 in open-air conditions as a cathode material for Li-ion...     

Anion doping in LiCoO2 cathode materials for Li-ion batteries: a first-principles study

Journal of Solid State Electrochemistry - In this work, anion (F, Cl, and S)-doped LiCoO2 cathode materials were systematically investigated by using first-principles calculations. The results show...     

Al2O3 coated LiCoO2 as cathode for high-capacity and long-cycling Li-ion batteries

In this study, we fabricated a Al₂O₃ layer coated on the surface of LiCoO₂ by a facile and scale-up sol-gel method. The proper thickness coating can improve the cycling life with the cut-off potential (4.5 V), which capacity retention is~73% after 500 cycles, and enhance the capacity, which shows~180 mAh/g.     

LiNbO3-coated LiCoO2 as cathode material for all solid-state lithium secondary batteries

The further enhancement of high-rate capabilities for all solid-state lithium secondary batteries is reported. A LiNbO₃ layer of nanometer thickness was interposed between LiCoO₂ and sulfide solid electrolyte as buffer layer. This greatly reduced the interfacial resistance in the cathode and enhanced the high-rate capabilities of solid-state lithium batteries, providing good prospects for practical application of lithium secondary batteries free from safety issues.     

Olivine LiCoPO4 phase grown LiCoO2 cathode material for high density Li batteries

Olivine LiCoPO₄ phase grown LiCoO₂ cathode material was prepared by mixing precipitated Co₃(PO₄)₂ nanoparticles and LiCoO₂ powders in distilled water, followed by drying and annealing at 120 °C and 700 °C, respectively, for 5 h. As opposed to ZrO₂ or AlPO₄ coatings that showed a clearly distinguishable coating layer from the bulk materials, Co₃(PO₄)₂ nanoparticles were completely diffused into the surface of the LiCoO₂ and reacted with lithium of LiCoO₂. An olivine LiCoPO₄ phase was grown on the surface of the bulk LiCoO₂, with a thickness of ∼7 nm. The electrochemical properties of the LiCoPO₄ phase, grown in LiCoO₂, had excellent cycle life performance and higher working voltages at a 1C rate than the bare sample. More importantly, Li-ion cells, containing olivine LiCoPO₄, grown in LiCoO₂, showed only 10% swelling at 4.4 V, whereas those containing bare sample showed a 200% increase during storage at 90 °C for 5 h. In addition, nail penetration test results of the cell containing olivine LiCoPO₄, grown in LiCoO₂ at 4.4 V, did not exhibit thermal runaway with a cell surface temperature of ∼80 °C. However, the cell containing bare LiCoO₂ showed a burnt-off cell pouch with a temperature above 500 °C.     

构建一维铜基配位聚合物作为锂离子电池正极材料

合成了一种新型的一维(1D)羰基配位聚合物[Cu (BGPD)(DMA)(H₂O)]·DMA (记为Cu-BD,H₂BGPD=N,N′-双(甘氨酰)均苯四甲酸二酰亚胺,DMA=二甲基乙酰胺),并考察了其用作锂离子电池正极材料的电化学性能。电化学测试结果表明,Cu-BD正极在50 mA·g^-1的电流密度下循环100圈后仍然保留50 mAh·g^-1的比容量,具有较好的循环稳定性。Cu-BD电极反应机理研究表明,BGPD^2-配体和Cu (Ⅱ)离子在充放电过程中都可能参与了电子转移过程。     

构建一维铜基配位聚合物作为锂离子电池正极材料

合成了一种新型的一维(1D)羰基配位聚合物[Cu(BGPD)(DMA)(H₂O)]·DMA(记为Cu-BD,H₂BGPD=N,N''-双(甘氨酰)均苯四甲酸二酰亚胺,DMA=二甲基乙酰胺),并考察了其用作锂离子电池正极材料的电化学性能。电化学测试结果表明,Cu-BD正极在50 mA·g^-1的电流密度下循环100圈后仍然保留50 mAh·g^-1的比容量,具有较好的循环稳定性。Cu-BD电极反应机理研究表明,BGPD配体和Cu(II)离子在充放电过程中都可能参与了电子转移过程。     

Defective layered Mn-based cathode materials with excellent performance via ion exchange for Li-ion batteries

Defective layered Mn-based materials were synthesized by Li/Na ion exchange to improve their electrochemical activity and Coulombic efficiency. The annealing temperature of the Na precursors was important to control the P3-P2 phase transition, which directly affected the structure and electrochemical characteristics of the final products obtained by ion exchange. The O3-Li_0.78[Li_0.25Fe_0.075Mn_0.675]Oδcathode made from a P3-type precursor calcined at 700...     

