Bacteria-Derived Biological Carbon Building Robust Li-S Batteries.

Lithium sulfur (Li-S) batteries are attracting increasing interest for high-density energy storage. However, the practical application is limited by the rapid capacity fading over repeated charge/discharge cycles which is largely attributed to the formation and shuttling of soluble polysulfide species. To address these issues, we develop a hierarchical structure composite with triple protection strategy via graphene, organic conductor PEDOT, and nitrogen and phosphorus codoped biological carbon to encapsulate sulfur species (GOC@NPBCS). This unique hierarchical structure can effectively immobilize the sulfur species while at the same time improve the electrical conductivity and ensure efficient lithium ion transport to enable excellent Li-S battery performance. In particular, the biological carbon derived from natural bacteria features inherent nitrogen and phosphorus codoping with a strong absorption to lithium polysulfides, which can greatly suppress the dissolution and shuttling of polysulfides that are responsible for rapid capacity fading. With these synergistic effects, the GOC@NPBCS cathode exhibits exceptionally stable cycling stability (an ultralow capacity fading rate of 0.045% per cycle during 1000 cycles at the current rate of 5 C), high specific capacity (1193.8 mAh g-1 at 0.5 C based on sulfur weight), and excellent rate capability.

In Situ Alloying Strategy for Exceptional Potassium Ion Batteries.

We report an in situ alloying strategy for obtaining homogeneous (Bi,Sb) alloy nanoparticles from (Bi,Sb)2S3 nanotubes for the exceptional anode of potassium ion batteries (KIBs). The operando X-ray diffraction results, along with transmission electron microscopy and energy-dispersive X-ray spectroscopy mappings, successfully reveal the phase evolution of this material, which is (Bi,Sb)2S3 → (Bi,Sb) → K(Bi,Sb) → K3(Bi,Sb) during the initial discharge and K3(Bi,Sb) → K(Bi,Sb) → (Bi,Sb) in the charging process. The in situ alloying strategy produces a synergistic effect and brings an outstanding electrochemical performance. It achieves ultrahigh discharge capacities of 611 mAh g-1 at 100 mA g-1 (0.135C) and 300 mAh g-1 at 1000 mA g-1 (1.35C) and retains a capacity as high as 353 mAh g-1 after 1000 cycles at 500 mA g-1 (0.675C) with a Coulombic efficiency close to 100%. In addition, the KIBs full cell, which is composed of this anode and a perylenetetracarboxylic dianhydride cathode, reaches an initial discharge capacity as high as 276 mAh g-1 at 500 mA g-1 and maintains 207 mAh g-1 after 100 cycles.

Nature of Bimetallic Oxide Sb2MoO6/rGO Anode for High-Performance Potassium-Ion Batteries.

Potassium-ion batteries (KIBs) are one of the most appealing alternatives to lithium-ion batteries, particularly attractive in large-scale energy storage devices considering the more sufficient and lower cost supply of potassium resources in comparison with lithium. To achieve more competitive KIBs, it is necessary to search for anode materials with a high performance. Herein, the bimetallic oxide Sb2MoO6, with the presence of reduced graphene oxide, is reported as a high-performance anode material for KIBs in this study, achieving discharge capacities as high as 402 mAh g-1 at 100 mA g-1 and 381 mAh g-1 at 200 mA g-1, and reserving a capacity of 247 mAh g-1 after 100 cycles at a current density of 500 mA g-1. Meanwhile, the potassiation/depotassiation mechanism of this material is probed in-depth through the electrochemical characterization, operando X-ray diffraction, transmission electron microscope, and density functional theory calculation, successfully unraveling the nature of the high-performance anode and the functions of Sb and Mo in Sb2MoO6. More importantly, the phase development and bond breaking sequence of Sb2MoO6 are successfully identified, which is meaningful for the fundamental study of metal-oxide based electrode materials for KIBs.

Graphene Armored with a Crystal Carbon Shell for Ultrahigh-Performance Potassium Ion Batteries and Aluminum Batteries.

Graphene is of great significance in energy storage devices. However, a graphene-based electrode is difficult to use in direct applications due to the large surface area and flexibility, which leads to the excessive consumption of electrolyte, low Coulombic efficiency, and electrode shedding behaviors. Herein, a special crystal carbon@graphene microsphere (CCGM) composite was successfully synthesized. The scalable carbonaceous microsphere composite displays a small specific surface area and a superior structure stability. As a potassium ion battery electrode in a half-cell, CCGM delivers an initial capacity of 297.89 mAh g-1 with a high Coulombic efficiency of about 99%. It achieves an excellent cyclic stability with no capacity loss after 1250 cycles at the low current density of 100 mA g-1 with a long performing period of more than one year. As the cathode for an aluminum battery, a reversible specific capacity of 99.1 mAh g-1 at 1000 mA g-1 is obtained. CCGM delivers a long cycle performance of about 10 000 cycles at 4000 mA g-1 with a capacity retention of nearly 100%. Our design provides a fresh thought for the improvement of graphene-based materials, and it will greatly facilitate the application of graphene in the field of energy storage.

An Ultrafast and Highly Stable Potassium-Organic Battery.

Potassium-organic batteries have a great potential for applications in the grid-scale energy storage owing to their low cost and abundant resources, although they suffer from the inferior cycle stability, fast capacity decay, and low power density. A highly reversible phase transformation of the organic cathode during potassiation/depotassiation is the key factor for the capacity retention, as revealed here. Consequently, the potassium-organic battery achieves a high power density of 9796 W kg-1 , a remarkable energy efficiency of 89%, a long cycle stability for 1000 cycles, a superior areal capacity around 2 mA h cm-2 , and a long-term cycling time over 8 months. Besides, the full cells also exhibit a superior rate performance and good cycle stability over 3000 cycles. This work provides new insight into the stabilization of the organic cathode, and demonstrates the enormous potential of organic cathodes for application in high-power potassium-ion batteries (PIBs), which may bring PIBs to new heights.

Offset Initial Sodium Loss To Improve Coulombic Efficiency and Stability of Sodium Dual-Ion Batteries.

Sodium dual-ion batteries (NDIBs) are attracting extensive attention recently because of their low cost and abundant sodium resources. However, the low capacity of the carbonaceous anode would reduce the energy density, and the formation of the solid-electrolyte interphase (SEI) in the anode during the initial cycles will lead to large amount consumption of Na+ in the electrolyte, which results in low Coulombic efficiency and inferior stability of the NDIBs. To address these issues, a phosphorus-doped soft carbon (P-SC) anode combined with a presodiation process is developed to enhance the performance of the NDIBs. The phosphorus atom doping could enhance the electric conductivity and further improve the sodium storage property. On the other hand, an SEI could preform in the anode during the presodiation process; thus the anode has no need to consume large amounts of Na+ to form the SEI during the cycling of the NDIBs. Consequently, the NDIBs with P-SC anode after the presodiation process exhibit high Coulombic efficiency (over 90%) and long cycle stability (81 mA h g-1 at 1000 mA g-1 after 900 cycles with capacity retention of 81.8%), far more superior to the unsodiated NDIBs. This work may provide guidance for developing high performance NDIBs in the future.

Super long-life potassium-ion batteries based on an antimony@carbon composite anode.

A highly stable Sb based anode material of well-confined Sb@graphene@carbon (Sb@G@C) was developed for high performance PIBs. The Sb@G@C electrode exhibits a reversible capacity of 474 mA h g-1 at 100 mA g-1 (second charge), an outstanding long cycle stability over 800 cycles with a capacity retention as high as 72.3% and an excellent rate performance.