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Polyaniline (PANI) has long been explored as a promising organic cathode for Li-ion batteries. However, its poor electrochemical utilization and cycling instability cast doubt on its potential for practical applications. In this work, we revisit the electrochemical performance of PANI in nonaqueous electrolytes, and reveal an unprecedented reversible capacity of 197.2 mAh g−1 (244.8 F g−1) when cycled in a wide potential range of 1.5 to 4.4 V vs. Li+/Li. This ultra-high capacity derives from 70% -NH- transformed to =NH+- during deep charging/discharging process. This material also demonstrates a high average coulombic efficiency of 98%, an excellent rate performance with 73.5 mAh g−1 at 1800 mA g−1, and retains 76% of initial value after 100 cycles, which are among the best reported values for PANI electrodes in battery applications. [ABSTRACT FROM AUTHOR]

Stable solid electrolyte interphase (SEI) with high Li+‐ion conductivity is desperately desired for lithium (Li) metal anodes. However, it remains challenging to build a robust SEI rationally for the Li‐metal anodes in carbonate electrolytes. Herein, a heterogeneous nitride‐rich SEI that consists of organic nitrides on the surface and inorganic nitrides inside by stepwise‐reduction electrolyte design is constructed. The heterogeneous structure endows SEI with the capability to capture and distribute Li+ on the surface and facilitate internal Li+ transportation, leading to the redistributed Li+ flux and uniform Li electrodeposition. With the newly‐formulated carbonate electrolyte, Li||Cu cells deliver a high Coulombic efficiency of 98.0% after 300 cycles at 0.5 mA cm‐2 and 0.5 mAh cm‐2. Meanwhile, superb cycling stability is also determined with full Li‐metal cells using LiNi1/3Mn1/3Co1/3O2 and high‐loading LiFePO4 (12.0 mg cm−2) cathodes. This study provides a promising strategy to regulate the SEI components and stabilize the Li anodes by rational electrolyte design. [ABSTRACT FROM AUTHOR]

Al 2 O 3 and AlPO 4 single-coated and double-coated LiNi 0.5 Co 0.2 Mn 0.3 O 2 materials have been synthesized by a wet-coating method in this paper. XRD, XPS, SEM, TEM, DSC as well as electrochemical methods are employed to investigate the structure, surface properties, thermal stability as well as electrochemical properties. The obtained layers are homogenously coated on the particles and the coating thickness is around 20–30 nm, the surface compositions are analyzed by XPS in detail as well. Comparing with those single-coated or uncoated samples, the double-coated one exhibits more superior thermal stability as well as electrochemical properties. The possible reason is mainly due to the dense and uniform coating layer as well as the formation of Li 3 PO 4 and LiAlO 2 on the cathode surface. Based on these results, it seems that Al 2 O 3 and AlPO 4 double-coating is an efficient strategy in improving the properties of LiNi 0.5 Co 0.2 Mn 0.3 O 2 materials, which can be also applied to other Ni-rich layered materials. [ABSTRACT FROM AUTHOR]

Na-doped Ni-rich layered oxide LiNi 0.5 Co 0.2 Mn 0.3 O 2 cathode materials are synthesized via co-precipitation method in this work. The crystal structure, thermal stability as well as electrochemical performance are studied. Results show that when the Na-doping amount is less than and equal to 2%, the samples can exhibit better electrochemical performance than the parent compound. One reason is that the Na doping can reduce the cationic mixing in the compound, as confirmed by X-Ray powder diffraction (XRD). Beside, results from X-ray photoelectron spectroscopy (XPS) and galvanostatic intermittent titration technique (GITT) show that the introduced sodium can also impact the chemical environment of lithium, making the latter become more easily de-intercalated from the bulk material. However, as the Na-doping amount increases, the electrochemical properties of the samples were deteriorated. Furthermore, results from differential scanning calorimetry (DSC) measurement indicate that the added Na + is also beneficial for improving the thermal stability of the layered oxide. [ABSTRACT FROM AUTHOR]

A novel solvo/hydrothermal assisted co-precipitation method is used to synthesis LiNi 1/3 Mn 1/3 Co 1/3 O 2 cathode material. The structural and morphological features of the synthesized samples are characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). High crystalline material can be obtained by this method from XRD results, which is also confirmed by TEM images. The obtained samples exhibit faceted, edge-blunted polyhedral morphology, which is helpful in the enhancement of the electrochemical properties. The reacting temperature has an important effect on the crystal structure and the morphology of the synthesized products, resulting in different electrochemical performance. The optimized LiNi 1/3 Mn 1/3 Co 1/3 O 2 can deliver an initial discharge capacity of 179 mA h g −1 in the range of 2.5–4.5 V@0.1 C, 150 mA h g −1 @1C, capacity retention of 93.4% after 100 cycles in the range of 2.5–4.2 V@1 C and 86.5% in the range of 2.5–4.5 V@1 C. [ABSTRACT FROM AUTHOR]

