Strategy of Enhancing the Volumetric Energy Density for Lithium–Sulfur Batteries

Abstract

ising candidates for the next generation of high energy storage system. Since proposed in the 1960s, [3] Li-S battery experienced an infancy stage in 1970-1990s, when researchers devoted to the fundamental redox reactions of sulfur in various electrolytes, [4] and a flourishing period after 2000 when high performance was achieved through sulfur/carbon (S/C) cathode and sulfurized-polyacrylonitrile (SPAN) cathode in ether-and carbonatebased electrolytes, respectively. [5] After 2009, great efforts have been made to further enahnce Li-S battery, including fabricating conductive cathode, [6] incorporating electrocatalyst, [7] modifying separator, [8] optimizing electrolyte, [9] and protecting lithium anodes. [10] The rational design of electrode structure with various carbon materials (1D, 2D, and 3D) greatly boosts the electrochemical performance of sulfur cathode. [11] Although the cycle stability is still struggling with 100 cycles, the gravimetric energy density (W G) of Li-S pouch cells has improved remarkably to promote the applications in which weight matters more than longevity. For example, Sion Power, a pioneer corporation in Li-S battery technology, has developed several prototypical Li-S cells with energy density of 350 Wh kg −1 /325 Wh L −1 for powering Airbus's Zephyr 7 drone for an 11-day nonstop flight in 2014. [12] Oxis Energy, another manufacture of Li-S battery, announced a new target of 500 Wh kg −1 in the near future after achieving 400 Wh kg −1 / 300 Wh L −1 for e-Buses, trucks, and marine applications. [13] Research institutions from China have also reported pouch Li-S cells with the energy density up to 400-600 Wh kg −1 for the potential application in unmanned aerial vehicle. [14] It is remarkable that the W G of Li-S battery has exceeded that of the best Li-ion batteries (250-300 Wh kg −1) with Ni-rich oxide cathode from Contemporary Amperex Technology Co., Ltd. (CATL), a giant manufacture of Li-ion batteries (Figure 1). With such great advantages, Li-S battery is possible to compete with commercial Li-ion batteries in specific field where high W G is the primary concern. Despite the attractive high W G , Li-S battery pales in comparison with Li-ion batteries in terms of volumetric energy density (W V). [18] Figure 1 compares W V and W G between Li-S and Li-ion batteries. With Ni-rich metal oxide as cathode, Li-ion batteries have already reached 700 Wh L −1 and can even exceed 1000 Wh L −1 for W V when coupling with high capacity Lithium-sulfur (Li-S) batteries hold the promise of the next generation energy storage system beyond state-of-the-art lithium-ion batteries. Despite the attractive gravimetric energy density (W G), the volumetric energy density (W V) still remains a great challenge for the practical application, based on the primary requirement of Small and Light for Li-S batteries. This review highlights the importance of cathode density, sulfur content, electroactivity in achieving high energy densities. In the first part, key factors are analyzed in a model on negative/positive ...

A Powerful One‐Step Puffing Carbonization Method for Construction of Versatile Carbon Composites with High‐Efficiency Energy Storage

“…[5][6][7][8] Currently, the scientific community is still eager for advanced carbon-based materials to achieve higher efficiency and better utilization of green energy. [9][10][11][12][13] To date, various carbonaceous materials (e.g., graphene, [14][15][16][17][18] carbon nanotubes, [19,20] C 60 , [21] carbon quantum dots [22] and carbon micro/nanofibers [23] ) and their composites have been explored and prepared by different methods including chemical vapor deposition, [23,24] chemical or electrochemical exfoliation, [25] and electrospinning, [26,27] but it is still a great challenge to fabricate versatile advanced carbon-based composites with controlled morphology, adjustable dimension and tunable composition by one-step synthesis process in large scale.The traditional preparation methods (e.g., direct annealing method, chemical vapor deposition (CVD) method, a sputtering method, hydrothermal/ solvothermal methods) for carbon and their composites are always multi-steps, which make it very difficult to precisely control morphology, dimension, and composition at the same time. [28][29][30] Meanwhile, limited by the equipment, the above methods are still suffering from high product cost and low yield, which further hinder their largescale commercial applications.…”

“…[5][6][7][8] Currently, the scientific community is still eager for advanced carbon-based materials to achieve higher efficiency and better utilization of green energy. [9][10][11][12][13] To date, various carbonaceous materials (e.g., graphene, [14][15][16][17][18] carbon nanotubes, [19,20] C 60 , [21] carbon quantum dots [22] and carbon micro/nanofibers [23] ) and their composites have been explored and prepared by different methods including chemical vapor deposition, [23,24] chemical or electrochemical exfoliation, [25] and electrospinning, [26,27] but it is still a great challenge to fabricate versatile advanced carbon-based composites with controlled morphology, adjustable dimension and tunable composition by one-step synthesis process in large scale.…”

Revamping Lithium–Sulfur Batteries for High Cell‐Level Energy Density by Synergistic Utilization of Polysulfide Additives and Artificial Solid‐Electrolyte Interphase Layers

“…The energy density went up when LPS was more concentrated from 0 to 2 m, resulting in a high volumetric energy density (650 Wh L −1 ) and gravimetric energy density (371 Wh kg −1 ) without significant capacity fading up to ≈200 cycles despite the high sulfur loading, which are superior to the most of the Li-S cells reported in the literature. [41] The high specific capacity (≈1300 mAh g −1 ) based on the sandwiched sulfur mass with a large areal capacity (6.5 mAh cm −2 ) implies enhanced sulfur utilization with the LPS additives in our cell design. Further increases of the LPS concentration, however, dropped the energy density and specific capacity, which would be caused by the harsh environment from the concentrated LPS electrolyte.…”

“…Another cell with a bare Li anode and 0 m LPS was included as a baseline (Figure S6a, Supporting Information), and its lower specific capacity compared with that of the A-SEI Li manifests the advantage of our A-SEI Li. The energy density values of our cells were obtained and compared with those in the literature under the assumption that the electrolyte volume per sulfur mass loading (E/S ratio) is 2 µL mg −1 of sandwiched sulfur [38][39][40][41] and N/P ratio of 2 due to the lack of information such as porosity, electrode thickness, and electrolyte volume in the literature. We accounted for the mass of the LPS additive when calculating the gravimetric energy density.…”

Design Engineering, Synthesis Protocols, and Energy Applications of MOF-Derived Electrocatalysts

“…Currently, global warming and air pollution have become two critical worldwide tasks in the twenty-first-century civilization caused by fossil fuel during production and use, which can be resolved only by using alternative environmentally friendly energy sources. Over the last decades, increasing endeavors have been devoted to energy alternative sources in particular wind energy [1,2], hydroelectric power [3][4][5][6][7][8], hydrogen energy [9][10][11], solar energy [12], and nuclear energy [13], which have already been served as complementary sources of energy to the traditional fossil fuels. One of the most promising is eco-friendly hydrogen energy and its applications for hydrogen fuel production, and hydrogen fuel cells [14][15][16].…”