IEST In-Situ Battery Gassing Volume Analyzer (GVM2200)

Battery Gassing Volume Analyzer(GVM) Series Detailed Operation Video

1. Lithium-ion Battery Gassing Behaviors

1.1 Formation

• The formation process of lithium-ion batteries (LIBs) is accompanied by a large amount of gas production, which is closely related to the chemical system of LIBs, including the anode and cathode materials, electrolyte components, and formation conditions.
• The formation conditions (such as current, cut-off voltage, temperature, pressure, etc.) greatly affect the time and the quality of the formation. Finding an effective method to evaluate the quality of the formation is of great significance for shortening the production cycle, improvingthe production efficiency and reducing the costs.
• At present, the formation process and conditions basically rely on the empirical judgement and lack scientific and effective means, which restricts the improvement of the formation technology as well as the in-depth research for the formation process.

1.2 Overcharge

• The risk of overcharge is a very important safety issue in actual use of LIBS.
• The overcharge of LIBs is usually accompanied by serious side reactions and produce largeamount of gas, which makes the volume or the intermal pressure of the LIBs increase rapidly increasing the risk of thermal runaway.

1.3 Storage or Long Cycling

• During the long-term storage or cycling, particularly under high-temperature condition, the sustained side reaction will generate the gas continuously, which is a very critical issue for thereliability of the LIBs.

2. Functions of In-situ Gassing Volume Analyzer

GVM series(In-Situ Gas Volume Analyzer) adopts high accuracy mechanical monitoring system, which can in-situ record cells’ volume changes in the whole charge-discharge process, and obtain cells’ accurate gassing volume and volume change rate during each stage.

• Efficiency improvement: Rapidly evaluate the gassing behavior of cells, shorten R&D period, and improve efficiency;
• Cost down: Help optimize formation process, improve production efficiency and decrease enterprise’s production cost;
• Cell Design Optimization: Quantify the gassing volume and gassing rate during the whole formation process. By combinning with the three-electrode analysis of formation curve, the systemic evaluation on the infuence of diferent design factors on the formation quality. Can be implemented which can help to optimize the performance of the LIBs byregulating and controlling the forming quality of SEl.
• Reliability & Safety Desian: The GVM series can also be used to study and analyze the qassing behaviors during the abuse tests, such as overcharge, high-temperature cycling and so on.

3. Device Constitutional Diagram and Software

• High-energy Learning Test System: long-term in-situ online monitoring, and meet the accuracy requirements;
• Dedicated Test Software: real-time collection and display of mechanical test system data, and automatically draw volume change curves;
• Auxiliary System: special structure design, convenient to intervene in supporting auxiliary system, realize test temperature adjustment control.

4. Applications: Formation-gassing Analyze

4.1 Different materials’ formation-gassing application

• The modified material A has a smaller particle size than the conventional material B, and the SEI film formation reaction is more sufficient during formation, and the gas production is larger;
• Quickly and intuitively evaluate the effect of the surface modification of the materials bycomparing the quantity and rate of the gas production of LIBs made by these materials underthe same cell design, which can help the R&D of new materials.

4.2 Different Electrolyte’s Formation-gassing Application(Test Condition: 25℃ 0.02℃)

• For the same electrolyte, the amount of the gas generated during the formation of the LiB made by the elecrolyte B with a certain additive are larger than the LIB made by the electrolyte A without this additive. Thus this additive can make the SEI forming reaction more complete.
• Quickly evaluate the influence of an additive on the formation proces of LIBs by comparing the quantity and rate ofthe gas production of LiBs made by electrolytes without this kind of additive. Combined with the thre-electrode method, it can help to improve the electrolyte formulation imn a targeted manner.

4.3 Different temperature and rate of formation conditions

• By setting different formation conditions, it can quantitatively obtain the starting voltage of the gas production under different formation conditions, as well as the gassing quantity and the gassing rate of different stage of the formation process, which can help to guide the improvement ofthe formationprocess and the technology ofLIBs and raise the production efficiency of the enterprise.

5. Applications: Overcharge-gassing analyze

5.1 Gassing Analysis for Different NCM Materials During Overcharging (Test Condition: 25’℃ 0.5C)

• With the increase of the Ni content in NCM materials, it can be found that the starting SOC point of the gas productiondecreases from 138% to 115%.
• By monitoring the normal charging process of the cells and the volume and temperature changes during the overcharge process, and comparing these data to the three-electrode curves, we can accurately gain the starting voltage and the reaction rate of violent side reactions, which can help us analyze the overcharge performance of the materials quantitatively, and improve the R&D efficiency in a targeted manner.

 5.2 Comparing the NCM811 Materials with Different Modified Methods(Test Condition: 45’c 0.5c 3~4.2V~5V/ Test Condition: 25’℃ 0.5C)

• In the normal voltage range, the volume change of the cell is less than 1.2%, which is basically due to the structural swelling caused by lithium intercalation. When the SOC of high Ni-2 is greater than 40%, the structural swelling of high Ni-1 is slightly greater than that of high Ni-2;
• After overcharging to 5v, the starting SOC of gas production of high Ni-2 is larger than that of high Ni-1, indicating that high Ni-2 can adapt to higher voltage range and release more capacity under the prerequisite of keeping the structure stability, which is profit for increasing the energy density of LIBs.
• The SOC and voltage corresponding to the starting point of the gas production can be obtained by in-situ continuouslymonitoring the gas production behavior under the overcharging, which is conductive to develop the next R&D work in a targeted manner.

5.3 Different Types and Contents of Electrolyte Additives

• Comparing the gassing behavior of the LIBs under overcharging with different types and contents of the electrolyte additives, it can be found that the reaction potential of additive-A is lower than that of additive-B, which can be a better additive to protect the LIBs under the overcharge condition.

6. Applications: Cycling

Different NCM Materials’ Overcharge-gassing Application(Test Condition: 60℃ 0.5℃ 3-4.2V)

• Cell-A and CellB are made by diferent NCM matemals. The volume change of Cell-B is larger than that of Cell-A during the long-term cycling and the irreversible volume change also increase from 0.01 mL to 0.04 mL.
• It can help to quantitatively analyze the cycling performance of diferent materials, modify the materials in a targeted manner, and improve the R&D efficiency.

7. Applications: Storage-gassing analyze

7.1 Comparing NCM811 modified conditions

• At 85°C, both the voltage drop and the gas production of NCM811 modified by Method-1 arelarger than that of NCM811 modified by Method.
• It can used to compare the advantages of different modification methods of materials by using this in-situ method to continuously monitor the gas production during storage, which can help toimprove the efficiency of R&D.

7.2 Comparing different type of electrode

• Cell-A and Cell-B are made by different electrolyte systems. From the volume change curves during the full-charge storage, it can be found that Cell-A produce more gas than Cell-B, indicating that the electrolyte of EL-A is much easier to produce the gas under high temperatre and high voltage.
• Help to quantitatively analyze the gas production performance of different electrolytes, modify the electrolytes in a targeted manner, and improve the R&D efficiency.

7.3 Comparing different storage temperature

• This cell has better storage performance at 70°C, while it produce more gas at 85°C
• By using in-situ method to continuously monitor the gas production during, the storage point and maximum point of gas production can be obtained, which is helpful for researchers to carry out the next step of R&D work in a targeted manner.

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