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Enhancing Cycle life of AGM battery by studying alternative Expanders and Optimizing BaSO4 content in Negative Active Material
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Resumo(s)
As baterias Absorbent Glass Mat (AGM) produzidas pela EXIDE são muitas vezes utilizadas em sistemas de alimentação ininterrupta (UPS). Uma limitação fundamental desta tecnologia é o baixo ciclo de vida atribuído à degradação que afetam os materiais ativos negativos (NAM) e positivos (PAM), incluindo passivação, shedding e a perda excessiva de água.
O objetivo principal da tese é aumentar em 50% o ciclo de vida da bateria, através da investigação dos aditivos alternativos no NAM. Foram estudadas quatro formulações: os produtos atuais (PA) com 0,5% de BaSO4 + Expander A, a primeira versão VT1 (1%BaSO4 + Expander A), a segunda versão VT2 (0,5% BaSO4 + Expander B) e a versão final VT3 (1%BaSO4 + Expander B).
Foram desenvolvidos dois protótipos: primeiro seguiu-se o processo industrial padrão, enquanto o segundo incluiu um aumento de 1,57% no eletrólito e um programa de formação ajustado (duração superior em 1,95% e corrente reduzida em 5,4%). O resultado mostrou uma melhoria da bateria após a formação, com redução da perda de água (-7,94%) e da resistência interna (-10,84%).
Foram realizados ensaios elétricos para validar as novas formulações incluindo testes de capacidade de descarga, impacto de stress a 55 °C durante 156 dias e ciclo da vida. Comparando com o produto atual (PA), o VT3 apresentou a maior capacidade de descarga (+1,25%). A 55 °C durante 156 dias, o VT3 exibiu a menor perda de água (71 g), menor aumento da resistência interna (+27%) e menor degradação da capacidade (-25%). No entanto, o VT3 apenas apresentou um aumento de 1% no ciclo de vida, enquanto as outras versões (VT1) exibiram o mesmo número de ciclos de vida que (PA).
The Absorbent Glass Mat (AGM) batteries manufactured by EXIDE are commonly used in Uninterruptible Power Supply (UPS) systems. A key limitation of this technology is its lowered cycle life due to degradation mechanism in the Negative Active Materials (NAM) and Positive Active Materials (PAM). These include passivation, shedding, and excessive water loss. The objective of this thesis is to increase 50% of cycle life of battery´s cycle life by investigating alternative additives in NAM. Four formulations were studied: the actual products (PA) with 0.5% BaSO4 + Expander A, first version VT1 (1%BaSO4 + Expander A), second version VT2 (0.5% BaSO4 + Expander B) and final version VT3 (1%BaSO4 + Expander B). Two prototypes were developed: the first based on standard industrial processes, while the electrolyte quantity was increased by +1.57% and formation program was optimized (longer duration +1.95%, reduced current − 5.4%) for the second prototype. The result showed improvement of battery after the formation, including reduced water loss (- 7.94%) and internal resistance (-10.84%). Electrical trials were performed to validate the new formulations through discharge capacity tests, impact of stress at 55°C for 156 days, and float life with daily discharge cycle life. By comparing with reference product (PA), the results showed that VT3 exhibited the highest discharge capacity (+1.25%). At 55ºC for 156 days, VT3 exhibited lowest water loss (71 g), minimal internal resistance growth (+27%) and lowest Capacity degradation (-25%). However, VT3 showed only a 1% increase in cycle life, while the other versions (VT1) exhibited the same number of cycle life as reference product (PA).
The Absorbent Glass Mat (AGM) batteries manufactured by EXIDE are commonly used in Uninterruptible Power Supply (UPS) systems. A key limitation of this technology is its lowered cycle life due to degradation mechanism in the Negative Active Materials (NAM) and Positive Active Materials (PAM). These include passivation, shedding, and excessive water loss. The objective of this thesis is to increase 50% of cycle life of battery´s cycle life by investigating alternative additives in NAM. Four formulations were studied: the actual products (PA) with 0.5% BaSO4 + Expander A, first version VT1 (1%BaSO4 + Expander A), second version VT2 (0.5% BaSO4 + Expander B) and final version VT3 (1%BaSO4 + Expander B). Two prototypes were developed: the first based on standard industrial processes, while the electrolyte quantity was increased by +1.57% and formation program was optimized (longer duration +1.95%, reduced current − 5.4%) for the second prototype. The result showed improvement of battery after the formation, including reduced water loss (- 7.94%) and internal resistance (-10.84%). Electrical trials were performed to validate the new formulations through discharge capacity tests, impact of stress at 55°C for 156 days, and float life with daily discharge cycle life. By comparing with reference product (PA), the results showed that VT3 exhibited the highest discharge capacity (+1.25%). At 55ºC for 156 days, VT3 exhibited lowest water loss (71 g), minimal internal resistance growth (+27%) and lowest Capacity degradation (-25%). However, VT3 showed only a 1% increase in cycle life, while the other versions (VT1) exhibited the same number of cycle life as reference product (PA).
Descrição
Palavras-chave
Negative Active Material (NAM) Barium Sulfate Expanders