배터리 테스트에서 3전극 셀 사용

배터리에는 일반적으로 양극과 음극이라는 두 개의 전극이 있습니다. 이온은 충전 및 방전 주기 동안 분리막을 통해 양쪽 전극으로 이동하고 그 과정에서 에너지를 방출합니다. 

배터리 테스트 셀은 세 번째 전극을 포함하도록 만들 수 있습니다. 이를 기준 전극(RE)이라고 합니다. RE를 사용하면 양극과 음극 사이의 테스트 결과를 분리하여 배터리 성능을 더 잘 분석할 수 있습니다.

배터리 소재를 연구할 때 기준 전극(RE)을 사용하면 연구자가 셀의 각 구성 요소가 전체 성능에 미치는 기여도를 측정하고 구분할 수 있습니다. 3전극 실험은 장기 테스트 중에 어떤 전극(양극 또는 음극)이 셀 성능을 제한하는지 파악하는 데 도움이 됩니다. 맹목적으로 하나 또는 둘 모두를 실험하는 대신 다양한 테스트 조건에서 각 전극이 셀 성능 저하에 어떻게 기여하는지를 파악하는 것이 중요합니다.

이것이 왜 중요한가요?

대부분 모두 electrochemical experiments and battery tests provide greater understanding of the cell when the anode and cathode results can be decoupled through use of a reference electrode.  This extends to what are traditionally considered “industrial” applications as well.  The dynamic charge-discharge profiles and fast charge simulations associated with commercial devices and electric vehicles can draw unique performance from a battery compared to low-rate constant current cycling.

Three-electrode testing is also beneficial for evaluating battery safety.  Minter and Juarez-Robles highlight how fast-charging, which is a highly sought characteristic for electric vehicles, creates a great need to detect and monitor lithium plating occurring on a cell anode.  [Minter RD, Juarez-Robles D, et al 2018 J Vis Exp., (135):57735.]  This can best be achieved using a three-electrode cell during testing.

One fundamental goal of battery research is to develop cells that are long-lasting.  This is especially important for electric vehicle and grid storage applications where the commercial cells and battery packs must last thousands of cycles and up to 10 years.  Three-electrode testing allows researchers to identify the limiting factor in their cell to focus attention where improvement is needed most.

다양한 테스트 상황에서 기준 전극을 사용하는 방법

• During HPPC test, which are common for 전기 자동차 애플리케이션를 사용하면 기준 전극을 사용하여 전극 분극을 확인할 수 있습니다.

• Performing EIS shows the decoupled impedance from anode and cathode individually when a three-electrode cell is utilized.

• The individual contribution of anode and cathode is revealed when demonstrating lithium loss due to SEI growth as a dominant aging mechanism.

• 차동 용량 분석은 양극과 음극의 전압 프로파일의 변화와 이들이 개별적으로 셀 성능 저하에 어떻게 기여하는지를 밝혀낼 수 있습니다.

안정적이고 신뢰할 수 있는 3전극 셀 제작의 장애물

Comparing results from a new three-electrode experiment to other published results needs to keep as many variables consistent as possible, such as electrode size, material amount, cell uniformity, etc., or else attempt to normalize results.  This is a principal reason why traditional cell types are modified to incorporate a reference electrode as “homemade” cell, so results are easier to compare with minimal normalization.  Researchers wish to demonstrate and compare their results to existing two-electrode data of the same cell type (cylindrical, pouch, coin).  However, since most battery material work is conducted using coincells, this is the natural choice for three-electrode experiments to compare the new results with the vast amount of tradition two-electrode data in publication.  The new experimental data will decouple the anode and cathode and provide new insights.

Suggestion

A wide range of three-electrode cell configurations—such as Swagelok-style cells, split-cell designs, and PAT cells—are available and commonly used for electrochemical studies. However, it is important to recognize that these systems also have limitations. They can be expensive, complex to assemble, and challenging to scale for practical applications. Additionally, data obtained from such specialized cells must be carefully normalized when compared with conventional battery formats (e.g., coin, cylindrical, or pouch cells). Therefore, these considerations should be thoroughly evaluated when selecting an appropriate testing configuration for your specific research or development objectives.