Introduction of Battery Pure Water Treatment Process

Pure water plays a critical role in the manufacturing of lithium batteries, lead-acid batteries, energy storage modules, and other electrochemical products. Water quality directly affects electrolyte purity, electrode coating quality, internal resistance, and battery stability.

To meet the growing quality requirements of modern battery production, manufacturers typically use one of three process routes:

• Ion Exchange System
• Two-Stage Reverse Osmosis (RO) System
• EDI (Electrodeionization) Ultrapure Water System

Below is a detailed introduction and comparison of these three battery pure water treatment processes.

Raw water → Raw water booster pump → Multi-media filter → Activated carbon filter → Water softener → Precision filter → Cation resin bed → Anion resin bed → Mixed bed → Microporous filter → Water point

Ion exchange utilizes cation and anion resins to remove dissolved ions such as calcium, magnesium, chloride, sulfate, etc. The final mixed bed produces high-purity water suitable for battery electrolyte production.

• Low initial equipment investment
• Stable and mature technology
• Good water quality when resin is freshly regenerated

• Requires frequent acid and alkali regeneration
• Generates hazardous regeneration wastewater
• High labor cost and maintenance effort
• Declining water quality as resin ages

Ion exchange is now less favored for new battery production plants due to environmental and sustainability challenges.

Raw water → Raw water booster pump → Multi-media filter → Activated carbon filter → Water softener → Precision filter → First-stage RO → pH adjustment → Intermediate water tank → Second-stage RO (positively charged membrane) → Pure water tank → Pure water pump → Microporous filter → Water point

Reverse osmosis uses a semipermeable membrane to remove 98–99% of dissolved salts, organics, bacteria, and particles. A two-stage RO system provides deeper desalination, producing water pure enough for most battery manufacturing steps.

• No acid/alkali regeneration required
• Reduced operating cost compared with ion exchange
• More environmentally friendly
• Stable water quality and easy automation
• Suitable for large-scale continuous production

• Higher initial cost than ion exchange
• Requires stable feedwater quality
• May still require final polishing (mixed bed or EDI) for ultra-high-purity applications

Two-stage RO has become widely adopted across lithium battery and energy storage system factories.

Raw water → Raw water booster pump → Multi-media filter → Activated carbon filter → Water softener → Precision filter → First-stage RO → Intermediate water tank → Intermediate water pump → EDI system → Microporous filter → Water point

The EDI system combines ion exchange resin, selective ion membranes, and a DC electric field to continuously remove ions without chemical regeneration.

Continuous water production with no shutdown required
No chemical regeneration—no acid, no alkali, no hazardous waste
Stable output up to 15–18 MΩ·cm, suitable for high-end battery production
Low maintenance and fully automatic operation
Environmentally friendly with lower long-term cost

• Highest initial capital investment
• Requires RO as pretreatment to ensure high inlet water quality

EDI is now the preferred method for producing ultrapure water for lithium battery electrode coating, electrolyte preparation, and precision rinsing.

CHIWATEC’s ultrapure water systems combine years of engineering experience with advanced membrane separation technology. Key advantages include:

 Innovative Hybrid Process Design

CHIWATEC frequently integrates RO + ion exchange or RO + EDI, achieving:

• Longer regeneration cycles for ion exchangers
• Reduced chemical usage
• Lower operating cost
• High reliability and long service life

 Advanced Reverse Osmosis Technology

• High salt rejection
• Long membrane lifespan
• Lower energy consumption
• Stable performance even under fluctuating water quality

 Environmentally Friendly Solutions

Compared with traditional resin-only systems, CHIWATEC designs significantly reduce:

• Chemical consumption
• Regeneration wastewater
• Labor intensity

 Flexible to User Applications

Systems can be customized for:

• Lithium battery production lines
• Lead-acid battery plants
• Energy storage systems
• Electrolyte manufacturing
• Coating, rinsing, and precision cleaning

Battery manufacturing relies heavily on pure and ultrapure water to ensure product consistency, electrolyte quality, and overall performance. While traditional ion exchange systems are cost-effective initially, their high maintenance and environmental burden limit their practicality today.

Modern battery factories increasingly choose:

• Two-stage RO systems for mid-level water purity
• EDI ultrapure water systems for high-end lithium battery production requiring stable 15–18 MΩ·cm water

With advanced RO + EDI integration and strong technical expertise, CHIWATEC provides efficient, reliable, and environmentally sustainable solutions tailored to battery industry needs.

Most lithium battery processes require water resistivity ≥ 10–15 MΩ·cm, while advanced applications may require ≥ 18 MΩ·cm.

RO + EDI is considered the best and most environmentally friendly solution for producing ultrapure water suitable for electrodes, electrolyte preparation, and rinsing.

It can be used in small or low-budget facilities, but chemical regeneration and wastewater discharge limit its long-term viability.

• No chemical regeneration
• Continuous operation
• Low operating cost
• More stable water purity

Yes. CHIWATEC designs tailored systems based on production scale, water quality requirements, and local raw water conditions.

Typically: multimedia filtration → activated carbon → softening → precision filtration. This ensures long membrane life and stable ultrapure water output.

Xi’an CHIWATEC Water Treatment Technology is a high-tech enterprise specialized in various water processing devices. Aside from these individual products, which cover a number of types and series, we can also help with related comprehensive engineering projects. Thanks to our hard work and dedication upon our founding, we are now one of the fastest-developing water treatment equipment manufacturers in Western China.

Further reading:

• What is the difference between pure water and general untreated water?
• Knowledge of pure water filter
• Comparison of pure water plant and purified water plant
• The working principle of pure water machine
• Production process requirements and system control working principle of pure water filling machine equipment