電芯體積變化的重要性與原因分析

The change of cell volume can be divided into solid swelling caused by side reaction and anode lithium plating and gassing swelling caused by formation, storage and abuse. Therefore, the volume test can be used to study the formation, electrolyte R&D, abuse improvement and so on.

電芯體積的變化可以分為由副反應(yīng)與陽(yáng)極嵌鋰引起的硬膨脹和化成及濫用等過(guò)程引起的產(chǎn)氣膨脹；所以，對(duì)于電芯體積的監(jiān)控可用于研究其化成工藝、電解液配方、濫用性能等開(kāi)發(fā)與優(yōu)化等。

聚焦與現(xiàn)狀痛點(diǎn)

At present, there is an urgent need for volume test systems for different scenarios. The status of measurement and evaluation methods is as follows.

目前，急需針對(duì)不同場(chǎng)景需求的體積測(cè)試系統(tǒng)，測(cè)量評(píng)估方法的現(xiàn)狀如下， ；

解決方案

電芯體積測(cè)試原理

基于阿基米德原理，通過(guò)測(cè)試被測(cè)物體在水中的浮力變化來(lái)測(cè)試其的體積或體積變化率；

Based on Archimedes' principle, the volume or volume change rate of the measured object is measured by measuring its buoyancy change in water.

原位體積測(cè)試系統(tǒng)參數(shù)

測(cè)試系統(tǒng)概覽

產(chǎn)品特色與優(yōu)勢(shì)Features and Advantages

應(yīng)用領(lǐng)域與方向

測(cè)試系統(tǒng)可靠性分析：長(zhǎng)程模式

過(guò)充改善原位產(chǎn)氣分析

電芯的過(guò)充濫用安全是電芯最重要的特性要求之一。電解液是決定電芯過(guò)充性能優(yōu)劣的關(guān)鍵因子。添加劑A的加入對(duì)電芯的過(guò)充性能有明顯改善，電芯過(guò)充SOC達(dá)到150%SOC其體積同步開(kāi)始快速增長(zhǎng)。此方法可結(jié)合單面疊片小電芯進(jìn)行過(guò)充產(chǎn)氣研究。

材料開(kāi)發(fā)評(píng)估：不同添加劑產(chǎn)氣應(yīng)用

從A,B,C,D,E,F6種添加劑配方的電芯化成-過(guò)充過(guò)程可以看出：

1. BCE三款添加劑的整體抗過(guò)充性能佳；

2. 儀器對(duì)電芯在化成過(guò)程產(chǎn)氣行為進(jìn)行精密實(shí)時(shí)的監(jiān)控，可以用于電解液配方開(kāi)發(fā)與篩選，提高研發(fā)效率。

硬膨脹體積測(cè)試：電解液配方開(kāi)發(fā)

Through the chart, we can see that the volume change rate of the type 2824C battery is large  than 8630N battery. The overall effect of the 2824C batteries electrolyte formula is worse;

隨著循環(huán)的進(jìn)行，電芯的不可逆體積都在增加，其中2824C組的增長(zhǎng)率大于8630N組；2824C樣品的體積膨脹大于8630N，分別為0.3mL和0.15mL左右；2824C電芯主要發(fā)生在恒壓階段，說(shuō)明此配方電芯的抗氧化性能更差，8630N配方抗氧化性能更好。

鈉電化成產(chǎn)氣研究：不同電解液配方

基于層狀氧化物正極的體系化成幾乎不產(chǎn)氣(0.5ml@ 0.01%膨脹率)，在充電高壓階段產(chǎn)氣速率快速增加，但總體相對(duì)很小(1.5ml@0.15%膨脹率) ；The cell based on the layered oxide cathode is almost no gas during formation (0.5ml@0.01%), the gas production rate increases rapidly in the high voltage stage, the overall gas production rate is relatively small (1.5ml@0.15% expansion rate).

四種電解液配方中C配方的效果佳；Formula C is the best one among the four electrolyte formulations;

鈉電產(chǎn)氣體積測(cè)試：不同溫度產(chǎn)氣機(jī)制分析

硬膨脹體積測(cè)試：不同倍率下體積分析

Batteries in different charge ratio in volume change almost unanimously, shows that the reliability of the batteries is relatively good.

不同倍率下電芯體積的膨脹率不同，對(duì)于不同倍率體積膨脹研究十分有必要。特別是對(duì)體積變化率小的材料體系，高精密原位體積測(cè)試方法的需求更重要，如下體積對(duì)于化成后的電芯，不同倍率充電下體積差異很小，幾乎都在同一個(gè)水平。

存儲(chǔ)低壓電芯分析

Except at 4.2V, all storages of single electrode at low OCV show the same result that increase of volume is attributed to anode for A&B cell.

通過(guò)體積測(cè)試分析可知，低壓電芯的產(chǎn)氣貢獻(xiàn)主要來(lái)自陽(yáng)極；

電芯體積膨脹預(yù)測(cè)與未來(lái)評(píng)價(jià)思考

Based on in-situ  volume testing system, through the volume of the cell cycle data, prediction and analysis volume under different conditions;

基于原位體積測(cè)試系統(tǒng)測(cè)試電芯循環(huán)過(guò)程的體積數(shù)據(jù)，用于電芯各種研發(fā)設(shè)計(jì)下評(píng)估；同時(shí)，最重要的用途是用于電芯不同工況下體積膨脹的預(yù)測(cè)與分析。