Poor rate capability and cycling performance are the major barriers to the application of lithium rich layered oxides as the next generation cathodes for lithium-ion batteries. In this paper, a novel tactics is applied to enhance the rate property and low temperature performance of lithium rich layered oxides materials by using graphene and multi-walled carbon nanotubes as the building blocks to form a hybrid 3D conductive network in the synthesized composites. Spray pyrolysis method is employed to obtain the target material. The hybrid 3D conductive network can decrease the reaction overpotential greatly, as well as reduce the cell resistance and enhance the lithium ion transportation in the bulk material, which are confirmed by cyclic voltammetry measurement and electrochemical impedance spectroscopy. The conductivity of the obtained composite is so high that no additional conductive agent is needed in the fabrication of electrodes. Our investigation further demonstrates that the conducting framework can efficiently alleviate the polarization of pristine lithium rich layered oxides material, leading to an outstanding enhancement in rate capability, low temperature performance and cycling stability. [ABSTRACT FROM AUTHOR]

The spinel LiNi 0.5 Mn 1.5 O 4 (LNMO) material is considered as a promising cathode in high-voltage lithium-ion batteries due to its advantageous voltage and capacity. Previous results indicate that the electrodes constructed by LNMO with the same compositions while differing in the crystallite geometries always exhibit various electrochemical performances. Here, to probe the relationships between the crystalline geometry of the obtained cathodes and their electrochemical properties, we synthesized different facet-exposed LNMOs with the same compositions using a template method. We demonstrate that the crystallite geometries of the hydroxide precursors can be tuned easily via varying the synthesize parameters, while the tuned precursors can be employed as the templates during the final product preparation. LNMOs enclosed by single {111} facets (LNMO-OH) and both {110} and {100} facets (LNMO-HP) are obtained and employed to elucidate the particle geometry-dependent electrochemical properties. Despite better rate capabilities exhibited for LNMO-HP because of the higher lithium diffusion coefficients along these crystal orientations, inferior cycling performance is released compared with its LNMO-OH counterpart. These insights can provide informative guidance in particle geometry-dependent material construction, thus helpful in realizing high-performance LNMO cathode. • Different facet-exposed LNMOs with the same compositions were synthesized. • The crystallite geometries of the hydroxide precursors can be tuned easily via varying the synthesize parameters. • Facet-exposed LNMOs exhibit various electrochemical properties. • Working mechanism of different LNMOs was investigated. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel PDDA/GO dual-layer coating strategy to effectively improve the performance of NCM811 is proposed in this paper. • NCM811 particles can be well-encapsulated in the resultant dual-layer by a simple electrostatic adsorption method. • The PDDA/GO coating depresses the LiF component, enables a homogeneous organic-enriched CEI film with fast Li diffusion and effective corrosion protection on cathodes. • NCM811-PDDA/GO cathodes exhibit a 77% capacity retention after 500 cycles at the current density of 50 mA g−1, against 28% for pristine NCM811. Cathode-electrolyte interphases (CEIs) are determinative to the electrochemical performance of lithium-ion batteries, especially those with Ni-rich cathodes. Herein, we employed the simple electrostatic adsorption (SEA) method to generate a homogenous polydimethyldiallyl ammonium chloride/ graphene oxide (PDDA/GO) dual-layer coating on the surface of a model single-crystalline Ni-rich cathode, LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811), and thus modified the CEIs in both compositions and microstructures. The PDDA/GO coating depresses the LiF component, enables a homogeneous organic-enriched CEI film with fast Li diffusion and effective corrosion protection on cathodes. Together with the mechanical confinement on cathodes, these characters of modified CEIs benefit the electrochemical stability effectively. For instance, NCM811-PDDA/GO cathodes exhibit a 77% capacity retention after 500 cycles at the current density of 50 mA g−1, against 28% for pristine NCM811. This study provides new insights in correlating the coating and CEIs, which effectively guide the development of Ni-rich cathodes for high performance. Such a simple strategy to form a homogeneous coating can also be extended into other electrode materials easily. [ABSTRACT FROM AUTHOR]