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In solid-state electrolytes, the large resistance at grain boundaries remains the bottleneck for high ionic conductivity. Here we develop an alternative and somewhat counterintuitive strategy to enhance their ionic conductivity via non-equilibrium microstructure. Using Li1.4Al0.4Ti1.6(PO4)3as an example, we demonstrate that semi-crystalline interphase between well crystallized ceramic phase and amorphous glass phase can be induced by spark plasma sintering, resulting in total ionic conductivity of 1.3 × 10−3S cm−1without any doping, which is 2 orders of magnitude higher than that derived by the conventional method. It is further demonstrated that the non-equilibrium structure is stable in ambient condition, yet can be converted into equilibrium structure by annealing with higher crystallinity but much lower ionic conductivity, proving that the non-equilibrium structure is indeed the key to the high performance. This opens door for its applications in electric vehicles, and the strategy is applicable to other ionic systems as well.

LiFePO4is one of the most outstanding cathodes for the high performance lithium-ion battery, while it is restricted by its unsatisfactory low temperature performance. Here we detect the structural dynamics and reaction routes of LiFePO4via operando condition with high rates, well reproducibility over cycles and low temperature in common laboratory X-ray without the synchrotron light source. The intermediate phases between LiFePO4and FePO4, driven by the overpotential and limited ion transfer rate along the bdirection at low temperature, are captured. Our results demonstrate that the existence of intermediate can greatly improve the diffusion kinetics of LiFePO4. The deep understanding of reaction routes of LiFePO4at low temperature will guide the further material optimization design. Besides LiFePO4, such high time resolution in-situX-ray diffraction testing method with laboratory source is available to understand the reaction mechanisms of other electrochemical reaction system.

Lack of suitable ion channels and low electronic conductivity hinder MnO2as an anode material for lithium-ion batteries. Multiple ion channels rapidly and selectively gate ion transport to maintain superior energy storage. We report a mesoporous N-doped C modified MnO2hollow nanotube with multiple Li-ion transport channels. When used as Li-ion batteries anode, due to multichannel ion transport of mesoporous N-doped C modified MnO2, the diffusion coefficient of Li+reaches ~ 10−8cm2s−1. And the batteries show excellent specific capacity (as high as 468.4 mA h g−1at 5 A g−1), superior rate capability (the current density from 100 A g−1to 5 A g−1), good cycling ability (preserving ~92.5% capacity after 10000 cycles). Our multiple ion channels design contributes a novel idea for preparing outstanding comprehensive performance anode materials for lithium-ion batteries.

High-speed electron transfer channels and short Li ion transport distance are beneficial to improvement of Li ion battery properties. Here, a two-step solution phase synthesis method is developed to construct the V2O5quantum dots/graphene hybrid nanocomposite by controlling nucleation and growth processes. It is demonstrated that the V2O5quantum dots with an average size of 2-3 nm are uniformly anchored on the graphene sheets. The specific capacity can achieve 212mAhg−1at 100mAg−1after 100 cycles. Significantly, the novel V2O5quantum dots/graphene shows a stable cycling performance with 89% capacity retention after 300 cycles. The improvement in electrochemical properties could be attributed to the short Li ion transfer distance, two-dimensional electron channels, homogeneous dispersion and immobilization of V2O5quantum dots. Meanwhile, it indicates that V2O5quantum dots/graphene is promising cathode material for use in long-life rechargeable lithium batteries. This design conception and synthesis strategy for V2O5could also be extended to other electrode material systems.