INVESTIGATING SULFATION IN LEAD ACID BATTERIESRSR Technologies, East Penn Manufacturing, Argonne National Laboratory

Tim Fister, Matthew Weimer, Eric Coleman, Pietro Papa-Lopes, Vojislav Stamenkovic, Nenad Markovic (ANL)

Matthew Raiford, Tim Ellis (RSR Technologies)

Subhas Chalasani, Kevin Smith (East Penn Manufacturing)

▪ Despite 100+ years of use, the energy density of lead acid batteries has considerable room for growth.

EXAMPLE: HIGH RESOLUTION TOMOGRAPHY

NEXT STEPS

EXAMPLE: REAL-TIME X-RAY DIFFRACTION

EXAMPLE: SURFACE SENSITIVE TECHNIQUES

MOTIVATION APPROACH METHODS

▪ Initial goal: focus on dissolution of PbSO4 at the negative Pb electrode. Improve reversibility by connecting growth/dissolution kinetics of PbSO4 with its morphology.

▪ Phase I: simplify reaction by starting with lead metal electrodes. Develop operandodiffraction, imaging, and spectroscopy methods.

▪ Phase II: Adapt these probes to model NAM pastes.

▪ Synchrotron-based diffraction and tomography:

- In situ (high energy, up to 100 keV)

- Real-time (Intensity = 1010 - 1013 photons/s)

- Spatial resolution (10-1000 nm)

▪ Novel lab based tools:

- In situ ICP/MS (part-per-trillion sensitivity)

- In situ AFM, QCM (atomic scale growth/dissolution)

▪ World class battery fabrication/testing labs.

▪ Models and strategies for the DCA have been inferred from electrochemical testing and post-mortem characterization. Argonne has unique capability to measure changes in species and morphology of electrode/electrolyte species in working cell.

▪ Dynamic Charge Acceptance (DCA) plays a key role in the energy density and lifetime of batteries, especially during operation at partial state of charge. The major issues affecting DCA are:

− Dissolution of PbSO4

− Intraplate conductivity− Gassing of O2 and H2

Stable PbSO4

Recharge

Dissolution

process

Crystal

Growth and

Formation

Discharge

PbSO4 Seeding Begins

Left: CAD rendering of diffraction cell. Right: Computed

tomography (CT) image of electrodeposited Pb.

Advanced Photon Source

CONCLUSIONS

2θ

▪ Single-shot powder diffraction (~0.5 s resolution)

▪ Easily measure the kinetics of sulfation/desulfation

AFM from the intial growth of PbSO4 on BaSO4.

We have solution and electrochemical AFM

cells for watching these processes in situ.

Top Top

250 μm

Side

Left: Cross section of a

NAM paste during cycling.

Note the change in porosity

at the interior of the

electrode.

Al

wire

▪ Surface diffraction and in situ atomic force microscopy provide atomic scale information on the nucleation and growth of PbSO4 single crystal surfaces.

▪ Synchrotron-based diffraction and tomography can be used to follow 3D changes in morphology with µm resolution.

▪ CT scans are fast (< 1 min) and use high energy x-rays (60-100 keV) to penetrate through lead-based electrodes.

50 μm

300 μm

Right: Electrodeposited

lead before and after

sulfation. Note the

preferential redeposition of

PbSO4 on the face

adjacent to the counter

electrode.

Schematic of single-shot powder

diffraction and photo of in situ cell

used for lead foils.

Studies so far include:

▪ Extended voltammetry on lead foils.

▪ Self-discharge reactions (chemical sulfation)

▪ Formation/cycling on model paste electrodes.

CV data

Formation

Crystal truncation rods (CTRs)

are sensitive to electrolyte

ordering near a charged

surface. Our group has looked

at hydration of 001-BaSO4

(Bracco et al. JPCC 2017) and

has begun work on PbSO4

precipitation on barite.

▪ In situ ICP-MS combined with RDE provides part-per-trillion sensitivity to Pb and other species present in the electric double-layer during cycling.

ANL studies seeding and

formation mechanism

(currently unknown)

ANL studies

dissolution

Current

data:

Ex situ

analysis of

PbSO4

▪ The growth and dissolution of PbSO4 in lead acid batteries is a multidimensional problem ranging from atomic scale changes at the charged interface to transport within a heterogeneous electrode.

▪ Argonne has developed tools capable of measuring sulfation during operation of a lead acid cell to validate and extend existing models based largely on electrochemistry alone.

▪ Further develop paste electrodes that are compatible for x-ray and ICP studies.

▪ Begin analogous studies on the positive electrode material.

▪ Incorporate modeling of crystal growth and continuum pack-level features.

Right: Pb concentration

measured in solution by

ICP/MS during cyclic

voltametry

Chemical

sulfation