In terms of technology characteristics of battery energy storage, lithium-ion batteries (phosphate iron lithium and ternary lithium batteries) have outstanding advantages due to the comprehensive impact of industry scale, system cost, energy and power characteristics, service characteristics, and recyclability. Lead-carbon batteries, all-vanadium flow batteries, and hierarchical utilization of lithium-ion batteries have competitive advantages in specific scenarios. Lead-acid batteries have short service life, lithium titanate batteries have high initial investment costs, sodium-sulfur batteries have significant safety issues and slow technological progress, and supercapacitors have high energy costs. The later technologies currently lack competitiveness in the market.
Industry scale determines the speed at which comprehensive technology parameters of battery energy storage are improved
In terms of industry scale, the ranking from large to small is: lithium-ion batteries, lead-carbon batteries, and all-vanadium flow batteries. The consumer and transportation lithium-ion battery industries can support the development of the energy storage market. In recent years, the rapid progress of phosphate iron lithium and ternary lithium batteries has benefited from this. In comparison, the previously thriving high-temperature sodium-sulfur battery has gradually faded out of the energy storage market due to its high technological threshold and insufficient participation of energy storage companies, resulting in slow technological progress.
The number of lithium-ion battery energy storage system suppliers far surpasses that of other battery energy storage technologies. Considering that each energy storage engineering project involves core equipment such as energy storage batteries, power management systems, energy storage inverters, fire equipment, and monitoring equipment, the entire supplier system is extremely large. Moreover, with the gradual release of the energy storage market, larger industrial companies will participate in it.
The energy and power characteristics of battery energy storage determine the land occupation space and its applicable scenarios
In terms of energy density, the ranking from large to small is: ternary lithium batteries (180-240Wh/kg), phosphate iron lithium batteries (120-150Wh/kg), lead-carbon batteries (25-50Wh/kg), all-vanadium flow batteries (7-15Wh/kg). For energy storage on the grid side (generally occupying the space of substations) and user-side energy storage that require high land occupation space, in addition to selecting suitable energy storage technology for the application scenario, energy density is also crucial for benchmarking land occupation space. Based on industry consensus, a 40-foot container is used as the standard, and the energy of the ternary lithium battery system can reach up to 4MWh, while that of the phosphate iron lithium battery is 2-3MWh, and that of the lead-carbon battery is 1.0-1.5MWh. Some companies can achieve up to about 2MWh.
Regarding power characteristics, the startup and response speed of electrochemical energy storage are both in the ms to s level, but due to different power densities, lead-carbon batteries are generally suitable for application scenarios with a discharge duration of 3 hours or more (3h rate or above), mainly used for industrial and commercial peak shaving, backup power and other fields. All-vanadium flow batteries are generally suitable for application scenarios with a discharge duration of 2.5 hours or more, mainly used for centralized renewable energy grid connection and large-scale peak-shaving. Lithium-ion batteries have a wide range of applications, covering power supply-side, grid-side, and user-side, and their advantages are particularly significant in power supply-side frequency regulation, grid-side energy storage, and other fields.
Service characteristics determine the safety of battery energy storage systems and the ease of operation and maintenance
In terms of safety during service, lithium-ion batteries use organic flammable electrolytes, and their consistency of battery monomers is poor. Safety problems caused by thermal runaway need to be taken seriously, and their operational difficulty is relatively high. Lead-carbon batteries and all-vanadium flow batteries belong to the category of aqueous batteries and have relatively good safety.
The recyclability of battery energy storage systems determines their environmental impact and needs to be included in cost evaluations
The recycling system for lead-acid batteries is the most complete, with a high lead recovery value, generally accounting for 20% of the battery investment cost. Due to their complex structure, the recyclability of lithium-ion batteries is poor. Currently, the widely used phosphate iron lithium batteries almost do not contain expensive metals, and their recovery value is essentially negative. There is no recycling demand for other types of battery energy storage technology due to their small application scale.