首次揭示固态电池界面新结晶无序相,解释锂枝晶成因。
Coupled reaction and diffusion governing interface evolution in solid-state batteries
- 用量子级精度模拟界面反应与扩散耦合过程
- 发现未被热力学预测的Li₂S₀.₇₂P₀.₁₄Cl₀.₁₄结晶无序相
- 无需实验拟合,可直接揭示锂迁移机制
理解并控制原子尺度反应对固态电池中固态电解质界面(SEI)形成至关重要。然而,由于难以实验表征埋藏界面以及模拟速度和精度限制,挑战依然存在。我们通过主动学习和深度等变神经网络势能,实现了对对称电池单元{ ext{symcell}}的大规模显式反应模拟,具备量子精度。为自动表征界面处耦合反应与互扩散,我们基于局部原子环境空间聚类构建无监督分类方法。分析揭示了此前未报道的结晶无序相Li₂S₀.₇₂P₀.₁₄Cl₀.₁₄在SEI中的形成,该相无法仅通过热力学预测,凸显了显式建模完整反应与传输动力学的重要性。模拟结果与实验观测的SEI形成一致,并阐明了锂蠕变机制,其特征为沿界面显著的锂运动,是枝晶引发的关键。本方法从第一性原理构建数字孪生,无需实验拟合参数,为深入理解复杂异质过程中固态合成与电化学的原子动态提供了能力。
原文摘要 · Abstract (English)
Understanding and controlling the atomistic-level reactions governing the formation of the solid-electrolyte interphase (SEI) is crucial for the viability of next-generation solid state batteries. However, challenges persist due to difficulties in experimentally characterizing buried interfaces and limits in simulation speed and accuracy. We conduct large-scale explicit reactive simulations with quantum accuracy for a symmetric battery cell, {\symcell}, enabled by active learning and deep equivariant neural network interatomic potentials. To automatically characterize the coupled reactions and interdiffusion at the interface, we formulate and use unsupervised classification techniques based on clustering in the space of local atomic environments. Our analysis reveals the formation of a previously unreported crystalline disordered phase, Li$_2$S$_{0.72}$P$_{0.14}$Cl$_{0.14}$, in the SEI, that evaded previous predictions based purely on thermodynamics, underscoring the importance of explicit modeling of full reaction and transport kinetics. Our simulations agree with and explain experimental observations of the SEI formations and elucidate the Li creep mechanisms, critical to dendrite initiation, characterized by significant Li motion along the interface. Our approach is to crease a digital twin from first principles, without adjustable parameters fitted to experiment. As such, it offers capabilities to gain insights into atomistic dynamics governing complex heterogeneous processes in solid-state synthesis and electrochemistry.
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