Insight into the Surface Reconstruction-Induced Structure and Electrochemical Performance Evolution for Ni-Rich Cathodes with Postannealing after Washing.

Ni-rich layered LiNixCoyAlzO2 (NCA, x ≥ 0.8) oxides have attracted wide attention as cathode materials for lithium-ion batteries due to their higher energy density and lower cost. However, the increase in the capacity for Ni-rich cathodes can cause faster capacity decay and increase sensitivity to ambient air exposure during the storage process. Especially, the residual lithium on the surface of Ni-rich cathodes will cause severe flatulence during cycling which greatly reduces the safety performance of the battery. Washing is an effective method to reduce residual lithium, but it will seriously damage the surface phase structure of Ni-rich materials. Here, we introduce a designed method involving two steps, washing and high-temperature annealing, which can ingeniously modify the surface phase structure of Ni-rich cathodes. The results show that the residual lithium content can be significantly reduced. The thin NiO-like rock-salt phase formed on the surface of Ni-rich cathode annealed at 600 °C improves the diffusion kinetics of Li+, reduces the polarization, and improves the electrochemical performance of Ni-rich materials, while the thick spinel-like phase formed at 400 °C hinders the diffusion kinetics of Li+, significantly increases the polarization, and eventually leads to the structural degradation of Ni-rich materials. As a result, the discharge capacity of the cathode annealed at 600 °C still retains 174.48 mA h g-1 after 100 cycles, with a capacity retention of 92.04%, much larger than the cathode annealed at 400 °C, for which the discharge capacity drops to 107.77 mA h g-1, with a capacity retention of 65.78%.

Dual-Modified Compact Layer and Superficial Ti Doping for Reinforced Structural Integrity and Thermal Stability of Ni-Rich Cathodes.

Nickel-rich layered oxides have been regarded as a potential cathode material for high-energy-density lithium-ion batteries because of the high specific capacity and low cost. However, the rapid capacity fading due to interfacial side reactions and bulk structural degradation seriously encumbers its commercialization. Herein, a highly stable hybrid surface architecture, which integrates an outer coating layer of TiO2&Li2TiO3 and a surficial titanium doping by incorporated Ti2O3, is carefully designed to enhance the structural stability and eliminate lithium impurity. Meanwhile, the surficial titanium doping induces a nanoscale cation-mixing layer, which suppresses transition-metal-ion migration and ameliorates the reversibility of the H2 → H3 phase transition. Also, the Li2TiO3 coating layer with three-dimensional channels promotes ion transportation. Moreover, the electrochemically stable TiO2 coating layer restrains side reactions and reinforces interfacial stability. With the collaboration of titanium doping and TiO2&Li2TiO3 hybrid coating, the sample with 1 mol % modified achieves a capacity retention of 93.02% after 100 cycles with a voltage decay of only 0.03 V and up to 84.62% at a high voltage of 3.0-4.5 V. Furthermore, the ordered occupation of Ni ions in the Li layer boosts the thermal stability by procrastinating the layered-to-rock salt phase transition. This work provides a straightforward and economical modification strategy for boosting the structural and thermal stability of nickel-rich cathode materials.

Interfacial Regulation of Ni-Rich Cathode Materials with an Ion-Conductive and Pillaring Layer by Infusing Gradient Boron for Improved Cycle Stability.

Ni-rich cathodes LiNixCoyAl1-x-yO2 (0.8 < x < 1) with high energy density, environmental benignity, and low cost are regarded as the most promising candidate materials for next-generation lithium batteries. Unfortunately, capacity fading derived from unstable surface properties and intrinsic structural instability under extreme conditions limits large-scale commercial utilization. Herein, an interface-regulated Ni-rich cathode material LiNi0.87Co0.10Al0.03O2 with a layer (R3̅m) core, a NiO salt-like (Fm3̅m) phase, and an ultrathin amorphous ion-conductive LiBO2 (LBO) layer is constructed by gradient boron incorporation and lithium-reactive coating during calcination. The ultrathin LBO layer not only exhausts residual lithium species but also acts as a layer for Li+ transport and insulation of detrimental reaction. The NiO salt-like phase in the subsurface could enhance the structural stability of the layer core for the pillar effects. With the positive role provided by the functional hybrid surface layer and boron doping, the modified cathode exhibits enhanced Li+ conductivity, structural stability, reversibility of the H2-H3 phase transition, suppressed side reactions, ameliorated transition-metal dissolution, and excellent electrochemical performance. Especially, a 1% wt boron-modified cathode delivers a discharge capacity of 211.99 mA h g-1 in the potential range of 3.0-4.3 V at 0.2 C and excellent cycle life with a capacity retention of 89.43% after 200 cycles at 1 C.

Dual Elements Coupling Effect Induced Modification from the Surface into the Bulk Lattice for Ni-Rich Cathodes with Suppressed Capacity and Voltage Decay.

