# US 10,177,398 B2 · Li-ion battery capacity and voltage prediction using quantum simulations

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- Number: US 10,177,398 B2
- Document ID: US10177398B2
- Status: Granted
- Kind: B2
- Application number: 12/953,068
- Filed: 2010-11-23
- Published: 2012-05-24
- Granted: 2019-01-08
- Earliest claimed: 2010-11-23
- Assignees: Eocell Ltd
- Applicants: Jun Li; Deepak Srivastava; Sang Yang
- Inventors: Jun Li; Deepak Srivastava; Sang Yang
- Web page: https://patentgrep.com/patent/US10177398B2

## CPC

- H01M 10/00: Secondary cells; Manufacture thereof
- H01M 10/052: Li-accumulators
- G06F 30/20: Design optimisation, verification or simulation (optimisation, verification or simulation of circuit designs G06F30/30)
- G06F 2111/10: Numerical modelling
- G16C 10/00: Computational theoretical chemistry, i.e. ICT specially adapted for theoretical aspects of quantum chemistry, molecular mechanics, molecular dynamics or the like
- G16C 20/30: Prediction of properties of chemical compounds, compositions or mixtures
- Y02E 60/10: Energy storage using batteries
- H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)
- G16C: COMPUTATIONAL CHEMISTRY; CHEMOINFORMATICS; COMPUTATIONAL MATERIALS SCIENCE
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

Provided are methods and computer programs for predicting lithium battery properties. One method includes operations for selecting candidate structures for the battery, and for obtaining a plurality of delithiated structures of the candidate structures with different lithium concentrations. The quantum mechanical (QM) energies of the delithiated structures are calculated, and a functional form is developed to obtain the voltage of the lithium battery. The functional form is a function of the lithium concentration and is based on the QM energies of the delithiated structures. Further, the capacity of the lithium battery is calculated based on a selected lithium concentration, where the functional form returns a cut-off voltage of the lithium battery when the lithium concentration is equal to the selected lithium concentration.

## Claims

### Claim 1

A method for fabricating a lithium battery which includes predicting lithium battery properties, the method comprising:
selecting candidate structures for a lithium battery;
obtaining a plurality of delithiated structures of the candidate structures with different lithium concentrations;
calculating quantum mechanical (QM) energies of the delithiated structures;
developing a functional form, wherein the function form is employed to obtain a voltage of the lithium battery, the functional form being a function of a lithium concentration and being based on the QM energies of the delithiated structures;
calculating a capacity of the lithium battery based on a selected lithium concentration using the functional form, wherein the capacity depends on a voltage of the functional form for the selected lithium concentration which is equal to a selected cut-off voltage;
selecting a desired candidate structure from the candidate structures which satisfies basic design requirements for building the lithium battery; and
fabricating the lithium battery with the candidate structure for testing.

### Claim 2 (depends on 1)

The method as recited in claim 1, wherein calculating the capacity further includes:
making the capacity equal to the selected lithium concentration times a maximum theoretical capacity of the candidate structures of the selected lithium concentration.

### Claim 3 (depends on 1)

The method as recited in claim 1, further including:
calculating a nominal voltage of the lithium battery as an average between the cut-off voltage of the lithium battery and a first parameter in the functional form.

### Claim 4 (depends on 3)

The method as recited in claim 3, wherein the functional form is a curve defined by a formula of V(x)=Voc+C1(x−1)+D(x−1)2+E(x−1)3, where
x is the lithium concentration;
Voc is a fitting parameter derived from average voltages obtained from the total QM energies of the delithiated structures at different sampling points;
C1 is a parameter related to a capacity value; and
D and E are parameters accounting for higher derivatives of the capacity.

### Claim 5 (depends on 3)

The method as recited in claim 3, wherein the functional form is a line defined by a formula of V(x)=Voc+C1(x−1), where
x is the lithium concentration; and
Voc and C1 are fitting parameters derived from average voltages obtained from the total QM energies of the delithiated structures at different sampling points.

### Claim 6 (depends on 1)

The method as recited in claim 1, further including:
adjusting the functional form to compensate for underestimation of voltages of a given class of material compared to experimentally obtained values of the same class of material.

### Claim 7 (depends on 1)

The method as recited in claim 1, further including:
repeating calculations of QM energies for additional lithium concentrations; and
iterating the calculation of the capacity with the additional lithium concentrations.

### Claim 8 (depends on 1)

The method as recited in claim 1, wherein calculating QM energies further includes:
determining whether the QM energy for a particular lithium concentration is already available; and
performing a simulation of the QM energy for the particular lithium concentration when the QM energy is not available.

### Claim 9 (depends on 8)

The method as recited in claim 8, further including:
adding results of the simulation performed to a database of QM energies.

### Claim 10 (depends on 1)

The method as recited in claim 1, wherein the QM energies are stored in a database.

### Claim 11 (depends on 1)

The method as recited in claim 1, wherein calculating QM energies is performed using density functional theory (DFT) based QM methods, semi-empirical methods, or empirical methods.

### Claim 12 (depends on 1)

The method as recited in claim 1, further including:
calculating electrochemical properties using a Halpin-Tsai combination of the electrochemical properties of individual structures obtained via QM energies.

### Claim 13 (depends on 1)

The method as recited in claim 1, further including calculating electrochemical properties using a weighted Halpin-Tsai combination according to different roles of individual structures obtained via QM energies in a composition of the lithium battery.

### Claim 14

A method of fabricating a lithium battery which includes a computer program embedded in a non-transitory computer-readable storage medium, when executed by one or more processors, for predicting lithium battery properties in the fabrication of a lithium battery, the method comprising:
employing the computer program which includes,
program instructions for selecting candidate structures for the battery,
program instructions for obtaining a plurality of delithiated structures of the candidate structures with different lithium concentrations,
program instructions for calculating quantum mechanical (QM) energies of the delithiated structures,
program instructions for developing a functional form to obtain a voltage of the lithium battery, the functional form being a function of a lithium concentration and being based on the QM energies of the delithiated structures, and
program instructions for calculating a capacity of the lithium battery based on a selected lithium concentration, wherein the capacity depends on a voltage of the functional form for the selected lithium concentration which is equal to a selected cut-off voltage;
selecting a desired candidate structure from the candidate structures which satisfies basic design requirements for building the lithium battery; and
fabricating the lithium battery with the candidate structure for testing.

### Claim 15 (depends on 14)

The method as recited in claim 14, wherein calculating the capacity further includes:
program instructions for making the capacity equal to the selected lithium concentration times a theoretical maximum capacity of the candidate structures of the selected lithium concentration.

### Claim 16 (depends on 14)

The method as recited in claim 14, further including:
program instructions for calculating a nominal voltage of the lithium battery as an average between the cut-off voltage of the lithium battery and a first parameter in the functional form.

### Claim 17 (depends on 16)

The method as recited in claim 16 wherein the functional form is a line defined by a formula of V(x)=Voc+C1(x−1), where
x is the lithium concentration; and
Voc and C1 are fitting parameters derived from average voltages obtained from the tota QM energies of the delithiated structures at different sampling points.

### Claim 18 (depends on 14)

The method as recited in claim 14, further including:
program instructions for adjusting the functional form to compensate for underestimation of voltages for a given class of material compared to experimentally obtained values for the same class of material.

### Claim 19 (depends on 14)

The method as recited in claim 14, further including:
program instructions for repeating calculations of QM energies for additional lithium concentrations; and
program instructions for iterating the calculation of the capacity with the additional lithium concentrations.