Full charge capacity estimation method and control device

Patent metadata

Field	Value
Publication number	US-2024186809-A1
Application number	US-202318506671-A
Country	US
Kind code	A1
Filing date	Nov 10, 2023
Priority date	Dec 2, 2022
Publication date	Jun 6, 2024
Grant date	—

Abstract

A bipolar LFP battery includes a plurality of cells that are stacked together. A positive electrode active material layer of each of the cells includes lithium iron phosphate. A ΔQ calculation unit calculates an increase ΔQ of a charge amount, during charging of the cell of the bipolar LFP battery. The increase ΔQ is an increase in the charge amount of the cell when the voltage of the cell increases from a first voltage to a second voltage. A full charge capacity estimation unit uses a full charge capacity map to estimate the full charge capacity of the cell, using the increase ΔQ of the charge amount as a parameter.

First claim

What is claimed is:

1 . A full charge capacity estimation method for each of a plurality of cells of a bipolar battery, the plurality of cells being stacked in a stack direction, a positive electrode active material of each of the plurality of cells including lithium iron phosphate, the full charge capacity estimation method comprising:
during charging of the bipolar battery, for each cell of the plurality of cells,
calculating an increase in a charge amount of the cell when a voltage of the cell increases from a first voltage to a second voltage; and
estimating a full charge capacity of the cell, using the increase in the charge amount, wherein
the first voltage and the second voltage fall within a predetermined voltage range in which the voltage of the cell increases as a positive electrode potential of the cell increases.

2 . The full charge capacity estimation method according to claim 1 , wherein
for each cell of the plurality of cells, the predetermined voltage range is a voltage range of the cell in which the voltage of the cell is a predetermined voltage or more, and the predetermined voltage is a voltage of the cell when dQ/dV is a second local minimum of a dQ/dV-voltage curve, where
the dQ/dV is a ratio of the increase in the charge amount, to an increase in the voltage of the cell, and
the dQ/dV-voltage curve is a curve representing a relation between the dQ/dV and the voltage of the cell when an SOC of the cell changes from 0% to 100%.

3 . The full charge capacity estimation method according to claim 2 , wherein the charging is performed at a rate of 0.1 C or less.

4 . The full charge capacity estimation method according to claim 1 , wherein the charging is CC charging or CCCV charging.

5 . A control device for a bipolar battery, the bipolar battery including a plurality of cells that are stacked in a stack direction, a positive electrode active material of each cell of the plurality of cells including lithium iron phosphate, the control device comprising:
a capacity estimation unit that estimates a full charge capacity of each cell by the full charge capacity estimation method according to claim 1 ; and an equalization control unit that equalizes respective charge amounts or respective SOCs of the plurality of cells, using the full charge capacity of each cell estimated by the capacity estimation method.

Assignees

• Toyota Motor Co Ltd

Inventors

• Tateishi Mitsuru
• Hasegawa Hajime
• Takeoka Shun
• Takeshita Shinya
• Okada Takashi
• Matsuda Chihiro
• Kawai Tomoyuki
• Arakawa Toshiya

Classifications

• H02J7/825 Primary

  Detection of fully charged condition · CPC title

• H02J7/82

  Control of state of charge [SOC] · CPC title

• G01R31/385

  Arrangements for measuring battery or accumulator variables (for monitoring G01R31/382) · CPC title

• G01R31/389 Primary

  Measuring internal impedance, internal conductance or related variables · CPC title

• H01M4/5825

  Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines · CPC title