Yoon Sun Geun, Vishnugopi Bairav S, Alsaç Elif Pınar, Jeong Won Joon, Sandoval Stephanie Elizabeth, Nelson Douglas Lars, Ayyaswamy Abhinand, Mukherjee Partha P, McDowell Matthew T
George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, United States.
School of Mechanical Engineering, Purdue University, West Lafayette, Indiana 47907, United States.
ACS Nano. 2024 Jul 29;18(31):20792-805. doi: 10.1021/acsnano.4c07687.
Solid-state batteries with Li metal anodes can offer increased energy density compared to Li-ion batteries. However, the performance of pure Li anodes has been limited by morphological instabilities at the interface between Li and the solid-state electrolyte (SSE). Composites of Li metal with other materials such as carbon and Li alloys have exhibited improved cycling stability, but the mechanisms associated with this enhanced performance are not clear, especially at the low stack pressures needed for practical viability. Here, we investigate the structural evolution and correlated electrochemical behavior of Li metal composites containing reduced graphene oxide (rGO) and Li-Ag alloy particles. The nanoscale carbon scaffold maintains homogeneous contact with the SSE during stripping and facilitates Li transport to the interface; these effects largely prevent interfacial disconnection even at low stack pressure. The Li-Ag is needed to ensure cyclic refilling of the rGO scaffold with Li during plating, and the solid-solution character of Li-Ag improves cycling stability compared to other materials that form intermetallic compounds. Full cells with sulfur cathodes were tested at relatively low stack pressure, achieving 100 stable cycles with 79% capacity retention.
与锂离子电池相比，具有锂金属负极的固态电池能够提供更高的能量密度。然而，纯锂负极的性能受到锂与固态电解质（SSE）界面处形态不稳定性的限制。锂金属与其他材料（如碳和锂合金）的复合材料表现出了更好的循环稳定性，但与这种增强性能相关的机制尚不清楚，尤其是在实际可行性所需的低堆叠压力下。在此，我们研究了含有还原氧化石墨烯（rGO）和锂银合金颗粒的锂金属复合材料的结构演变及相关的电化学行为。纳米级碳支架在脱锂过程中与SSE保持均匀接触，并促进锂向界面的传输；即使在低堆叠压力下，这些效应也能在很大程度上防止界面断开。在锂电镀过程中，需要锂银合金来确保rGO支架被锂循环填充，并且与形成金属间化合物的其他材料相比，锂银的固溶特性提高了循环稳定性。在相对较低的堆叠压力下对含硫阴极的全电池进行了测试，实现了100次稳定循环，容量保持率为79%。
