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Abstract: A strategy to synthesize a Fe3O4@carbon nanotube (CNT) composite with high tap density of 1.22 g cm−3 and electronic conductivity of 4.1 S cm−1 is developed. The Fe3O4@CNT composite exhibits an extremely high capacity of over 1263 mAh g−1, even after 125 cycles at a current density of 100 mA g−1. Additionally, a lithium‐ion full battery of Fe3O4@CNT|LiNi0.5Mn1.5O4 with an energy density of 2283 Wh kganode−1 (381 Wh kgcathode−1) is successfully configured. After optimization of the work voltage windows and electrolyte additives, it has a capacity retention of 71 % after more than 400 cycles. Using this synthetic strategy, additional metal oxide@CNT (e.g., Co3O4, MnO2, CuO, ZnO) composites with high lithium storage capability are explored, and their electrochemical differences versus the cathode of LiNi0.5Mn1.5O4 are investigated in light of their superior performances. Applying this type of metal oxide‐based composite in full cells is a significant step to the development of high‐energy lithium‐ion batteries and to further applications in current sodium‐ion batteries. [ABSTRACT FROM AUTHOR]

• A series of Nb-doping products are successfully prepared by solid phase strategy. • The suitable mole ratio of Nb-doping in LiNi 0.8 Co 0.1 Mn 0.1 O 2 is identified to 0.1 %. • Lower Nb-doping benefits to higher capacity, the higher endows good rate capability. • The Nb-doping is conducive to high structural stability and electron conductivity. • The Nb-doping Ni-rich cathode delivers a more stable thermal safety. Nickel-rich layered oxides have garnered great attention as promising cathode materials in lithium-ion batteries for their high specific capacity, rate capability and comparatively lower cost. However, the long cycling with a high current scenario is still a critical challenge, resulting from the lattice cracks and high temperature which are induced by rapid Li-ions intercalation/extraction and local heat accumulation under component voltage. Besides the deterioration of electrochemical performance, these limitations further lead to the impairment of structure or even thermal runaway for nickel-rich layered oxides. Herein, considering the superiorities of niobium element with multilevel electron orbitals and suitable atomic radius, a strategy of nickel-rich material modified by niobium-doping is proposed. The incorporated niobium forms a strong niobium-oxygen bonding, which promotes structure stability, ions diffusivity, and electron conductivity of nickel-rich cathode (LiNi 0.8 Co 0.1 Mn 0.1 O 2). Accordingly, the niobium-doping cathode deliver the specific capacities of 166.4 mAh g−1 and 151.02 mAh g−1 after 100 cycles at 1 C and 5 C (1C = 200 mAh g−1), especially with the capacity retention of 88.90 % and 89.06 %. Moreover, the niobium-doping cathode exhibit a more stable thermal safety with a reversibility around 76.75 % after 100 cycles at 1 C under 50 ℃, whereas is only 36.03 % for blank sample. Accompanied with exploring the stabilization for crystalline structure and superficial electronic structure, a generic approach to synthesize excellent Ni-rich cathode materials is identified, accelerating their endurance application in complicated scenes, particularly at high-temperature and high-rate operation conditions. A series of Nb-doping products are successfully prepared by solid phase strategy, in which the suitable mole ratio of Nb-doping in LiNi 0.8 Co 0.1 Mn 0.1 O 2 is identified to around 0.1 %; The lower content of Nb-doping benefits to higher capacity, conversely, the higher endows better rate capability; As expatiated, this shows that the Nb-doping is conducive to high structural stability and electron conductivity, especially, the Nb-doping Ni-rich cathode delivers a more stable thermal safety. [Display omitted] [ABSTRACT FROM AUTHOR]

Ni-rich layered oxide, one of the most promising cathode materials for lithium-ion batteries (LIBs) with high energy density, is suffering from the intrinsic hypersensitivity to moisture and acid gas (CO 2 , SO 2 , etc.) in the environment, leading to the generation and growth of residual lithium compounds (e.g. Li 2 CO 3), accompanied by surficial phase transition, high alkalinity and electrochemical deterioration. Eliminating these negative effects would require considerable energy and manpower, which hinders the promotion of Ni-rich cathode materials. Herein, we introduced crosslinked poly-methylhydrosiloxane (PMHS) and hydroxy‑terminated poly-dimethylsiloxane (denoted as PDMS-OH) hydrophobic film to in situ coat single-crystal LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811), isolating its Ni-rich electrode surface from moisture and acid gas to prevent side reactions. Specifically, the desired crosslinking layer, which is optimized by increasing the relative content of PMHS and decreasing the absolute content of PDMS-OH, endows the coated NCM811 with an appreciable improvement in hydrophobicity and storage performances and effectively suppresses the formation and growth of residual lithium compounds on the surface of NCM811 particles in a simulated damp-heat storage environment. Simultaneously, the crosslinked coating diminished the extraction of Li and Ni during exposure and maintained the high electrochemical performance of NCM811. This proposed strategy to crosslink polysiloxane film on the surface of Ni-rich cathode materials greatly alleviates the problem of storage failure, which will promote the practical popularization of Ni-rich cathode materials in LIBs. In situ crosslinked polysiloxanes coating layer endows surface of Ni-rich oxide cathode material with appreciable and durable hydrophobicity, successfully improving the ability of Ni-rich oxide cathode to resist severe environments and preventing electrochemical deterioration from side reactions induced by H 2 O or other acid gasses. [Display omitted] [ABSTRACT FROM AUTHOR]

