Xiaoguang Yin

An efficient solver for the pseudo-2-dimensional (P2D) model of Li-ion batteries is developed based on the open-source computational fluid dynamics platform OpenFOAM. Species and charge conservation equations are solved in a segregated manner: potential and concentration of electrolyte and solid electrode are solved sequentially. The non-linearity and interlinkage are handled by an iterative procedure. In the P2D model, solving Li-ion (de)intercalation in solid particles implicitly is time-consuming. The Picard method is employed for calculating solid concentration explicitly without the need to solve the discretized equations system. In one time step, Li-ion concentration of future time is recursively approximated until convergence. The explicit solving of solid concentration in combination with the overall iterative procedure makes solving of the P2D model efficient. Nonlinear source terms are linearized whenever possible to retain stability. Adaptive time-stepping is devised, grounded on the derivative of open circuit voltage (OCV) with regard to Li-ion concentration at the particle surface. The developed solver is validated in detail with respect to COMSOL. Performance under various operation conditions, such as discharge of rate 10 C, hybrid charge-discharge cycle, and urban dynamometer driving schedule (UDDS), demonstrates its robustness.

Lithium metal is one of the most promising anode materials for next-generation batteries. However, the growth of lithium dendrites and the high reactivity of lithium cause serious safety and cyclability problems. A comprehensive understanding of the lithium deposition behavior, especially during the initial deposition stages, is critical for its performance improvement. The influences of current density and capacity on the nucleation size, site distribution, and growth pattern were discussed via in situ electrochemical AFM (EC-AFM) and COMSOL simulation, suggesting that lithium deposition initially follows reaction- and then transport-limited mechanisms. In addition, the solid electrolyte interface (SEI) during lithium deposition was systematically analyzed by conductive-AFM, AFM force probing and X-ray photoelectron spectroscopy (XPS) depth profiling to give a comprehensive picture of the electronic, mechanical and chemical properties of SEI film under realistic conditions.

High areal capacity and stable Coulombic efficiency (CE) in lithium metal anodes (LMAs) play pivotal roles in developing high-energy-density rechargeable batteries. However, few reported LMAs delivering high and stable CE (> 50 cycles) under ultrahigh areal capacity (>10 mA h cm−2). We demonstrated that the simultaneous homogenization of electric field and Li ion flux by using self-supported and surface-oxidized 3D hollow porous copper fibers (3D-HPCFs) can greatly increase both the areal capacity and reversibility of Li deposition. Li can be easily confined inside the hollow porous fibers and within the interspaces among fibers without uncontrollable Li dendrites. The 3D-HPCF-based anode can be deeply cycled at high capacity of 15 mA h cm-2 with average CE of 98.87% for 53 cycles, enabling a practical cell to realize high capacity retentions at a surplus Li of 10%. This work provides a novel Li deposition-regulation technology in LMAs targeting for next-generation high-energy-density batteries.

Dendrite‐induced short circuit and capacity loss present major barriers to high‐energy‐density lithium (Li) metal batteries. Many approaches have been proposed to regulate or restrain the formation of Li dendrite, yet it has not been fully eliminated. Herein, a dredging tactic with hemisphere‐like concaves is designed to horizontally release the stress during Li deposition, making both upper smooth Li and nether granular Li dwell inside the compartmented tummy. With such protuberance‐free Li metal anode, an ultrahigh Coulombic efficiency over 96% of the half‐cell is maintained after 490 cycles and capacity retention of 100% for the full cell paired with a LiFePO₄ cathode after 140 cycles (with low N/P ratio of ≈5) is achieved simultaneously. This study contributes to a deeper comprehension of electrochemical metal deposition and promotes the development of safe batteries.