Construction of 3D Electronic/Ionic Conduction Networks for All-Solid-State Lithium Batteries.

High and balanced electronic and ionic transportation networks with nanoscale distribution in solid-state cathodes are crucial to realize high-performance all-solid-state lithium batteries. Using Cu2 SnS3 as a model active material, such a kind of solid-state Cu2 SnS3 @graphene-Li7 P3 S11 nanocomposite cathodes are synthesized, where 5-10 nm Cu2 SnS3 nanoparticles homogenously anchor on the graphene nanosheets, while the Li7 P3 S11 electrolytes uniformly coat on the surface of Cu2 SnS3 @graphene composite forming nanoscaled electron/ion transportation networks. The large amount of nanoscaled triple-phase boundary in cathode ensures high power density due to high ionic/electronic conductions and long cycle life due to uniform and reduced volume change of nano-Cu2 SnS3. The Cu2 SnS3 @graphene-Li7 P3 S11 cathode layer with 2.0 mg cm-2 loading in all-solid-state lithium batteries demonstrates a high reversible discharge specific capacity of 813.2 mAh g-1 at 100 mA g-1 and retains 732.0 mAh g-1 after 60 cycles, corresponding to a high energy density of 410.4 Wh kg-1 based on the total mass of Cu2 SnS3 @graphene-Li7 P3 S11 composite based cathode. Moreover, it exhibits excellent rate capability and high-rate cycling stability, showing reversible capacity of 363.5 mAh g-1 at 500 mA g-1 after 200 cycles. The study provides a new insight into constructing both electronic and ionic conduction networks for all-solid-state lithium batteries.

High-Energy All-Solid-State Lithium Batteries with Ultralong Cycle Life.

High energy and power densities are the greatest challenge for all-solid-state lithium batteries due to the poor interfacial compatibility between electrodes and electrolytes as well as low lithium ion transfer kinetics in solid materials. Intimate contact at the cathode-solid electrolyte interface and high ionic conductivity of solid electrolyte are crucial to realizing high-performance all-solid-state lithium batteries. Here, we report a general interfacial architecture, i.e., Li7P3S11 electrolyte particles anchored on cobalt sulfide nanosheets, by an in situ liquid-phase approach. The anchored Li7P3S11 electrolyte particle size is around 10 nm, which is the smallest sulfide electrolyte particles reported to date, leading to an increased contact area and intimate contact interface between electrolyte and active materials. The neat Li7P3S11 electrolyte synthesized by the same liquid-phase approach exhibits a very high ionic conductivity of 1.5 × 10-3 S cm-1 with a particle size of 0.4-1.0 µm. All-solid-state lithium batteries employing cobalt sulfide-Li7P3S11 nanocomposites in combination with the neat Li7P3S11 electrolyte and Super P as the cathode and lithium metal as the anode exhibit excellent rate capability and cycling stability, showing reversible discharge capacity of 421 mAh g-1 at 1.27 mA cm-2 after 1000 cycles. Moreover, the obtained all-solid-state lithium batteries possesses very high energy and power densities, exhibiting 360 Wh kg-1 and 3823 W kg-1 at current densities of 0.13 and 12.73 mA cm-2, respectively. This contribution demonstrates a new interfacial design for all-solid-state battery with high performance.

Modulation of the interfacial architecture enhancing the efficiency and energy density of ferroelectric nanocomposites via the irradiation method.

Flexible dielectric materials such as poly(vinylidene fluoride)-based nanocomposites with high energy density are employed for applications in modern electronic and electric systems. In this study, we improve traditional methods by optimizing the interfacial structure, achieving a 34% increase in energy density without reduced discharge efficiency. Herein, a simple solution-cast method is used to prepare poly(vinylidene fluoride-co-trifluoroethylene) nanocomposites filled by γ-methacryloyl-propyltrimethoxysilane (MPMS) grafting barium titanate nanoparticles, forming a class of cross-linking networks by irradiation. More additional interfaces arising from irradiation cross-linking give rise to high discharge energy density, and the small crystalline domain and cross-linking network enhance the charge-discharge efficiency. Furthermore, we find two types of cross-linking centers on the network. One is more beneficial to energy density, and the other is more beneficial to efficiency. Regulating two types of cross-linking centers can balance efficiency and energy density. In summary, this work provides a promising strategy for exploiting advanced flexible dielectric materials to meet application requirements.

Engineering a Robust Interface on Ni-Rich Cathodes via a Novel Dry Doping Process toward Advanced High-Voltage Performance.

Ni-rich layered oxides have become the main force of cathode materials for EV cells with high energy density owing to their satisfactory theoretical capacity, cost-effectiveness, and low toxicity. However, the high-voltage stability of Ni-rich cathode materials still has not fulfilled the demand of power batteries due to their intrinsic structural and electrochemical instability. The commonly used modification procedures are achieved via a wet process, which may lead to surface lithium-ion deficiency, phase change, and high costs during manufacturing. Herein, we construct a multifunctional Ti-based interfacial architecture on the surface of LiNi0.6Co0.2Mn0.2O2 (NCM) cathode materials via a novel dry interface modifying process in which no solvent is employed. The Ti-based interfacial architecture accelerates the transportation of lithium ions and consequently stabilizes the interfacial structure. This approach significantly improves the cycling stability in half cells, with a 15% increase in capacity retention over 100 cycles at 1 C under a high voltage of 4.5 V. Impressively, few internal cracks are observed in a modified sample after 500 times of charge and discharge between 2.75 and 4.35 V at 1 C rate, and the capacity retention can reach 93%.

Core-Shell Fe1- xS@Na2.9PS3.95Se0.05 Nanorods for Room Temperature All-Solid-State Sodium Batteries with High Energy Density.

High ionic conductivity electrolyte and intimate interfacial contact are crucial factors to realize high-performance all-solid-state sodium batteries. Na2.9PS3.95Se0.05 electrolyte with reduced particle size of 500 nm is first synthesized by a simple liquid-phase method and exhibits a high ionic conductivity of 1.21 × 10-4 S cm-1, which is comparable with that synthesized with a solid-state reaction. Meanwhile, a general interfacial architecture, that is, Na2.9PS3.95Se0.05 electrolyte uniformly anchored on Fe1- xS nanorods, is designed and successfully prepared by an in situ liquid-phase coating approach, forming core-shell structured Fe1- xS@Na2.9PS3.95Se0.05 nanorods and thus realizing an intimate contact interface. The Fe1- xS@Na2.9PS3.95Se0.05/Na2.9PS3.95Se0.05/Na all-solid-state sodium battery demonstrates high specific capacity and excellent rate capability at room temperature, showing reversible discharge capacities of 899.2, 795.5, 655.1, 437.9, and 300.4 mAh g-1 at current densities of 20, 50, 100, 150, and 200 mA g-1, respectively. The obtained all-solid-state sodium batteries show very high energy and power densities up to 910.6 Wh kg-1 and 201.6 W kg-1 based on the mass of Fe1- xS at current densities of 20 and 200 mA g-1, respectively. Moreover, the reaction mechanism of Fe1- xS is confirmed by means of ex situ X-ray diffraction techniques, showing that partially reversible reaction occurs in the Fe1- xS electrode after the second cycle, which gives the obtained all-solid-state sodium battery an exceptional cycling stability, exhibiting a high capacity of 494.3 mAh g-1 after cycling at 100 mA g-1 for 100 cycles. This contribution provides a strategy for designing high-performance room temperature all-solid-state sodium battery.