System for electro-magnetic induction spectroscopy (EMIS) of battery cells while forming and cycling

A system for testing a battery cell includes a test fixture configured to enclose the battery cell, a battery cycler configured to alternately charge and discharge the battery cell, an antenna mounted on a surface of the test fixture, the antenna configured to detect an electromagnetic signature of the battery cell and generate a signal indicative of the electromagnetic signature, and a detection module configured to receive the signal and detect characteristics of the battery cell based on the signal.

INTRODUCTION

The present disclosure relates to systems and methods for measuring an electro-magnetic signature of a battery cell.

A battery (e.g., a battery for hybrid and/or electric vehicles) includes a separator arranged between electrodes (e.g., an anode and a cathode) of the battery. The separator is a permeable membrane that electrically isolates the electrodes from one another to prevent short circuiting while also allowing ionic flow between the electrodes.

SUMMARY

A system for testing a battery cell includes a test fixture configured to enclose the battery cell, a battery cycler configured to alternately charge and discharge the battery cell, an antenna mounted on a surface of the test fixture, the antenna configured to detect an electromagnetic signature of the battery cell and generate a signal indicative of the electromagnetic signature, and a detection module configured to receive the signal and detect characteristics of the battery cell based on the signal.

In other features, the test fixture includes a bottom plate and a top plate mounted on and spaced apart from the bottom plate, and the battery cell is arranged between the bottom plate and the top plate.

In other features, the antenna is arranged on an antenna plate and the antenna plate is arranged on an upper surface of the bottom plate.

In other features, the battery cell is arranged on the antenna plate such that the antenna is arranged between the battery cell and the antenna plate.

In other features, the detection module is arranged within the test fixture adjacent to the antenna plate.

In other features, the detection module is arranged on the antenna plate.

In other features, the detection module is external to the test fixture.

In other features, a second test fixture is vertically stacked above the test fixture and the second test fixture includes a second antenna mounted on a surface of the second test fixture.

In other features, a plurality of second test fixtures are in a vertically-stacked arrangement with the test fixture and each of the plurality of second test fixtures includes a respective one of a plurality of antennas.

In other features, the test fixture is arranged within the temperature-controlled chamber.

In other features, the detection module is configured to perform electromagnetic induction spectroscopy on the signal.

In other features, the characteristics include a presence or absence of dendrites in the battery cell.

In other features, the battery cell is a lithium ion battery cell.

In other features, the battery cell is a pouch cell.

In other features, the battery cell is a coin-cell type battery.

In other features, the battery cell is a cylindrical battery.

A system for testing a battery cell includes at least one test fixture configured to enclose the battery cell. The at least one test fixture includes a bottom plate, a top plate mounted on and spaced apart from the bottom plate, an antenna mounted on an upper surface of the bottom plate, and the battery cell. The battery cell is arranged within the test fixture on the bottom plate such that the antenna is located between the battery cell and the bottom plate. A battery cycler is configured to alternately charge and discharge the battery cell. The antenna is configured to detect an electromagnetic signature of the battery cell during the charging and discharging and generate a signal indicative of the electromagnetic signature. A detection module is configured to receive the signal and detect characteristics of the battery cell based on the signal.

In other features, the at least one test fixture includes a plurality of test fixtures in a vertically-stacked arrangement.

In other features, the characteristics include a presence or absence of dendrites within the battery cell.

In other features, the battery cell is a lithium ion battery cell.

DETAILED DESCRIPTION

Hybrid electric and electric vehicles typically include one or more rechargeable batteries each including a plurality of battery cells. Types of rechargeable batteries include, but are not limited to, lithium ion, lithium-sulfur (Li—S), lithium metal, and/or other types of rechargeable batteries.

Over a lifetime of use, batteries experience large numbers of charging and discharging cycles. In some batteries (e.g., lithium ion batteries), ions returning across a battery separator from a cathode side of a cell to an anode side of a cell may not be redistributed evenly on a surface of the anode. Buildup of ions form dendrites which, over time, may pierce the separator, contact the cathode, and cause a short circuit.

