Element Energy, Inc.

Maxim Integrated Products, Inc.

Georgy Zerkalov

Rainer Johannes Fasching

Arnaud Devie

Anthony John Stratakos

Seth Marshall Kahn

Corrado Cammi

Anderson Rennie John

Yoosok Saw

Jason Allen Wortham

Tina Alikahi

Hushnak Singh

Nathan Thomas Brinkerhoff

Described herein are methods and systems for detecting variation in minor total-impedance contributors in sets of electrochemical cells. For example, a method comprises maintaining a substantially constant current through the set of electrochemical cells and obtaining multiple voltage readings of the cells while the substantially constant current is maintained. The method then proceeds with determining multiple differential capacity values from the multiple voltage readings, characterizing one or more peaks in the multiple differential capacity values, and determining the variation in the minor total-impedance contributor based on one or more peaks. More specifically, partial capacitance values can be assigned to different impedance channels based on these peaks or, more specifically, based on the separation of adjacent peaks. The variation in the minor total-impedance contributor can be attributed to one or more of a tap-weld quality, electrolyte wetting, tape damage, active material activation energy variations, and diffusion variation of the ion-conducting material.

Methods and systems for detecting variations in minor total-impedance contributors in electrochemical cells

Described methods and systems are used for in-situ impedance spectroscopy analysis of battery cells in multi-cell battery packs. Specifically, the cell impedances are determined while the pack continues to operate, such as being charged or discharged. For example, the pack voltage/power output remains unchanged while this analysis is initiated, performed, and ended. Cell impedance is determined based on the cell's response to the signal applied to the cell. For example, a current through the cell is charged while monitoring cells' voltage response. Although the power output of the changes during this testing, but the operation of the pack is not impacted due to the power compensation provided by one or more other cells in the pack thereby ensuring uninterrupted operation of the pack. This in situ testing is provided by the unique architecture of the pack, comprising multiple nodes and individual node controllers.

Methods and systems for in-situ impedance spectroscopy analysis of battery cells in multi-cell battery packs

Described methods and systems provide in-situ leakage current testing of battery cells in battery packs even while these packs operate. Specifically, an external electrical current is discontinued through a tested battery cell using a node controller, to which the tested battery cell is independently connected. Changes in the open circuit voltage (OCV) are then detected by the node controller for a set period time. Any voltage change, associated with taking the tested cell offline, is compensated by one or more other cells in the battery pack. The overall pack current and voltage remains substantially unchanged (based on the application demands), while the in-situ leakage current testing is initiated, performed, and/or completed. The OCV changes are then used to determine the leakage current of the tested cell and, in some examples, to determine the state of health of this cell and/or adjust the operating parameters of this cell.

Methods and systems for on demand in-situ leakage current testing

A method for managing a plurality of stacks of electrochemical cells, where the plurality of stacks are electrically coupled in parallel in a battery. The method includes (a) operating the plurality of stacks to execute a global operating strategy, (b) controlling one or more first power converters to change operation of one or more first stacks of the plurality of stacks to execute a first local operating strategy of operating the one or more first stacks at one of a constant power and a constant current, and (c) controlling one or more second power converters to change operation of one or more second stacks of the plurality of stacks to compensate for change in operation of the one or more first stacks caused by executing the first local operating strategy, and thereby maintain the global operating strategy of the battery while executing the first local operating strategy.

Controllers for managing a plurality of stacks of electrochemical cells, and associated methods

A method for adaptive electrochemical cell management in an energy storage system including a plurality of battery management system (BMS) nodes, the method including (1) obtaining a first signal identifying one or more degradation mechanisms of a first cell assembly of a first BMS node of the plurality of BMS nodes, the first cell assembly including one or more first electrochemical cells, and (2) controlling a first BMS node controller of the first BMS node in response to the first signal, to change a state of operation of the first cell assembly to mitigate the one or more degradation mechanisms of the first cell assembly, independently of operation of a second BMS node of the plurality of BMS nodes.

Systems and methods for adaptive electrochemical cell management

Methods and systems for in-situ leakage current testing of cells in multi-cell battery packs

An integrated circuit device includes a controller, a voltage source coupled to the controller, a voltage sampler coupled to the controller, a to current detector coupled to the controller and memory coupled to the controller, where memory includes code segments executable by the controller for: (a) measuring a cell voltage to determine an initial voltage; (b) holding the cell voltage at the initial voltage using a power source; and (c) determining the leakage current of the cell by the current provided by the current power source with a low current detector. The power source can be one or both of a voltage source and a current source.

Battery cell analyzer

An integrated circuit device includes a controller, an optional current source coupled to the controller, a voltage sampler coupled to the controller, a current detector coupled to the controller, and memory coupled to the controller, where memory includes code segments executable by the controller to: (a) apply a current pulse to a cell; (b) measure a voltage of the cell during the current pulse; (c) calculate an impedance of the cell from the measured voltage; and (d) determine an operational state of the cell from the impedance.

Battery cell end of life and defect detection system

An integrated circuit device includes a controller, a voltage source coupled to the controller, a voltage sampler coupled to the controller, a low current detector coupled to the controller; and memory coupled to the controller, where memory includes code segments executable by the controller for: (a) measuring a cell voltage to determine an initial voltage; (b) holding the cell voltage at the initial voltage using a power source; and (c) determining the leakage current of the cell by the current provided by the current power source with a low current detector. The power source can be one or both of a voltage source and a current source.

A method for charging a battery includes (a) applying a charging current pulse to the battery, (b) after the step of applying the charging current pulse to the battery, measuring a first voltage across the battery, (c) estimating an equilibrium voltage of the battery, (d) determining a Nernst voltage of the battery from a difference between the first voltage and the equilibrium voltage, and (e) controlling charging of the battery at least partially based on the Nernst voltage.

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Santa Clara, CA, United States of America

Georgy Zerkalov