Barry on Batteries: The Multi-Chemistry Manufacturing Challenge

Battery material processors may handle multiple battery designs that each present unique challenges for their operations. Manufacturers will need to be flexible for the different battery chemistries and applications to be successful.  

For example, the electrolytes and the anode or cathode materials are different in each type of battery. Handling these unique properties requires the separation of solvent systems and separate solids handling. 

Managing Multiple Battery Chemistries on the Manufacturing Floor

For example, there are small-format, medium-format and large-format batteries, and each design may require a different battery type, materials of construction and chemistry. Each chemistry involves fundamental tradeoffs, including energy density, cycle life, safety, power output and cost.  

These variations call for specific protocols at every production stage. Standard operating procedures (SOPs) must address slurry mixing parameters, mixer selection and component addition sequences. Each chemistry requires its own recipe for mixing speeds, cycle times, drying times and final assembly.

Following from the SOPs, each battery process will have different process control parameters, quality control requirements, tracking and batch to batch (battery to battery) integrity requirements and data collection for full traceability. 

Each process also requires unique safety systems to address different hazards. Health, safety and environmental engineers must be well versed in handling multiple process lines, safety data sheets, environmental emissions and internal operator exposures.  

The complexity of the battery process itself is further complicated by the varied applications for each battery type. Lithium cobalt oxide (LCO) batteries, commonly found in smartphones, tablets, and laptops, have a chemistry that offers high volumetric energy density, which is what matters when the internal volume is fixed. This is why LCO has become the default choice for phones and other compact devices. In the LCO battery, the cathode is layered lithium cobalt oxide (LiCoO₂), and the anode is graphite.

For cordless power tool batteries, LCO is less common because of lower power output and shorter life. Power tools use lithium nickel manganese cobalt oxide (LiNiMnCoO2 - NMC), which balances high energy density and specific power requirements.  

EV Battery Chemistries and Cell Formats Drive Process Complexity

Electric vehicles (EV) batteries are a bit more complicated. There are two types of batteries currently being used: lithium nickel cobalt aluminum oxide (NMC/NCA) as well as lithium iron phosphate (LiFePO4 – LFP). Once again, there are tradeoffs. LFP stores less energy than NMC batteries but are much less expensive. NCA batteries, used by Tesla for example, have a high nickel content, about 80%, so supply-chain management is critical. There are three different for the lithium-ion cell designs.  

For example, the Ultium cells from General Motors and LG are pouch-type designs. These cells are generally made by laminating flat electrodes and separators and then sealing them in a flexible, heat-sealed pouch or bag made of a flexible material, often aluminum or other polymers. In an entry-level Chevy Blazer or Equinox, two dozen cells make up one module, and 10 modules comprise one pack.  

Tesla uses cylindrical cells, which are tube-like in shape, where all the positive and negative electrodes, separator and electrolytes are wrapped together and contained within a metal casing.  These cells are not as space-efficient compared to pouch designs but are much lighter and saving weight which requires less energy to move a car.

Newer designs are prismatic, shaped as square or rectangular bricks. These have the benefits of a flat, and often stackable, design where the electrode materials are typically arranged in layers, and the cell is enclosed in a sturdy metal casing. The result is a lighter, space-efficient design. For commercial EVs, such as school buses, the requirements are different than passenger EVs in terms of weight and driving distance, as well as for charging. In this case, the preferred battery type is typically LFP. 

Emerging Battery Technologies Expand Processing Requirements

Now, to add further complications to the market, several other battery types exist. Lithium manganese oxide batteries have higher voltage compared with cobalt-based designs but with lower energy density. These also are used in power tools as well as medical devices. Lithium titanate batteries have high power density and extended cycle life over a wide temperature range. These are used in specialized commercial applications where cost-efficiency is not as critical.  

Before we move away from the EV application, there is a new technology called lithium manganese-rich (LMR) that GM is investigating. Kurt Kelty, the company’s vice president of battery, propulsion and sustainability, discussed LMR at the recent Advanced Automotive Battery Conference. An LMR battery uses more affordable manganese instead of cobalt, offering higher energy density for longer range at lower cost of manufacturing.  

There are two other applications that have been in the news frequently. The first one is small-scale aviation or drones. For these applications, it’s all about the weight of the battery and saving a few kilograms. Battery technologies, such as solid-state (SSB), sodium-ion and lithium-sulfur (Li-S) are being considered.    

In an SSB, there is no liquid electrolyte, as the solid electrolyte acts as the physical barrier between the anode and cathode. The solid electrolyte can be constructed of sulfide, ceramic or a polymer or a combination. SSBs also are now being installed in EVs, as announced by Mercedes Benz. For Li-S, the lithium metal is the anode and sulfur is the cathode, which increases the energy density at much lower weight. Sodium-ion batteries eliminate the lithium and use aluminum instead of copper for again, less weight and lower costs.  

Another important application is the energy storage system (ESS). ESS is becoming more popular as the grid faces new demands from data centers for AI applications. ESS offers temperature-resistant properties, up to 270°C, with the benefits of high-voltage, high-heat charging without degradation.

The battery market is evolving and changing at breakneck speed as policies and regulations evolve. Engineers need to be flexible in chemistries, process optimization, customer applications, manufacturing and supply-chain management to keep pace. 

There will be multiple winners in this battery race.