Injection of phase transition from a layered to rock-salt phase into the bulk lattice and side reactions on the interfacial usually causes structure degradation, quick capacity/voltage decay, and even thermal instability. Here, a self-formed interfacial protective layer coupled with lattice tuning was constructed for Ni-rich cathodes by simultaneous incorporation of Zr and Al in a one-step calcination. The migration energy between Zr and Al from the surface into the bulk lattice induces dual modifications from the surface into the bulk lattice, which effectively decrease the formation of cation mixing, the degree of anisotropic lattice change, and the generation of microcracks. With the stabilization role provided by the doped Zr-Al ions and protective function endowed by the surface layer, the modified cathode material exhibits significantly enhanced capacity and voltage retention. Specifically, the capacity retention for the modified cathode material reaches 99% after 100 cycles at 1 C and 25 °C in a voltage range of 3.0-4.3 V, which outperformed that for the pristine cathode (70%). The declination values of the average voltage for the modified cathode are only 0.025 and 0.097 V after 100 cycles at 1 C in voltage ranges of 3.0-4.3 and 2.8-4.5 V, respectively, which are much lower than those for the pristine cathode (0.230 and 0.405 V). The synchronous accomplishment of modification from the surface into the bulk lattice for Ni-rich materials with multiple elements in a one-step calcination process would provide some referenced value for the preparation of other cathode materials.

Engineering and characterization of a baculovirus-expressed mouse/human chimeric antibody against transferrin receptor.

Transferrin receptor (TfR) has been explored as a target for antibody-based therapy of cancer. In the previous study, we reported a murine anti-TfR monoclonal antibody (mAb) 7579 had good anti-tumor activities in vitro. In an attempt to reduce its immunogenicity and enhance its ability to recruit immune effector mechanism in vivo, we herein developed its chimera in the baculovirus/insect cell expression system based on the mating-assisted genetically integrated cloning (MAGIC) strategy. The chimeric light and heavy chains, containing human IgG1 constant regions, were correctly processed and assembled in insect cells, and then secreted into the mediums as heterodimeric H(2)L(2) immunoglobulins. Furthermore, analyses of antigen-binding assay and competitive binding assay indicated that the chimeric antibody possessed specificity and affinity similar to that of its parental murine antibody. Results of the antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC) assay verified that the chimeric antibody could efficiently mediate ADCC and CDC against TfR-overexpressing tumor cells. These results suggested that this baculovirus-expressed chimeric anti-TfR IgG1 might have the potential to be used for cancer immunotherapy. Meanwhile, the MAGIC strategy, facilitating the rapid generation of chimeric mAbs, could be one of the efficient strategies for antibody engineering.

B7-H4 transfection prolongs beta-cell graft survival.

B7-H4, a recently discovered member of B7 family, can negatively regulate T cell responses. However, it is not clear whether B7-H4 negatively function in cell transplantation. In this study we investigated the immunosuppressive effect of B7-H4 on beta-cell transplantation. An insulinoma cell line, NIT-1, transfected with B7-H4 (B7-H4-NIT) was established, and transplanted to diabetic C57BL/6 mice by intraperitoneal injection. Proliferation assay of splenocytes in vitro showed that B7-H4-NIT suppressed alloreactive T cell activation. The proportion of IFN-gamma-producing cells in recipient spleen was significantly reduced and the number of Treg cells was upregulated in B7-H4-NIT group compared to the control, EGFP-NIT. The expression of mRNA coding IFN-gamma was lower but that of IL-4 was higher in B7-H4-NIT transplanted recipients than in the control animals. The results of ELISA also revealed the same trends. Diabetic mice reached normalglycemic quickly and gained weight after transplantation of B7-H4-NIT. More importantly, the survival time for recipients transplanted with B7-H4-NIT cells was significantly longer than that with EGFP-NIT cells. These results indicate that B7-H4 transfection prolongs beta-cell graft survival.

An anti-transferrin receptor antibody enhanced the growth inhibitory effects of chemotherapeutic drugs on human non-hematopoietic tumor cells.

Transferrin receptor (TfR) has been used as a target for antibody-based therapy of cancer. Combining anti-TfR antibodies with chemotherapeutic drugs shows potential as one of the strategies for cancer therapy. In this study, we investigated the effects of anti-TfR monoclonal antibody 7579 alone or in combination with chemotherapeutic drugs (5-fluorouracil or doxorubicin) on non-hematopoietic tumor cells (HepG2 and MCF-7) in vitro. We found that 7579 mAb alone could dramatically down-regulate surface TfR expression on tumor cells. Consequently, marked S phase arrest and apoptosis were observed in 7579 mAb-treated tumor cells. In combination with 5-fluorouracil or doxorubicin, 7579 mAb enhanced the growth inhibitory effects of chemotherapeutic drugs on tumor cells. Results of 7AAD/Annexin V staining demonstrated that 7579 mAb enhanced the cytotoxic effects of chemotherapeutic drugs on tumor cells by mainly promoting tumor cell necrosis. Using the median-effect/combination-index isobologram method, we further evaluated the nature of 7579 mAb/chemotherapeutic drug interactions. Synergistic interaction was observed for 7579 mAb combined with 5-fluorouracil whereas additive efficacy was observed for 7579 mAb plus doxorubicin. Our study provided the basis to further develop 7579 mAb-containing chemoimmunotherapy for non-hematopoietic malignancies.