A facile gaseous sulfur treatment strategy for Li-rich and Ni-rich cathode materials with high cycling and rate performance

Na2S Treatment and Coherent Interface Modification of the Li-Rich Cathode to Address Capacity and Voltage Decay

“…35 Moreover, S-doped LMR synthesized by gaseous sulfur treatment displays improved electrochemical performance. 30,38 Thus far, a couple of questions have arisen. How can we simultaneously induce surface oxygen substitution with S and epitaxial coating layer?…”

A Redox Couple Strategy Enables Long‐Cycling Li‐ and Mn‐Rich Layered Oxide Cathodes by Suppressing Oxygen Release

“…As seen from the first charge/discharge curves at 0.1C (Figure 2a), all the samples display a similar profile with a sloping line below 4.4 V and a plateau between 4.4 and 4.6 V, which can be assigned to the cationic redox and anionic redox, respectively. [13,14] In addition, the corresponding dQ/dV profiles also demonstrate that the same redox process of the bare and Na 2 S-modified electrodes and no peaks associated with Li-S batteries can be found (Figure S5, Supporting Information). In fact, the pure Li 2 S, Na 2 S, or K 2 S electrodes prepared by aqueous binder show almost no capacity in the working voltage range of LMRO (Figure S6, Supporting Information).…”

“…In the S 2p XPS spectra, the two doublet peaks present at 162.0 and 167.4 eV can be attributed to S 2− and SO 3 2− , respectively. [14,44] S 2− is the dominant species before cycling, and only a small portion of S 2− is oxidized to SO ), thereby suppressing the oxygen release and enhancing the cycling stability of the electrode. More importantly, the S 2− can be regenerated during discharging and will participate in the next charging process (Figure 3f and Figures S13 and S14, Supporting Information).…”

“…escaped oxygen can react with the electrolyte easily, inducing the electrolyte decomposition and formation of a non-conducting cathode electrolyte interface (CEI). [14] Second, the lattice oxygen release will lead to the reduction of transition metal cations and facilitate the migration of transition metal to neighboring Li slabs, resulting in phase transformation from layered to spinel-like phase, consequently leading to voltage fading and capacity decay. [15,16] Last, first-principle calculations reveal that triggering of the redox process leads to a sharp decrease of both the formation energy of oxygen vacancies and the migration barrier of O 2 2− , therefore enabling the migration of oxygen vacancies from the surface into the bulk lattice of the cathode, eventually resulting in nanovoid formation and bulk lattice degradation.…”

Highly Reversible Anion Redox of Manganese‐Based Cathode Material Realized by Electrochemical Ion Exchange for Lithium‐Ion Batteries

“…with multi-electron transfer and higher specific capacity has gradually attracted people's attention. [12][13][14][15][16][17] An increasing number of advanced characterization technologies and researches have proved the feasibility and authenticity of anion energy storage. [18][19][20] This has opened up a new field for improving the specific capacity of the cathode material, and is expected to promote the development of LIBs into a new era.…”