Nanoengineering to achieve high efficiency practical lithium–sulfur batteries

Abstract

Rapidly increasing markets for electric vehicles (EVs), energy storage for backup support systems and high-power portable electronics demand batteries with higher energy densities and longer cycle lives.

Improved Redox Reaction of Lithium Polysulfides on the Interfacial Boundary of Polar CoC2O4 as a Polysulfide Catenator for a High‐Capacity Lithium‐Sulfur Battery

“…On such surfaces, the soluble LiPS are chemically converted to polythionate, and lower molecular weight LiPS species via the disproportionation reaction, except for the production of inactive sulfate species (SO 3 2− and SO 4 2− ), occurring over 170 eV. The reaction mechanism conforms with other recently published reports, wherein an electrocatalytic redox activity was strongly emphasized for the LiPS redox reaction [48–54] …”

Room‐Temperature Sodium–Sulfur Batteries and Beyond: Realizing Practical High Energy Systems through Anode, Cathode, and Electrolyte Engineering

“…[ 233 ] Li–NMC systems typically operate up to ≈ 4.2 V versus Li/Li + , with a nominal cell voltage around 3.6 V. Li–S cells have a lower average voltage of around 2.2 V, [ 234 ] but can still reach practical energy densities of at least 350–600 Wh kg −1 due to the high specific capacity of sulfur. [ 235,236 ] Although Na–S batteries function on similar cathode chemistries, they have a significantly lower working voltage range from about 0.6 to 2.7 V, and a mid‐point voltage ≈1.7–1.8 V versus Na/Na + . This arises from the standard reduction potential of Li/Li + (−3.04 V) being more negative than Na/Na + at −2.71 V versus standard hydrogen.…”

“…[ 15 ] Unsurprisingly, areal S‐loading for Na–S batteries have been kept fairly low in the literature to date, usually less than 2 mg (S) cm −2 , and this is also not a parameter commonly considered for optimization studies. As a point of comparison with Li–S batteries, their areal capacity has to reach at least ≈4 mAh cm −2 to compete with the average Li‐ion battery, [ 236 ] or a minimum of 6 mAh cm −2 to match state‐of‐the‐art levels necessary for electric vehicle applications. [ 240 ] Even assuming 100% sulfur utilization, sulfur loads will need to reach at least 2.4–3.6 mg (S) cm −2 .…”

Interconnected NiCo2O4 nanosheet arrays grown on carbon cloth as a host, adsorber and catalyst for sulfur species enabling high-performance Li–S batteries

“…Firstly, low electronic conductivity of sulfur (5×10 −30 S cm −1 ) and Li 2 S/Li 2 S 2 inevitably causes the low utilization of the sulfur cathode 17,18 . Secondly, there is a significant volume change upon cycling caused by the density difference between sulfur (2.36 g cm −3 ) and Li 2 S (1.66 g cm −3 ) [19][20] , which might lead to structure collapse of the electrode. Thirdly, the high solubility of intermediate lithium polysulfides (LiPS) produced upon cycling causes active material loss and shuttling problem.…”