Method for determining the degradation state of a secondary battery, and system for determining the degradation state of a secondary battery
JP2026100452APending Publication Date: 2026-06-19TOYOTA BATTERY CO LTD
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- TOYOTA BATTERY CO LTD
- Filing Date
- 2024-12-09
- Publication Date
- 2026-06-19
AI Technical Summary
Technical Problem
Existing methods for determining the degradation state of secondary batteries, such as lithium-ion batteries, fail to account for changes in cell thickness due to both the formation of the SEI film and the swelling of active materials, leading to inconsistent state of health (SOH) estimates.
Method used
A method and system that measure the rate of increase in cell thickness and spring constant, using a formula (SOH=(K'-K0)/T'×c+C) to determine the degradation state, considering both SEI film formation and active material swelling.
Benefits of technology
Accurately determines the degradation state of secondary batteries by accounting for various thickness changes, enabling more precise SOH estimation and decision-making on battery reuse or disposal.
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Smart Images
Figure 2026100452000001_ABST
Abstract
To provide a method for determining the degradation state of a secondary battery that takes into account not only the cell thickness change due to SEI film formation, but also the swelling of the active material itself during charging and discharging, and the cell thickness change due to the arrangement of the active materials. [Solution] A method for determining the deterioration state of a secondary battery, comprising the steps of: preparing a secondary battery to be determined; measuring the rate of increase in the thickness of the cells of the secondary battery; measuring the spring constant of the cells of the secondary battery; and determining the deterioration state of the secondary battery based on the value of SOH in the following formula (1). In formula (1), K' represents the measured spring constant of the cell, T' represents the rate of increase in the thickness of the cell, and K0 represents the spring constant of the cell in the initial state of the secondary battery. SOH=(K'-K0) / T'×c+C Equation (1)
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