High power LiCoO2 cathode materials with ultra energy density for Li-ion cells

Hydrothermally prepared 100 nm-sized LiCoO₂ with a plate morphology packed in a crucible resulted in 40 μm-sized particles that consisted of aggregated < 1 micron-sized particles after annealing at 900 °C for 3 h. In the condition where the optimized electrode pore volume was 20%, 4.1 g/cc of electrode density was obtained, which corresponded to 3 Wh/cc, which is the highest value among the cathode materials. Furthermore, the LiCoO₂ showed excellent capacity retention of 78% after 290 cycles in a Li-ion cell under 7 C rate cycling.     

Review and prospect of layered lithium nickel manganese oxide as cathode materials for Li-ion batteries

Layered structural lithium metal oxides with rhombohedral α-NaFeO₂ crystal structure have been proven to be particularly suitable for application as cathode materials in lithium-ion batteries. Compared with LiCoO₂, lithium nickel manganese oxides are promising, inexpensive, nontoxic, and have high thermal stability; thus, they are extensively studied as alternative cathode electrode materials to the commercial LiCoO₂ electrode. However, a lot of work needs to be done to reduce cost and extend the effective lifetime. In this paper, the development of the layered lithium nickel manganese oxide cathode materials is reviewed from synthesis method, coating, doping to modification, lithium-rich materials, nanostructured materials, and so on, which can make electrochemical performance better. The prospects of lithium nickel manganese oxides as cathode materials for lithium-ion batteries are also looked forward to.     

锂离子电池正极材料LiCoO2的微波合成及结构表征

改变原料的Li,Co摩尔配比，利用微波法制备出锂离子电池正极材料LiCoO2，同时考察了微波辐照时间对反应体系温度的影响，并采用电子显微镜、红外光谱和X射线衍射技术对产品的晶体结构进行分析。结果表明，Li,Co的摩尔比的1.05:1时，所合成的LiCoO2晶体纯度高，具有良好的层状结构。与传统合成法相比，微波合成法具有反应时间短，能耗低，合成效率高，颗粒均匀性良好等特点。     

Effect of sonochemistry: Li- and Mn-rich layered high specific capacity cathode materials for Li-ion batteries

Li- and Mn-rich layered Li_1.2Ni_0.13Co_0.13Mn_0.54O₂ cathode material was synthesized using sonochemical method followed by annealing at 700, 800, and 900 °C for 10 h. The material was characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), Raman spectroscopy, and electrochemical techniques. Its performance as a cathode material for Li-ion batteries was examined. With the sample annealed at 900 °C, an initial specific capacity of 240 mAh g^?1 was obtained, which decreased to 215 mAh g^?1 after 80 cycles, thus retaining about 90 % of its initial capacity. In contrast, samples annealed at lower temperatures exhibited lower capacity retention upon cycling. Thus, the final annealing temperature was found to have a significant effect on the electrochemical stability of this material in terms of capacity, average voltage, and rate capability. The advantage of this synthesis, which includes a sonochemical stage, compared with a conventional co-precipitation synthesis, was also confirmed.     

Synthesis,microstructure, and electrochemical performance of Li-rich layered oxide cathode materials for Li-ion batteries

Russian Chemical Bulletin - Li-rich layered oxides Li1.2Mn0.54Ni0.13Co0.13O2 were synthesized by modified Pechini method using various compositions of the reaction mixture. Difference in the...     

