Lithium batteries serve as the energy storage medium in commercial and industrial energy storage systems, and the effectiveness, costs, and sustainability of energy solutions depend upon the operational efficiency of the batteries. For businesses focused on stable energy supply, the technical challenge of extending the cycle life of lithium batteries is imperative to the environmentally sound use of energy.

As the first company in the industry and the commercial energy storage field to assist and witness the evolution of lithium battery energy storage from the first generation to the fourth generation, our 16 years of deep cultivation in the industry and the commercial energy storage, Origotek Co. Ltd has customized energy solutions. In doing so, we have helped balance energy demands and battery life in peak shaving, backup power supply, and virtual power plants and had insights optimizations on energy battery performance. In this article, industrial practices and technological innovations will be merged to diagram the core cycle life reduction lithium batteries and cycle life industrial practices.

1. Core Factors Affecting Lithium Battery Cycle Life  

The cycle life of a lithium battery is defined as the number of charge-discharge cycles the battery is capable of undergoing before the battery reaches a capacity of 80% of the original capacity. There is an industry standard of 80% to define cycle life capabilities. There are a number of interrelated aspects to this metric, and being able to articulate the various aspects of this metric is foundational for extending the life of a battery.  

1.1 Electrode Material Degradation  

The positive and negative electrodes of lithium batteries are the core sites for lithium ion intercalation and deintercalation. Over numerous cycles, the electrode material (lithium cobalt oxide, lithium iron phosphate, etc.) crystal structures collapse, and the number of lithium ions available is decreased. For instance, in the long-term high-current charging scenario of commercially available energy storage products, the formation of "dead lithium" on the negative electrode is accelerated. "Dead lithium" is lithium ions that cannot re-intercalate into the positive electrode, and as a result, the battery capacity and cycle life are severely diminished.

1.2 Charge-Discharge Management Errors

One of the most common reasons for battery life shortening is the improper setting of charge-discharge parameters. Overcharging (loss of voltage control) can cause the decomposition of the electrolyte as well as the oxidation of electrode materials, and over-discharging (loss control under the cut-off voltage) causes the negative electrode to suffer irreversible damage. In real-world situations, some businesses neglect the correspondence between the battery specifications and the battery charging equipment, leading to overcharge/over-discharge situations. This is particularly damaging to the cycle life of battery systems installed for industrial and commercial purposes.

1.3 Fluctuations in Environmental Temperatures

Temperature control is an important feature of lithium battery systems. When the temperature exceeds 45°C, battery electrolytes become highly fluid and side reactions occur that include unwanted electrolyte decomposition and corrosion of the electrode. On the other extreme, under-0°C conditions, lithium-ion movement is frozen and intercalation is incomplete, leading to increased internal resistance. In the extreme cases of battery systems where temperature is not controlled, battery cycle life can be reduced between 30%-50% which remains a significant problem for energy storage and industrial and commercial applications considering the different the diverse geographies.

2. Technical Strategies to Maximize Lithium Battery Cycle Life

The Origotek Co., Ltd. has integrated optimization efforts stemming from the above factors into the R&D and design of its fourth-generation industrial and commercial energy storage products. Such strategies are geared towards improving the battery cycle life while maintaining stability under complex application scenarios.

2.1 Optimize Electrode Material Formulation

For the fourth-generation products, we changed the electrode material ratios by including trace amounts of niobium to the positive electrode to enhance the stabilization of the crystal structure and applying a porous carbon coating to the negative electrode to minimize the formation of "dead lithium". This has resulted in a greater than 20% increase in the cycle life of our industrial and commercial energy storage batteries compared to the third generation, now exceeding 6,000 cycles under standard charge-discharge conditions.

2.2 Implement Intelligent Charge-Discharge Management

For industrial and commercial applications, we have customized a Charge and Discharge Management System (C&DMS) that independently determines and adapts parameters of current and voltage for any charge state (SOC) and temperature scenario.  
• During charging, when SOC is 80% and greater, it switches to constant current to prevent over charging.  
• During discharging, the circuit is cut off when SOC is 20% and lower to prevent over-discharging.  
• It is integrated to communicate in real time with the energy management system and with SOC-optimized peak shaving to improve discharge and charge strategy for virtual power plant scheduled operations.

2.3 Adopt Active Temperature Control Technology

All our industrial and commercial energy storage systems have temperature flattening features. Therefore the energy storage systems have a dual-mode active temperature system with features for cooling and heating.  
• Under high-temperature conditions, cooling by temperature controlled liquid heat exchangers maintains the battery at a temperature of 25-35°C.  
• Under low-temperature conditions, a PTC heater with a heat exchanger warms batteries and keeps them above 5°C. Concretely, before charging, battery heating is done till the battery is above 5°C to norm, allowing lithi intercalation to take place.

This greatly enhances the life and reliability of the systems in and around temperature extremes.

3. Application of Life-Extension Strategies in Industrial and Commercial Energy Storage  

As far as sustainable energy use in industrial and commercial scenarios is concerned, long-life batteries is just a part of the equation. Integration of battery and demand-energy management is key. This has been validated by Origotek Co., Ltd. in several customer use examples.  

For instance, in the customizable energy storage system virtual power plant project in Shandong (10MWh), optimizing battery life strategies made a considerable difference. With an intelligent BMS and temperature control system, the batteries cycle life has been maintained at over 90 of the initial state after 2 years (over 1,500 cycles). The customer energy dispatch efficiency improved 15, and the total cost battery replacement cost dropped almost 40.  

In another peak shaving project in Tianjin for a manufacturing enterprise, our 4th generation industrial and commercial energy storage products modified charging and discharging rhythms based on enterprise production schedules which helped sustain the enterprise in energy transformation. The battery system has operated stably for 4 years and has supported the enterprise’s energy transformation efforts seamlessly.

Conclusion

Lithium battery cycle life is achieved when technology for the materials is integrated, smart management is put into place, and all environmental factors are taken into consideration. From a practical perspective, the reduction in the cost of energy storage and the battery life extension is a win-win for industrial and commercial enterprises in the ecosystem.  

With the energy storage for industrial and commercial use market, the aggressively learned energy storage practices and expertise of The Origotek Co., Ltd are going to remain focused on the design of custom battery performance optimization solutions in line with the iteration of the fourth generation of energy storage systems. We are going to keep helping our customers in the industrial and commercial sectors with energy storage systems on the journey of investing in energy sustainability and in the societies of developing countries.