Tris(trimethylsilyl) borate (TMSB) is used as electrolyte additive to overcome the severe capacity fading of LiCoPO 4 cathode at high voltage. The presence of TMSB effectively improves the cyclic stability of LiCoPO 4 cathode in Ethylene carbonate (EC)-based electrolyte between 3 V and 5 V, when the electrolyte contains with 1 wt% TMSB shows the best cycle performance. For instance, LiCoPO 4 cathode delivers an initial discharge capacity of 144 mA h g − 1 at 0.1C and with a capacity retention of 76% after 50 cycles, while it's only 132 mA h g − 1 and 45% for that in normal electrolyte without TMSB. The linear sweep voltammetry (LSV) and cyclic voltammetry (CV) results indicate that TMSB oxidizes preferentially to normal electrolyte and forms a stable SEI film on LiCoPO 4 surface at the first cycle which effectively reduces the electrode polarization. The electrochemical impedance spectroscopy (EIS) results reveal that the stable SEI film alleviates the growth of SEI layer on the LiCoPO 4 surface and relieves the resistance increase to facilitate Li-ion transfer the interface between electrode and electrolyte. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) reveal that a 20 nm film can be observed on the cathode surface after 50 cycles as the electrolyte containing with 1 wt% TMSB. Moreover, X-ray photoelectron spectrometer (XPS) patterns confirm that the oxidation products of TMSB participate in the SEI film formation. The enhancement of electrochemical performances is attributed to the thin and steady protective SEI film that originates from TMSB, which stabilizes the interface of the cathode and electrolyte, suppresses the continuous decomposition of normal electrolyte at 5 V high voltage and relieves the resistance increase to facilitate Li-ion transfer at the interface during the cycling process. [ABSTRACT FROM AUTHOR]

A low-cost, environment friendly and scalable strategy was proposed to prepare ZnO@graphene (ZnO@G) composites, in which ZnO nanoparticles can be evenly modified by graphene without obvious agglomeration and the tap density can reach to 1.68 g cm−3. When employed as an anode for Li-ion battery, the as-prepared ZnO@G (15 wt% graphene) exhibited an excellent reversible capacity of 720 mAh g−1 at 200 mA g−1 and 480 mAh g−1 even at 1600 mA g−1. Furthermore, a concept of high energy Li-ion full battery configurated the pre-lithiation ZnO@G (10 wt% graphene) anode and commercial LiCoO 2 and LiNi 0.8 Co 0.1 Mn 0.1 O 2 cathode was successfully assembled. Under the varying of pre-lithiation time to tune the appropriate compensating amount of initial irreversible capacity, one full battery of ZnO@G || LiCoO 2 delivered a reversible capacity around 400 mAh g−1 (vs. anode) at 100 mA g−1 with working potential around 3.8 V and a high energy density of 1478 Wh kg−1 (vs. anode; 206.9 Wh kg−1 vs. cathode); meanwhile, other full battery of ZnO@G || LiNi 0.8 Co 0.1 Mn 0.1 O 2 exhibited a reversible capacity around 280 mAh g−1 (vs. anode) at 400 mA g−1, and it possessed a high energy density of 1787.2 Wh kg−1 (vs. anode; 446.8 Wh kg−1 vs. cathode) at 400 mA g−1 and behaved superior rate capability. Furthermore, a proposition of surface multiple effect on the ZnO-based anode induced by graphene is demonstrated and it could be extended to designing some other advanced electrodes, benefiting from pre-lithiation process, the metal oxides electrode is identified to be a promising commercialized anode in high energy batteries. A composite of ZnO and graphene with difference mass ratios was fabricated by ball milling method, and it could be employed as anode towards a high energy lithium-ion full battery after a pre-lithiation treatment. Image 1 • The ZnO and graphene composites were successfully prepared by eco-friendly method. • The electrochemical properties can be revised by surface modification of graphene. • The composites show enhanced cycling stability and rate capability in Li-ion battery. • The pre-lithiation effect on initial irreversible capacity control was illuminated. • A new concept of high energy full battery was proposed and assembled. [ABSTRACT FROM AUTHOR]