A novel carbon-coated LiCoO2 as cathode material for lithium ion battery

Using a commercially available LiCoO₂ as starting material, a surface-modified cathode material was obtained by coating it with a nano layer of amorphous carbon. The carbon-coated LiCoO₂ was characterized by X-ray diffraction analysis, scanning electronic microscopy, transmission electronic microscopy, electrochemical impedance spectroscopy and measurement of charge/discharge behavior. Results show that the carbon-coated LiCoO₂ displays marked lower charge transfer resistance, higher lithium ion diffusion coefficient and much better rate capability than the original LiCoO₂. It also indicates promising application of lithium ion batteries in the areas requiring charge and discharge at high rate.     

Synthesis and electrochemical properties of nanostructured LiCoO2 fibers as cathode materials for lithium-ion batteries

Nanostructured LiCoO2 fibers were prepared by the sol-gel related electrospinning technique using metal acetate and citric acid as starting materials. The transformation from the xerogel fibers to the LiCoO2 fibers and the nanostructure of LiCoO2 fibers have been investigated in detail. The LiCoO2 fibers with 500 nm to 2 mum in diameter were composed of polycrystalline nanoparticles in sizes of 20-35 nm. Cyclic voltammetry and charge-discharge experiments were applied to characterize the electrochemical properties of the fibers as cathode materials for lithium-ion batteries. The cyclic voltammogram curves indicated faster diffusion and migration of Li+ cations in the nanostructured LiCoO2 fiber electrode. In the first charge-discharge process, the LiCoO2 fibers showed the initial charge and discharge capacities of 216 and 182 (mA.h)/g, respectively. After the 20th cycle, the discharge capacity decreased to 123 (mA.h)/g. The X-ray diffraction and high-resolution transmission electron microscopy analyses indicated that the large loss of capacity of fiber electrode during the charge-discharge process might mainly result from the dissolution of cobalt and lithium cations escaping from LiCoO2 to form the crystalline Li2CO3 and CoF2 impurities.     

Single-source realization of Na-doped and carbon-coated LiMnPO4 nanocomposite for enhanced performance of Li-ion batteries

Journal of Solid State Electrochemistry - LiMnPO4 is of great interest as the promising cathode material in lithium-ion batteries for its low cost and good stability, but still suffers from limited...     

All boron-based 2D material as anode material in Li-ion batteries

To design the high-energy-density Li-ion batteries, the anode materials with high specific capacity have attracted much attention. In this work, we adopt the first principles calculations to investigate the possibility of a new two dimensional boron material, named BG, as anode material for Li-ion batteries. The calculated results show that the maximum theoretical specific capacity of B_G is 1653 m Ah g~(-1)(LiB1.5).Additionally, the energy barriers of Li ion and Li vacancy diffusion are 330 meV and 110 meV, respectively, which imply fast charge and discharge ability for BGas an anode material. The theoretical findings reported in this work suggest that BGis a potential candidate as anode material of high-energy-density Li-ion batteries.     

锂硫电池正极材料研究进展

总结了近几年来锂硫电池正极材料的研究进展,简要阐释了锂硫电池正极材料的研究现状、存在的问题及其面临的挑战.通过碳材料的引入,导电聚合物的复合,金属氧化物的添加均不同程度地提高了硫电极材料的电导率,有效抑制了多硫化物的溶解,为体积膨胀提供了空间,从而改善了锂硫电池的活性物质利用率和循环稳定性.简化工艺,降低成本,提高硫的负载量,这将是下一阶段锂硫电池研究的重点.     

Ammonia leaching mechanism and kinetics of LiCoO2 material from spent lithium-ion batteries

In this paper, the ammonia leaching process and high-energy ball milling method were adapted to recover spent LiCoO₂ material. The ammonia reduction leaching mechanism of LiCoO₂ material in the ammonia-sodium sulfite-ammonium chloride system was elucidated. Compared with untreated LiCoO₂ material, the leaching equilibrium time of LiCoO₂ after ball-milled for 5 h was reduced from 48 h to 4 h, and the leaching efficiency of lithium and cobalt was improved from 69.86% and 70.80% to 89.86% and 98.22%, respectively. Importantly, the apparent activation energy and leaching kinetic equation of the reaction was calculated by the shrinking core reaction model, indicating that the reaction was controlled by the chemical reaction.