Systems and methods according to the present disclosure are configured to measure electromagnetic signatures of a battery cells during manufacture. For example, individual cells may be tested prior to assembly and installation by cycling the cells through multiple charging and discharging cycles. During cycling, each cell is mounted within a test fixture and an antenna detects the electromagnetic signature of the cell. The antenna outputs a signal that includes an indication of the electromagnetic signature. An electromagnetic induction spectroscopy (EMIS) module is configured to receive the signal and perform EMIS on the electromagnetic signature. Although described herein with respect to vehicle batteries (e.g., rechargeable batteries for electric or hybrid vehicles), the principles of the present disclosure may be applied to batteries used in non-vehicle applications.

An example battery (e.g., a battery cell)100for powering a load104is shown inFIG.1. For example, the battery100corresponds to a lithium ion, Li—S, or lithium metal battery for a vehicle. The battery100includes an anode108, a cathode112, and a separator116arranged between the anode108and the cathode112. For example, the separator116is comprised of a flexible, permeable membrane. When powering the load104(i.e., discharging), current flows from the anode108to the cathode112and through the load104in a direction indicated by arrow120. Conversely, when charging (e.g., using a motor or other charging source), current flows from a charging source through the cathode112and into the anode108in a direction opposite the arrow120.

An electrolyte material124contained within the battery100surrounds the anode108and the cathode112. The separator116electrically isolates the anode108and the cathode112from each other while allowing charged ions of the electrolyte material124to flow through the separator116as shown by arrows128. In some conditions, buildup of ions returning from the cathode112to the anode108may form dendrites132extending from a surface of the anode108toward the separator116. Systems and methods according to the present disclosure detect an electromagnetic signature of the battery100that may indicate the presence or absence of the dendrites132.

Referring now toFIG.2, an example system200for detecting an electromagnetic signature of a battery cell (e.g., a pouch cell)204under test is shown. The battery cell204is mounted within a test fixture208including an integrated antenna plate212. For example, the antenna plate212may be mounted on or within a bottom surface (as shown), a sidewall surface, an upper surface, etc. of the test fixture208. When arranged within the test fixture208, the battery cell204is in direct contact or in close proximity to the antenna plate212. In this manner, an antenna (not shown inFIG.2) mounted on or within the antenna plate212is coupled to the electromagnetic signature of the battery cell204during charging and discharging. In some examples, the test fixture208is enclosed within a temperature-controlled chamber216.

During testing (e.g., prior to assembly and installation of a battery including the battery cell204), a battery cycler220is connected to the battery cell204and performs multiple charging and discharging cycles. For example, the battery cycler220is configured to alternately charge (e.g., supply a DC current to) and discharge (e.g., draw current from) the battery cell204for a predetermined testing period. The antenna plate212outputs a signal224(e.g., via a coaxial cable) indicative of the electromagnetic signature of the battery cell204. For example, certain conditions of the battery cell204(e.g., the presence or formation of dendrites) may cause an AC response in the electromagnetic signature of the battery cell204. Conversely, the signal224may have zero or constant magnitude (e.g., may be undetectable, notwithstanding noise or other interference) when dendrites or other anomalies are not present.

A detection module (e.g., an EMIS module)228is configured to receive the signal224and perform EMIS on the electromagnetic signature. For example, the EMIS module228implements a filtering device (e.g., an AC filtering device) configured to isolate the electromagnetic signature of the battery cell204in the signal224. The EMIS module228may be located inside the test fixture208, external to the test fixture208but within the temperature-controlled chamber216, external to the test fixture208and the temperature-controlled chamber216, etc. In some examples, the EMIS module228is mounted within the test fixture208(e.g., adjacent to the antenna plate212, on a same substrate or printed circuit board (PCB) as the antenna, etc.) to reduce noise associated with transmitting signal over a length of wire.

Examples of the system200are shown in more detail inFIGS.3A and3B. InFIG.3A, the EMIS module228is external to the test fixture208and the temperature-controlled chamber216. InFIG.3B, the EMIS module228is mounted within the test fixture208. As shown inFIG.3B, the EMIS module228is directly adjacent to the antenna plate212. In other examples, the EMIS module228may be mounted on the antenna plate212, on a same plate, substrate, or PCB as the antenna, etc. In one example, the antenna plate212corresponds to or includes an integrated circuit including the antenna and the EMIS module228.

An antenna300is mounted on or within the antenna plate212. For example, the antenna300comprises copper (e.g., a copper trace formed on or in the antenna plate212). In some examples, the antenna plate212is a PCB and the antenna300is a copper trace formed on or within the PCB. One or more tuning elements304may be coupled to the antenna300to allow tuning of an impedance of the antenna300to match an output impedance (e.g., an impedance of a wire or cable carrying the signal224and the EMIS module228). For example, the tuning element304may include fixed or adjustable components such as resistors, capacitors, inductors, etc. configured as an impedance tuning network.

