Gradient three-dimensional current collector with lithiophilic nanolayer regulation for efficient lithium metal anode construction.

Metallic lithium (Li) is highly desirable for Li battery anodes due to its unique advantages. However, the growth of Li dendrites poses challenges for commercialization. To address this issue, researchers have proposed various three-dimensional (3D) current collectors. In this study, the selective modification of a 3D Cu foam scaffold with lithiophilic elements was explored to induce controlled Li deposition. The Cu foam was selectively modified with Ag and Sn to create uniform Cu foam (U-Cu) and gradient lithiophilic Cu foam (G-Cu) structures. Density Functional Theory (DFT) calculations revealed that Ag exhibited a stronger binding energy with Li compared to Sn, indicating superior Li induction capabilities. Electrochemical testing demonstrated that the half cell with the G-Cu@Ag electrode exhibited excellent cycling stability, maintaining 550 cycles with an average Coulombic efficiency (CE) of 97.35%. This performance surpassed that of both Cu foam and G-Cu@Sn. The gradient modification of the current collectors improved the utilization of the 3D scaffold and prevented Li accumulation at the top of the scaffold. Overall, the selective modification of the 3D Cu foam scaffold with lithiophilic elements, particularly Ag, offers promising prospects for mitigating Li dendrite growth and enhancing the performance of Li batteries.

Self-Formed Protection Layer on a 3D Lithium Metal Anode for Ultrastable Lithium-Sulfur Batteries.

Lithium metal anodes are a key component of high-energy-density lithium-sulfur (Li-S) batteries. However, the issues associated with lithium anodes remain unsolved owing to the immature lithium anode construction and protection technology, which leads to internal short circuits, poor capacity retention, and low coulombic efficiency for high-sulfur-loading Li-S batteries. Herein, a highly stable 3D lithium carbon fiber composite (3D LiCF) anode for high-sulfur-loading Li-S batteries was demonstrated, in which a self-formed hybrid solid-electrolyte protection layer was constructed on a lithium metal surface through codeposition of thiophenolate ions and inorganic lithium salts by using diphenyl disulfide as a co-additive in the electrolyte. The aromatic components from thiophenolate could improve the stability of the protection layer, and the 3D structure of the carbon fiber could effectively buffer the volume effect during lithium cycling. A Li-S battery based on a 3D LiCF anode exhibited excellent cycling stability with an energy efficiency of 89.2 % for 100 cycles in terms of a high energy density of 22.3 mWh cm-2 (10 mAh cm-2 area capacity of lithium cycling). This contribution demonstrates versatile and ingenious strategies for the construction of a 3D lithium anode structure and protection layer, providing an effective solution for practical stable Li-S batteries.

Reversibility of Noble Metal-Catalyzed Aprotic Li-O2 Batteries.

The aprotic Li-O2 battery has attracted a great deal of interest because, theoretically, it can store far more energy than today's batteries. Toward unlocking the energy capabilities of this neotype energy storage system, noble metal-catalyzed high surface area carbon materials have been widely used as the O2 cathodes, and some of them exhibit excellent electrochemical performances in terms of round-trip efficiency and cycle life. However, whether these outstanding electrochemical performances are backed by the reversible formation/decomposition of Li2O2, i.e., the desired Li-O2 electrochemistry, remains unclear due to a lack of quantitative assays for the Li-O2 cells. Here, noble metal (Ru and Pd)-catalyzed carbon nanotube (CNT) fabrics, prepared by magnetron sputtering, have been used as the O2 cathode in aprotic Li-O2 batteries. The catalyzed Li-O2 cells exhibited considerably high round-trip efficiency and prolonged cycle life, which could match or even surpass some of the best literature results. However, a combined analysis using differential electrochemical mass spectrometry and Fourier transform infrared spectroscopy, revealed that these catalyzed Li-O2 cells (particularly those based on Pd-CNT cathodes) did not work according to the desired Li-O2 electrochemistry. Instead the presence of noble metal catalysts impaired the cells' reversibility, as evidenced by the decreased O2 recovery efficiency (the ratio of the amount of O2 evolved during recharge/that consumed in the preceding discharge) coupled with increased CO2 evolution during charging. The results reported here provide new insights into the O2 electrochemistry in the aprotic Li-O2 batteries containing noble metal catalysts and exemplified the importance of the quantitative assays for the Li-O2 reactions in the course of pursuing truly rechargeable Li-O2 batteries.

[Comparative observation of efficacy on lumbar disc herniation treated with acupotomology and operation].

OBJECTIVE: To compare the efficacy difference between acupotomology and operation in the treatment of lumbar disc herniation (LDH). METHODS: One hundred and eighty-four cases were randomized into an acupotomology group (109 cases) and an operation group (75 cases). In acupotomology group, acupotomology was applied to relevant local soft tissues in LDH and the reactive points in the distribution of superior gluteal nerves, at the outlet of sciatic nerve and in the nerve innervate area of the lower extremities separately. In operation group, the small-windowed discectomy through small incision was adopted. The clinical efficacies were assessed between two groups. RESULTS: In acupotomology group, the clinical cured rate was 82.6% (90/109) and the effective rate was 96.3% (105/109). In operation group, they were 86.7% (65/75) and 97.3% (73/75) respectively. There were no significant differences in statistics between two groups (both P > 0.05). CONCLUSION: Acupotomology is definitely effective in the treatment of lumbar disc herniation and its efficacy is similar to that of operation.