Method, a non-transitory storage medium and a battery grading apparatus for automatically grading a lithium-ion battery

A method for automatically grading a lithium-ion battery by a battery grading apparatus, comprising:

• Step A:
• preprocessing a cell of the lithium-ion battery with formation and grading, obtaining a measured current and/or voltage data of charging/discharging during the process of formation and grading, and preprocessing the obtained current and/or voltage data;
• Step B:
• plotting the preprocessed current and/or voltage data into a measurement curve, matching the measurement curve with a stored standard reference curve for charging and discharging, and calculating a linear distance, a square of the linear distance and a first order differential distance between the measurement curve and the standard reference curve;
• and
• Step C:
• calculating weighted distances and weighted summation distances for the calculated linear distance, the square of the linear distance and the first order differential distance respectively, comparing and matching the weighted summation distances with a preset corresponding threshold range for each of a plurality of preset grading levels, and outputting a matching outcome resulting from matching the weighted summation distances with the preset corresponding threshold range for respective preset grading level,
• wherein Step A further comprises smoothing, filtering and interpolating of the measured current and/or voltage data,
• wherein the smoothing, filtering and interpolating of the measured current and/or voltage data comprise:
• performing a fast Fourier transform (FFT) operation on the measured current and/or voltage data in a time domain to produce data in a frequency domain;
• adding a window for smoothing and filtering the produced data in the frequency domain to produce filtered data in the frequency domain;
• interpolating the filtered data in the frequency domain by padding zeros to the filtered data to produce interpolated data in the frequency domain;
• and
• converting the interpolated data in the frequency domain to data in a time domain with an inverse Fast Fourier Transform.

A non-transitory computer-readable storage medium, having computer-executable instructions embodied thereon, wherein, upon executed by one or more processors of an electronic device, the computer-executable instructions cause the one or more processors to:

• preprocess a cell of the lithium-ion battery with formation and grading, obtain a measured current and/or voltage data of charging/discharging during the process of formation and grading, and preprocessing the obtained current and/or voltage data;
• plot the preprocessed current and/or voltage data into a measurement curve, match the measurement curve with a stored standard reference curve for charging and discharging, and calculate for a linear distance, a square of the linear distance and a first order differential distance between the measurement curve and the standard reference curve;
• and
• calculate weighted distances and weighted summation distances for the calculated linear distance, the square of the linear distance and the first order differential distance respectively, compare and match the weighted summation distances with a preset corresponding threshold range for each of a plurality of preset grading levels, and output a matching outcome resulting from matching the weighted summation distances with the preset corresponding threshold range for respective preset grading level,
• wherein the calculating weighted distances and weighted summation distances for the calculated linear distance, the square of the linear distance and the first order differential distance respectively, comparing and matching the weighted summation distances with the preset corresponding threshold range for each of the plurality of preset grading levels, and outputting the matching outcome comprise:
• Step C1:
• estimating a start point of the measurement curve relevant to the standard reference curve;
• Step C2:
• dividing the measurement curve into several segments, weighting each segment with a unique weighting factor, and calculating the weighted summation of the linear distance, the weighted summation of the square of the linear distance and the weighted summation of the first order differential distance;
• Step C3:
• comparing and matching the weighted summation distances with the preset threshold range of one of the plurality of preset grading levels and outputting the matching outcome to automatic grading equipment;
• and
• Step C4:
• receiving the matching outcome from the battery grading apparatus and grading the lithium-ion battery into at least one grading level by the automatic grading equipment to accomplish lithium-ion battery grading.

A battery grading apparatus comprising a memory and a processing system including at least one processor, the processing system being configured to:

• preprocess a cell of the lithium-ion battery with formation and grading, obtain a measured current and/or voltage data of charging/discharging during the process of formation and grading, and preprocessing the obtained current and/or voltage data;
• plot the preprocessed current and/or voltage data into a measurement curve, match it with a stored standard reference curve for charging and discharging, and calculate for a linear distance, a square of the linear distance and a first order differential distance between the measurement curve and the standard reference curve;
• and
• calculate weighted distances and weighted summation distances for the calculated linear distance, the square of the linear distance and the first order differential distance respectively, compare and match the weighted summation distances with a preset corresponding threshold range for each of a plurality of preset grading levels, and output a matching outcome resulting from matching the weighted summation distances with the preset corresponding threshold range for respective preset grading level,
• wherein the calculating weighted distances and weighted summation distances for the calculated linear distance, the square of the linear distance and the first order differential distance respectively, comparing and matching the weighted summation distances with the preset corresponding threshold range for each of the plurality of preset grading levels, and outputting the matching outcome comprise:
• Step C1:
• estimating a start point of the measurement curve relevant to the standard reference curve;
• Step C2:
• dividing the measurement curve into several segments, weighting each segment with a unique weighting factor, and calculating the weighted summation of the linear distance, the weighted summation of the square of the linear distance and the weighted summation of the first order differential distance;
• Step C3:
• comparing and matching the weighted summation distances with the preset threshold range of one of the plurality of preset grading levels and outputting the matching outcome to automatic grading equipment;
• and
• Step C4:
• receiving the matching outcome from the battery grading apparatus and grading the lithium-ion battery into at least one grading level by the automatic grading equipment to accomplish lithium-ion battery grading.