The antenna300is configured to have an area and outer perimeter substantially the same as (i.e., as near as possible to, such as an outer perimeter within 5 mm of) the battery cell204. In other words, the antenna300is arranged to cover an entire area of the electromagnetic signature of the battery cell204. In this manner, the antenna300is configured to detect anomalies (e.g., indications of dendrites) anywhere in the battery cell204. Further, a shape of the antenna300is configured to maximize coverage of the battery cell204. For example, as shown, the antenna300has a spiral shape. In other examples, the antenna300may have other suitable shapes that maximize a pitch and/or density of antenna traces within the outer perimeter of the battery cell204.

The antenna plate212may be comprised of a polymer support or film (e.g., a polyester film) arranged on a mounting surface312of the test fixture208. For example, the antenna plate212may be attached to the test fixture208using an adhesive layer308. In other examples, the antenna plate212and/or the antenna300may be embedded within the mounting surface312of the test fixture208, the antenna300may be attached to or mounted directly on the mounting surface312of the test fixture208, etc.

As shown, the test fixture208corresponds to a housing comprising a bottom plate316and a top plate320. The top plate320is connected to and spaced apart from the bottom plate316using posts or dowels324(e.g., one post324arranged at each corner of the test fixture208). The bottom plate316and the top plate320define an interior volume to house the battery cell204(e.g., a pouch cell including positive and negative terminals328arranged to be connected to the battery cycler220). For example, the mounting surface312corresponds to an upper surface of the bottom plate316, the antenna plate212is attached to the bottom plate316, and the battery cell204is arranged on the antenna plate212.

In another example system400shown inFIG.4, a plurality (e.g., two or more) test fixtures404configured to hold a respective battery cell408are vertically stacked (i.e., stacked in a column). Each test fixture404may be connected to a respective EMIS module412(as shown). In other examples, two or more test fixtures404(each of the test fixtures404in a given column) may be connected to and share a same one of the EMIS modules412. One or more vertical stacks of the test fixtures404may be arranged in a temperature-controlled chamber416. The system400may include one temperature-controlled chamber416or multiple temperature-controlled chambers416each including one or more vertical stacks of the test fixtures404. The EMIS modules412may be arranged within the test fixtures404, external to the temperature-controlled chambers416, etc. Each of the test fixtures404may be configured to connect to a respective battery cycler220or two or more of the test fixtures404may share a same battery cycler220.

Although described above with respect to a pouch cell or a generally rectangular battery cell204, the principles of the present disclosure may also be implemented for testing other types of batteries or battery cells. For example, inFIG.5A, a test fixture500shown in isometric and cross-sectional views is configured to retain a coin-cell type battery504. The test fixture500includes a cup508or other hollow cylinder configured to enclose the battery504. The battery504is retained between a top electrode or terminal512, a conductive spring or other biasing element516, and a bottom electrode or terminal520. For example, the top electrode512is integrated with a cap524of the test fixture500.

As shown, an antenna528(e.g., a flexible or tape antenna) is affixed to an outer surface (e.g., a sidewall) of the test fixture500. In other examples, the antenna528may be arranged on a top, bottom, or interior surface of the test fixture500. The antenna528is configured to detect an electromagnetic signature of the battery504during charging and discharging (e.g., while connected to a battery cycler via the top electrode512and the bottom electrode520).

InFIG.5B, a test fixture540shown in isometric and cross-sectional views is configured to retain a cylindrical battery or battery cell544. The test fixture540includes a cup548or other hollow cylinder configured to enclose the battery544. The battery544is retained between a top electrode or terminal552, a conductive spring or other biasing element556, and a bottom electrode or terminal560. For example, the top electrode552is integrated with a cap564of the test fixture540.

As shown, an antenna568(e.g., a flexible or tape antenna) is affixed to an outer surface (e.g., a sidewall) of the test fixture540. In other examples, the antenna568may be arranged on a top, bottom, or interior surface of the test fixture540. The antenna568is configured to detect an electromagnetic signature of the battery544during charging and discharging (e.g., while connected to a battery cycler via the top electrode552and the bottom electrode560).