华中科技大学孙永明研究团队揭示了实际可充电锂金属袋电池的离子隔离锂损失。相关研究成果发表在2025年1月13日出版的《科学通报》。

可充电锂（Li）金属电池的退化主要归因于活性锂的损失，包括孤立的锂（也称为“死锂”）和固体电解质界面（SEI Li）。理解LI死亡的形成对于制定减轻Li损失的策略至关重要。

该文中，研究人员揭示了另一种形式的死Li的存在，称为离子隔离Li（I-iLi），它与传统上公认的电子隔离Li（E-iLi）不同。通过对高能袋式电池在特定健康状态（SOH）下，电解质依赖性容量恢复的定量分析，阐明了这一现象，SOH源于电解质去湿引起的锂离子渗流网络内的断开。

此外，研究人员提出了取决于锂沉积物的孔隙率和电解质保留率的，电解质填充率（EFR）作为评估电极润湿性的标准。为了维持高EFR环境，研究人员引入了应力调制，来压缩阳极结构并减轻电解质降解，将I-iLi含量从0.1 MPa时的21%显著降低到1 MPa时的1%。

利用这些见解，一个原型无阳极LiNi_0.95Mn_0.03Co_0.02O₂||铜袋电池（1.4 Ah），实现了551 Wh kg^-1的非凡电池级能量密度，并在0.2℃下100次循环后保持70%的容量。

附：英文原文

Title: Revealing ionically isolated Li loss in practical rechargeable Li metal pouch cells

Author: Yongming Sun a

Issue&Volume: 2025/01/13

Abstract: The degradation of rechargeable lithium (Li) metal batteries is primarily attributed to active Li loss, encompassing isolated Li, also known as “dead Li”, and solid electrolyte interphase (SEI-Li). Comprehending the formation of dead Li is pivotal for devising strategies to mitigate Li loss. Herein, we reveal the existence of an alternative form of dead Li, termed ionically isolated Li (I-iLi), which diverges from the traditionally recognized electronically isolated Li (E-iLi). This phenomenon is elucidated through a quantitative analysis of electrolyte-dependent capacity recovery at a specific state of health (SOH) in high-energy pouch cells, which originates from disconnections within the Li-ion percolation network induced by electrolyte de-wetting. Furthermore, we propose the electrolyte infilling ratio (EFR), contingent upon the porosity of Li deposits and electrolyte retention, as a criterion to evaluate electrode wettability. To uphold a high EFR environment, we introduce stress modulation to compact the anode structure and mitigate electrolyte degradation, significantly reducing the I-iLi content from 21% at 0.1 MPa to 1% at 1 MPa. Harnessing these insights, a prototype anode-free LiNi0.95Mn0.03Co0.02O2||Cu pouch cell (1.4 Ah) achieves an extraordinary cell-level energy density of 551 Wh kg-1 and maintains 70% capacity after 100 cycles at 0.2 C.

DOI: 10.1016/j.scib.2025.01.030

Source: https://www.sciencedirect.com/science/article/abs/pii/S2095927325000544