Solid-State Lithium Battery State Estimation Using Electrochemical Models
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Solution Overview
Problem
Existing battery management systems struggle to accurately estimate and manage the state of charge (SOC) and state of health (SOH) of solid-state lithium batteries, failing to fully utilize their high energy and power density due to reliance on equivalent circuit models that do not account for the unique electrochemical processes in solid-state batteries.
Innovation Solution
An electrochemical model-based method and system that constructs a transfer function between output voltage and input current, transforms internal reaction control equations, and simplifies partial differential equations to generate executable code for a battery management system, enabling accurate estimation of SOC, SOH, and battery state parameters like temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an equivalent circuit model is used to estimate and manage battery state in a traditional real vehicle battery management system, then the system is simple to implement, but it is difficult to fully exert the advantages of high energy density and high power density of solid-state batteries and accurately express the true operating state of the battery
Solution Approach 1:
The patent transforms the continuous electrochemical partial differential equations into a discrete-time state-space model by changing the mathematical representation parameters. This involves discretizing time variables and converting continuous parameters into discrete states that can be processed by digital battery management systems, thereby maintaining high estimation accuracy while enabling practical implementation.
Solution Approach 2:
The patent replaces the traditional equivalent circuit model (electrical analogy) with an electrochemical model based on fundamental electrochemical principles. This substitution uses actual electrochemical reaction mechanisms and mass transport equations to describe battery behavior, providing more accurate state estimation that reflects the true operating conditions of solid-state batteries.
2Reliability
If a new electrochemical model is constructed to accurately describe solid-state battery internal reactions, then the state estimation accuracy is improved, but the model construction and code generation complexity increases
Solution Approach 1:
The patent segments the complex electrochemical system into distinct state variables (lithium concentration in electrodes, electrolyte concentration, open-circuit voltage, overpotential) and processes them through separate computational modules. The model is divided into state definition, state update, and output calculation sections, making the implementation more manageable and easier to integrate into existing battery management systems.
Solution Approach 2:
The patent introduces a transfer function as an intermediary element that connects the electrochemical model to the battery management system. This transfer function serves as a bridge that translates complex electrochemical calculations into standardized output formats compatible with existing BMS architectures, facilitating easier integration without sacrificing model accuracy.
3Measurement precision
If partial differential equations are used to model electrochemical reactions in solid-state batteries, then the model accuracy is improved, but the computational burden and processing time increase
Solution Approach 1:
The patent performs preliminary discretization and simplification of the partial differential equations during the model development phase. By pre-defining the discrete-time state-space representation and pre-calculating the transfer function coefficients, the computationally intensive continuous mathematics is converted into straightforward discrete calculations that can be executed rapidly in real-time battery management applications.
Data Source
AI summary
Provided are an electrochemical model-based method and system for estimating a state of a solid-state lithium battery, where the method includes: a model construction step, for constructing an electrochemical model of a power solid-state lithium battery; and a code generation step, for converting the electrochemical model after simulated into executable code and importing the executable code into a battery management system to estimate the state of the power solid-state lithium battery.