Fenghua Zheng

Nanoscale Surface Modification of Lithium‐Rich Layered‐Oxide Composite Cathodes for Suppressing Voltage Fade

Lithium-rich layered oxides are promising cathode materials for lithium-ion batteries and exhibit a high reversible capacity exceeding 250 mAh g(-1) . However, voltage fade is the major problem that needs to be overcome before they can find practical applications. Here, Li1.2 Mn0.54 Ni0.13 Co0.13 O2 (LLMO) oxides are subjected to nanoscale LiFePO4 (LFP) surface modification. The resulting materials combine the advantages of both bulk doping and surface coating as the LLMO crystal structure is stabilized through cationic doping, and the LLMO cathode materials are protected from corrosion induced by organic electrolytes. An LLMO cathode modified with 5 wt % LFP (LLMO-LFP5) demonstrated suppressed voltage fade and a discharge capacity of 282.8 mAh g(-1) at 0.1 C with a capacity retention of 98.1 % after 120 cycles. Moreover, the nanoscale LFP layers incorporated into the LLMO surfaces can effectively maintain the lithium-ion and charge transport channels, and the LLMO-LFP5 cathode demonstrated an excellent rate capacity.

Enhancing Sodium Ion Battery Performance by Strongly Binding Nanostructured Sb2S3 on Sulfur-Doped Graphene Sheets

Sodium ion batteries (SIBs) have been considered a promising alternative to lithium ion batteries for large-scale energy storage. However, their inferior electrochemical performances, especially cyclability, become the major challenge for further development of SIBs. Large volume change and sluggish diffusion kinetics are generally considered to be responsible for the fast capacity degradation. Here we report the strong chemical bonding of nanostructured Sb2S3 on sulfur-doped graphene sheets (Sb2S3/SGS) that enables a stable capacity retention of 83% for 900 cycles with high capacities and excellent rate performances. To the best of our knowledge, the cycling performance of the Sb2S3/SGS composite is superior to those reported for any other Sb-based materials for SIBs. Computational calculations demonstrate that sulfur-doped graphene (SGS) has a stronger affinity for Sb2S3 and the discharge products than pure graphene, resulting in a robust composite architecture for outstanding cycling stability. Our study shows a feasible and effective way to solve the long-term cycling stability issue for SIBs.

V5S8–graphite hybrid nanosheets as a high rate-capacity and stable anode material for sodium-ion batteries

Here we report chemically-exfoliated V5S8 and graphite hybrid nanosheets (ce-V5S8–C) as a novel anode material for sodium-ion batteries (SIBs). It exhibits much improved sodiation capacity, rate capability, reversibility and stability compared to other major SIB anode materials.

Surface Modification of Na3V2(PO4)3 by Nitrogen and Sulfur Dual-Doped Carbon Layer with Advanced Sodium Storage Property

Nitrogen and sulfur dual-doped carbon layer wrapped Na3V2(PO4)3 nanoparticles (NVP@NSC) have been successfully fabricated by the facile solid-state method. In this hierarchical structure, the Na3V2(PO4)3 nanoparticles are well dispersed and closely coated by nitrogen and sulfur dual-doped carbon layer, constructing an effective and interconnected conducting network to reduce the internal resistance. Furthermore, the uniform coating layers alleviate the agglomeration of Na3V2(PO4)3 as well as mitigate the side reaction between electrode and electrolyte. Because of the excellent electron transfer mutually enhancing sodium diffusion for this extraordinary structure, the NVP@NSC composite delivers an impressive discharge capacity of 113.0 mAh g-1 at 1 C and shows a capacity retention of 82.1% after 5000 cycles at an ultrahigh rate of 50 C, suggesting the remarkable rate capability and long cyclicity. Surprisingly, a reversible capacity of 91.1 mAh g-1 is maintained after 1000 cycles at 5 C under the elevated temperature of 55 °C. The approach of nitrogen and sulfur dual-doped carbon-coated Na3V2(PO4)3 provides an effective and promising strategy to enhance the ultrahigh rate and ultralong life property of cathode, which can be used for large-scale commercial production in sodium ion batteries.

Sn-MoS2-C@C Microspheres as a Sodium-Ion Battery Anode Material with High Capacity and Long Cycle Life

Sodium ion batteries (SIBs) have been regarded as a prime candidate for large-scale energy storage, and developing high performance anode materials is one of the main challenges for advanced SIBs. Novel structured Sn-MoS2 -C@C microspheres, in which Sn nanoparticles are evenly embedded in MoS2 nanosheets and a thin carbon film is homogenously engineered over the microspheres, have been fabricated by the hydrothermal method. The Sn-MoS2 -C@C microspheres demonstrate an excellent Na-storage performance as an anode of SIBs and deliver a high reversible charge capacity (580.3 mAh g-1 at 0.05 Ag-1 ) and rate capacity (580.3, 373, 326, 285.2, and 181.9 mAh g-1 at 0.05, 0.5, 1, 2, and 5 Ag-1 , respectively). A high charge specific capacity of 245 mAh g-1 can still be achieved after 2750 cycles at 2 Ag-1 , indicating an outstanding cycling performance. The high capacity and long-term stability make Sn-MoS2 -C@C composite a very promising anode material for SIBs.

