Temperature variations significantly impact the energy-power tradeoffs in batteries, influencing performance, efficiency, and longevity. The relationship between energy and power is inherently tied to electrochemical kinetics, material properties, and interfacial phenomena, all of which are temperature-dependent. Understanding these effects requires examining fundamental mechanisms such as Arrhenius kinetics, electrolyte viscosity changes, and solid-electrolyte interphase (SEI) resistance, alongside standardized testing protocols that quantify these behaviors.

At the core of temperature-dependent battery behavior is the Arrhenius equation, which describes the rate of electrochemical reactions as a function of temperature. The equation states that reaction rates increase exponentially with temperature, following the form k = A * exp(-Ea/RT), where k is the rate constant, A is the pre-exponential factor, Ea is the activation energy, R is the universal gas constant, and T is the absolute temperature. This relationship explains why power delivery—a function of reaction kinetics—diminishes at low temperatures. For example, lithium-ion batteries may experience a 50% reduction in available power at -20°C compared to 25°C due to slowed charge transfer at the electrodes. Conversely, elevated temperatures accelerate reactions, improving power capability but often at the expense of long-term energy retention due to parasitic side reactions.

Electrolyte viscosity is another critical factor affected by temperature. In liquid electrolytes, viscosity increases exponentially as temperature decreases, impeding ion mobility and increasing internal resistance. At -30°C, the viscosity of a typical lithium-ion battery electrolyte can be 10 times higher than at 25°C, severely limiting power output. This effect is quantified in standardized tests such as DIN EN 62660-1, which evaluates low-temperature discharge performance. High temperatures reduce viscosity, enhancing ion transport and power delivery, but also accelerate electrolyte decomposition, leading to gas generation and capacity fade over time.

The solid-electrolyte interphase (SEI) layer, a passivating film on anode surfaces, exhibits temperature-dependent resistance. At low temperatures, SEI resistance increases due to reduced ionic conductivity, further constraining power output. Studies show that SEI resistance can double between 25°C and -10°C in graphite-based anodes. At high temperatures, SEI stability becomes a concern. Prolonged exposure above 60°C can lead to SEI breakdown and reformation, consuming active lithium and reducing energy capacity. SAE J2464 outlines abuse tests that evaluate SEI stability under thermal stress, measuring capacity loss after high-temperature storage.

Cold-temperature operation primarily limits power due to the factors above, but energy capacity can also be reduced. At -20°C, a lithium-ion battery may deliver only 70% of its room-temperature energy due to incomplete lithium intercalation and increased polarization. This is reflected in testing standards like IEC 61960, which specifies discharge capacity measurements at various temperatures. High temperatures, while improving power, degrade energy capacity over time through mechanisms such as transition metal dissolution in cathodes (e.g., Mn in NMC) and lithium plating. Accelerated aging tests per UL 1973 demonstrate that storage at 45°C can double the rate of capacity fade compared to 25°C.

The tradeoff between energy and power is further complicated by pulse versus continuous operation. At low temperatures, pulsed discharge may allow higher peak power than continuous discharge due to reduced cumulative polarization. SAE J1798 standardizes pulse power testing for electric vehicle batteries, capturing these dynamics. High-temperature operation may sustain higher continuous power but risks rapid energy degradation if thermal thresholds are exceeded.

Material selection also mediates temperature effects. For example, lithium iron phosphate (LFP) cathodes exhibit better high-temperature stability than nickel-rich NMC cathodes but suffer greater power loss at low temperatures due to lower electronic conductivity. Electrolyte additives, such as fluorinated carbonates, can widen the operational temperature range by stabilizing the SEI and reducing viscosity, as evidenced in tests following ASTM D7563.

Standardized protocols provide frameworks for evaluating these tradeoffs. DIN EN 62660-2 assesses energy and power capability across temperatures for automotive applications, while IEEE 1188 defines cycling tests for stationary storage. These standards ensure consistent measurement of key parameters like DC internal resistance (per IEC 61960), which directly reflects temperature-dependent power losses.

In summary, temperature variations create a complex interplay between energy and power in batteries. Low temperatures hinder power delivery through slowed kinetics, increased viscosity, and SEI resistance, while high temperatures enhance power but degrade energy retention through accelerated aging mechanisms. Standardized testing protocols provide essential benchmarks for quantifying these effects, enabling informed design and operational decisions. The optimal balance between energy and power depends on application-specific temperature profiles and lifetime requirements, emphasizing the need for tailored electrochemical systems and rigorous thermal characterization.