Multi-Scale Electrolyte Transport Simulations for Lithium Ion Batteries

Abstract

Establishing a link between atomistic processes and battery cell behavior is a major challenge for lithium ion batteries. Focusing on liquid electrolytes, we describe parameter-free molecular dynamics predictions of their mass and charge transport properties. The simulations agree quantitatively with experiments across the full range of relevant ion concentrations and for different electrolyte compositions. We introduce a simple analytic form to describe the transport properties. Our results are used in an extended Newman electrochemical model, including a cell temperature prediction. This cross-scale approach provides quantitative agreement between calculated and measured discharge voltage of a battery and enables the computational optimization of the electrolyte formulation.

DandeLiion v1: An Extremely Fast Solver for the Newman Model of Lithium-Ion Battery (Dis)charge

“…The DandeLiion solver has been validated against (i) in-house code implemented in MAT-LAB [15], (ii) the Battery Library in Dymola [18], a proprietary code, (iii) COMSOL Multiphysics, a commercial package [19], (iv) PyBaMM, an open source project [20], and (v) the experiments and simulations described in the work of Ecker et al [16,17]. For the cross-verification with Dymola, the code was parametrised using the same model and battery properties as described in [21]. In [11] it has been compared to (vi) an approximate, simplified, reduced-order battery cell model, showing very good agreement between the two different approaches, even for relatively high discharge rates up to around 12C.…”

Ion Transport in Organic Electrolyte Solutions for Lithium-ion Batteries and Beyond

“…In this section, we will focus on the atomistic modeling studies of electrolytes for LIBs. Several computer simulation studies are available in the literature [77,98,99,106,107,[130][131][132][133][134][135][136][137][138][139] that focus on diffusion in such organic liquid solutions. In particular, the DFT calculations and AIMD simulations have been used for simulating the diffusion of Li + within the liquid EC solvent [140].…”

Extremely Fast Solvers for Newman-Type Models of Li-Ion Cell (dis)Charge

“…The DandeLiion solver has been validated against (i) in-house code implemented in MAT-LAB [15], (ii) experiments and simulations described in the work of Ecker et al [16,17], and alternative implementations of the DFN model in both (iii) the Battery Library in Dymola [18], a proprietary code, and (iv) PyBaMM, an open source project [19]. For the crossverification with Dymola, the code was parametrised using the same model and battery properties as described in [20]. In [11] it has been compared to (v) an approximate, simplified, reduced-order battery cell model, showing very good agreement between the two different approaches, even for relatively high discharge rates up to around 12C.…”

“…The first equation in (32) is required to set a reference value for the potential, and we select the value of zero at x = L 1 for convenience and without loss of generality. The algebraic equations for the potential in anode Φ a , which result from discretisation of equation (20) and the boundary conditions (7a) and (8), are…”

“…The algebraic equations for the potential in cathode Φ c , which result from discretisation of equation (20) and the boundary conditions (9) and (10a), are…”