MoS2-covered SnS nanosheets as anode material for lithium-ion batteries with high capacity and long cycle life

A designed hierarchical nanostructure consisting of SnS nanosheets and ultrathin MoS2 nanosheets was achieved by a facile hydrothermal process with the assistance of fluoride and glucose. In this unique architecture, on the one hand, SnS and MoS2 nanosheets can greatly reduce the Li-ion and electron diffusion distance in the electrode. On the other hand, MoS2 nanosheets and amorphous carbon can not only prevent the direct exposure of SnS to the electrolyte but also maintain the structural stability of the electrode. In addition, the MoS2 nanosheets can offer more active sites for hosting lithium ions, resulting in higher capacity. When evaluated as anode material for lithium-ion batteries (LIBs), this SnS/MoS2–C composite exhibited stable cycling performance (989.7 mA h g−1 at 0.2 A g−1 after 60 cycles), superior rate capability (675 mA h g−1 even at 5.0 A g−1) and a long cycle life (718 mA h g−1 at 2.0 A g−1 after 700 cycles). Therefore, this SnS/MoS2–C composite is a promising candidate as anode material for next-generation high-performance LIBs.

N/S Co-doped Carbon Derived From Cotton as High Performance Anode Materials for Lithium Ion Batteries

Highly porous carbon with large surface areas is prepared using cotton as carbon sources which derived from discard cotton balls. Subsequently, the sulfur-nitrogen co-doped carbon was obtained by heat treatment the carbon in presence of thiourea and evaluated as Lithium-ion batteries anode. Benefiting from the S, N co-doping, the obtained S, N co-doped carbon exhibits excellent electrochemical performance. As a result, the as-prepared S, N co-doped carbon can deliver a high reversible capacity of 1,101.1 mA h g−1 after 150 cycles at 0.2 A g−1, and a high capacity of 531.2 mA h g−1 can be observed even after 5,000 cycles at 10.0 A g−1. Moreover, excellently rate capability also can be observed, a high capacity of 689 mA h g−1 can be obtained at 5.0 A g−1. This superior lithium storage performance of S, N co-doped carbon make it as a promising low-cost and sustainable anode for high performance lithium ion batteries.

High pyridine N-doped porous carbon derived from metal–organic frameworks for boosting potassium-ion storage

Potassium ion batteries (PIBs) have been regarded as promising energy storage devices for large-scale energy storage owing to the abundance of potassium resources. In this work, high pyridine N-doped porous carbon synthesized at 600 °C (NPC-600) derived from metal–organic frameworks (MOFs) has been fabricated and employed as the anode material for PIBs. NPC-600 can deliver a high reversible specific capacity (587.6 mA h g−1 at 50 mA g−1), outstanding rate properties (186.2 mA h g−1 at 2 A g−1) and cycling performance (231.6 mA h g−1 at 500 mA g−1 after 2000 cycles). This excellent electrochemical performance could be attributed to the increased amounts of pyridine N and neglectable change of the interlayer space during the potassiation/depotassiation process of NPC-600, which can provide additional adsorption sites to “capture” more K ions and ensure structural stability. This simple synthesis approach and unique structure make NPCs a promising candidate for next generation rechargeable PIBs.

Nitrogen-doped bamboo-like carbon nanotubes as anode material for high performance potassium ion batteries

Potassium ion batteries (KIBs) have attracted tremendous attention because of the abundance of potassium resources and the applicability of carbonaceous materials for use as anodes, which indicates that the manufacturing techniques of lithium ion batteries can be directly transferred to KIBs. However, the huge volume change during the potassiation/depotassiation process, and the poor kinetics of the large K+ ions seriously restrict the electrochemical performance of graphite because the K+ ions are squeezed into the restricted interlayer spacing. Compared with well-crystallized graphite, amorphous carbon has a more flexible structure, but its capacity contribution is mainly dependent on a capacitive storage mechanism. Therefore, finding a carbon material with a suitable degree of graphitization and structure is necessary to achieve superior electrochemical properties. In the research reported in this paper, nitrogen-doped bamboo-like carbon nanotubes composed of amorphous carbon and discontinuous graphene layers with a porous hollow structure were prepared. Benefiting from its unique structure, this material delivered a high, reversible capacity of 204 mA h g−1 at 500 mA g−1 after 1000 cycles, and exhibited a remarkable rate capability of 186 mA h g−1 at 1000 mA g−1.