Analysis on The Deterioration Mechanism of Lead-Acid Batteries June 13-16, 2017 Hiroki Hirano, Takayuki Kimura, Keiji Sumiya Advanced Technology Research & Development Center
Contents 1. Required battery performance for ISSV 2. Observation of separators after hydration short 3. Compositional analysis of grid corrosion 4. Crystal structure analysis of grid corrosion
Mass production volume of environment-responsive cars (Million) The trend of environment-responsive cars market 2 Main power sources are lead-acid batteries Year Prospects for Energy and Storage Battery/Material Fujikeizai (2016) Lead-acid batteries will be used as main power sources.
State of charge State of charge ISSV / required battery performance 100% (a) Normal car 3 Full charge 100% Drive Start (b) ISS car Stop (traffic light, etc.) Run Stop Stop Run Run Insufficient charge Time ISS car: The battery is discharged while stopping and restarting the car the battery becomes the partial of state charge Required performance High charge acceptance, durability for cycle, and high hydration short resistance
Major failure mode in lead-acid battery Major failure modes in lead-acid battery 4 1 2 Component Failure Mode States of deterioration separator hydration short short-circuit after over-discharge cathode grid corrosion surface corrosion by chemical reaction softening degradation of capacity PAM becomes weakened after many cycles PbSO 4 formation on grid surface anode sulfation large crystal growth of lead surface Analyze hydration short and grid corrosion 1 Hydration short 2Grid corrosion
1Hydration short/ cross section observation The cross-sections of the separators of no-additive, sodium sulfate-additive and additive X samples were observed by using SEM. no-additive sodium sulfate-additive additive X 5 The thickness of the samples with no-additive and additive X did not decrease. The thickness of the sample with the sodium sulfate-additive considerably decreased. The cross section analysis is unable to detect the detailed structure of the precipitate.
1Hydration short/ X-ray CT 3D imaging Analysis of the 3D structure of internal deposits in separators by X-ray CT no-additive sodium sulfate-additive additive X 6 Needle-like deposits were observed in the separator of the no-additive sample. Spherical deposits were observed in the sodium sulfate-additive sample. In contrast, deposits are hardly detected in the additive X sample. X-ray CT 3D imaging can stereoscopically visualize the deposits.
Intensity (cps) Intensity (cps) 2Grid corrosion/ compositional analysis SEM Raman spectra 7 Corrosion layer Grid 5 μm Analysis of the components in the corrosion layer Near-surface Component A CCD image Raman shift (cm -1 ) Corrosion-grid-interface Corrosion layer Grid 10 μm Component A Component B Two layers were existed. Raman shift (cm -1 )
2Grid corrosion/ compositional Raman imaging Test CCD image Component A (530cm -1 ) Component B (143cm -1 ) 8 Corrosion test 1 10 μm 5 μm 5 μm Corrosion test 2 10 μm 5 μm 5 μm Corrosion test 3 10 μm 5 μm Each sample consists of two layers. 5 μm
2Grid corrosion/ crystal structure analysis (Diffraction) EBSD: Electron Backscatter Diffraction Cross sectional SEM 9 Spot2 Spot1 Spot3 1 μm Spot1 Spot2 Spot3 Fuzzy band contrast Fuzzy band contrast about 50 nm grain size, or amorphous component B Component B analyzed by Raman spectrum cubic Pb Cubic Pb (derived from the grid)
2Grid corrosion/crystal structure mapping 10 SEM Band contrast Orientation mapping Color of crystal phase 1 μm Component B Cubic Pb 0.2 μm The grain size of component B became gradually smaller toward the surface.
Conclusions 11 The new analytical methods were established for the deterioration of lead acid batteries.
11. Acknowledgement 12 Acknowledgement; The authors wish to express their gratitude for the technical contribution and useful advice given by S. Minoura, T. Okoshi, T. Shibahara, and K. Suzuki of R&D Headquarters, Hitachi Chemical Co., Ltd.
12. References 13 [1] Prospects for Energy and Storage Battery/Material Fujikeizai (2013) [2] Y. Guo, W. Yan, J. Hu, J. Electrochem. Soc., 154 (2007) A1-A6 [3] D. Pavlov, Lead-Acid Batteries, Elsevier (2011) [4] S. Minoura, K. Maeda, N. Tanaka, T. yamana, H. Takeuchi, T. Kondo, S. Kobayashi, Y. Tokunaga, K. Sasaki, Shin-kobe Technical Report, 17 (2007) 11-15